Study on Wide-Band Piezoelectric Micro-Machined Ultrasound Transducers (pMUT) by Combined Resonance Frequencies and Controlling Poling Directions

For application to medical ultrasound imaging, we designed and prototyped a pMUT array of placing two types of pMUT cells with resonance frequencies of 8 MHz and 13 MHz in a simultaneously driven channel. In such transducer, spurious mode due to phase cancellation occurs in the transmitting and receiving characteristics between the resonance frequencies. By controlling the combination of polarization directions of the piezoelectric material on the respective pMUT cells, we found the spurious can be relaxed and the bandwidth can be widened.