UBC Undergraduate Research

Development of micropump using thermally activated hydrogels Vohradsky, Honza; Fu, Jun Wei; Edgcumbe, Philip 2011

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     Rm. 3112 2332 Main Mall Vancouver, BC V6T 1Z4  Dear Dr. Boris Stoeber,  We are enclosing the report “Development of micropump using thermally activated hydrogels”. The report was written by Honza Vohradsky, Jun Wei Fu and Philip Edgcumbe as a requirement for the UBC Engineering Physics APSC 479 report.  The goal of this project is to design and fabricate a thermally activated peristaltic micropump in a monolithic multi-layer polydimethylsiloxane (PDMS) device.  Designing a new type of micropump in the field of microfluidics is important because microfluidics is a fast growing field with applications in everything from micro-PCR to digital microfluidics for early cancer detection.  Project objective #1, eliminate leakage, and objective #3, production of portable microfluidic device were completed.  Project objective #2, microvalves with response time of <3 seconds incorporated into a micropump was not completed.  In early January, 2011 we discovered that replacing 15% Pluronic with 17% Pluronic and spinning on PDMS at 8000rpm allowed for good gel formation and elimination of leakage on the device.  In the next few weeks we will test the spin-on technique with 17% Pluronic and hope to complete objective #2 shortly.  Sincerely,  Honza Vohradsky, Jun Wei Fu and Philip Edgcumbe  Enclosure Executive Summary  The aim of this project is to design and fabricate a thermally activated peristaltic micropump in a monolithic multi-layer polydimethylsiloxane (PDMS) device.  The advantage of our micropump over the conventional pressure activated micropumps is that our design only requires one pressure-control valve whereas the conventional approach requires one pressure-control valve for each valve. The goal of the project is to incorporate the newly designed micropump into a fully portable microfluidic device that can be used to pump fluid and cells through the chip. The goal is to design thermally activated valves with a response time of <3 seconds and micropumps that can pump fluid at 0.1 nL/sec. Designing a new type of micropump in the field of microfluidics is important because microfluidics is a fast growing field with applications in everything from micro-PCR to digital microfluidics for early cancer detection. The equipment and resources of this project fall into three distinct sub-categories. They are: Design, fabrication and testing. For device design we used a computer with 2D AutoCAD drawing capabilities and a printer for transparencies with 10um resolution is required. For fabrication, we used a cleanroom with wet bench, spinner, hot plate, UV light, gold for evaporation, gold evaporator, PDMS mixing facilities, oxygen plasma, plasma bonding and lab space is required. For testing, we used an inverted microscope, pressure source and fluorescent particles. The project is sponsored by Dr. Boris Stoeber and he has agreed to provide the resources and equipment that we need to make this project a success. This is an exciting project which has the potential to offer a significant new tool to the field of microfluidics. Project objective #1, eliminate leakage, and objective #3, production of portable microfluidic device were completed.  Project objective #2, microvalves with response time of <3 seconds incorporated into a micropump was not completed.  Leakage was eliminated by spinning on uncured PDMS onto a glass slide, curing the PDMS and then bonding the glass slide to a PDMS multi-layer device.  A portable carriage with pressure sources, microcontroller and power supply was designed and built for carrying our microfluidic device and a program developed for the microcontroller to operate the microfluidic pump.  The development of the micropump was not completed because of inconsistent Pluronic gel behavior and it took us until January, 2011 to eliminate leakage in our device.  All team members are committed to continuing the project at a collective work rate of 10 hours per week until the micropump works on the portable device. Key recommendations are to make and test more microfluidic devices with spin-on PDMS and characterize device response time, pumping rate and pressure.  Further, we will test the adhesion promoter GE SS412 for improving the spin-on PDMS bonding to glass.  2  Contents 1 Introduction ............................................................................................................................. 7 1.1 Background and Motivation ............................................................................................ 7 1.1.1 Technical Background .............................................................................................. 7 1.1.2 State of the art technology - A comparison ............................................................ 8 1.1.3 Alternative strategies .............................................................................................. 9 1.1.4 Results from previous experimental work ............................................................ 11 1.1.5 Project Sponsor ..................................................................................................... 11 1.1.6 Power consumption calculation ............................................................................ 11 2 Discussion .............................................................................................................................. 13 2.1 Design ............................................................................................................................ 13 2.1.1 Macroscopic Portable Device ................................................................................ 13 2.1.2 Fluid Supply Systems ............................................................................................. 13 2.1.3 Heater Power and Controller ................................................................................ 14 2.1.4 Series 4 Design ....................................................................................................... 16 2.2 Testing ........................................................................................................................... 20 2.2.1 Overview ................................................................................................................ 20 2.2.2 Pluronic Rheology .................................................................................................. 20 2.2.3 Plasma Bonding ..................................................................................................... 22 2.2.4 Parylene Bonding ................................................................................................... 23 2.2.5 RTD Tests ............................................................................................................... 25 2.2.6 Electrolysis Test ..................................................................................................... 28 3 Project Deliverables ............................................................................................................... 31 3.1 Deliverables ................................................................................................................... 31 3.2 As presented in our Project Charter (Appendix B - Recipe for 10 um SPR220-7.0 Mold for 4-inch Si Wafers ................................................................................................................... 31 3.2.1 Deliverable 1: Microvalve with 3 second response time ...................................... 33 3.2.2 Deliverable 2: Portable device ............................................................................... 33 3.2.3 Deliverable 3: Peristaltic pump ............................................................................. 33 3.3 Financial Summary ........................................................................................................ 33 3.3.1 Macro Components ............................................................................................... 33 3.3.2 Micro Components ................................................................................................ 34 3  3.4 Ongoing Commitments by Team Members .................................................................. 34 4 Conclusion ............................................................................................................................. 35 4.1 Important Results .......................................................................................................... 35 4.2 Project Review ............................................................................................................... 35 4.2.1 Gel formation of Pluronic could easily be predicted, achieved and reproduced .. 35 4.2.2 There would be no electrolysis in the device. ....................................................... 36 4.2.3 We were confident that we had appropriate steps and contingency plans to quickly eliminate leakage in our device. ............................................................................... 37 4.2.4 PDMS spun onto a glass slide at high rpm (>1000rpm) would have extremely high porosity due to stretching of the polymer. ........................................................................... 38 5 Recommendations ................................................................................................................. 39 5.1 Specific Recommendations ........................................................................................... 39 5.2 General Recommendations ........................................................................................... 39 References ..................................................................................................................................... 40 6 Appendices ............................................................................................................................ 42 6.1 Appendix A - AZ 5214E Photoresist Datasheet .............................................................. 42 6.2 Appendix B - Recipe for 10 um SPR220-7.0 Mold for 4-inch Si Wafers ......................... 48 6.3 Appendix C - Project Charter (No signatures) ............................................................... 50 6.4 Appendix D  - Team Member's Time Contributions ...................................................... 53 6.5 Appendix E - Arduino Code for Controlling One Cycle of Valve Operation ................... 54             4                 6.9 Appendix I - Series 4 Lithography Masks ..................................................................... 130 6.10 Appendix J - Cleanroom Wafer Fabrication Record .................................................... 132 6.11 Appendix K - Glass Slide Record .................................................................................. 138 6.12 Appendix L - Macro Assembly ..................................................................................... 144   5  Figure 1 - Block Diagram of macroscopic portable device ............................................................ 13 Figure 2 - Macroscopic portable device ........................................................................................ 13 Figure 3 - Round-tipped pogo pin.  Source: Sparkfun <http://www.sparkfun.com/products/9173> ............................................................................... 14 Figure 4 - Circuit diagram, npn transistor amplifier circuit ........................................................... 15 Figure 5 – Heater designs; a) Series 3; b) Series 4 ......................................................................... 17 Figure 6 – Heating area details; a) Series 3; b) Series 4 ................................................................ 17 Figure 7 – Control channel heating area details; a) Series 3C; b) Series 3A; c) Series 4B.  The orange box indicates the nominal area of flow. ............................................................................ 18 Figure 8 - Time lapse of gel formation and dissolution.  Heater voltage 13V was held constant with pressure varied. a) 1psi, no flow;  b) 3psi, no flow; c) 5psi, no flow; d) 13 psi with flow. .... 19 Figure 9 - Control channel; a) Series 3B; b) Series 4B.  The orange and green boxes indicate the diffusion barrier and the valve actuation areas, respectively. ...................................................... 19 Figure 10 – Control channel heating area details; a) Series 3C; b) Series 3A; c) Series 4B.  The orange box indicates the nominal area of flow. ............................................................................ 20 Figure 11 - Viscosity vs temperature for 3 tested batches of Pluronic ......................................... 21 Figure 12 - Press used to apply 1MPa pressure during parylene thermal bonding. ..................... 24 Figure 13 – RTD resistance vs heater voltage for the bare and covered heater cases ................. 26 Figure 14 - Experimental apparatus, hotplate test ....................................................................... 27 Figure 15 - Resistance vs. temperature for the bare, covered dry channel, and covered wet channel .......................................................................................................................................... 27 Figure 16 – Schematic of the electrolysis test apparatus; a) crossed leads; b) parallel leads; c) conventional connection ............................................................................................................... 29 Figure 17 – Electrolysis seen when the device is connected as in Figure 16 (a); a) before the application of 4V; b) t=2s after power applied; c) t=7s d) t=14s.  Recorded using 10x lens. ........ 30 Figure 18 – Dirty PECVD Plasma Chamber .................................................................................... 38 Figure 19 – Team member’s time contributions vs. time ............................................................. 53   6  Table 1 - Properties of Pluronic batches tested by Rheology ....................................................... 21 Table 2 - Macro Component Breakdown ...................................................................................... 33 Table 3- Micro Component Breakdown ........................................................................................ 34   7  1 Introduction 1.1 Background and Motivation We propose to develop a thermally activated micropump and implement the technology in a portable microfluidic device. The thermally activated micropump will be a new kind of tool in the field of microfluidics. Microfluidics is a fast growing field with many interesting applications in biology and beyond. 1.1.1 Technical Background 1.1.1.1 An introduction to microfluidics The field of microfluidics involves the manipulation of small (10-9 to 10-18 liters) amounts of fluids with channels that are tens to hundreds of micrometers across. The early microfluidic devices were developed to use very small quantities of samples and reagents and to do low cost analysis of chemical solutions. Microfluidics owes its ongoing popularity not only to its size but also due to the behavior of fluidics at the microscale. Namely, microfluidics operates in a regime of low Reynolds number (i.e.: the ratio of momentum of a fluid to its viscosity is low) which allows for laminar flow. Further, factors like fluidic resistance, surface tension and energy dissipation starts to dominate the system.  1.1.1.2 Paradigm shift: Application of polydimethysiloxane (PDMS) for multilayer microfluidic chips and valves Microfluidics, and its associated ability to take advantage of the behavior of solutions at the microscale, was first explored in detail in the 1990s. Manz et al.'s paper written in 1992, is an example of one of the first articles in the field1. However, the era of rapid and affordable microfluidic device prototyping only came of its own in 2000. In 2000, Unger et al published an article titled: "Monolithic Microfabricated Valves and Pumps by Multilayer Soft Lithography"2. In this article, Unger et al showed the world how to use Polydimethysiloxane (PDMS) to make simple multilayer valves. Unger's valves are simple to make and simple to operate. The multi- layer devices consist of a fluidic channel and control channel. The control channel and the fluidic channel are on top of each other and where they cross they are separated by a thin member (approx. 10μm). The crossing point between the control and fluidic channel is where a valve is. To activate the valve, pressure is applied in the control channel the membrane deflects into the fluidic channel. The membrane is easily deflected because PDMS, the elastomer used to make  1 A. Manz, et al., "PLANAR CHIPS TECHNOLOGY FOR MINIATURIZATION AND INTEGRATION OF SEPARATION TECHNIQUES INTO MONITORING SYSTEMS - CAPILLARY ELECTROPHORESIS ON A CHIP," Journal of Chromatography, vol. 593, pp. 253-258, 1992. 2 M. A. Unger, et al., "Monolithic microfabricated valves and pumps by multilayer soft lithography," Science, vol. 288, pp. 113-116, 2000. 8  the device is a soft material with Young’s modulus of 750 kPa3.  The pressure of the various valves is controlled outside of the chip by an array of solenoid valves.  1.1.2 State of the art technology - A comparison 1.1.2.1 Current microfluidic valving strategies Since flow control is an integral part of microfluidic devices, many research groups have proposed alternative designs for valves and pumps. For example, materials with large thermal expansion coefficients have been used to open and close4 and hydrogels have been used to develop pH-sensitive microvalves5 or other thermally sensitive hydrogels have been heated up by a laser6. Each of the proposed valve and pump designs has drawbacks. The large thermal coefficient valves have poor response time, the pH sensitive hydrogels have very limited applications and the laser activation of thermally sensitive valves introduces added complexity and cost to the system.  