Piezoelectric thick film for power-efficient haptic actuator

Abstract

Emerging haptic technology based on piezoelectric actuators enables to realize innovative tactile human–machine interface. The standard solution is based on stand-alone bulk ceramics glued directly on the haptic device. Thin-film actuators with metal–insulator–metal structure have been developed to directly integrate actuators on haptic plates. The thickness of thin films is limited to 2  μm, leading to large capacitance and, thus, too high-power consumption. To solve this issue, we developed haptic devices based on a 10  μm-thick PZT film deposited on a 0.65 mm-thick platinized silicon substrate. These thick films are made of a PZT composite slurry associated with sol-gel sol infiltration. They are dense and exhibit a permittivity of 1000 and dielectric loss lower than 0.05. Our fabricated haptic device containing three actuators connected in series exhibits an antisymmetric Lamb wave resonant mode at 62.0 kHz, in line with finite element modeling. At the limit of touch detection (1  μm out of plane deflection), the power consumption of the haptic device is 150 mW at 40 V. This represents a 15-fold consumption reduction with respect to the same haptic device made with 0.5  μm-thick PZT thin films.