Development of MEMS gas sensors equipped with metal organic frameworks

Abstract

In this study, we investigate the potential usage of electrostatic MEMS resonators for CO2 sensing. The MEMS sensor consists of two cantilever microbeams supporting a microplate coated with a Metal Organic Framework (MOF), namely ZIF-8. The detector material, ZIF-8, is synthesized using eco-friendly and sustainable production techniques and then deposited on the microplate to functionalize the sensor. An experimental setup, deploying the motion-induced current technique, is implemented and deployed to analyze the response of the gas sensor upon exposure to CO2. This method relies on a conversion mechanism that detects the motion of the sensor and translates it into a current signal. The experiments demonstrated the capability of the developed gas sensor to detect CO2. Motion-induced current measurements detected the nonlinear dynamic features of the sensor resulting from the presence of CO2 in various concentrations. We show effective deployment of frequency and amplitude changes in peak output current as detectors for the presence of CO2 and quantifiers of its concentration. Following the frequency-based approach, the sensor achieved a sensitivity of S=0.105 Hz/ppm. We also investigated a CO2 sensing mechanism that relies on the sudden and significant increase in the current amplitude at the onset of bifurcation. This sensing mechanism reached a sensitivity of S=0.903 pA/ppm.