Under-Display Ultrasonic Fingerprint Recognition With Finger Vessel Imaging

While fingerprint technology has been widely used in mobile devices for user identification, the existing fingerprint sensors can only capture 2D images of the fingerprint and are thus vulnerable to spoofing attacks using 2D replicas of fingerprint. Ultrasonic fingerprint recognition via imaging the structures beneath the human skin can be a promising approach for preventing spoofing attacks on fingerprint-based identification devices. In this study, under-display ultrasonic fingerprint recognition (UDUFR) was investigated for the first time via imaging a finger vessel underneath the fingerprint. A 40 MHz ultrasonic fingerprint sensor composed of PZT-5H piezoelectric active material was firstly developed, which demonstrated broad bandwidth (73.9%) and high loop sensitivity (-27.5 dB) for UDUFR applications. UDUFR experiments were performed to demonstrate the effectiveness of the proposed technique using a two-layer polydimethylsiloxane (PDMS) phantom which consists of a dummy fingerprint in the surface layer and a finger vessel mimicker in the inner layer. Electronic images of the fingerprint and finger vessel with a resolution of 500 × 500 DPI were successfully obtained. The results reported in this study open up new avenues for the next generation of robust and secure UDUFR technology.