A soft microfabricated capacitive sensor for high dynamic range strain sensing

This work demonstrates an all-elastomer MEMS capacitive strain sensor with high dynamic range (5000:1), and features an inexpensive molding microfabrication process. The sensor is comprised of conductive elastometric comb capacitors embedded in a dielectric. Two different sensor designs, lateral combs (LC) and transverse combs (TC), were developed to evaluate sensor sensitivity as a function of load orientation. Both sensors have combs with a gap of 30 μm, length of 4 mm, and depth of 65 μm. A linear elastic analytical model was developed to predict change in capacitance as a function of strain, and experimental results show a reasonable agreement with the theoretical predictions. The observed strain responses have high linearity and dynamic range, and negligible hysteresis. The strain resolution of the LC and TC sensors is 100 μstrain and 500 μstrain, respectively, tested up to 50% strain.