High sensitivity, high density micro-hydraulic force sensor array utilizing stereo-lithography fabrication technique

We introduce a micro-hydraulic force sensor with the ability to maintain high sensitivity at reduced footprint size to realize an array of force sensors with capability resembling human fingertip touch sensing. This sensor utilizes a micro-hydraulic structure as an enhanced sensing mechanism along with a tactile interface fabricated with a low cost, fast prototyping stereo-lithography apparatus. The sensor is capable of delivering high average sensitivity of 87 fF/mN (maximum observed: 260 fF/mN), a minimum detectable capacitance change of 80 aF at quiescence and a spatial resolution of 1 mm. It is sensitive enough to detect the fall of a 38.5 nL water droplet. The sensor full-scale force range with a 2-μm thick parylene membrane is 15 mN. With an array using 15 μm thick parylene, the full-scale range can be expanded to 180 mN.