Face-shear mode ultrasonic tactile sensor array

Ultrasonic sensors using piezoelectric resonators are widely used for the chemical and biomedical applications because of their high sensitivity to applied loads, simple structures, and relatively low cost. In this study, we investigated an ultrasonic tactile sensing array using face-shear mode PMN-PT single crystal resonators, based on the sensing mechanism that electric impedance of a piezoelectric resonator is dependent on its surface acoustic load. An 8 × 8 sensing array was designed, fabricated and characterized. The electrical impedance changes induced by the applied surface loads including acoustic loads and surface forces were measured, and then, the contact shape of applied object was mapped by recording electric impedances of 64 elements.