A Millimeter-Scale, High-Power Density Linear Piezoelectric Resonant Actuator

Micro/nano systems integrated with piezo-actuation technology have garnered significant attention in recent years. Here, we report a millimeter-scale linear piezoelectric resonant actuator (LPRA) operating in two orthogonal, coupled first-order bending vibrations modes. The proposed LPRA is made of a piezoceramic-metal composited bar with a center hole defect, which causes a sudden stiffness reduction in dense composite bar, leading to a prominent increase in the center vibration amplitude, thereby significantly enhancing the electromechanical coupling and interface actuation effect. A two-phase equivalent circuit is further derived to explain the enhancement behavior of the artificial defect. Under one pair of orthogonal voltages of 100 V_pp at 190.8 kHz, the elaborated micro-LPRA with a weight of only 0.149 g can frictionally drive a slider moving linearly via its center resonant vibrations, generating a maximum pulling load of 0.34 N, a maximum velocity of 308 mm/s, and a minimum step displacement of only 30 nm in open-loop control. Correspondingly, its power density is as high as 0.67 W/cm³, which is about 3 to 20 times higher than those reported previously. The proposed LPRA and its stiffness tuning strategy will bring great beneficial for future micro, smart devices/systems development.