Harnessing Nonlinear Squeeze-Film Damping Effects for Gas Sensing

In this paper, we exploit the potential of the inherent Squeeze-Film Damping (SQFD) effect in electrostatic Micro-Electro-Mechanical Systems (MEMS) resonators for gas detection applications, without the need for detector material coatings. We consider a MEMS device made of a microplate supported by two cantilever beams under electrostatic actuation via an underneath electrode. The motion-induced current is used to analyze the gas sensor’s response when exposed to different gases, namely, argon, nitrogen, air, oxygen, and carbon dioxide. This method involves detecting the sensor’s motion and converting it to an electrical signal. The experimental study provided evidence for the potential tunability of the gas sensor through the use of various detection mechanisms to detect and distinguish between different gases thanks to the high sensitivity of the SQFD to the gas viscosity. These mechanisms depend on nonlinear dynamic features arising from the strong coupling between the microplate and the surrounding fluid, combined with electrostatic actuation. Notable mechanisms include bifurcation, hysteresis, and softening behavior associated with the elastic effect of SQFD and enable to achieve low limit of detection in the order of a few ppm.