Development and Experimental Validation of a Non-Linear, All-Elastomer In-Plane Capacitive Pressure Sensor Model

A large deformation mechanics model is applied to predict capacitance changes in an all-elastomer capacitive tactile sensor, and the predictive model is experimentally validated. The compressive model predicts a non-linear relationship between the contact normal force and resulting capacitance change due to changes in electrode gap and electrode layer thickness. Broad parametric studies demonstrate that higher sensitivities can be achieved with lower modulus materials and smaller electrode gaps. Sensors are fabricated using a reusable silicon mold and experimental results are compared to predictions from the capacitance model. Capacitance-force model predictions yielded by the calibrated capacitance analytical model are shown to be in remarkable agreement with experimental measurements. A fringe effects term included in the capacitance model highlights the limitations of the parallel plate model especially for sensors with large electrode layer gaps.