1.1.2.2 Our proposal - a novel microfluidic valving strategy Our design uses Pluronic F127, a triblock copolymer, which when heated, has a phase transition from low viscosity to a soft, high viscosity cubic crystalline gel phase. We heat the Pluronic with an on-chip heater that is made of gold and selectively deposited by evaporation. Gel formation controls the multilayer valve by determining whether or not the external pressure reaches and deflects the valve. The advantage of our design is that it promises a fast response time and it is simple to fabricate and operate. 7 We will use the thermally activated micropump to build a low- power portable microfluidic device capable of moving cells in a loop in the microfluidic chip.  1.1.2.3 Currently available portable microfluidics technologies Microfluidics is a rapidly developing field where applications are being found for the technology at a rapid pace. Currently, there are many commercial implementations of benchtop microfluidic systems capable of carrying out complex experiments at significant time and cost savings. One area of particular promise is being able to deliver medical diagnostic tests in the field. This has two key advantages: firstly, results of the test can be reported immediately, and  3 J. C. Lotters, et al., "The mechanical properties of the rubber elastic polymer polydimethylsiloxane for sensor applications," Journal of Micromechanics and Microengineering, vol. 7, pp. 145-147, 1997. 4 K. Pitchaimani, et al., "Manufacturable plastic microfluidic valves using thermal actuation," Lab Chip, vol. 9, pp. 3082-7, 2009. 5 D. J. Beebe, et al., "Functional hydrogel structures for autonomous flow control inside microfluidic channels," Nature, vol. 404, pp. 588-+, 2000. 6 K. Tashiro, et al., Micro flow switches using thermal gelation of methyl cellulose for biomolecules handling. Berlin: Springer-Verlag Berlin, 2001. 7 B. Stoeber, et al., "Flow control in microdevices using thermally responsive triblock copolymers," Journal of Microelectromechanical Systems, vol. 14, pp. 207-213, 2005. 9  secondly, the cost of doing such a test is dramatically reduced without the need to equip and staff a wet lab. To our knowledge, only electrokinetics have been demonstrated using a portable (i.e. one that can be unplugged from the wall) device.8 The company closest to bringing a product to market may be Micronics Microfluidics in the form of immunoassay and immunohematology systems. However, there is no mention of either system or their technologies in the academic literature. 1.1.3 Alternative strategies 1.1.3.1 Choosing polydimethysiloxane (PDMS) over glass for microfluidic chip We had to choose between using PDMS or glass for our device. The five main differences between PDMS and glass are: Fabrication process, bonding, softness of material, heat transfer coefficient and heat capacity. For PDMS the fabrication process involves making a photo-resist via UV exposure that once fabricated can be used repeatedly for multiple PDMS chips. PDMS can be bonded to glass very easily via oxygen plasma treatment. PDMS is very soft, it has a Young’s modulus of 750 kPa. Finally, it has a heat transfer coefficient of 0.21 w m-1K-1 and heat capacity of 1500 w m-2 K-1 (Niu, ZQ; Chen, WY; Shao, SY, et al). For glass, the fabrication process is more involved. Fabrication includes etching glass using hydrofluoric acid (HF) and anodic bond of the silicon to glass. This process uses HF, a dangerous chemical, is more expensive, and no mold is created. Glass is very hard so any valve would have had to be built by putting a PDMS membrane between two glass layers. Glass has a heat transfer coefficient of 0.75 w m-1K-1 and heat capacity of 834.61 w m-2 K-1 (Niu, ZQ; Chen, WY; Shao, SY, et al). The lower heat capacity of the glass is attractive because our heaters will inevitably heat the surrounding channel walls. A low heat capacity assures that heating the surrounding walls does not interfere too much with the heating or cooling of the solution in the microfluidic chip. Further, unlike PDMS channels, glass channels do not expand under pressure. Expanding channels extend response time because more fluid needs to be cycled in and out of the valve for each cycle. Even though glass has a lower heat capacity and non-expanding fluidic channels, we chose to use PDMS. The advantage of cheaper, simpler and faster fabrication process for PDMS more than outweighs the advantages that glass has to offer. 1.1.3.2 Chip fabrication considerations Another key consideration was the method of fabrication for the fluidic chip. To date, the fabrication procedure we have used is multilayer soft lithography. This process begins with the design of a mask using Solidworks. This is then printed on transparency sheets using laser printers to form a mask. This mask is then used to selectively etch a silicon wafer with UV  8 D. Erickson, et al., "A miniaturized high-voltage integrated power supply for portable microfluidic applications," Lab on a Chip, vol. 4, pp. 87-90, 2004. 10  exposure. Using a typical office printer, feature sizes of 250μm are achievable; by using high resolution 20 000 dpi printers, feature sizes of up to 10μm are possible.9  The key advantage of this method is that has well characterized, repeatable results in terms of channel dimensions. Drawbacks of it are the need for ~20min of cleanroom time and the turnover time for shipment of high-resolution transparency prints from a US supplier (CAD Art Services).  Recently, novel methods of prototyping soft fluidic chips have been examined, the most notable of which being the use of Shrinky Dink prestressed thermoplastic sheets. This material is used for children's toys whereby designs can be drawn onto the sheets and then heated to induce shrinking of the material. In fabricating microfluidic devices, Shrinky Dinks can be used either to make a mould for the PDMS or be used to make the fluidic chip itself.10,11  Yet another mould making method is to transfer the layout from a laser printed piece of glossy paper to brass plate to selectively shield desired areas from an etching agent. 12  All of these methods are capable of giving feature sizes acceptable to the needs of this project with the benefit of significantly reduced cost, iteration time, and eliminating cleanroom time. However, since we have no firsthand experience with these methods and are not expecting the need for a large number of design iterations, we have opted to continue with the soft lithography process.  1.1.3.3 Connecting macro to micro The gold heater traces are embedded between the PDMS and glass, with only small pads exposed to which leads are attached to provide power. Currently, the leads are attached by soldering, which frequently causes problems with jumpers since the pad spacing is quite tight. Our solution was to re-design our heater pads to fit the standard protoboard spacing and use pogo-pins attached to a protoboard which are perfectly aligned with our heater pads.  This design modification streamlined our testing procedues.   9 A. Singhal, et al., “Microfluidic Measurement of Antibody-Antigen Binding Kintetics From Low- Abundance Samples and Single Cells. 10 C. J. Easley, et al., "Rapid and inexpensive fabrication of polymeric microfluidic devices via toner transfer masking," Lab on a Chip, vol. 9, pp. 1119-1127, 2009. 11 C. S. Chen, et al., "Shrinky-Dink microfluidics: 3D polystyrene chips," Lab on a Chip, vol. 8, pp. 622-624, 2008. 12 A. Grimes, et al., "Shrinky-Dink microfluidics: rapid generation of deep and rounded patterns," Lab on a Chip, vol. 8, pp. 170-172, 2008. 11  1.1.3.4 Pressure source considerations To build a portable device, a pressure source to drive the control fluid independent of central lab compressed air is required. For this application, several configurations of camp stove fuel reservoirs were considered, along with a custom solution. Camp stove fuel reservoirs offer fluid capacity ranging from 325 - 975mL and an integrated pump. The fluidic chip is expected to require 1.54x10^-9 m^3/s, giving an expected run time of 2.44 days, which is extremely oversized. Instead, the Stoeber lab has a small, custom-designed reservoir which was modified to retain pressure and allow for a pressure relief valve and gauge.  1.1.4 Results from previous experimental work This is an important project for our sponsor, Dr. Boris Stoeber, because he has worked extensively with Pluronic and is keen to see it's applications in microfluidics. In 2005, Dr. Stoeber published an article showing that Pluronic could be used to stop flow in glass channel. In 2010, Dr. Stoeber published an article with graduate student Mr. Vahid Bazargan which is a proof-of- concept article for thermally activated microvalves.13This project is a natural extension to that publication because we propose to make a micropump using a similar concept and show how the technology can be applied on a portable device. Critically, we propose to improve the microvalves response time from 20 seconds to 3 seconds and to implement a micropump. We have made significant changes to Mr. Bazargan's design to improve our response time. Philip worked with Dr. Stoeber during the summer to design and develop the micropump. However, the design and fabrication steps proved to be more difficult than anticipated and as of the end of the summer, Philip had sent in two design iterations and fabricated several devices. He was able to form a Pluronic gel in the microfluidic chips and could see valve deflection when a large pressure was applied to the system. However, leakage of PDMS between the gold, glass and PDMS remains an ongoing problem by the end of the summer Philip had not successfully deflected the membrane of the valve via gel formation. At the end of the summer the project was far from done. There is still a lot of work to do to solve the leakage problem, to optimize and characterize the design and to build a portable microfluidic device. 1.1.5 Project Sponsor The sponsor for this project is Dr. Boris Stoeber, a Professor at UBC that is cross-appointed in electrical and mechanical engineering.  1.1.6 Power consumption calculation Power Drain: Arduino = 25mA Pressure Transducer = 20mW, Ip = (20mW)/(5V) = 4mA  13 V. Bazargan, et al., “Flow Control Using a Thermally Actuated Microfluidic Relay Valve”. Journal of Microelectromechanical Systems, 2010. 12  Heaters = (15mW) x 6heaters = 90mW, Ih = (90mW) / (5V) = 18mA Total Current = 25mA + 4mA + 18mA = 47mA  Battery Charge = 565mAh = 2034C  Time to drain the battery = (2034 C) / (47*10^-3A) = 43300s = 12h  It will take 12 hours of continuous operation to drain the battery.  13  2 Discussion 2.1 Design 2.1.1 Macroscopic Portable Device One of our key objectives is was the design of a portable device that allowed us to actuate the micropump without any fixed air or electric utilities.  To achieve this, we designed a pressure/fluid storage reservoir with power provided from 2 9V batteries controlled by an Arduino Mini.  Fluidic Device Control Channel Fluid Reservoir Fluidic Channel Fluid Reservoir Pressure Charger Pressure Charger Heater Power and Controller  Figure 1 - Block Diagram of macroscopic portable device  Figure 2 - Macroscopic portable device 2.1.2 Fluid Supply Systems The pressure charger and reservoirs for the fluidic and control channels are identical systems designed to supply fluid at constant pressure.   The reservoirs are pressurized at the beginning of the experiment; since its capacity is much greater than the volume of fluid delivered, the pressure at the beginning and end can be assumed to be constant. 14  The reservoir was furnished with a Schrader valve to allow for flexibility in the initial source of pressure.  In the lab, this can be provided from compressed air utilities while in the field, a hand bike pump can be used. 2.1.3 Heater Power and Controller In the past, the heaters have been connected to the fluidic device by soldering wires to heater pads on the glass slide.  To improve this, we have made 2 main improvements:  Pogo pins  Arduino-controlled heating 2.1.3.1 Pogo Pins Previously, to power the heaters, wires needed to be soldered by hand to heater pads.  This meant that the pads had to be relatively large and there was a high chance of shorting pads together during soldering.  Because of how the gold is deposited onto the glass slides, removing and resoldering wires will often damage the pad, rendering the heater unusable. A pogo pin is a spring-loaded connector commonly used for attaching electronics equipment temporarily to produced systems for testing and initial programming.  The spring-loaded action allows the connector to make solid, repeatable contact with the pad and allows for differences in height due to manufacturing variation.  Using pogo pins as opposed to allows for a higher density of electrical interconnects to the device, potentially allowing a greater number of heaters and sensors to be implemented in the same envelope; whereas previously, the pad density was governed by the pad area needed for hand soldering, we now are able to use standard protoboard spacing of 0.1” for ease of fabrication.  In the future, it will be possible to reduce the pad pitch to slightly larger than the pogo pin tip diameter.  Figure 3 - Round-tipped pogo pin.  Source: Sparkfun <http://www.sparkfun.com/products/9173> 2.1.3.2 Arduino-Controlled Heating The Arduino Pro Mini microcontroller has 14 GPIO pins, of which 6 have PWM implemented. The use of a microcontroller to control heating levels allows for greater precision of heating, as well as the ability to experiment with different heating curves.  To boost the available current, a basic npn transistor amplifier circuit was used. 15   Figure 4 - Circuit diagram, npn transistor amplifier circuit The code used to control one cycle of valve operation is shown in Appendix E. The code is quite simple, as all that it needs to do is turn heaters on and off in the proper sequence. It uses two PWM outputs, one for each heater. The voltage to be sent to the heater through the PWM output needs to be high enough to cause Pluronic gel formation but not as high as to cause electrolysis. Therefore the values sent to the PWM outputs will change depending on the heaters and the powers necessary to form gel formation. Theoretically, the power necessary to cause gel formation should be constant and as such the output of the PWM should be determined based only on the resistance of the heater. However, in reality the power delivered to the Pluronic depends on the heat transfer properties of the heaters and other factors. Therefore the power necessary to turn the heater on needs to be determined experimentally using a DC power supply. This experimental power is equal to the average power output of the PWM, which in turn depends on the duty cycle set in the code. The average power of the PWM output is:  (      )       Where nPWM is the value (between 0 and 255) sent to the PWM output in the code, V is the voltage output of the Arduino after amplification and R is the resistance of the heater. This power needs to be equal to the power PDC necessary to cause gel formation which is experimentally determined from voltage as:      Where VDC is the power supply voltage necessary to cause gel formation and R is the resistance of the heater. Setting these equal and solving for the PWM value gives: 16       nPWM is equal to the variable  int PWMvalveOn   in the code of Appendix E. Finally, it should be noted that the value VPWM is not the 5V voltage output of the Arduino board but rather the 18V signal after amplification, i.e. VPWM = 18V. In addition, the time delays between the different parts of the valve cycle need to be determined and set in the code. These time delays need to be determined experimentally when the response time of the valve is determined and they need to be as low as possible to minimize the valve’s response time. The time delays are likely the same for each valve. 2.1.4 Series 4 Design 2.1.4.1 Goals The Series 4 design is a general revision of the heater and control channel layers.  Compared to the Series 3 design, the main goals were:  Protoboard compatibility  Integrated temperature sensing  Greater fluid path length  Larger valve actuation area  Removal of other channels and diffusion barriers 2.1.4.2 Protoboard Compatability To eliminate the problems associated with soldering wires to the heater pads, we opted to connect the heaters to power sources and other devices using pogo pins soldered to standard pitch (0.1”) protoboards.  Since no soldering of wires would be needed, the pad size can be much smaller, allowing for greater density of electrical interconnects; whereas the Series 3 heater pads required 61mm2 for 4 interconnects, we were able to put 6 pads in a 74mm2 envelope.  17  (a)                                      (b) Figure 5 – Heater designs; a) Series 3; b) Series 4  2.1.4.3 Integrated Temperature Sensing  Since Pluronic has a small temperature range in which it forms a gel.  Both above and below this range, the fluid has identical flow properties, making it difficult to tell if the fluid is above or below the gelation temperature.  To measure the temperature, a RTD was implemented by interdigitating two heater systems.  In this way, one can be used as a heater and the other as an RTD.  An added advantage of this design is redundancy; if using the RTD is not necessary, two independent heaters are available in each heating area.  (a)                                                          (b) Figure 6 – Heating area details; a) Series 3; b) Series 4 2.1.4.4 Greater Fluid Path Length From our experiments on the Series 3 devices, we believe there is a strong relationship between total wall area heated and the ability for the formed gel to prevent flow.  