This paper presents a piezoresistive differential pressure sensor based on a silicon-on-insulator (SOI) structure for low pressure detection from 0 to 30 kPa. In the design phase, the stress distribution on the sensing membrane surface is simulated, and the doping concentration and geometry of the piezoresistor are evaluated. By optimizing the process, the realization of the pressure sensing diaphragm with a controllable thickness is achieved, and good ohmic contact is ensured. To obtain higher sensitivity and high temperature stability, an SOI structure with a 1.5 µm ultra-thin monocrystalline silicon layer is used in device manufacturing. The device diaphragm size is 700 µm × 700 µm × 2.1 µm. The experimental results show that the fabricated piezoresistive pressure sensor has a high sensitivity of 2.255 mV/V/kPa and a sensing resolution of less than 100 Pa at room temperature. The sensor has a temperature coefficient of sensitivity (TCS) of −0.221 %FS/°C and a temperature coefficient of offset (TCO) of −0.209 %FS/°C at operating temperatures ranging from 20 °C to 160 °C. The reported piezoresistive microelectromechanical systems (MEMS) pressure sensors are fabricated on 8-inch wafers using standard CMOS-compatible processes, which provides a volume solution for embedded integrated precision detection applications of air pressure, offering better insights for high-temperature and miniaturized low-pressure sensor research.

This paper delves into the enhancement of dynamic performance in Piezoelectric Micromachined Ultrasonic Transducers (PMUTs) under forced vibration in pulse wave mode, with an emphasis on mitigating blind area and enhancing axial resolution. The investigation begins with a theoretical framework that elucidates the relationship between the resonant frequency of the device and various excitation parameters, such as the applied frequency and the burst count. Empirical findings illustrate that the operation of PMUTs under forced vibration conditions significantly curtails the duration of ringdown by 40% compared to their resonant performance. Furthermore, acoustic range evaluations indicate that this methodology substantially reduces the blind area by 37.5% and amplifies the axial resolution of echo signals by approximately 440%. The study concludes that the proposed technique, noted for its universality and straightforwardness, provides a robust solution for enhancing near-range detection capabilities in ultrasonic sensors, thereby heralding considerable progress in the domain of precise acoustic measurements. This paper not only explicates the fundamental mechanisms but also substantiates the feasibility and efficacy of employing forced vibration in PMUT across diverse applications.