Photodefinable silicone MEMS gaskets and O-rings for microfluidics packaging

Fully-integrated MEMS gaskets and O-rings made of SU8 and photosensitive silicone are described and tested under varying conditions of compressive stress. An analytical theory of microgasket sealing behavior is also presented. The theory shows the critical importance of device surface flatness. The microgasket is found to be capable of deforming approximately 25% of its initial thickness and forming leak-free fluidic seals at inlet pressures below 50 psi. The microgasket is incorporated into a modular microfluidic system that exhibits system leak rates lower than 2.3 nL/min for working pressures up to 250 psi. Fabricated chip-to-chip interconnects exhibit a low dead volume of approximately 9 nL while further optimization can reduce dead volume per interconnect to about 1 nL.