Couple Stress Effect on Micro/Nanocantilever-based Capacitive Gas Sensor

Micro/nanocantilevers have been employed as sensors in many applications including chemical and biosensing. Due to their high sensitivity and potential for scalability, miniature sensing systems are in wide use and will likely become more prevalent in micro/nano-electromechanical systems (M-NEMSs). This paper is mainly focused on the use of sensing systems that employ micro/nano-size cantilever beams for sensing gaseous molecules. Micro/nanocantilever-based gas sensing is concerned with determining the micro/nanocantilever resonance shift or detecting the micro/nanocantilever deflection due to adsorption event. This paper has considered the former approach, i.e., determining the resonance shift. In order to explain these changes more clearly, a micro/nanobeam has to be modeled by considering some micro/nano scale parameters. A modeling based on classic elasticity theory potentially is unable to consider micro/nano scale parameters which have considerable effects on the behavior of the micro/nanobeams. The effect of couple stress on the stiffness of cantilever beams remains an outstanding problem in the physical sciences. So in this paper, a modeling based on couple stress theory has been applied to explore the behavior of a micro/nanobeam due to the adsorption of gaseous molecules. This work has attempted to advance the field of micro/nanocantilever based gas sensing by shedding more light on the mechanical behavior of micro/nanocantilever.