My thesis involves the development of polymer-based microfluidic systems. I performed the testing of channel integrity on PDMS (polydimethylsiloxane) based microfluidic systems depending on the size of the channel / side wall area and pressure of the fluid. Additionally, in a series of experiments, the bonding of various polymeric carriers (for example PMMA – polymethyl-methacrylate, PI – polyimide, PET – polyethylene-terephthalate) to PDMS-based microfluidic elements and the strength of the bond formed were examined.
My work involves designing channel systems with different geometries and manufacturing PDMS-based microfluidic cells using 3D printed molds and multi-step polymer machining technologies. The essential part of the task was the bonding of the produced PDMS microfluidic cells (adhesive free bonding) to different types of materials (glass, PET, PMMA, PI), the testing of different bonding technologies (e.g. oxygen plasma or corona discharge surface activation, silanisation etc.) as well as the qualification of the binding forces that have been measured with peeling tests.
I performed integrity tests on microfluidic systems with different channel geometry bonded to the glass substrate, during which I rated failures affecting the carrier-PDMS bonds due to overpressure coupled to the canal system. I have observed and proved by introductory experiments that the maximum load that can be connected to the canal system (as expected) depends on the ratio of the floor area of the channel / sidewall. The developed measurement method will be able to test the integrity of other channel systems in the future, and the measurement results are useful for developing PDMS based microfluidic systems.