A Miniature Two‐Degree‐of‐Freedom Bipedal Piezoelectric Motor Driven by Low Voltage

ABSTRACT The demand for miniaturized, multi‐degree‐of‐freedom (DOF) piezoelectric motors with high power density and low driving voltage is growing across advanced technology fields. Achieving compact size while maintaining multi‐DOF motion and superior performance remains challenging. This study presents a bio‐inspired two‐DOF bipedal piezoelectric motor (BPM), which is fabricated via the multilayer co‐fired technology. The motor consists of a 1.9 mm ^Height × 1.9 mm ^Width × 7 mm ^Length bipedal piezoelectric stator (BPS) that is equipped with two friction tips, and the motor operate in coupled longitudinal and bending ( L _1,X B _2,Z and B _2,Y B _2,Z ) vibration modes. At a peak‐to‐peak driving voltage of 3.3 V _PP , the motor achieves velocities of 115 mm s ⁻¹ (X‐axis) and 110 mm s ⁻¹ (Y‐axis), maximum loads of 120 mN (X‐axis) and 110 mN (Y‐axis), as well as minimum step resolutions of 0.41 µm (X‐axis) and 0.33 µm (Y‐axis). Notably, it achieves a power density per unit voltage of 25.64 mW cm ^{− 3} V ⁻¹ , which is more than 40 times higher than previous reported multi‐DOF piezoelectric motors. These results demonstrate the motor's potential for applications in micro‐nano processing, portable electronics, and biomedical devices.