In particular, design 3B, which uses dense columns in the heating area instead of zig zag channels, did not appear to hold a gel at all.  For this reason, we wanted to increase the total fluid path length under the heating area. 2.1.4.5 Larger Valve Actuation Area The volumetric flow rate from a peristaltic pump is dependent on the volume of fluid it is able to displace.  To increase our pumping capacity, the fluidic channel was tripled through the pumping zone, requiring the valve area to be stretched.  18   (a)                                  (b)                                  (c) Figure 7 – Control channel heating area details; a) Series 3C; b) Series 3A; c) Series 4B.  The orange box indicates the nominal area of flow.   (a)                                                                                          (b)  19  (c)                                                                                          (d) Figure 8 - Time lapse of gel formation and dissolution.  Heater voltage 13V was held constant with pressure varied. a) 1psi, no flow;  b) 3psi, no flow; c) 5psi, no flow; d) 13 psi with flow. 2.1.4.6 Removal of Other Channels and Diffusion Barriers Series 3 includes a coolant flow channel and a diffusion prevention channel beside the primary flow path.  In characterizing these devices, we saw that the fluid would leak along heater traces into these side channels.  Removing these would simplify the overall design and may increase reliability.   (a)              (b) Figure 9 - Control channel; a) Series 3B; b) Series 4B.  The orange and green boxes indicate the diffusion barrier and the valve actuation areas, respectively. 2.1.4.7 Greater Fluid Path Length From our experiments on the Series 3 devices, we believe there is a strong relationship between total wall area heated and the ability for the formed gel to prevent flow.  In particular, design 3B, which uses dense columns in the heating area instead of zig zag channels, did not appear to hold a gel at all.  For this reason, we wanted to increase the total fluid path length under the heating area. 20   (a)                                  (b)                                  (c) Figure 10 – Control channel heating area details; a) Series 3C; b) Series 3A; c) Series 4B.  The orange box indicates the nominal area of flow. 2.2 Testing 2.2.1 Overview In the context of the deliverables we hoped to achieve, several experiments were designed to address individual issues.  Presented chronologically, these tests were:  Plasma Bonding:  Parylene Bonding:  Pluronic Rheology: Since we were unable to form Pluronic gel as expected in the fluidic devices, the quality of the Pluronic itself became suspect.  To verify the viscometric properties, rheology was carried out on several samples.  RTD: A key feature of the Series 4 heater design is the addition of an integral RTD.  To verify that it functions as predicted and produces repeatable data, the resistance of several samples of this device was tested under known temperature conditions.  Electrolysis: Although the formation of bubbles had been seen within the control channel in the past, this had been attributed to heating the fluid past its boiling temperature.  To investigate if electrolysis was possible and how to detect it, an experiment was designed to rule out other sources of bubbles and check for this effect. 2.2.2 Pluronic Rheology 2.2.2.1 Introduction 21  When we had difficulty getting consistent results for Pluronic gelation in the device, we first attempted to check the Pluronic response by putting it in an oven and on a hotplate.  For these experiments, we varied the temperature from ambient to 65 degrees and did not observe gelation at any temperature in this range.  As this is far higher than the published gel temperature, this result was very unexpected.  These experiments were consistent between over 6 batches of Pluronic made with the following parameters varied:  Water type: distilled and deionized  Fluorescent tracer particles: in the mix and not To undertake a more careful analysis the thermal properties of Pluronic, we used a rheometer to check if the viscosity profile is as expected. 2.2.2.2 Methods We tested 3 samples using an Anton Paar MRC series rheometer using the cone and plate geometry.  Their preparation parameters are as shown in Table 1. Batch Number Target Pluronic % by wt Fluorescent Particles [g]1 Water [g] Pluronic [g] Pluronic % by wt. 2 15 0.114 8.37932 1.5037 11 15 0 4.2603 0.7497 14.96 12 15 0.0345 4.2187 0.7848 15.57 1The fluorescent particles are provided to us in a concentrated, 0.02% solution with water. 2 This sample was prepared with DI water; subsequent samples were all prepared with distilled water. Table 1 - Properties of Pluronic batches tested by Rheology 2.2.2.3 Results The results are presented in Figure 11.  Figure 11 - Viscosity vs temperature for 3 tested batches of Pluronic 0 500 1000 1500 2000 2500 3000 31 32 33 34 35 36 37 V is co si ty  [ P a· s]  Temperature [˚C] 12 11 2 22  2.2.2.4 Analysis The erratic viscosity measurements above the gel temperature can be attributed to the fluid being a two-phase system whereby there are areas of gel and liquid, depending on localized temperature differences.    This effect also explains why we do not see the fluid return back to a liquid at high temperatures as expected. 2.2.2.5 Conclusion The lower bound on the gelation temperature varies between 32-34˚C.  We do not see a temperature at which the gel re-liquefies; this is believed to be since the phase there may be a two-phase (gel and liquid) system present between the cone and plate whereby there are areas of liquid and gel.  This means that due to the experimental apparatus, all the data above the lower gelation temperature should be treated as suspect. 2.2.3 Plasma Bonding 2.2.3.1 Introduction Oxygen plasma bonding is a very popular technique in the field of microfluidics.  It is used to create a bond between PDMS to PDMS or PDMS to glass.  Oxygen plasma improves adhesiveness by cleaning the surface of contaminants and introducing reactive chemical groups.  In PDMS, the -O-Si(CH3)2- group is converted to a silanol group (-OH) which changes the PDMS surface chemistry from hydrophobic to hydrophilic and allows for Si-O-Si bonds between PDMS to PDMS surfaces or PDMS to glass surfaces. We use the direct bonding via oxygen plasma both for bonding our multi-layer devices to glass and for bonding our multi-layer devices to the 10um of PDMS that is spun onto the glass surface. 2.2.3.2 Methods The following parameters were varied:  Power: 15, 30 watts  Time: 10, 15, 20 seconds  Weight: 0, 4, 8 pounds The following parameters were not varied:  Gas composition: 100% oxygen  Chamber pressure: 500mtorr 2.2.3.3 Conclusions There was no apparent link between the variation of the plasma parameters and the quality of the bond.  The best 30 watts, 15 seconds and 4 pounds, although even this would yield approximately 30% success. 23  2.2.4 Parylene Bonding 2.2.4.1 Introduction / Motivation Parylene bonding is an alternate method of bonding PDMS to PDMS or PDMS to glass. As mentioned above, one of the issues we were having with the device was leakage of Pluronic along the gold heater traces at the glass-PDMS interface. Sometimes the bond between the PDMS and the glass failed completely and the PDMS was partially coming off the glass, rendering the chip unusable. The method that we have been using to bond the PDMS to glass was plasma bonding, a standard bonding method widely used in microfluidics. This method works very well for bonding PDMS to plain glass but the gold heater traces have a significant negative effect on the bond strength (though they are only 100nm in height). To resolve this issue, we have explored an alternate bonding method, parylene bonding. This method is not as widely used as diffusion or plasma bonding so there is less available literature on the subject. Parylene is the name given to a family of polyparaxylylene polymers that are typically used as moisture and dielectric barriers. As such, it is often coated on printed circuit boards and, due to its biocompatibility, also on medical devices. This biocompatibility makes parylene a potentially useful material in the fabrication BioMEMS devices. Parylene is typically deposited on the desired surface by chemical vapour deposition, which also results in the parylene polymerization. There are 3 different types of parylene and the one that we were using for the bonding test is Parylene-C. Should the parylene bonding method prove to be successful, it would make a useful new bonding method for the UBC MEMS group. 2.2.4.2 Method First of all, the two surfaces to be bonded are coated with a thin layer of parylene. The coating is done in a parylene coating chamber where parylene is evaporated, directed towards the chamber containing the glass slides and PDMS to be coated, and then the vapour deposits on everything inside the chamber with a uniform thickness. We investigated the bonding process based on available literature and used parameters that other researchers have reported as having produced positive results. The resulting bonding method is as follows. After the coating is finished, the two layers are pressed together in a high temperature environment for 30 minutes. The idea is that during this time the parylene is heated above its glass transition temperature and as a result the chains on the two surfaces interlink, resulting in a bond. The bonding process needs to be done in a vacuum oven as parylene has a tendency to oxidize at high temperatures. Since the Stoeber lab does not possess a vacuum oven, we performed the experiment together with Kevin Heyries, a postdoc in Dr. Hansen’s lab and used the Hansen lab’s vacuum oven and cleanroom. In addition, the plates need to be pressed together quite strongly. The published papers recommend pressures of 0.5MPa - 16MPa. To minimize damage to the chip and the microfluidic channels, we used a pressure at the lower end of the range, 1MPa. We designed and built a 24  thermal press held together by 5 bolts which could be adjusted by a torque wrench to achieve the desired pressure. The temperature of the oven and the baking time were also parameters that needed to be set. According to Noh, Moon et al.14 the ideal temperature is between 160°C and 200°C. In fact, the results were the same within experimental uncertainty for this range of temperatures. Therefore we used a temperature of 160°C. The baking time does not have an effect on the bond strength, as long as it is greater than about 10 minutes. Therefore we baked the chips for 30minutes, then turned off the oven and waited for it to cool down to below 90°C (glass transition temperature of parylene).   Figure 12 - Press used to apply 1MPa pressure during parylene thermal bonding. 2.2.4.3 Results After the parylene was pulled from the oven, it was allowed to cool to room temperature. Then we placed it under the inverted microscope and attempted to run water through it. However, we have observed complete channel collapse as though the channels did not even exist and the water did not flow through the parylene bonded channels. At a pressure of 30psi the bonding failed. Thus parylene bonding has proved to be a method unsuitable for our purposes, as it resulted in a weak bond and complete channel collapse. The channels collapsed due to the high pressure that was applied to the PDMS during the thermal bonding. After all, applying 1MPa of pressure to a small channel made of an elastic material is very likely to squeeze it and bond the top of the channel to the bottom of the channel. Therefore to eliminate channel collapse, we need to lower the applied pressure.  14 H. S. Noh, et al., "Wafer bonding using microwave heating of parylene intermediate layers," Journal of Micromechanics and Microengineering, vol. 14, pp. 625-631, Apr 2004. 25  After the channel failed, we tried peeling the PDMS off the glass. It was quite easy to peel it off near the edges but the PDMS was strongly bonded to the glass in the center. The reason is that when the elastic PDMS was pressed during the thermal bonding, the pressure was the highest in the center of the chip and decreased towards the outside due to elastic strain in the material. This suggests that pressure has a significant effect on the bonding properties, with high pressure being necessary to bond properly. Therefore to increase the bonding strength we need to increase the applied pressure, contradictory to the channel collapse requirement. 2.2.4.4 Conclusion Parylene bonding is not a method that can be used in our project and thus was abandoned. 2.2.5 RTD Tests 2.2.5.1 Introduction The series 4 glass slide heating area comprised of two independent heater systems.  These were interdigitated, introducing redundancy as well as the provision to use one as a resistance temperature detector (RTD).  The relationship between resistance an temperature is governed by the equation      (     )    Where: T = temperature of the device  T0 = ambient temperature  R = measured resistance  R0 = resistance at ambient  α = temperature coefficient of resistance, a material property In general, α is typically found in a table.  In our case, since the heater is a combination of chromium and gold, α is not well-defined.  Thus, to find α, we needed to find a relationship between R, T0 and R0.  To achieve this, we used several tests. 2.2.5.2 Methods, Results 2.2.5.2.1 Test 1: Heating one set, detecting with the other In this experiment, we attached one of the heaters to a power supply and HP 34401A DMM.  We then varied the power to the heater and measured the change in resistance seen by the RTD. This was done on two slides, one bare (i.e. no PDMS) and one covered with 5psi 15% Pluronic flow.  The data from this test is presented in Figure 13 shows that the results were quite different for these two cases.  To reduce experimental uncertainty, the experiment was modified to remove variables. 26   Figure 13 – RTD resistance vs heater voltage for the bare and covered heater cases 2.2.5.2.2 Test 2: Hotplate heating Instead of heating the slide with the on-slide heaters, we used a Fisher Isotemp hotplate.  This hotplate had an integral temperature display but its resolution was ±5˚C and was an element temperature, rather than a hotplate surface temperature.  To determine the temperature more accurately, we used the Omega HH23 thermocouple reader and J-type thermocouple measuring the slide temperature.  The hotplate temperature was then varied and the thermocouple temperature and RTD resistance were measured for three cases:  Bare heater  Covered heater, no fluid  Covered heater, fluid flowing at 5psi. The apparatus is shown in Figure 14; the results are shown in Figure 15. -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0 2 4 6 8 R e si st an ce  [ kΩ ] Voltage [V] Bare Heater Covered Channel 27   Figure 14 - Experimental apparatus, hotplate test  Figure 15 - Resistance vs. temperature for the bare, covered dry channel, and covered wet channel  2.2.5.3 Analysis 2.2.5.4 Analysis The goal of the data analysis is to come up with a relationship that allows us to determine the temperature of any RTD we will be using in the future based on its resistance. The relationship between resistance and temperature for and RTD is:  ( )     (    (    )) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0 20 40 60 80 R e si st an ce  [ kΩ ] Temperature [˚C] Wet channel Bare Heater Dry channel 28  Where R0 is the resistance at the temperature T0 and α is a material property at the temperature T0. As is obvious from the above equation, the relation between resistance and temperature is linear, in agreement with our experimental results. Thus a linear relation has been fitted to the data. The results are: Dry channel:     R(T) = 0.0011960T + 0.3724058   *Ω+ Wet Channel:   R(T) = 0.0013129T + 0.3784029   *Ω+ Bare Heater:     R(T) = 0.0016149T + 0.5567747   *Ω+ As mentioned above, R0 and α need to be specified at a certain temperature. For simplicity, this temperature T0 will be 20°C, as most tabulated results are at this temperature. The resulting relationship is: Dry channel:     R(T) = 0.4116058Ω * ( 1 + 0.004761838/°C * ( T - 20°C) ) Wet Channel:   R(T) = 0.4046609Ω* ( 1 + 0.003244444/°C * ( T - 20°C) ) Bare Heater:     R(T) = 0.5890727Ω* ( 1 + 0.002741427/°C * ( T - 20°C) ) The resistances at 20°C, R0 are quite variable due to variations that result from the manufacturing of the devices. The evaporation and lift-off of the RTD gold traces is not always reproducible and sometimes even results in unusable RTD’s. However, for our purposes it is not necessary to have exactly the same resistance in all the RTD’s that we produce because we can always measure the 20°C resistance in order to be able to take temperature measurements with our RTD device.  The more important constant is α, also known as the temperature coefficient of resistance. Theoretically, α should be a material property and should not be affected by the state of the channel (dry/wet/bare). However, according to our results α varies in between experiments. Therefore in order to use the RTD to measure temperature we need to conduct more hotplate experiments and determine the average value of α. As we improve our experimental technique, we may be getting more and more consistent results. The tabulated value for the temperature coefficient of resistance of gold is    0.003715 /°C which is quite close to the values that we found. However our RTD is not made entirely out of gold; rather it is a 50nm layer of chromium and a 60nm layer of gold. 2.2.6 Electrolysis Test 2.2.6.1 Introduction The unusual results of RTD Test 1 caused us to ask if electrolysis was causing the strange results. Furthermore, throughout the characterizations of devices dating back even to the series 3 fluidic chips, when we have applied in excess of 10V, we have seen the formation of bubbles.  