200 kHz pMUT using PZT on PDMS membrane for sonar applications

An effort to enhance receiving response of piezoelectric micromachined ultrasonic transducer (pMUT) at low frequency is reported. PMUT is fabricated on the glass substrate with the vibrating membrane formed by a layer of polydimethylsiloxane (PDMS) polymer. Lead zirconate titanate, Pb(Zr, Ti)O3 (PZT) is utilized as the piezo-active layer and nickel as electrodes. Spin coating and low temperature wafer bonding are proposed as part of the key fabrication methods. Fabricated transducer is characterized in the compact acoustic tank setup using 500 kHz and 1.25 MHz reference projectors. Analyses reveal the resonance frequency of pMUT is at 200 kHz where maximum receiving response at −36.6 dB re 1V at 10 λ and 20 V peak to peak of drive voltage on reference projector. Finally, response spectrum of the transducer is plotted against two commercial hydrophones at equivalent frequency band for validation and comparison.