Microwave-Induced Thermoacoustic Imaging Using Aluminum Nitride PMUT

This paper reports the novel application of an aluminum nitride (AlN) multi-cell piezoelectric micromachined ultrasonic transducer (PMUT) device in microwave-induced thermoacoustic imaging (MITAI). PMUT is used as the ultrasonic transducer (UT) in thermoacoustic imaging for the first time. This proposed PMUT device has an improved frequency response due to the design of cells with cavities in variant diameters. The device was characterized and tested in a microwave-induced thermoacoustic reconstruction process. The utilization of PMUT device was proved to achieve significantly higher quality images from reconstruction. The results from the proposed PMUT showed a decrease of 53% in mean square error (MSE) and increased the structural similarity (SSIM) by 19.7 times. This will potentially enable smaller yet better medical MITAI equipment.