Since 29  electrolysis had never been seen in past work by Bazargan et. al15, it was not initially suspected and instead, the effect was attributed to overheating of the fluid to the point of boiling .  In theory, electrolysis would happen whenever a potential of 1.23V is created in water.  In our experiments, we typically explored voltages between 0-9V and did not believe any electrolysis occurred. 2.2.6.2 Methods To determine at what voltage electrolysis will occur, a power supply was attached to the heater set.  Since the magenta side is separate from the blue one, any current would pass through the fluid, allowing for electrolysis.  To investigate if the location of electrolysis in the heating zone varies, 3 geometries were tested as shown in Figure 16.  For all experiments, the power was varied from 0-6V with 15% Pluronic containing fluorescent beads being pushed through the control channel at 5psi.  (a)                                           (b)                                             (c) Figure 16 – Schematic of the electrolysis test apparatus; a) crossed leads; b) parallel leads; c) conventional connection 2.2.6.3 Results In both apparatus setups (a) and (b), the electrolysis would occur at random locations within the heating zone.  Throughout the entire experiment, the current flow would remain constant at 0.045mA.  Electrolysis was seen as small bubbles approximately 5 microns in diameter being formed in the control channel at a heater trace.  These would first appear at 2.89V.  As the voltage was increased, the bubbles would appear more in more locations within the heating zone and with greater diameters.  Only above 4V are the bubbles large and widespread enough to be seen under UV illumination.  From 2.89-4V, the only way to see the electrolysis is under visible light, which is not typically when characterizing fluidic devices.  15 V. Bazargan, et al., “Flow Control Using a Thermally Actuated Microfluidic Relay Valve”. Journal of Microelectromechanical Systems, 2010. 30   (a)                                                                     (b)  (c)                                                                    (d) Figure 17 – Electrolysis seen when the device is connected as in Figure 16 (a); a) before the application of 4V; b) t=2s after power applied; c) t=7s d) t=14s.  Recorded using 10x lens. 2.2.6.4 Conclusions Throughout our device characterizations, we have applied voltages far above the electrolysis threshold.  Because this effect is not visible under UV light until 4V, we have considered voltages below this level to be safe; however, it is not apparent that the application of greater than 2.89V will cause electrolysis.  Since this is not high enough to cause reach the gelation temperature of 15% Pluronic, the heater will need to be electrically isolated or redesigned with lower resistance to keep the applied voltage low.  31  3 Project Deliverables 3.1 Deliverables 3.2 As presented in our Project Charter (Appendix B - Recipe for 10 um SPR220-7.0 Mold for 4-inch Si Wafers  Preparation Steps   Wafer is cleaned with Acetone, then Methanol, then Isopropanol Alcohol, and then gently blown with N2 gas.   Wafer is baked for dehydration for 20 minutes at 200°C, then cooled to room temperature for 10 min.  Spin Coating   The wafer is centered on the spinner chuck and vacuum sealed.   HMDS (hexamethyldisilazan) drops are placed on the wafer using a dropper until 50% of the wafer is covered.   HMDS is spun at 3500 rpm for 35 seconds. Let the wafer sit for 1 minute on the spinner before pouring photoresist.   SPR220-7.0 photoresist is poured over the wafer straight from the bottle, covering roughly half the area. The bottle should be cleaned thoroughly with a clean wipe before and after pouring. The wafer is spun for 5 sec at 500 rpm and 40 sec at 1500 rpm.   The wafer is let sit on the spinner for 1-2 minutes.  Photoresist Soft bake   The wafer is gradually warmed to 90 C, by using a layer of aluminum foil or wipe on the hotplate. After 1 minute transfer it directly to the 90 C hotplate, let it sit there for 2 min, then transfer to another hotplate at 115 C, let it sit for 3 min.   The wafer is slowly cooled to room temperature for 10 min  UV-Light Exposure   The wafer is loaded into the Canon PLA-501F double-side 100mm mask aligner.   The printed mask on a transparent sheet is attached to a thick glass plate and is loaded as the photomask into the mask aligner.   UV-light is exposed to the layer for 70 sec.   The wafer is let sit on the mask aligner for 1 min.   The wafer is cooled down at the room temperature 21°C for 30 min for dehydration.  Photoresist Develop   An MF 319 bath and a DI-water bath are prepared.   The wafer is placed into the MF-319 for 5 min and visually checked.    If the developments looks completed, the wafer is placed into the water bath for 1 min and is rinsed with DI water and dried with a N2 gun.   The pattern is checked under the microscope and especially the corners and posts are examined for complete development. The developing process can be repeated if additional development is needed. 32    The thickness of the pattern then is measured using the Wyko NT1100 interferometer.  Reflow Process   The wafer is placed on the hot plate for 2 min at 90°C.   The hotplate is set for 140 C and ramps up for 5 minutes, then the hotplate is shut off.   The wafer remains on the hotplate for 5 minutes for gradual cooling, then taken off and allowed to cool to room temperature.   The shape and the thickness of the pattern then are measured using Wyko NT1100 optical.  33   Appendix C), the following deliverables were agreed upon at the start of the project: 1. A hydrogel actuated microvalve that has a response time of less than 3 seconds. 2. A portable device that allows the use of the fluidic chip independent of fixed power and air systems. 3. A peristaltic pump composed of hydrogel actuated valves capable of moving a cell in a loop. 3.2.1 Deliverable 1: Microvalve with 3 second response time The design of the new Series 4 fluidic chips was completed.  Due to ongoing fabrication and Pluronic issues, the performance has not been characterized.  At present, we are able to form gel using the PDMS-coated chips, but these devices clog rapidly to allow for sustained characterization. 3.2.2 Deliverable 2: Portable device The hardware for this device is complete.  The code that drives the PWM heater controls has been written but due to the unavailability of functioning fluidic chips, it has not been validated. 3.2.3 Deliverable 3: Peristaltic pump Due to ongoing fabrication and Pluronic issues, we have not been able to actuate valves with any degree of reliability.  The requirement for 2 adjacent valves to function predictably has not been seen, causing us to not achieve this deliverable. 3.3 Financial Summary 3.3.1 Macro Components The cost of the macroscopic components is as follows: Description Qty Vendor Cost Per Total Cost Purchased by Funded by Arduino Mini RB-Ard-02 1 Robotshop.ca 28.16 28.16 Project Lab Stoeber Lab Pogo Pins 20 Sparkfun.com 0.95 19 Project Lab Stoeber Lab 9V Battery 1 London Drugs 6.49 6.49 Project Lab Stoeber Lab Pressure Reservoir 1 Stoeber 0 0 Stoeber Lab Stoeber Lab Pressure Gauge 2 McMaster 10.70 21.40 Project Lab Stoeber Lab Table 2 - Macro Component Breakdown 34  3.3.2 Micro Components Description Qty Vendor Cost Per Total Cost Purchased by Funded by Cleanroom time 12 UBC 45 540 Stoeber Lab Stoeber Lab Transparency 1 CAD/CAS Art Services 120 120 Stoeber Lab Stoeber Lab Gold Evaporation 3 UBC 60 180 Stoeber Lab Stoeber Lab Table 3- Micro Component Breakdown 3.4 Ongoing Commitments by Team Members The team will continue to collectively put in a sum of 10 hours per week in an effort to complete the items as outlined in Section 5.1. 35  4 Conclusion 4.1 Important Results Below is a list of important discoveries made during the project. 1. Parylene-parylene bonding does not work for PDMS microfluidic devices because the microfluidic devices collapse under the pressure applied to the two PDMS pieces to activate parylene bonding between them. 2. Diffusion of water through the PDMS, and resulting increase in Pluronic concentration in the microfluidic device is not an issue.  We never saw the gel stop flowing of its own accord. 3. Spin-coating our glass slides with uncured PDMS at 8000rpm results in a 10um PDMS thickness and eliminates leakage. 4. We can form gel in our devices with 17% Pluronic.  15% Pluronic and below are not good candidates for gel formation. 5. It is possible to achieve heaters with 80nm thickness.  Previously, Vahid used heaters with 250nm and there was concern that imperfections would have a dominant role below 250nm and make the heater non-fucntional..  4.2 Project Review We completed two of our three objectives.  We complete objective #1, eliminate leakage and objective #3, production of portable microfluidic device.  We did not complete objective #2, microvalves with response time of <3 seconds incorporated into a micropump..  We did not complete objective #2 because there were many unforeseen challenges in the fabrication and gel activation process.  Four assumptions we made from the outset of the project were: 1. Gel formation could easily be predicted, achieved and reproduced. 2. There would be no electrolysis in the device. 3. We were confident that we had appropriate steps and contingency plans to quickly eliminate leakage in our device. 4. PDMS spun onto a glass slide at high rpm (>1000rpm) would have extremely high porosity due to stretching of the polymer.  4.2.1 Gel formation of Pluronic could easily be predicted, achieved and reproduced We had inconsistent Pluronic behaviour throughout our experiments at both the macroscopic and microscopic level.  Pluronic is supposed to reproducibly form a gel at a concentration dependent gel point.  We calculated approximately how much power we needed from our heaters to heat up the fluid in our microchannels beyond the gel point.  However, the Pluronic seemed to only sometime form a gel despite application of identical parameters.  The following three paragraphs describe a situation in which the gel formation seemed to be lost over the period of two hours. In early October we used design iteration 3 and 15% Pluronic to show that after we initially put Pluronic in our devices that we could get formation in both the snake design and dense column 36  designs.  We observed that the snake design had better gel formation and pressure holding abilities and concluded that the more surface area the better the gel holding capability of the device. We tested the snake design to 13psi and the gel held for the entire test, the dense columns failed at 7psi. When the snake design device was first connected and the control channel pressure inlet pumped at 10psi we observed gel formation and complete stoppage of flow within one second of turning on the heater at  490mW of power.  Within five seconds of turning off the heater there was full liquification of the gel and fluid flow had recovered to its previous high velocity. The device was left in place with Pluronic flowing through the device while other experiments were performed.  After two hours had gone by we tried the same experiment with identical pressure and power parameters and could not get gel formation.  It was only at a pressure of one psi that we could get gel formation again.  We still do not understand why the gel behaviour changed over the course of the two hour experiment.  Pluronic from the same bottle was continually cycled through the device and the resistance of the heater and power applied was the same. Inconsistent Pluronic behaviour was also observed at the macroscopic level as well.  For example, when we initially placed 15% Pluronic (batch #2) in an oven we observed that from 35C to 45C the Pluronic was a solid gel, we could flip the Pluronic bottle upside down and the Pluronic stayed in place.  At 50C the Pluronic became a liquid again.  The Pluronic was kept in a tightly sealed bottle overnight and the following day when the same bottle was placed at 40C the Pluronic did not respond as before.  It became more viscous but it still continually flowed to the bottom of the bottle.  We made more Pluronic mixtures but none of them had the same response we originally observed. When we could not reproducibly get gel formation by heating the Pluronic in the microfluidic channels or by heating the big bottle of Pluronic in the lab oven we started to suspect the Pluronic itself so we proceeded to do viscometry measurements with a viscometer.  The viscometer persuasively showed that the 15% Pluronic had a sharp viscosity increase between 32C and 34C. We still cannot explain the inconsistent Pluronic behaviour in which we had gel formation and then a few hours later with identical parameters could not reproduce the same gel formation. Further, we cannot explain why the viscometry shows a sudden spike in viscosity and why the Pluronic in the microfluidic device did not have the same behaviour.  The most likely explanation is that the range of gel formation for 15% Pluronic is small and we consistently overheat the Pluronic past the gel formation point.  However, this is an unsatisfactory explanation because we have carefully tested the full range of power that can be applied to the heaters. 4.2.2  There would be no electrolysis in the device. Bazargan et al. undertook a similar project in 2008 which included creating a valve with two heaters in a microfluidic device.  He heated the Pluronic by applying 25 mW of power (4.29 volts 37  and 5.83mA) across a 250nm thick gold heater.  Vahid did not observe electrolysis so we did not expect to have electrolysis.  However, we did observe electrolysis and the electrolysis may have contributed to our poor gel performance. 4.2.3  We were confident that we had appropriate steps and contingency plans to quickly eliminate leakage in our device. We could not eliminate leakage in our device by either parylene-parylene bonding or varying plasma treatment parameters for PDMS to glass bonding.  Our final solution is to spin on uncured PDMS on a glass slide at 8000 rpm which gave a thickness of 10um and a PDMS to PDMS bonding surface that can hold pressure up to 20 psi and does not have any leakage.  We did not consider spinning on PDMS in our initial project proposal because Vahid told us that PDMS spun on at (>1000rpm) would be porous and prone to extensive diffusion. In section 3.4 of our project proposal we proposed two new techniques by which we could eliminate leakage. 1) Collaboration with Dr. Eric Lagally to implement Dr. Lagally’s recently published peptide bonding technique16.  We planned to treat the PDMS with (3-aminopropyl)-trimethoxysilane (APTMS; 97%) and the glass and gold with 10% TMS-EDTA.  The treatment results in peptide bond formation between the PDMS and glass and PDMS and gold.  Philip did one round of unsuccessful tests in late August and we did not choose to pursue this option. 2) Collaboration with Dr. Carl Hansen to implement parylene-parylene bonding.  This technique was pursued by Honza and it was declared unsuccessful on November 19th, 2010. We predicted that if either of the two techniques did not work we could further optimize the direct glass to PDMS bonding by reducing the gold heater thickness, modifying the plasma treatment time, modifying the bake time and adjusting the weights we placed on the PDMS after bonding.  However, despite an exhaustive round of testing with the PECVD plasma machine we could not get consistent PDMS to glass bonds.  Sometimes we had too much collapse and other times we had leakage everywhere. On December 13th, 2010 Mario Beaudoin, UBC Cleanroom Manager, sent an email with attached picture to the UBC cleanroom noting that the inside of the PECVD machine was very dirty.  We were never taught how to clean the internal chamber of the PECVD and most of our tests were done before December 13th, 2010 so the dirtiness of the PECVD may have contributed to our poor bonding results. 38   Figure 18 – Dirty PECVD Plasma Chamber 4.2.4 PDMS spun onto a glass slide at high rpm (>1000rpm) would have extremely high porosity due to stretching of the polymer. Vahid told us that PDMS spun on at (>1000rpm) would be porous and prone to extensive diffusion.  Thus, we did not consider spinning on PDMS onto our glass slide until early January, 2011 when it was obvious that parylene-parylene bonding and plasma treatment bonding parameter modification had not worked.  39  5 Recommendations The recommendation section is broken into two sub-sections.  The first sub-section is the specific recommendations that are directly related to the ongoing project goal of developing a micropump.  The second sub-section is more general and includes retrospective recommendations about work flow and other project management strategies. 5.1 Specific Recommendations 1. Increase PDMS spin-on speed.  Uncured PDMS is currently spun onto the glass slide at 8000rpm which results in a 10um thickness.  8000rpm is the upper bound of the spin speed of the spinner that is available to us in Dr. Stoeber’s lab.  Finding a spinner capable of faster spin speeds will allow us to further reduce the PDMS thickness and increase response time. 2. Test adhesion promoter GE SS4120 in hopes of increasing the pressure that the triple layer PDMS devices can withstand. 3. Measure response time of individual valves. 4. Measure pumping rate and pumping pressure of final micropump. 5. Explore the discrepancy in the viscometry results between the 15% Pluronic that do and do not have fluorescent beads. 6. Repeat viscometry measurements for 17% Pluronic and compare to 15% Pluronic results.  5.2 General Recommendations 1. Recreate Vahid’s results.  Use the identical microfluidic and heater design and identical project parameters to recreate Vahid’s results.  If we had done this at the outset of the project we would quickly have identified that we needed 17% Pluronic instead of 15% Pluronic.  