On gas permeation in PDMS

A theoretical model of gas permeation in polydimethylsiloxane (PDMS) is conducted for two prior works involving MEMS sensors and actuators. The issue for modeling a sensor is about using PDMS slabs to replace Pyrex glass as the packaging substrate for bulk-micromachined pressure sensors. The leakage pressure due to gas permeation in PDMS reveals the time-varying behavior of exponential decay. The issue for modeling an actuator is the flow rate in a PDMS-based gas permeation pump. The nonlinear dependence of the flow rate with the diffusion area can be explained by this model. The prediction of this theoretical result is therefore in qualitative agreement with two previous experimental data sets by a conventional curve-fitting technique.