A surface micromachined microtactile sensor array

This paper discusses the design and testing of an eight-by-eight tactile capacitive array sensor for detection of sub-millimeter features and objects, where the entire sensor array is smaller than normal human spatial resolution of 1mm. Each square tactel is less than 100μm on a side, with similar spacing between elements. The structural material was doped polysilicon with an air gap dielectric of 0.5μm. A thin (5080μm) protective layer of silicone rubber was adhered to the polysilicon surface of the sensor to provide interpolation of normal loads between elements. The sensors were tested and possessed good spatial uniformity, the capability of detecting millinewton forces, and good interpolation between elements. The sensors had severe hysteresis problems, but no detectable proximity effects.