Recreating Vahid’s device will help to establish whether our ongoing poor results are due to a poor design or something that is wrong with the Pluronic solution. 2. Optimization and large scale production of multi-layer microfluidic chips.  We should have made three identical control channel wafers and three polyeurathane molds so that we could make 12 microfluidic multi-layer chips at once.  We only made microfluidic chips in batches of 4 which proved to be very time consuming.  40  References  [1] D. J. Beebe, et al., "Functional hydrogel structures for autonomous flow control inside microfluidic channels," Nature, vol. 404, pp. 588-+, 2000. [2] C. S. Chen, et al., "Shrinky-Dink microfluidics: 3D polystyrene chips," Lab on a Chip, vol. 8, pp. 622-624, 2008. [3] C. J. Easley, et al., "Rapid and inexpensive fabrication of polymeric microfluidic devices via toner transfer masking," Lab on a Chip, vol. 9, pp. 1119-1127, 2009. [4] D. Erickson, et al., "A miniaturized high-voltage integrated power supply for portable microfluidic applications," Lab on a Chip, vol. 4, pp. 87-90, 2004. [5] A. Grimes, et al., "Shrinky-Dink microfluidics: rapid generation of deep and rounded patterns," Lab on a Chip, vol. 8, pp. 170-172, 2008. [6] S. W. Lee and S. S. Lee, "Shrinkage ratio of PDMS and its alignment method for the wafer level process," Microsystem Technologies-Micro-and Nanosystems-Information Storage and Processing Systems, vol. 14, pp. 205-208, 2008. [7] J. C. Lotters, et al., "The mechanical properties of the rubber elastic polymer polydimethylsiloxane for sensor applications," Journal of Micromechanics and Microengineering, vol. 7, pp. 145-147, 1997. [8] A. Manz, et al., "PLANAR CHIPS TECHNOLOGY FOR MINIATURIZATION AND INTEGRATION OF SEPARATION TECHNIQUES INTO MONITORING SYSTEMS - CAPILLARY ELECTROPHORESIS ON A CHIP," Journal of Chromatography, vol. 593, pp. 253-258, 1992. [9] Z. Q. Niu, et al., "DNA amplification on a PDMS-glass hybrid microchip," Journal of Micromechanics and Microengineering, vol. 16, pp. 425-433, 2006. [10] H. S. Noh, et al., "Wafer bonding using microwave heating of parylene intermediate layers," Journal of Micromechanics and Microengineering, vol. 14, pp. 625-631, Apr 2004. [11] E. Ouellet, et al., "Novel carboxyl-amine bonding methods for poly(dimethylsiloxane)-based devices," Langmuir, vol. 26, pp. 11609-14, 2010. [12] K. Pitchaimani, et al., "Manufacturable plastic microfluidic valves using thermal actuation," Lab Chip, vol. 9, pp. 3082-7, 2009. [13] X. T. Qiu, et al., "Localized Parylene-C bonding with reactive multilayer foils," Journal of Physics D-Applied Physics, vol. 42, 2009. [14] B. Stoeber, et al., "Flow control in microdevices using thermally responsive triblock copolymers," Journal of Microelectromechanical Systems, vol. 14, pp. 207-213, 2005. 41  [15] K. Tashiro, et al., Micro flow switches using thermal gelation of methyl cellulose for biomolecules handling. Berlin: Springer-Verlag Berlin, 2001. [16] M. A. Unger, et al., "Monolithic microfabricated valves and pumps by multilayer soft lithography," Science, vol. 288, pp. 113-116, 2000. [17] A. Singhal, et al., “Microfluidic Measurement of Antibody-Antigen Binding Kintetics From Low-Abundance Samples and Single Cells. [18+ V. Bazargan. “Micro Flow Control Using Thermally Responsive Polymer Solutions”. A thesis submitted in partial fulfillment of the requirements for the degree of master of applied science in the Faculty of Grad Studies at UBC.  2008   42  6 Appendices  6.1 Appendix A - AZ 5214E Photoresist Datasheet 43   AZ 5214 E Image Reversal Photoresist      44  GENERAL INFORMATION This special photoresist is intended for lift-off-techniques which call for a negative wall profile. Although they are positive photoresists (and may even be used in that way) comprised of a novolak resin and naphthoquinone diazide as photoactive compound (PAC) they are capable of image reversal (IR) resulting in a negative pattern of the mask. In fact AZ 5214E is almost exclusively used in the IR-mode. The image reversal capability is obtained by a special crosslinking agent in the resist formulation which becomes active at temperatures above 110°C and - what is even more important - only in exposed areas of the resist. The crosslinking agent together with exposed PAC leads to an almost insoluble (in developer) and no longer light sensitive substance, while the unexposed areas still behave like a normal unexposed positive photoresist. After a flood exposure (no mask required) this areas are dissolved in standard developer for positive photoresist, the crosslinked areas remain. The overall result is a negative image of the mask pattern. As everybody knows a positive photoresist profile has a positive slope of 75 - 85° depending on the process conditions and the performance of the exposure equipment (only submicron-resists get close to 90°). This is mainly due to the absorption of the PAC which attenuates the light when penetrating through the resist layer (so called bulk effect). The result is a higher dissolution rate at the top and a lower rate at the bottom of the resist. When AZ 5214E is processed in the IR-mode this is reversed as higher exposed areas will be crosslinked to a higher degree than those with lower dose, dissolution rates accordingly. The final result will be a negative wall profile ideally suited for lift-off. The most critical parameter of the IR-process is reversal-bake temperature, once optimised it must be kept constant within ± 1°C to maintain a consistent process. This temperature also has to be optimised individually. In any case it will fall within the range from 115 to 125°C. If IR-temperature is chosen too high (>130°C) the resist will thermally crosslink also in the unexposed areas, giving no pattern. To find out the suitable temperature following procedure is suggested: Coat and prebake a few substrates with resist. Without exposing them to UV-light subject them to different reversal- bake temperatures, i.e. 115°, 120°, 125° and 130°C. Now apply a flood exposure of > 200mJ/cm² and afterwards immerse them into a standard developer make up, i.e. AZ 351B, 1:4 diluted, or AZ 726 MIF for 1 minute. From a part of the substrates the resist will be removed, another part (those exposed to a too high temperature) will remain with the resist thermally crosslinked on it. Optimum RB-temperature now is 5° to 10°C below the temperature where crosslinking starts. The flood exposure is absolutely uncritical as long as sufficient energy is applied to make the unexposed areas soluble. 200 mJ/cm² is a good choice, but 150 - 500 mJ/cm² will have no major influence on the performance. Finally it should be noted that the imagewise exposure energy is lower than with normal positive processes, generally only half of that. So a good rule of thumb is: compared to a standard positive resist process, imagewise exposure dose should be half of that, flood exposure energy double of that for AZ 5214E IR-processing. Once understanding and being familiar with this IR-procedure it is quite simple to set up a different process for lift- off. A T-shaped profile can be achieved by the following process sequence: The prebaked AZ 5214E photoresist is flood exposed (no mask) with a small amount of UV energy, just to generate some exposed PAC at the surface. Now the reversal-bake is performed to partially crosslink this top areas. By this treatment a top layer with a lowered dissolution rate compared to the bulk material is generated. After this the resist is treated like a normal positive photoresist (imagewise exposure and development) to generate a positive image! Due to the lower dissolution rate in the top layer a T-shaped profile with overhanging lips will be the result.  45  PHYSICAL and CHEMICAL PROPERTIES  FILM THICKNESS [µm] as FUNCTION of SPIN SPEED (characteristically)  PROCESSING GUIDELINES  HANDLING ADVISES Consult the Material Safety Data Sheets provided by us or your local agent! This AZ Photoresists are made up with our patented safer solvent PGMEA. They are flammable liquids and should be kept away from oxidants, sparks and open flames. Protect from light and heat and store in sealed original containers between 0°C and 25°C, exceeding this range to -5°C or +30°C for 24 hours does not adversely affect the properties. Shelf life is limited and depends on the resist series. The expiration date is printed on the label of every bottle below the batch number and coded as [year/month/day]. AZ Photoresists are compatible with most commercially available wafer processing equipment. Recommended materials include PTFE, stainless steel and high-density poly-ethylene and -propylene.    AZ 5214E Solids content [%]   28.3 Viscosity [cSt at 25°C]   24.0 Absorptivity [l/g*cm] at 377nm   0.76 Solvent  methoxy-propyl acetate (PGMEA) Max. water content [%]  0.50 Spectral sensitivity  310 - 420 nm Coating characteristic  striation free Filtration [µm absolute]  0.1  spin speed [rpm]  2000  3000  4000  5000  6000  AZ 5214E  1.98  1.62  1.40  1.25  1.14  Dilution and edge bead removal AZ EBR Solvent Prebake  110°C, 50", hotplate Exposure  broadband and monochromatic h- and i-line Reversal bake  120°C, 2 min., hotplate (most critical step) Flood exposure  > 200 mJ/cm² (uncritical) Development  AZ 351B, 1:4 (tank, spray) or AZ 726 (puddle) Postbake  120°C, 50s hotplate (optional) Removal  AZ 100 Remover, conc.  46           The information contained herein is, to the best of our knowledge, true and accurate, but all recommendations are made without guarantee because the conditions of use are beyond our control. There is no implied warranty of merchantability or fitness for purpose of the product or products described here. In submitting this information, no liability is assumed or license or other rights expressed or implied given with respect to any existing or pending patent, patent application, or trademarks. The observance of all regulations and patents is the responsibility of the user. AZ, the AZ logo, BARLi , Aquatar and Kallista are registered trademarks of Clariant AG.  Clariant GmbH Business Unit Electronic Materials Rheingaustrasse 190 D-65203 Wiesbaden Germany Tel. +49 (611) 962-6867 Fax +49 (611) 962-9207 Clariant Corporation Business Unit Electronic Materials 70 Meister Avenue Somerville, NJ 08876-1252 USA Tel. +1 (908) 429-3500 Fax +1 (908) 429-3631 Clariant (Japan) K.K. Business Unit Electronic Materials 9F Bunkyo Green Court Center 2-28-8 Honkomagome Bunkyo-Ku Tokyo 113, Japan Tel. +81 (3) 5977-7973 Fax +81 (3) 5977-7894 Clariant Industries Ltd. Business Unit Electronic Materials 84-7, Chungdam-dong, Kangnam-ku  47  Seoul Republic of Korea Tel. +82 (2) 510-8000/8442 Fax +82 (2) 514-5918  48   6.2 Appendix B - Recipe for 10 um SPR220-7.0 Mold for 4-inch Si Wafers  Preparation Steps   Wafer is cleaned with Acetone, then Methanol, then Isopropanol Alcohol, and then gently blown with N2 gas.   Wafer is baked for dehydration for 20 minutes at 200°C, then cooled to room temperature for 10 min.  Spin Coating   The wafer is centered on the spinner chuck and vacuum sealed.   HMDS (hexamethyldisilazan) drops are placed on the wafer using a dropper until 50% of the wafer is covered.   HMDS is spun at 3500 rpm for 35 seconds. Let the wafer sit for 1 minute on the spinner before pouring photoresist.   SPR220-7.0 photoresist is poured over the wafer straight from the bottle, covering roughly half the area. The bottle should be cleaned thoroughly with a clean wipe before and after pouring. The wafer is spun for 5 sec at 500 rpm and 40 sec at 1500 rpm.   The wafer is let sit on the spinner for 1-2 minutes.  Photoresist Soft bake   The wafer is gradually warmed to 90 C, by using a layer of aluminum foil or wipe on the hotplate. After 1 minute transfer it directly to the 90 C hotplate, let it sit there for 2 min, then transfer to another hotplate at 115 C, let it sit for 3 min.   The wafer is slowly cooled to room temperature for 10 min  UV-Light Exposure   The wafer is loaded into the Canon PLA-501F double-side 100mm mask aligner.   The printed mask on a transparent sheet is attached to a thick glass plate and is loaded as the photomask into the mask aligner.   UV-light is exposed to the layer for 70 sec.   The wafer is let sit on the mask aligner for 1 min.   The wafer is cooled down at the room temperature 21°C for 30 min for dehydration.  Photoresist Develop   An MF 319 bath and a DI-water bath are prepared.   The wafer is placed into the MF-319 for 5 min and visually checked.    If the developments looks completed, the wafer is placed into the water bath for 1 min and is rinsed with DI water and dried with a N2 gun.   The pattern is checked under the microscope and especially the corners and posts are examined for complete development. The developing process can be repeated if additional development is needed.   The thickness of the pattern then is measured using the Wyko NT1100 interferometer.  Reflow Process   The wafer is placed on the hot plate for 2 min at 90°C.  49    The hotplate is set for 140 C and ramps up for 5 minutes, then the hotplate is shut off.   The wafer remains on the hotplate for 5 minutes for gradual cooling, then taken off and allowed to cool to room temperature.   The shape and the thickness of the pattern then are measured using Wyko NT1100 optical.  50   6.3 Appendix C - Project Charter (No signatures)  Project Charter  -  APSC 459/479, Engineering Physics Project Lab  Project Number, Title: 1071, A Micropump Using Thermally Activating Hydrogels  Project Summary: The aim of this project is to design and fabricate a thermally activated peristaltic micropump in a monolithic multi-layer polydimethylsiloxane (PDMS) device.  This project will incorporate the newly designed micropump into a fully portable microfluidic device that can be used to pump fluid and cells through the chip. The goal is to design thermally activated valves with a response time of <3 seconds and micropumps that can pump fluid at 0.1 nL/sec.  Start Date: September 27, 2010                     End Date: December 14, 2010  Statement of Deliverables: o A hydrogel actuated microvalve that has a response time of less than 3 seconds. o A portable device that allows the use of the fluidic chip independent of fixed power and air systems. o A peristaltic pump composed of hydrogel actuated valves capable of moving a cell in a loop.  Criteria for Success: o A hydrogel actuated microvalve that has a response time of less than 3 seconds. o A portable device that allows the use of the fluidic chip independent of fixed power and air systems. o A peristaltic pump composed of hydrogel actuated valves capable of moving a cell in a loop. o Team members become familiar with state of the art fabrication, bonding and microfluidic device characterization  Initial Budget Estimate and Source of Funds: Total expected costs: $928. Source of Funds: Dr. Stoeber and Granting Agencies. For details, see proposal.  51  Project Scope - Activities in Scope o Design, fabrication, characterization of all microfluidic devices supporting portable systems.   Activities out of Scope o None. Assumptions and Anticipated Risks (for detailed analysis, see proposal) o Peptide bonding and parylene bonding does not result in a leak-free bonding o Eric Lagally Unavailable o PIV does not work o Peristaltic valve kills cells o Water jet cutter is taken out of service o Heating is not consistent across heater o Cannot get thermally activated micropump to work.    Stakeholders:  Project Sponsor: Boris Stoeber Team Members: Philip Edgcumbe, Jun Wei Fu, Jan Vohradsky Project Lab: Jon Nakane, Chris Waltham, Bernhard Zender Advisor: Vahid Bazargan  Communication and Meeting Schedule: The Team Members will provide written weekly reports on Monday.  The Team Members will meet with the Project Sponsor weekly on Tuesday.  Other communication with stakeholders and resources by email and telephone as needed.   Other Issues: None.    Project Charter Sign-Off    Name/Date         Name/Date Project Sponsor Project Sponsor   52   Name/Date         Name/Date        Name/Date        Name/Date Team Member 1 Team Member 2  Team Member 3 Project Lab   53  6.4 Appendix D  - Team Member's Time Contributions Presented in Figure 19 is a graph of the team’s time contributions to the project per week.  The cumulative hours contributed is compared to the required 10 hours per week per team member.  Figure 19 – Team member’s time contributions vs. time  0 50 100 150 200 250 300 350 400 450 500 1 2 3 4 5 6 7 8 9 10 11 12 13 H o u rs  Week 0 50 100 150 200 250 300 350 400 450 500 1 2 3 4 5 6 7 8 9 10 11 12 13 H o u rs  Week 131  6.9 Appendix I - Series 4 Lithography Masks  PRODUCED BY AN AUTODESK EDUCATIONAL PRODUCT PR O D U C ED  B Y A N  A U TO D ES K  E D U C A TI O N A L PR O D U C T PRODUCED BY AN AUTODESK EDUCATIONAL PRODUCT PR O D U C ED  B Y A N  A U TO D ESK  ED U C A TIO N A L PR O D U C T 133  6.10 Appendix J - Cleanroom Wafer Fabrication Record  P hotore sist D ate (dd/m m ) Tim e at start of process (24:00) H M D S  spin (length of tim e @  speed- rpm ) Tim e that w afer is left on spinner after H M D S spin (m in) S P R  220- 7.0 spin (length of tim e @  speed- rpm ) Tim e that w afer is left on spinner after S P R  spin S oft bake step 1: length of tim e (m in) @  tem peratur e (celcius) S oft bake step 2: length of tim e @  tem per ature celcius Tim e cooling before exposure (m in) A llign vacuu m  needl e press ure E xpo sure tim e (sec) D evelopm e nt Tim e until first feature are readily apparent D evelopm e nt tim e (tim e w hen glass slide or w afer rem oved from  developer) Feature height (m icrons) C om m ents Q uestions P rofile height w ith alpha profilom eter 2 spr 220- 7.0 (spin program  m istake)~1 20 @  1500 70 6 -M ade spinner program m ing m istake so w afer w ith S P R  spun for ~ 120secs instead of 40 secs. 10 2 3 spr 220- 7.0 40 @ 1500 70 3 I fabricated this design w ith P atrick and w e both used the sam e program …  yet his features w ere 8 m icrons. The only difference is that I developed m y w afer four hours after exposure. I didn’t think this w ould be an issue because S arah had told m e that som e groups w ait an entire day before doing developm ent. 3 4 spr 220- 7.0 40 @  1500 70 2.5 4 5 spr 220- 7.0 40 @  1500 5 6 spr 220- 7.0 23/06 8:00:00 35 @  3500 2 5 @  500 40 @  1300 2 2 @  90 3 @  115 10 yes - 75 8 - This w as the 2nd w afer in a batch of 3 that P artrick and I m ade. - First w afer had bubbles form  im m ediately w hen w e placed it on the hot plate. - P ut alum inum  foil on hot plate to try to increase heat uniform ity of hot plate surface.  