The low temperature coefficient and high linearity of the input-output characteristics are both required for high-performance microelectromechanical systems (MEMS) capacitive accelerometers. In this work, a structural designing of a bulk MEMS capacitive accelerometer is developed for both low temperature coefficient and high linearity. Firstly, the contrary effect of the wide-narrow gaps ratio (WNGR) on the temperature coefficient of the scale factor (TCSF) and linearity error is discussed. Secondly, the ability of an improved structure that can avoid the contrary effect is illustrated. The improved structure is proposed in our previous work for reducing the temperature coefficient of bias (TCB) and TCSF. Within the improved structure, both the TCSF and linearity error decrease with increasing WNGR. Then, the precise designing of the improved structure is developed for achieving lower TCB, TCSF, and linearity error. Finally, the precise structural designing is experimentally verified.

The ultrasonic motors (USM) based on microelectromechanical systems (MEMS) technology utilize the inverse piezoelectric effects to drive the rotor through the friction force to realize the torque output. Therefore, the generation of a stable traveling wave within the stator is a key to USM performance, which heavily depends on the quality factor ( Q ) and the mode match level of a stator resonator. The current ring stators of micromotor exhibited an apparent mode mismatch and a relatively low Q value due to the displacement constraints and anchor loss of supporting beams. This article, through the modal analysis and energy dissipation evaluation of stators, proposes an elaborate design to improve the mode match and Q value by positioning the supporting beams at the saddle points of the B ₁₃ modal shape and introducing a buffering annular frame between beams and substrate. The designed stator has the natural frequency of 101.63 and 100.90 kHz and Q value of 89.5 obtained from the finite element method. And the prototype experiment shows the natural frequencies of two modes are 100.76 and 101.5 kHz, respectively, the maximum deflection of the stator under driving voltage of 0.5 and 1 V are 3.96 and 4.43 μ m, respectively, and the Q value is 84.58. Both the frequency and rotation tests indicate the proposed motor displays, a much higher Q , and extremely better mode match than current ones.

The piezoelectric thin-film traveling-wave micro-motor based on the microelectromechanical systems (MEMS) process has the advantages of compact size, easy integration and batch production. However, the piezoelectric thin-film micro-motor still exits a serious shortcoming of very small output torque. This paper proposes a novel lead zirconate titanate (PZT) piezoelectric thin-film motor with stator teeth to improve the output torque. Firstly, theoretical analysis and finite element simulations were performed to determine the design parameters of the stator teeth. The device preparation is completed by combining with wafer-scale MEMS fabrication techniques, in which the base Si layer of PZT-SOI wafer is thinned and etched to form the stator tooth structure based on the deep reactive ion etching (DRIE) process. Finally, the performance testing results showed that the novel motor achieved a large output torque of 39.4 $\mu$ N $\cdot$ m under a low driving voltage of 4.5 Vpp. The large output torque is 2.65 times higher than that of the previously reported piezoelectric thin-film motor with a much higher driving voltage of 11 Vpp. 2023-0099