A Broadband Piezoelectric Micromachined Acoustic Transducer with Variable Mass Loading

Broadband transducers occupy an important position in acoustic emission technology and its applications. The acoustic emission signals are usually caused by sudden local energy in materials or components, where the bandwidth needs to be wide. Therefore, it is inseparable from the broadband receiving transducer to extract a variety of useful information from the acoustic emission signal. Here, we present a broadband piezoelectric micromachined acoustic transducer by applying variable masses under different cantilever beams. The acoustic transducer operates in both the audible frequency band and ultrasound frequency band. The bandwidth is 2.54kHz and 37.1kHz when the sensor signal is attenuated by half (-6dB) in the primary and higher-order modes. Compared with previous transducers, the broadband transducer exhibits a flatter frequency response around the resonance region and a high output voltage in a wide frequency range. This is of great benefit to receive sound signals.