O ne or tw o bubbles form ed w hen w e placed the w afer on the hot plate.  H ow ever, w e w ere quite pleased w ith the w afer; - E ach tim e after pressing m ask load and allign w e checked to see if the glass slide w ith the m ask on it w as held in place.  W e found that it w as not been held in place.  H ow ever, P atrick said that previously the glass slide w as not held in place for him  and his m old had still w orked out succesfully so w e w ent ahead w ith the process. - B ecause w e had spun the S P R  m ore slow ly (1300 rpm  instead of 1500 rpm ) w e decided to expose m y w afer for 75 seconds instead of 70 seconds.  I w as very surprised at how  w ell the features w ere defined.  I could see the pattern on the w afer very easily - far better than I w ould have liked. - O nce w e had pressed allign w e m oved the glass slide that w as sitting on the m ask ali gner around to test the vaccuum  and even noted that w could pivot the glass slide on w hat appeared to be the w afer.  This m ight be partly w hy part of the w afer (0.5 cm  on the outside part of the w afer for 30%  of the circum ference) did not develop very w ell. - Full developm ent took about 6 m inutes. - O bservation w ith m icroscope show ed the sam e problem  w ith the colum ns (30 m icrons across instead of 10 m icrons across and poorly defined edges) - M aybe bubbles are from  heat shock?  S hould w e perhaps transfer the w afers to a hot plate that is at 60 degrees before transfering it to a 90 degree plate? A llison does som ething like this. - B ad idea to soft bake w afers on alum inum  and not increase tem perature or duration of baking. - Future plan is to put w afer on alum inum  foil for 30 secs and then rem ove the alum inum  foil and start the tim er for the regular baking process. 6 7 spr 220- 7.0 24/06 7:30:00 35 @  3500 2 5 @  500 40 @  1150 2 2 @  90 3 @  115 10 yes - 60 1:30:00 15:00:00 3 13 7 8 spr 220- 7.0 24/06 7:30:00 35 @  3500 2 5 @  500 40 @  1100 2 2 @  90 3 @  115 10 yes - 60 2:30:00 11:00:00 8 - this developed and let off m ore photoresist faster 8 9 spr 220- 7.0 25/06 7:30:00 35 @  3500 4 5 @  500 40 @  1500 2 3 @  90 3@ 115 10 yes - and the plate w as actuall y sucke d onto the top 60 1:00:00 6:00:00 9.5 - the only reason I had soft bake of 3 @  90 instead of 2 @  90 has not changed. - I w as doing w ide channel fabrication (design C  and design F) - I found that the colum ns in design  had the colum ns but design C  on the other end of the w afer did not have the 10 m icron colum ns develop. - I found that the glass slide w as suctioned very strongly to the m ask ali gner today.  This is likely because P atrick had cleaned the glass plat before w e used it today. 9 H 2 S hipley 18-13 25/06 7:30:00 2 1 @  115 10 20 I follow ed the exact recipe that Jonas gave m e. H 2 H 3 S hipley 18-13 ##### 1800 spun H M D S  on for 15 secs at 3500 rpm  and let it sit for 10 m ins.  This is because I m ade a m istake in the program m ing of the spinner.  I w ent ahead and baked to m ake the H M D S  less dangerous. Let spr sit for 7 m in w hile I w aited for the hot plate to cool.  I didn't put on enough photoresist so this w afer w as essentially w aster.  A  critical part w as not covered.  I did not expose this w afer. H 3 H 4 S hipley 18-13 ##### 1800 5 @  200 5@  500 35 @  3500 2 5 @  200 5@  500 40 @  2500 2 1 @  115 10 no - becau se I place d glass slide on dum m y wafer and the m ask directl y on top of the dum m y wafer. 20 5 secs 2.5 m in I w ill let the w afer sit for 90 secs after H M D S  and S hiple y 18-13 spinnin before m oving to the next step.  B oth H M D S  and photo-resist w ill get a slow  spin-on tim e. H 4 H 5 S P R  220-7.0 ##### 1800 5 @  200 5@  500 35 @  3500 2 5 @  200 5@  500 40 @  2500 2 1 @  115 10 no - ditto above 20 5 secs 2.5 m in exposure com plete at 8:34pm .  N ote: this heater recipe did not w ork. H 5 H 6 S hipley 18-13 ##### 1600 5 @  200 5@  500 35 @  3500 2 5 @  200 5@  500 40 @  2500 2 1 @  115 10 no - ditto above 20 5 secs 2.5 m in glass slides H 6-H 10 w ere under-developed.  I suspected that they w ere dirty but it turns out that I w as just looking at under-developed heater.  I left them  over the w eekend and exposed them  to U V  light so it w as too late to do anything.  V ahid show ed m e how  he could still scratch the heater electrode surface (w here there should have been only glass) and thus knew  that it w as under-developed.  I tried putting tw o of the heaters back in developer but the entire plate w as com pletely cleaned off.  N ote. H 6 H 7 S hipley 18-13 ##### 1600 5 @  200 5@  500 35 @  3500 2 5 @  200 5@  500 40 @  2500 2 1 @  115 10 no - ditto above 20 5 secs 2.5 m in H 7 H 8 S hipley 18-13 ##### 1600 5 @  200 5@  500 35 @  3500 2 5 @  200 5@  500 40 @  2500 2 1 @  115 10 no - ditto above 20 5 secs 2.5 m in H 8 H 9 S hipley 18-13 ##### 1600 5 @  200 5@  500 35 @  3500 2 5 @  200 5@  500 40 @  2500 2 1 @  115 10 no - ditto above 20 5 secs 2.5 m in H 9 H 10 S hipley 18-13 ##### 1600 5 @  200 5@  500 35 @  3500 2 5 @  200 5@  500 40 @  2500 2 1 @  115 10 no - ditto above 20 5 secs 2.5 m in H 10 H 11 S hipley 18-13 5 @  200 5@  500 35 @  3500 2 5 @  200 5@  500 40 @  2500 2 1 @  115 10 no - ditto above 20 5 secs 2.5 m in H 11 H 12 S hipley 18-13 5 @  200 5@  500 35 @  3500 2 5 @  200 5@  500 40 @  2500 2 1 @  115 10 no - ditto above 20 5 secs 2.5 m in H 12 H 13 S hipley 18-13 5 @  200 5@  500 35 @  3500 2 5 @  200 5@  500 40 @  2500 2 1 @  115 10 no - ditto above 20 5 secs 2.5 m in H 13 H 14 S hipley 18-13 5 @  200 5@  500 35 @  3500 2 5 @  200 5@  500 40 @  2500 2 1 @  115 10 no - ditto above 20 5 secs 2.5 m in - sat on hot plate on paper tow el for about 90 seconds and then 30 seconds on the hot plate.  S oft bake w as longer than usual. S low  to develop H 14 H 15 S hipley 18-13 5 @  200 5@  500 35 @  3500 2 5 @  200 5@  500 40 @  2500 2 1 @  115 10 no - ditto above 20 5 secs 2.5 m in - I m ight have spun it at 3500 rpm  instead of 2500 rpm .  N ot sure. W hen I w ent to adjust the program  for H 16 H D M S  I found it already at 3500 rpm  instead of the 2500rpm  I expect.  I could have already changed it back.  B ut I doubt it. H 15 H 16 S hipley 18-13 5 @  200 5@  500 35 @  3500 2 5 @  200 5@  500 40 @  2500 2 1 @  115 10 no - ditto above 20 5 secs 2.5 m in - S tarted spinning it w hile I w as still in the program .  It reach 2500 rpm  very quickly (about 500 rpm /sec) and then stayed around 2500 rpm  for about 5 secs before I stopped it and properly started the program . H 16 H 17 S hipley 18-13 5 @  200 5@  500 35 @  3500 2 5 @  200 5@  500 40 @  2500 2 1 @  115 10 no - ditto above 20 5 secs 2.5 m in H 17 H 18 S hipley 18-13 5 @  200 5@  500 35 @  3500 2 5 @  200 5@  500 40 @  2500 2 1 @  115 10 no - ditto above 20 5 secs 2.5 m in H 18 H 19 S hipley 18-13 5 @  200 5@  500 35 @  3500 2 5 @  200 5@  500 40 @  2500 2 1 @  115 10 no - ditto above 20 5 secs 2.5 m in H 19 10 S P R  220-7.0 15/07 19:00:00 10@ 500 40 @  3500 10 10@ 500 40@ 1500 2 65 - H M D S  sat on w afer for 10 m in instead of the usual 1 m in because I found the S P R  220-7.0 lip w as covered in dried up  very carefully. - P D M S  really stuck to this w afer. 10 11 S P R  220-7.0 15/07 19:00:00 10@ 500 40 @  3500 2 10@ 500 40@ 1500 2 65 11 12 S P R  220-7.0 15/07 23:00:00 10@ 500 40 @  3500 2 10@ 500 40@ 1500 2 65 - w ide channel C  and F (only w ide channel F can be used because C  is m issing som e of its colum ns) 12 13 S P R  220-7.0 15/07 23:00:00 10@ 500 40 @  3500 2 10@ 500 40@ 1500 2 65 - snake design C ,D ,E  and F - good, I used this w afer a lot and then I broke it in half.  N ow  only design C  and E  are still useable. 13 14 S P R  220-7.0 19/07 17:00:00 10@ 500 40 @  3500 2 10@ 500 40@ 1500 2 2@ 90 3@ 110 5 saw  needl e, no vacuu m  on plate 65 7:30:00 - accidentally put heater at 110 instead of 115 for 2nd step of soft bake 14 15 S P R  220-7.0 19/07 17:00:00 10@ 500 40 @  3500 2 10@ 500 40@ 1500 2 2@ 90 3@ 110 5 saw  needl e, no vacuu m  on plate 65 6:30:00 - accidentally put heater at 110 instead of 115 for 2nd step of soft bake - cleaned 15 H 20 S hipley 18-13 26/07 14:00:00 10@ 500 40 @  3500 10@ 500 40@ 1500 ~2 1@ 115 10 yes 20 5 secs 2:30:00 2 - H eater C  - snake design - I spun H M D S  at 2500 and then again at 3500 (because the first tim e w as too slow , a m istake) H 20 H 21 S hipley 18-13 26/07 14:00:00 10@ 500 40 @  3500 10@ 500 40@ 1500 ~2 1@ 115 10 yes 20 5 secs 3:45:00 - H eater B   - snake design H 21 H 22 S hipley 18-13 26/07 14:00:00 10@ 500 40 @  3500 10@ 500 40@ 1500 ~2 1@ 115 yes 25 10:00:00 - H eater C  - snake design: exposed on july 27 at 1:38pm - right m ost heater doesn't have connection - gold evaporated H 22 H 23 S hipley 18-13 27/07 11:30:00 10@ 500 40 @  3500 10@ 500 40@ 1500 ~2 1@ 115 yes 20 (3 to 7 m ins) - H eater F - w ide channel - no good, heater elem ents still connected together I m ixed up H 23 and H 29 because their indelible labels w ashed off in the acetone bath.  O ne of H 23 and H 29 had a strange developm ent w here after the 3rd tim e of rinsing and sitting in acetone the gold becam e orange and the heating elem ents w ere m uch less clear. H 23 H 24 S hipley 18-13 27/07 11:30:00 10@ 500 40 @  3500 10@ 500 40@ 1500 ~2 1@ 115 yes 20 (3 to 7 m ins) - H eater A  - snake design - good - G old evaporated - P ut in acetone bath on July 27th.  Left in bath for 24 hours, no good results. H 24 H 25 S hipley 18-13 27/07 11:30:00 10@ 500 40 @  3500 10@ 500 40@ 1500 ~2 1@ 115 yes 20 3:00:00 - H eater F - w ide channel - good - G old evaporated H 25 H 26 S hipley 18-13 27/07 11:30:00 10@ 500 40 @  3500 10@ 500 40@ 1500 ~2 1@ 115 yes 20 (3 to 7 m ins) G old elem ent: 0.3 m icrons - H eater E  - snake design - good - G old evaporated onto this one - First one to develop (evening of July 27th... I didn't have a good scratching tool yet so I destroyed all of the heater connections) H 26 H 27 S hipley 18-13 27/07 11:30:00 10@ 500 40 @  3500 10@ 500 40@ 2000 ~2 1@ 115 yes 25 7:00:00 - H eater B  - snake design - good - G old evaporated - P ut in acetone at 1:10pm  on July 29 H 27 h28 S hipley 18-13 27/07 14:00:00 10@ 500 40 @  3500 10@ 500 40@ 2000 ~2 1@ 115 yes 25 (3 to 7 m ins) - H eater C  - snake design - new  S 1813 and did not clean slide - good - G old evaporated I m ixed up H 23 and H 29 because their indelible labels w ashed off in the acetone bath.  O ne of H 23 and H 29 had a strange developm ent w here after the 3rd tim e of rinsing and sitting in acetone the gold becam e orange and the heating elem ents w ere m uch less clear. h28 h29 S hipley 18-13 27/07 14:00:00 10@ 500 40 @  3500 10@ 500 40@ 2000 ~2 1@ 115 yes 25 (3 to 7 m ins) - H eater C  - snake design - new  S 1813 and did not clean slide - good - evaporated gold onto this but I placed it upside dow n in the evaporator so the gold w as evaporated onto the w rong side so I can't use it. h29 yes H 30 spr220- 7.0 29-07 17:30:00 10@ 500 40 @  3500 10@ 500 40@ 4000 1 2@ 115 (not very sure - m ight have been 1@ 115) yes 60 4:40:00 N ote for H 30-H 33: I cleaned the glass slides w ith acetone, IP A , w ater, N 2 blow ing, 5 m ins at 110, 10 m ins cooling.  B ut they still looked quite dirty. - H eater E  snake design - over-developed or over-exposed.  There seem s to be m ore heater than their should be and the corners are not very sharp - I planned to do soft bake of 2@ 115 but I m ight have done 1@ 115 out of habit... this m ight explain the poor results. H 31 spr220- 7.0 29-07 17:30:00 10@ 500 40 @  3500 10@ 500 40@ 4000 1 2@ 115 (not very sure - m ight have been 1@ 115) yes 60 4:40:00 - H eater A  w ide channel - over-developed or over-exposed.  There seem s to be m ore heater than their should be and the corners are not very sharp. - I planned to do soft bake of 2@ 115 but I m ight have done 1@ 115 out of habit... this m ight explain the poor results. H 32 S hipley 18-13 29-07 17:30:00 10@ 500 40 @  3500 10@ 500 40@ 1500 1 1@ 115 yes 28 - H eater A  w ide channel - did not use the 10 secs on cloth before soft bake for this glass slide (accident) - terrible features, can barely m ake out the elem ents, bubbly H 33 S hipley 18-13 29-07 17:30:00 10@ 500 40 @  3500 10@ 500 40@ 1500 1 1@ 115 yes 28 - H eater B  snake design - ok to good result h34 S hipley 18-13 30/07 12:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 1500 1 1@ 115 yes 22 2:00:00 - w ide channel A - very very blurry features, cannot even see elem ents.  E ric O uelette (student in Lagally lab) suggested it w as because the m ask and photoresist on the glass slide (4cm  x 7.5cm ) w ere not m aking contact. H ow ever, he agreed that I w as setting up the glass slide on the m ask alligner correctly.  H e also suggested that I use M F-24A  instead of M F- 319 for developm ent.  V ahid said that M F-24A  and M F-319 are quite sim ilar and that it w as not im portant. h35 30/07 12:30:00 yes H 35 and H 36 got m ixed up... I exposed one of the slides tw ice and the other not at all.  I only realized the m istake once I put the slide I had not exposed in the developer and nothing happened. h36 30/07 12:30:00 1 yes h37 S P R  220-7.0 30/07 12:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 yes 50 1:50:00 - w ide channel A - good results h38 spr 220- 7.0 30/07 15:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 yes 50 <2 - W ide channel F - good - N ote: for H 38-H 43 I w as really careful to m ake sure to w ait 10 m ins for slides to cool after I dehydrated them  after w ashing, I w aited 10 m ins after soft bake and 20 m ins after exposure.  A ll of the slides (H 38-H 43) w orked w ell.  I'm  hesitant to attribute the success to the extended w aiting tim es.  O f H 30-H 37, H 35 and H 36 w ere m ixed up.  I suspect that H 30 and H 31 got 1@ 115 instead of 2@ 115 and.  That leaves H 32 (terrible - s1813), H 33 (good -s1813), H 34 (terrible - s1813), H 37 (good shipley 220-7.0).  I can't explain w hy H 32 and H 34 did not w ork out... m aybe it w as the w ait tim es. h39 S hipley 18-13 30/07 15:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 1500 1 1@ 115 10+ yes 25 <2 - W ide channel F h40 spr 220- 7.0 30/07 15:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 10+ yes 50 <2 - S nake design A - O k h41 spr 220- 7.0 30/07 15:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 10+ yes 55 (acci dent) <2 - snake design C - very good h42 S hipley 18-13 30/07 15:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 1500 1 1@ 115 10+ yes 25 <2 - snake design B h43 S hipley 18-13 30/07 15:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 1500 1 1@ 115 10+ yes 25 <2 - snake design E H 44 S hipley 18-13 ##### 18:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 1500 1 1@ 115 60 m in yes - heater snake design D - quick check = good H 45 S hipley 18-13 ##### 18:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 1500 1 1@ 115 60 m in yes 25 10s 2 - heater snake design C - - quick check = good H 46 S hipley 18-13 ##### 18:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 1500 1 1@ 115 60 m in yes 25 10s 2 - heater L5 - quick check = good H 47 S hipley 18-13 ##### 18:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 1500 1 1@ 115 60 m in yes 25 - heater w ide channel A - quick check = ok to good h48 spr ##### 18:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 60 m in yes 53 10s 2 - heater L5 - exposure of 53 w as an accident.  It should have been 50 - quick check = good h49 spr ##### 18:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 60 m in yes 50 - heater w ide channel A - quick check = ok to good 16 spr 220- 7.0 ##### 9:45:00 5 secs @ 500rpm 35 secs @ 3500rpm 1 5 secs @ 500rpm 40 secs @  1500rpm 1 2@ 90 3@ 115 20 yes 65 1m in 7 9.6 - D esign 3A ,3B ,3C  and 3D h50 s1813 16/8/2 010 17:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 1@ 115 60 m in 50 - dirty specs after spinning h51 s1813 16/8/2 010 17:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 1@ 115 60 m in 50 - dirty specs after spinning h52 spr 220- 7.0 16/8/2 010 17:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 60 m in yes 50 1:40:00 - started developm ent 40 m ins after exposure - all good except for top right heater h53 spr 220- 7.0 16/8/2 010 17:30:00 10@ 500 40 @  4000 1 10@ 500 40@ 4000 1 2@ 115 60 m in yes 50 1:40:00 - bake tim e questionable - a bit over 2 m in - started developm ent 40 m ins after exposure - all good h54 spr 220- 7.0 16/8/2 010 17:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 60 m in yes 50 2:00:00 - spun on H M D S  at 4000rpm  by m istake - w aited 35 m ins after exposure before developm ent - bottom  left heater = good - centre left heater = ok - centre right heater = good - top three heaters are all m erged together h55 spr 220- 7.0 16/8/2 010 17:30:00 10@ 500 40 @  4000 1 10@ 500 40@ 4000 1 2@ 115 60 m in yes 50 2:05:00 - only w aited 10 secs before rem oving glass slide from  m ask alligner - 40 m ins bw  exposure and developm ent - top 3 are good, bottom  three are m erged... passable but far from  ideal h56 spr 220- 7.0 16/8/2 010 17:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 60 m in 50 - dirty, can't use h57 spr 220- 7.0 16/8/2 010 17:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 60 m in 50 - spun on H M D S  at 4000rpm  by m istake - dirty can't use h58 spr 220- 7.0 16/8/2 010 17:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 2000 1 2@ 115 60 m in 50 - spun on spr at 2000rpm  by m istake h59 spr 220- 7.0 16/8/2 010 17:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 60 m in yes 50 2:30:00 - tw o of three of top heaters are m erged together so I can't use them . B ottom  heaters are good. - started developm ent 16 m ins after exposure h60 spr 220- 7.0 16/8/2 010 17:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 60 m in yes 50 2:00:00 - top left 2 heaters are good the rest all have som e m erging m aking them  less than ideal - 40 m ins sitting out betw een exposure and developm ent h61 spr 220- 7.0 16/8/2 010 17:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 60 m in yes 50 1:40:00 - all good h62 spr 220- 7.0 16/8/2 010 17:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 60 m in yes 50 1:40:00 - bottom  three are good - one of three of top one are good h62b spr 220- 7.0 16/8/2 010 17:30:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 60 m in yes 50 1:40:00 - bottom  three are good - one of three of top one are good 17 spr 220- 7.0 ##### 16:10:00 5 secs @ 500rpm 40 secs @ 3500rpm 15 5 secs @ 500rpm 40 secs @  1500rpm 1 2@ 90 3@ 115 30 no - can see vacuu m  is on (m ain vacuu m  displa y) 65 1 7 - turned on U V  light at 4:20pm - had lon g delay betw een H M D S  and S P R  220-7.0 application because couldn't open the spr container and spent a lot of tim e cleaning the lid. - w hen I took w afer out of spinner after spinning on spr it looked really good and sm ooth.  