Low-pressure gas sensor exploiting the Knudsen thermal force: DSMC modeling and experimental validation

Abstract

We present performance modeling and experimental validation of a novel MEMS vacuum gas sensor based on the Knudsen thermal force. Direct simulation Monte Carlo (DSMC) modeling of thermally-driven gas flow and force measurements show a non-monotonic dependence on ambient pressure, peaking at a Knudsen number on the order of unity. Combining force dependence on pressure with the monotonically varying heat transfer rate allows both ambient pressure and species concentration to be determined if the constituents are known. The DSMC modeling also shows that thermal gradients between the shuttle and heater induce complex vortical flow structures that could be applied to control mixing/separation in gas-phase microfluidic devices.