Feasibility study of ultrasonic biometrics based on finger vessel imaging by epitaxial-PZT/Si piezoelectric micromachined ultrasonic transducer

[Display omitted] •Developed pMUTs based on the Epitaxial PZT and Polycrystalline PZT thin film.•Characterized the performances of the Epi-PZT and Poly-PZT pMUT in a body-coupled media FC-70.•Constructed a phased array system based on an Epi-PZT pMUT linear array and demonstrated the beamforming.•Demonstrated a 2-D ultrasonic image by using the Epi-PZT pMUT phased array.•Demonstrated the feasibility of the highly secure finger vessel biometrics by pMUT. In this study, we demonstrated a potential usability of a piezoelectric micromachined ultrasonic transducer (pMUT) for a high-performance body-coupled ultrasonic imager based on an epitaxial lead zirconate titanate (Epi-PZT) thin film. A finger vessel biometrics was proposed as one of its applications. At first, transmitting abilities and receiving sensitivities of the single-element pMUT based on Epitaxial-PZT (Epi-PZT) and polycrystalline-PZT (Poly-PZT) were evaluated as a fundamental study. It was experimentally verified that the Epi-PZT was a preferable material for a higher performance pMUT. Then, the linear array driven by a commercially-available pulser board was constructed, and successfully formed a focused ultrasonic beam. Finally, we demonstrated the ultrasonic imaging of a polydimethylsiloxane-based phantom by using the Epi-PZT pMUT array. We believe this achievement is a great step to realize the finger vessel biometric by pMUT.