I put the w afer onto 1 sheet of paper tow el that I had just placed on the heater surface.  In the first four seconds on the paper tow el on the surface four bubbles appeared on the w afer.  A lso, I noticed that the reflection of li ght off the w afer also changed w hile it w a been heated.  Instead of of clean reflection all the w ay across it started to have islands (som e large som e sm all) of reflection. - at 4:42pm  I took w afer off 115C  and left it to cool. - let sit for 7 m inutes betw een exposure and developm ent - looked good under the m icroscope after exposure.  W ei W ei noted a few  dark streaks that alm ost w ent all the w ay across the channels. P hilip is not sure w hat it is but feels that it is a sm all im perfection and that the fabrication process is good so w e should continue w ith the other tw o. - at 6:20pm  started reflow .  P ut 4 tim e folded napkin flat on 90C  hot plate im m ediately before placing w afer on napkin.  Let sit for 1 m in. R em oved napkin and left on hot plate until 90C  for 5 m in.  R am ped tem p up to 140C  over a period of 5 m in w ith w afer on hot plate.  Left on hot plate at 140C  for 5 m ins then turned off heater and left w afer on heater for 10 m inutes. 18 spr 220- 7.0 ##### 17:10:00 5 secs @ 500rpm 40 secs @ 3500rpm 1 5 secs @ 500rpm 40 secs @  1500rpm 1 2@ 90 3@ 115 25 no - can see that vacuu m  is on thoug h 65 1 6m in - tw o spots after spinning - three m ore spots appeared during heating - saw  a spec of dust on it w hen w e w ere about to do exposure... not sure w here the dust cam e from . 19 spr 220- 7.0 ##### 17:10:00 5 secs @ 500rpm 40 secs @ 3500rpm 1 5 secs @ 500rpm 40 secs @  1500rpm 1 2@ 90 3@ 115 12 no - can see that vacuu m  is on thoug h 65 40sec 6m in - w ei w ei did this process on his ow n w ith P hilip's supervision - perfect w afer.  N o specs after spinning or after soft bake. - this w afer ended up been a w rite-off because w e put the glass slide dow n w ith the transparency facing up instead of sitting directly on top of the w afer.  This m eant that the exposure pattern w as w ay off.  W e had to throw  out this w afer. H 63 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 20 no - ditto above 55 20 secs 2 m in - H 4S - accidentally exposed for 55 secs. I m eant to expose for 50s - after exposure and developm ent the slide looks good.  There is one im perfection at heater 11.  C ontact m ight be broken. - defined new  convention for heaters.  There are 12 heaters per slide and w e num ber them  in row s of 3 going from  left to right. H 64 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 10+ no - ditto above 55 2 - H 4L - tw o specs after spinning. - - generally good after developm ent.  S lightly concern that the glass and photoresists seem  quite dirt y.  Lots of 5 m icron specs.  O nly heate 11 has a piece of spec big enough that m akes m e think it m ight not form  a full heater. H 65 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 no - ditto above 7um -23 m in after exposure - no blem ishes, m edium  dirty H 66 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 no - ditto above 55 7um - H 4L - 45 m in after exposure - quite clean but blem ishes at 3,6 and 8 H 67 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 10+ no - ditto above 55 2 - H 4S D idn't take the slide off the paper tow l on the oven for 2 m inutes.  B ake it for an extra 1 m in to com pensate. - w iped dow n transparency before exposure - generally clean.  S light blem ish on heater 1. - I rinsed w ith D I w ater for extra long tim e. - 8 m in after exposure H 68 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 no - ditto above 60 2 - H 4W - accidentally left it on uv for 5 extra secs - 16 m in after exposure - extra rinse.  generally clean.  5 is slightly suspect. - A ll heater conduct.  H eater 4,5,6,9 and 12 did not have good lift-off. 8 has sm all part that didn't com e off for lift-off. I w ill use this slide for plasm a bonding and place pdm s on heaters 7-12. H 69 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 10+ no - ditto above 55 2 - H 4L - very clean, very good.  S light blem ish at 11.  I rinsed this one w ith w ater after developm ent for an extra long tim e. - 45 m in after exposure H 70 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 10+ no - ditto above 55 2 -D eveloped before exposure.  w ashed w ith D I w ater, then exposed. - 14 m ins after exposure - extra rinse.  generally clean.  N o blem ishes. - A ll heater conduct and have resistance of approx. 300 ohm .  H eaters 6,8,9,11 and 12 didn't have good lift-off H 71 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 no - ditto above 55 2 - 7 m in after exposure - extra rinse. generally clean.  N um ber 12 has hair lying across it. - A ll heater traces conduct except for #12. H 72 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 10+ no - ditto above 55 2 -H 4L 20 spr 220- 7.0 ##### 22:00:00 5 secs @ 500rpm 40 secs @ 3500rpm 1 5 secs @ 500rpm 40 secs @  1500rpm 1 2@ 90 3@ 115 n/a n/a n/a n/a n/a n/a - W afer cam e from  box of w afers in bioM E M S  lab.  The box w as no longer sealed and left out in bioM E M S  so there are specs of dust on the w afer.  W e used the cleanroom  m icroscope and found a w aver w ith w hat appeared to be no dust on it.  W e scanned the entire w afer w ith the 5x objective and saw  nothing.  A fter pouring and spinning on the P D M S  and placing the w afer on several layers of paper tow el on the 90C  heater w e found that at least 50 bubbles appeared on the w afer. This m ust be because of the dirtiness of the w afer because w afers 17, 18 and 19 did not have this problem  and they com e from  the box of w afers that w ere kept in the cleanroom . 21 spr 220- 7.0 27/12/ 2010 22:00:00 5 secs @ 500rpm 40 secs @ 3500rpm 2 5 secs @ 500rpm 40 secs @  1500rpm 1 2@ 90 3@ 115 10+ no, 65 2 10 - A s per B en M ustin's suggestion I cleaned the w afer w ith acetone, ipa and m ethanol, blow  dried it and let it sit for 45 m inutes on the hot plate at 200C  and then cool dow n at room  tem p at 200C .  B en su ggested I l it sit for 10 m inutes but I had a long conversation w ith S ultan so the w afers sat for 45 m inutes on the hot plate. - N o specs appeared during heating, good final result. 22 spr 220- 7.0 27/12/ 2010 22:00:00 5 secs @ 500rpm 40 secs @ 3500rpm 2 5 secs @ 500rpm 40 secs @  1500rpm 1 2@ 90 3@ 115 10+ no, 65 2 10 10.2um - A s per B en M ustin's suggestion I cleaned the w afer w ith acetone, ipa and m ethanol, blow  dried it and let it sit for 45 m inutes on the hot plate at 200C  and then cool dow n at room  tem p at 200C . - O nly shook developing try every three m inutes.  This m ay explain w hy the tw o left fluidic channels do not have w ell defined edges. H 73 s1813 29/12/ 2010 1600 10@ 500 40 @  3500 1 10@ 500 40@ 1500 1 1@ 115 10+ no 25 3 2um - this is a reject because photoresist didn't cover entire glass slide.  but w ent ahead to see how  exposure w orks H 74 s1813 29/12/ 2010 1600 10@ 500 40 @  3500 1 10@ 500 40@ 1500 1 1@ 115 no 25 1.5 - happy w ith developer results.  D esign looks very good.  heater trace #2 has one part w ith slightly rough edges but should still w ork fine. M aybe slightly overdeveloped - valleys for heater traces are a little fat. H 75 s1813 29/12/ 2010 1600 10@ 500 40 @  3500 1 10@ 500 40@ 1500 1 1@ 115 no 25 1.5 - happy w ith developer results.  D esign looks very good.  heater trace #2 has one part w ith slightly rough edges but should still w ork fine. S harp features, sharper then H 74.  This is strange because both had 25 second exposure and both w ere in sam e developer bath for sam e length of tim e +/- 5 secs - m ore spots on this one - i suspect the spots com e from  the perm anent m arker dissolving.  I could see the spots in the solution.  I should use fine tip m arker to m inim ize this problem . H 76 s1813 29/12/ 2010 1600 10@ 500 40 @  3500 1 10@ 500 40@ 1500 1 1@ 115 - m ight have som e w ater w ith photoresist because i cleaned the pipette bulb w ith w ater after it got som e photoresist in it and w hen I next used it (on this heater) som e w ater cam e out. - happy w ith results.  A ll good H 77 s1813 29/12/ 2010 1600 10@ 500 40 @  3500 1 10@ 500 40@ 1500 1 1@ 115 no 25 2 - photoresist does not cover glass slide entirely so w on't use.  O ne of the heaters also has som ething on it w hich spans three traces. H 78 s1813 29/12/ 2010 1600 10@ 500 40 @  3500 1 10@ 500 40@ 1500 1 1@ 115 no 25 2 - good.  I find that it is slightly overdeveloped.  I w orry that gold traces are not spaced far enough apart. H 79 s1813 29/12/ 2010 1600 10@ 500 40 @  3500 1 10@ 500 40@ 1500 1 1@ 115 no 25 2 - all good. H 80 s1813 29/12/ 2010 1600 10@ 500 40 @  3500 1 10@ 500 40@ 1500 1 1@ 115 no 25 1 - I feel this is the best glass slide i have.  I w as agitating it the w hole tim e but i only let if sit in developer for 1 m inute instead of tw o.  The features are m uch m ore sharp and the gold traces w ill be spaced farther apart from  each other.  I stopped developing a little before the last of the developer cam e off. H 81 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 10+ no - ditto above 55 2 - all good after developm ent H 82 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 10+ no - ditto above 55 2 - all good after developm ent H 83 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 10+ no - ditto above 55 2 - generally good except for: 4,5, 8,12.  A ll the bad ones have dirt on them .  M aybe this is because I didn't use a new  developer.  I re-used the developer bath from  H 81, H 82 - batch 2 H 84 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 10+ no - ditto above 55 2 - generally good except for: 8 (but its a m inor blem ish), and 6 (m inor blem ish) - still go ahead and develop. - batch 3 H 85 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 10+ no - ditto above 55 2 - generally good except for: 6,7,8,10.  A ll the bad ones have dirt on them .  M aybe this is because I didn't use a new  developer.  I re-used the developer bath from  H 81, H 82 - batch 2 H 86 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 10+ no - ditto above 55 2 - all good - batch 3 H 87 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 10+ no - ditto above 55 2 - all good, cleanest glass slide by far.  This is interesting because I did not use perm anent m arker.  I suspect that perm anent m arker contributes to a dirty glass slide.  S urprisingly, 1-6 looks slightly over- developed w hereas 7-12 looks really good.  It's hard to understand how  one half of a slide can be over developed. - batch 4 H 88 spr 220- 7.0 ##### 21:00:00 10@ 500 40 @  3500 1 10@ 500 40@ 4000 1 2@ 115 10+ no - ditto above 55 2 - all good, cleanest glass slide by far.  This is interesting because I did not use perm anent m arker.  I suspect that perm anent m arker contributes to a dirty glass slide - batch 4 139  6.11 Appendix K - Glass Slide Record  H eater # PD M S design Single (S) or double (D ) layer PD M S - if D include the thin layer spin speed D ate that glass and PD M S bonded together Post-bonding treatm ent. C ooking tim e (C T) and W eight (W ) on device Plasm a cleaning treatm ent.  BioM EM S (B) or cleanroom  (C ) Pressure w here leakage occurs across gold (psi) Pressure w here leakage occurs betw een PD M S and glass (psi) C om m ents 23456789 SD -D D 20/7/2010 B - very dirty surface => long strands of hair. - right valve has channel collapse and the m em brane bonding to the glass slides. - cannot use this chip. - I suspect that there are tw o slide 9s 1011 SD -B D 22/7/2010 C T: 48 hours in the oven B - I placed the pdm s on the activated glass surface and then picked it up to reallign it. - O nly the right valve has a connected heater and it leaks in m any places.  It w ould take several m inutes to fill actual channels in the valve because there is so m uch leakage. 12B SD -A D B - R ight valve has gold heater that is very poorly defined and has hair on the slide too... but for som e reason there is no leakage to 20 psi.  Sm all leakage started around 20 psi. 13141516 Vahid's old heater Tw o good snake designs cut into tw o pieces each D  - ? rpm 10/8/2010 W :C leanroom phone C : Vahid recipe.  G lass aligning (G A), w ait tim e (W T) #1: N o G A, no W T #2: N o G A, yes W T #3: Yes G A, yes W T #4: Yes G A, yes W T 10 20 Leakage and very dirty w it lots of hair on it.  W hen I w as hole punching the device I leaned over the exposed devices and m aybe that’s w hen som e hair fell dow n? 17 12/8/2010 181920 H 46 3A (ok to bad allignm ent) and 3B (good allignm ent) D  - 2700rpm 17/8/2010 W : ? C  - direct placem ent - Vahid's recipe 10-12psi 25+ This is the good slide w ith the new  design that is m y best hope yet in term s of flow  stoppage.  There is leaking along the gold both betw een the interior channels and side channel (that is there for allignm ent puropose) and the inside channel and the coolant channel. 21 . 22 3C  and 3D . D  -3000rpm 20/8/2010 W : cleanroom phone (5m in) C  - direct placem ent - Vahid's recipe 23 H 62 3A and 3B D - 3000rpm 23/8/2010 W : tw o scrap alum inum  blocks in bioM EM S C T: 4 hours in bioM EM S oven B - direct placem ent (betw een 30secs and 1 m in) - 45 seconds of plasm a - Looks dirty.  This is frustrating because I used tape to rem ove dust from  PD M S and I used com pressed air to rem ove dust from the heaters before plasm a treatm ent so I expected the bond to be clean. 24 H 41 Snake D esign C 2000 3/10/2010 W : 8lbs brick C T: 14 hours in BioM EM S 65deg C oven C  - direct placem ent - Vahid's recipe 13psi Brought PD M S slides from  cleanroom  to BioM EM S lab for ~5m in before brick w as placed on.  H eater w as not used previously because of gold specks on surface.  Tested it and leakage did not start until 13psi over very thick gold surface of 13psi. 25 blank glass slide 3D 2000 3/10/2010 W : 8lbs brick C T: 14 hours in BioM EM S 65deg C oven C  - direct placem ent - Vahid's recipe D id not see any leakage.  H ighest pressure w e w ent to w as 21 psi. This PD M S w as suspect because it did not cure properly. 26 H 53 3B and 3C D - 2000 8/10/2010 - pressed freshly plasm a treated pdm s w ith back- end of tw eezers quite hard.  This likely contributed to channel collapse. The glass slide w as cracked w hen it w as rem oved from the oven.  This chip either had an 8lb or 3lb w eight on it.  I (Philip) am 90%  sure it w as 8 lb. C  - direct placem ent - Vahid's recipe - W ei W ei m ixed the PD M S for this device. M 40 - slide 26 m ovie w as created for design 3C  that show s that dense colum ns do not provide good holding point for gel. - D esign 3C , Snake D esign, has serious m em brane collapse.  The m ain channel leaving the pressure outlet is 90%  collapsed and the solution needs to go a long w ay along the collapsed channels before getting into the heater elem ent of the device.  D esign 3C also has a glass crack that runs across it. - D esign 3B has dense colum ns and w e show ed it is not very good at holding a gel. H eater # PD M S design Single (S) or double (D ) layer PD M S - if D include the thin layer spin speed D ate that glass and PD M S bonded together Post-bonding treatm ent. C ooking tim e (C T) and W eight (W ) on device Plasm a cleaning treatm ent.  BioM EM S (B) or cleanroom  (C ) Pressure w here leakage occurs across gold (psi) Pressure w here leakage occurs betw een PD M S and glass (psi) C om m ents 27 blank glass slide 3A single layer, 10:1 21/10/2010 10 m ins at room tem p then. W : 8lb brick, C T: 24 hours in bioM EM S 65C oven C  - direct placem ent - Vahid's recipe: pow er: 30, pressure: 500, tem p:25, O 2:100, tim e: 20secs N o gold on chip N ever saw leakage.  Tested until 30 psi. The collapsed pdm s stayed collapse so there w asn't m uch room  for flow . - I gently touched the entire PD M S surface w ith m y finger until I could see the plasm a bond starting to occur.  I did not exert m ore than half a pound of force w ith the flat of m y finger so the chip felt at m ost the pressure equivalent to a 3 lb w eight. - Full channel collapse after 24 hr in oven. 28 blank glass slide 3C single layer, 10:1 21/10/2010 10 m ins at room tem p then. W : 3lb m etal block, C T: 24 hours in bioM EM S 65C oven C  - direct placem ent - Vahid's recipe: pow er: 30, pressure: 500, tem p:25, O 2:100, tim e: 20secs N o gold on chip N ever saw leakage.  Tested until 30 psi. Very fast flow  because no channel collapse in the fluidic channel. - I gently touched the entire PD M S surface w ith m y finger until I could see the plasm a bond starting to occur.  