All-elastomer in-plane MEMS capacitive tactile sensor for normal force detection

An all-elastomer microelectromechanical systems (MEMS) sensor to detect an applied normal force by measuring a change in capacitance was designed and fabricated; this is the first sensor of its kind to utilize in-plane conductive elastomer capacitors. Other works have demonstrated capacitive tactile sensors, but capacitors were oriented out-of-plane and often required more complex fabrication processes. This fabrication process uses silicon to mold and cure conductive and dielectric elastomers, which requires fewer steps and enables nonplanar electrode geometries. Experimental results for planar geometries matched a reduced order model for low strains (up to 15% strain) and a 10 μm dielectric gap resulted in a sensitivity of 85 fF/N. An “interdigitated” nonplanar electrode geometry was also fabricated and found to increase sensitivity by an order of magnitude (up to 1.1 pF/N) over basic “flat plate” electrodes.