A model for chemically-induced mechanical loading on MEMS

The development of full displacement field measurements as an alternative to the optical lever technique to measure the mechanical response for MEMS components in their environment calls for a modeling of chemically-induced mechanical fields (i.e., stress, strain, and displacements). As these phenomena usually arise from species adsorption, adsorbate modification or surface reconstruction, they are surface-related by nature and thus require some dedicated mechanical modeling. The accompanying mechanical modeling proposed herein is intended to represent the chemical part of the system free energy and its dependence on the surface amount. It is solved in the cantilever case thanks to an asymptotic analysis, and an approached closedform solution is obtained for the interfacial stress field. Finally, some conclusions regarding the transducer efficiency of cantilevers are drawn from the energy balance in the accompanying model, highlighting the role of surface functionalization parameters in micro-mechanical sensors engineering.