An ultra-compact piezoelectric motor with self-satisfied symmetry for enhanced performance

The symmetry and compactness of the structure has a considerable impact on the properties of piezoelectric motors, including step size, threshold voltage, and effective length. This is particularly evident in motors driven by the inertia principle. Asymmetric and eccentric designs have been observed to result in greater deflections and wobbling during operation, which in turn leads to additional energy loss derived from the energy generated by piezoelectric deformation and further impedes enhancements in overall compactness. In order to address this issue, we present an inertial piezoelectric motor that offers high stability and adaptive symmetry in this paper. The motor's structure ensures that the four edges of the sliding shaft always remain tangent to the inner wall of the piezoelectric tube, thereby achieving a uniform distribution of pressure and friction while ensuring the motor's self-satisfying symmetry and coaxial alignment. The effective length of the piezoelectric motor is only 9 mm, which is just 30% of the length of a conventional inertial piezoelectric motor, exemplifying a remarkably high degree of compactness. With a step size ranging from 0.1 to 1 μm at room temperature and a threshold voltage of about 30 V, these motors are small, simple, and extremely compact, demonstrating significant potential for applications in scanning tunneling microscopes used in narrow and confined spaces.