Microfabrication and characterization of dual-frequency piezoelectric micromachined ultrasonic transducers

Dual-frequency piezoelectric micromachined ultrasonic transducers (pMUTs) have been fabricated with the same microfabrication process flow as the traditional pMUT and characterized by methods including impedance analysis and pulse-echo measurements. The measurement results indicate that dual-mode resonances with minimized crosstalk on a single pMUT diaphragm can be realized by optimizing the configuration of two top electrodes. And the dual-frequency pMUT with almost no crosstalk was demonstrated by pulse-echo experiments. This is a debut for the development of dual-frequency ultrasound-on-a-chip technology for next-generation biomedical applications such as super harmonic imaging.