Piezoelectric tactile integrated circuit sensor

Abstract

A two-dimensional, electrically multiplexed tactile sensor was realized by coupling a piezoelectric polyvinylidene fluoride (PVDF) polymer film to a monolithic silicon integrated circuit (IC). The IC incorporates 64 sensor electrodes arranged in a symmetrical 8×8 matrix. Each electrode occupies a 400×400-μm square area, and they are separated from each other by 300 μm. A 40-μm-thick piezoelectric PVDF polymer film was attached to the electrode array with a nonconductive urethane adhesive. The response of the tactile sensor is linear for loads spanning 0.8–135 grams of force (gf). The time required to electrically interrogate, measure, and record the response of the sensor’s set of 64 taxels is less than 50 ms, the hysteresis level is tolerable, and, for operation in the sensor’s linear range, taxel crosstalk is negligible. The historically persistent stability and response reproducibility limitations associated with piezoelectric-based tactile sensors have been resolved by implementing a precharge voltage bias technique to establish known pre- and postload sensor responses. A rudimentary tactile object image measurement procedure has been devised to recognize the silhouette of a sharp edge, square, trapezoid, isosceles triangle, circle, toroid, slotted screw, and cross-slotted screw.