UBC Theses and Dissertations

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UBC Theses and Dissertations

Design, microfabrication, and characterization of a moulded PDMS/SU-8 inkjet dispenser for a lab-on-a-printer platform technology Bsoul, Anas Amjad Mohammad


This thesis presents a novel concept, lab-on-a-printer, whereby microfluidic modules are directly integrated into an inkjet dispenser. To enable this concept, a novel inkjet dispenser that can be integrated with microfluidic modules is designed, fabricated, and characterized. To limit the risk of cross contamination which is critical to many targeted applications, the inkjet dispenser is designed to have a modular structure that enables reusing its actuation unit and the disposal of its microfluidic chip. Furthermore, a low-cost fabrication process for the disposable microfluidic chip, mainly based on simple Polydimethylsiloxane (PDMS) moulding and SU-8 epoxy-based negative photoresist casting processes, is developed to reduce its cost. The use of PDMS in the fabrication of the microfluidic chip creates a path for its integration with pre-existing PDMS-based microfluidic modules. The fabricated inkjet dispensers are characterized to understand their limitations and identify their potential applications. For instance, droplet-to-droplet variations and maximum printable ink viscosity are used as characterization metrics. Diameters of more than 50,000 droplets per tested device are found to have a coefficient of variation (CV) in a range of 0.8% - 2.5% for each of 10 tested devices. A water and glycerol mixture with a viscosity of ~19 mP·s is identified as the mixture with maximum printable viscosity. Numerical simulations are employed to identify the key design parameters for the inkjet dispenser. These simulation results, combined with manufacturability constraints, are used to derive techniques for improving performance, hence broadening the potential applications of the technology. This resulted in inkjet dispensers with improved performance, where the maximum printable viscosity is doubled, meeting and surpassing commercial devices. Finally, a novel approach to integrate microfluidics with the inkjet dispenser is presented. This approach is successfully implemented to integrate the inkjet dispenser with a microfluidic mixer to demonstrate the capability of the integrated lab-on-a-printer platform concept, specifically the capability of printing patterns with a configurable ink composition. The presented lab-on-a-printer concept has potential applications in multiple scientific fields including biology, chemistry, and printable electronics.

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Attribution-NonCommercial-NoDerivatives 4.0 International