I did not exert m ore than half a pound of force w ith the flat of m y finger so the chip felt at m ost the pressure equivalent to a 3 lb w eight. - Very little channel collapse after 24 hr in oven (at first I thought there w as none).  A tiny bit of collapse on 1/6 of chip (one side of one of the valves) 29 blank glass slide 3B single layer, 10:1 21/10/2010 10 m ins at room tem p then. W : 0lb, C T: 24 hours in bioM EM S 65C oven C  - direct placem ent - Vahid's recipe: pow er: 30, pressure: 500, tem p:25, O 2:100, tim e: 20secs N o gold on chip M aybe saw leakage at 25psi. D ifficult to tell because flow resistance is so low  that the fluorescent dye reservoir is used up at 30 psi in only a few  seconds. G enerally, good leakage protection. - I gently touched the entire PD M S surface w ith m y finger until I could see the plasm a bond starting to occur.  I did not exert m ore than half a pound of force w ith the flat of m y finger so the chip felt at m ost the pressure equivalent to a 3 lb w eight. - O nly collapse that occured after 24 hr in oven w as in the coolant channels. 30 blank glass slide 3D single layer, 10:1 21/10/2010 5 m ins at room tem p then. W : 8lb brick, C T: 24 hours in bioM EM S 65C oven C  - direct placem ent - pow er: 30, pressure: 500, tem p:25, O 2:100, tim e:10secs N o gold on chip - So m uch channel collapse that I can not get any flow  in the chip.  I didn't see any leakage... but that's of lim ited value because no fluid left the pressure inlet area. - I gently touched the entire PD M S surface w ith m y finger until I could see the plasm a bond starting to occur.  I did not exert m ore than half a pound of force w ith the flat of m y finger so the chip felt at m ost the pressure equivalent to a 3 lb w eight. - - Full channel collapse after 24 hr in oven. 31 blank glass slide SD -E single layer, 10:1 23/10/2010 N o finger pressing, bond and then w eight only. W : 8lb C T: 24 hours in bioM EM S C  - direct placem ent - Vahid's recipe: pow er: 30, pressure: 500, tem p:25, O 2:100, tim e: 20secs N o gold on chip - Tested to 20 psi and saw  no leakage. - For slides 31-34 I cleaned w ith acetone, IPA and w ater and 10m in at 115C  and 10 m in at room  tem p before bonding. I placed the PM D S on glass as soon as they cam e out of the PEC VD  and I could see the bond occuring.  I did not put any pressure on the PD M S im m ediately after placing the PD M S on the glass w ith m y finer like i did previously.  I instead put the respective w eights onto the PD M S.  This took about tw o m inutes after bonding because the w eights w ere in the gow ning room  and I had to place the pdm s on the glass first. - C ollapse everyw here.  I could only get flow  in one of the three valves because there w as so m uch collapse in the pressure inlet. In the channel that I did get flow  it w as only tem porary because the pressure outlet w as blocked.  There w as no leakage up until 20 psi w hich is w here I stopped testing. 32 blank glass slide SD -C single layer, 10:1 23/10/2010 N o finger pressing, bond and then w eight only. W : 3lb C T: 24 hours in bioM EM S C  - direct placem ent - Vahid's recipe: pow er: 30, pressure: 500, tem p:25, O 2:100, tim e: 20secs N o gold on chip - Tested to 20 psi and saw  no leakage. - C ollapse everyw here 33 blank glass slide SD -F single layer, 10:1 23/10/2010 N o finger pressing, bond and then w eight only. W : 0lb C T: 24 hours in bioM EM S C  - direct placem ent - Vahid's recipe: pow er: 30, pressure: 500, tem p:25, O 2:100, tim e: 20secs N o gold on chip - Tested to 20 psi and saw  no leakage in top left valve (M 71). - Tested and saw m ajor leakage from  one part of channel to another at 5 psi in bottom right valve (M 72) - C ollapse in m any places 34 blank glass slide SD -D single layer, 10:1 23/10/2010 N o finger pressing, bond and then w eight only. W : 8lb C T: 24 hours in bioM EM S C  - direct placem ent - pow er: 30, pressure: 500, tem p:25, O 2:100, tim e:10secs N o gold on chip - Tested to 20 psi on left (M 73) and right channels and saw  no leakage. There is significant collapse at pressure outputs (near bottom ) so flow  can not leave the channels. - C ollapse in m any places H eater # PD M S design Single (S) or double (D ) layer PD M S - if D include the thin layer spin speed D ate that glass and PD M S bonded together Post-bonding treatm ent. C ooking tim e (C T) and W eight (W ) on device Plasm a cleaning treatm ent.  BioM EM S (B) or cleanroom  (C ) Pressure w here leakage occurs across gold (psi) Pressure w here leakage occurs betw een PD M S and glass (psi) C om m ents 35 H 52 3C  and 3D D - 3000rpm 25/10/2010 N o finger pressing, bond and then w eight only. W : 8lb/2 (I had the brick lying on both chips) C T: 24 hours in bioM EM S C  - direct placem ent - Vahid's recipe: pow er: 30, pressure: 500, tem p:25, O 2:100, tim e: 20secs - Failure at 5 psi for all three channels on chip on the "top" part of the glass slide.  ie: nearest to L5S - - Failure at 5 psi for all three channels on chip on the bottom  of the chip. - Tested to 10 psi and saw  no leakage - After I saw  5 psi failure on the gold heater I set up a T junction to try and see how  m uch pressure the PD M S to glass boundary could hold.  H ow ever, I w as only to go up to 12 psi before the path along the gold from  the control channel to coolant channel started to leak. - I confirm ed that the valves are w orking.  I applied 10 psi at pressure inlet and could see the valves m oving up and dow n. - a few  places w ith collapse.  But not m uch to speak of. 36 blank glass slide single layer 31/10/2010 light finger pressing c: 3lb C T: 24 hrs in bioM EM S C  - direct placem ent - Vahid's recipe: pow er: 30, pressure: 500, tem p:25, O 2:100, tim e: 20secs - no gold - Tested to 30 psi via T junction test and saw  no leakage - no collapse anyw here - glass slide cracked w hen I w as placing w eight on top of it so I could only test tw o of the three valves. 37 blank glass slide single layer 31/10/2010 no finger pressing c: 8lb/2 C T: 24 hrs in bioM EM S C  - direct placem ent - pow er: 30, pressure: 500, tem p:25, O 2:100, tim e:10secs - no gold - Slide 3D  : - Tested to 30 psi via T junction test and saw  no leakage - Slide 3B: - Tested to 20 psi via flow  technique and saw  no leakage - this slide has tw o m ulti-layer chips on it.  3B and 3D .  3D  is flaw less, it has no collapse and holds pressure to 30 psi.  3B w as cut too sm all so the pressure outlets are not fully enclosed so solution can leak out from  the part of the pressure output w hich has an interface w ith the outside air.  3B w as only test to 20 psi on one channel and it did not leak.  There is som e collapse in the coolant channel and in the colum n areas near the collapsed pressure outlets. 38 blank glass slide single layer 31/10/2010 no finger pressing c: 8lb/2 C T: 24 hrs in bioM EM S C  - direct placem ent - pow er: 15, pressure: 500, tem p:25, O 2:100, tim e:10secs - no gold - Slide 3A: Tested to 30 psi via T junction test and saw  no leakage - Slide 3C :  Tested to 30 psi via T junction test and saw  no leakage (N ote: I did see leakage in the center valve but I have not reported it as leakage because it w as sim ply a piece of hair or dust that had fallen on the device and causing the leakage. - Slide 3A: C ollapse in right valve (defined w rt the num bering 3A on top left of chip) at pressure inlet and outlet.  Bottom  is very badly collapsed, only allow s tw o stream s of 20 m icrons across through. C entre valve had no collapse.  After about 10 secds at 30 psi all of the colum ns in the bottom  part of the centre valve had their adhesion fail so that I could not longer see the colum ns w hen the pressure w as on (note, I probably w ent over psi because the pressure valve w as about three full turnns of the adjuster past the m ax display).  O n left valve, top and bottom , the colum ns failed at 30 psi after a few  seconds.  For the left valve I w as careful not to exceed 30 psi. - Slide 3C : N o collapse anyw here. 3000 spin 11/7/2010 39 parylene-parylene -com plete collapse on both pdm s chips.  At 30 psi, could not push any solution into the chip. 40 parylene-parylene - com plete collapse on 11/12 pressure inlets so that at 30 psi w e could not push any solution into the chip.  O ne pressure inlet w as not totally collapsed so w e could push solution into the chip. H ow ever, there w as lots of leakage.  It flow ed out of the channels alm ost as if the channel boundaries w eren't there. 41 blank glass 4C m ulti-layer 20/11/2010 Bonded im m ediately, no finger pressing, 0.5 lb w eight on pdm s from  2m in-20m in at room  tem p. Then 45 m in in oven. C  - direct placem ent - Vahid's recipe: pow er: 30, pressure: 500, tem p:25, O 2:100, tim e: 20secs n/a n/a - This w as a very thin m ulti-layer device.  I tested it at 5psi and found that m ost of the fluid cam e out at the pressure inlet because the seal w as not very good for such a thin PD M S chip. - N ote: I found hair on the chip.  I cleaned glass slide w ith aceton, ipa and w ater and i took pdm s directly off w afer so I didn't think I needed to tape it.  I suspect the hair fell onto the PD M S.  I think it is w orthw hile to tape the PD M S so that it is protected up until treatm ent and cleaned just before the bonding w hen the tape is rem oved. 42 blank glass super thin m ulti- layer 21/11/2010 - N o finger pressing. W : 8lb C T: 36hrs C  - direct placem ent - Vahid's recipe: pow er: 30, pressure: 500, tem p:25, O 2:100, tim e: 20secs - pdm s for this chip w as cured at 65C  for 24+ hours before plasm a bonding - C ollapse on tw o areas before zigzags in control channel - everything else is fine. 43 blank glass super thin m ulti- layer 21/11/2010 - N o finger pressing. W : 4lb C T: 36hrs C  - direct placem ent - Vahid's recipe: pow er: 30, pressure: 500, tem p:25, O 2:100, tim e: 20secs - pdm s for this chip w as cured at 65C  for 24+ hours before plasm a bonding - m inor collapse in coolant channel and side of inlet - but generally good. H eater # PD M S design Single (S) or double (D ) layer PD M S - if D include the thin layer spin speed D ate that glass and PD M S bonded together Post-bonding treatm ent. C ooking tim e (C T) and W eight (W ) on device Plasm a cleaning treatm ent.  BioM EM S (B) or cleanroom  (C ) Pressure w here leakage occurs across gold (psi) Pressure w here leakage occurs betw een PD M S and glass (psi) C om m ents 44 blank glass super thin m ulti- layer 21/11/2010 - N o finger pressing. W : 0.5lb C T: 36hrs C  - direct placem ent - Vahid's recipe: pow er: 30, pressure: 500, tem p:25, O 2:100, tim e: 20secs - pdm s for this chip w as cured at 65C  for 24+ hours before plasm a bonding - no significant collapse. 45 H 4L heater tw o m ulti-layer chips 21/11/2010 - N o finger pressing. W : 0.5lb C T: 36hrs C  - direct placem ent - Vahid's recipe: pow er: 30, pressure: 500, tem p:25, O 2:100, tim e: 20secs - pdm s for this chip w as only cured at 65C  for 4 hours before plasm a bonding - extensive channel collapse.  C ould barely push any fluid through. This m ight be because the PD M S only had a four hour bake tim e. 46 blank glass slide 4C one double-layer chip 24/11/2010 - N o finger pressing. W : 4lb C T: 26hrs C  - direct placem ent - pow er: 30, pressure: 500, tem p:40, O 2:100, tim e:15secs no failure up to 30psi. - acetone, ipa and w ater clean and 115C  for 5 m ins before plasm a - Pdm s prepared on N ov. 21 and only had 4 hours in oven for curing on N ov. 21st.  It set out at room  tem p from  N ov. 21st to N ov. 24th. - valved closes around 12 psi.  M inor collapse but generally happy w ith bonding results. 47 H 4X heater 4D one double-layer chip 24/11/2010 - N o finger pressing. W : 4lb C T: 26hrs C  - direct placem ent - pow er: 30, pressure: 500, tem p:40, O 2:100, tim e:15secs no apparent leakage, although no high pressure testing w as done on this device. no failure until 12 psi and later had very bad failure at 10 psi during flushing of device.. - - acetone, ipa and w ater clean and 115C  for 5 m ins before plasm a -- Pdm s prepared on N ov. 21 and only had 4 hours in oven for curing on N ov. 21st.  It set out at room  tem p from  N ov. 21st to N ov. 24th. - 2/3 of the PD M S control layer w as left on the w afer w hen it w as pulled off so the device only had one functioning valve. - valve closes around 12 psi.  M inor collapse but generally happy w ith bonding results. - see video M 94 48 H 4X heater 4B, 4D tw o double-layer chip 30/11/2010 - N o finger pressing. W : 4lb C  - direct placem ent - pow er: 30, pressure: 500, tem p:25, O 2:100, tim e:15secs - note: i did not plasm a treat to clean inside of pecvd like jonas suggested before bonding.  need to rem em ber to do that in future. - Valves 1-3 w ere w ere not properly bonded, causing a w idespread rupture w hen fluid w as pushed in. - Valve 4 exhibited significant collapse. - The 7-9 valves on this chip appeared to be viable, but the PD M S covered the set of pads closest to the device. - Valve 10 w as partially collapsed; valve12 w ere com pletely collapsed such that fluid could not be pum ped through. 49 blank glass slide - spun at 3500 rpm  1 m in after m ixing - acetone, ethyl alcohol, w ater, hot plate clean 50 blank glass slide - spun at 7000 rpm  5 m in after m ixing - air clean only 51 blank glass slide - spun at 3500 repm  8 m in after m ixing - air clean only 52 Vahid's old device. Vahid used this device 2 years ago for his research.  W e w ant to see if w e can recreate the sam e results that he got. - H eight of gold traces is 400nm - Vahid gave us this slide 53 H 70 4A D  - PD M S m ade in late nov and pulled off w afer #18 on dec 27 28/12/2010 no finger pressing W : 4lb C T: ___ C  - direct placem ent - pow er: 30, pressure: 500, tem p:25, O 2:100, tim e:15secs In one of the channels the bonding failed at 30psi. The next channel survived 30psi and the rest of the channels w ere not tested. Philip w rites on Jan. 9: O nly info I could find w as in w ork record D 366 w hich says: "Tried pum ping w ater through the channel. First channel has leakage all the w ay to the outside. The m iddle channel seem s O K w hen I am  running w ater through it. There is som e collapse but I am  able to pum p w ater through the channel." 54 H 63 4A, 4B D 30/12/2010 B - 40seconds The PD M S on the com pleted chip had to be trim m ed. This probably reduced the bonding strength of the spun-on PD M S-glass bond. All of the channels on the device subsequently failed badly at 25- 30psi. - O n D ec 30 Philip spun on a thin layer of PD M S at 8000 rpm . - 3/6 blocked and the heaters are bad. - 9/12 toast - H eater 5 hairy but flow  is good. - H eater 8/11 hairy. Flow  good. 55 H 69 Jan.4: - cleaned slide w ith acetone, IPA and w ater and put glass slide at 115C  for 10 m inutes then let it cool. - Prepared 10:1PD M S w ith 3:30 m ixing and 2:30 defoam ing and spun on at 8000rpm  for 1 m in. - Put in 65C  oven at 14:50. Jan.5: Thin m em brane w as ruined so I poured 50 gram s of PD M S onto the slide and plan to pull off all of the PD M S after the PD M S has cured in the oven.  I'll have to spin on new  8000rpm  PD M S onto this glass slide H eater # PD M S design Single (S) or double (D ) layer PD M S - if D include the thin layer spin speed D ate that glass and PD M S bonded together Post-bonding treatm ent. C ooking tim e (C T) and W eight (W ) on device Plasm a cleaning treatm ent.  BioM EM S (B) or cleanroom  (C ) Pressure w here leakage occurs across gold (psi) Pressure w here leakage occurs betw een PD M S and glass (psi) C om m ents 56 H 72 - Valve 2-5 leaked at 10 psi - Valve 1-4 leaked at 5 psi after I lifted needle out of PD M S and that caused the PD M S to com e up.  The needle w as really stuck in so I don't think this m eans there w as bad PD M S-glass bonding. - Jan.5:  I cleaned heater 72 w ith acetone, ipa and w ater and 115C for 5 m inutes and poured 10:1 PD M S (3:30 m ixing and 2:30 defoam ing) onto it and spun it at 8000 rpm  and placed it in the oven. Tom orrow  it w ill be ready to bond to the last tw o of the m ulti- layer PD M S chips I m ade today. 57 sm all blank glass slide A single m ultilayer valve from  the Jan. 5th w afer #21 fabrication. B - 40 seconds.  Put 250 m L beaker on it and left it in the over for 10 m inutes after plasm a treatm ent.  I cleaned the PD M S w ith tape and did not clean the glass slide at all. 1psi - Fluorescent dye started leaking out of channels before I'd even turned on the pressure.  It seem ed like the capillary pressure w as pulling the fluorescent dye forw ard and out.  W hen I took the needle out of the chip the PD M S alm ost cam e off the glass.  This w as an EXTR EM ELY bad bond. There is no w ay I could have tested the m ulti-layer valve w ith this. - The heaters on this device w ere extrem ely hairy. 58 H 4W 4A (covers valve 7-12) and 4D (covers valve 1-6). D ouble layer, spin speed of 2000 rpm , 80 m inutes before allignm ent, 1/7/2011 W : 450 gram w eight over both PD M S chips (so 225 gram s per chip) C T: 20 m inutes. B - 40 seconds.  I cleaned both surfaces w ith tape before plasm a bonding. - heaters on 2/5 and 8/11 are bad. all other valves w ere ruptured in experim enting. 59 H 4W 4B on both triple layer 2000rpm 1/9/2011 - heater 1 jum pered - heater 3 has broken trace - instant rupture w hen 5psi applied to 7,8 and 9. 1,2,3,10,11 and 12 w ere ruptured from  surgery to clear pads. - pushing fluid from  side 5, I could not get it through the area 5 zig zags at 15psi.  attem pts to m assage the chip failed.  The device ruptured at 20psi. - pushing from  side 4, the flow  is sluggish and needs >10psi.  there is leakage to the fluidic layer such that the fluid prefers to fill the fluidic channel instead of entering the area 1 zig zags. 60 H 4W triple layer 2000rpm 1/9/2011 - 9/12 faulty pdm s and cut off before bonding. - holes not punched in control channel for 1-6. - device w as a com plete failure from  the start. 145  6.12 Appendix L - Macro Assembly  4 3 0 .8 7 7 1 .1 2 5 0 1 5 9 .6 1 2 4 7 .6 1 4 5 .7 2

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