Investigation of the mechanical bending and frequency shift induced by adsorption and temperature using micro- and nanocantilever sensors

Abstract

The marked progress in MEMS/NEMS technology has demanded the development of a fundamental understanding of cantilever-based sensing principles. One of the challenges of cantilever-based detection is identifying and discerning the most influenced parameters responsible for the observed changes in the cantilever response. For example, effects of various force fields such as those induced by atom/molecular adsorption and variations in temperature may occur simultaneously, increasing the number of parameters that need to be concurrently measured to ensure the reliability of sensors. In this paper, we, therefore, systematically investigate the interplay between these two distinctly different mechanisms and attendant mechanical response. To this end, a theory model is proposed to predict the mechanical bending and resonance frequency shift of micro- and nanocantilevers taking into account atom/molecular adsorption and variations in temperature at the same time. The adsorption induced mechanical responses of microcantilevers are modeled for the van der Waals interaction in presence of surface effect. Thermal effects addressed here include the thermal mismatch between the substrate and coating layer owing to different thermal expansion coefficients and the temperature-dependent material properties. The theoretical and computational model developed here will allow one to gain an insight into not only the mechanical responses observed experimentally but also the fundamental, novel detection principles for sensing applications.