Development of micropump using thermally activated hydrogels Vohradsky, Honza; Fu, Jun Wei; Edgcumbe, Philip
[Missing Title page] 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.
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