Noninvasive Stress Detection Based on Piezoelectric Micromachined Ultrasonic Transducers for Bolt Loosening Warning. - Zhikang Li; Jiazhu Li; Yihe Zhao; Zixuan Li; Xuan Shi; Shaohui Qin; Jie Li 074; Jiawei Yuan; Qi Ma; Zilong Zhao; Shiwang Zhang; Zheng Yuan; et al. (IEEE Trans. Instrum. Meas., 2024)