An ultrasonic scanner to probe 3-D finger skin structures for biometric recognition

To use the three-dimensional (3-D) structure of finger skin for personal identification, a 3-D ultrasonic finger skin scanner is implemented by combining a commercial 25 MHz ultrasound transducer, a three-axis motor system, an analog-to-digital converter a field-programmable gate array, a Universal Serial Bus 3.0 interface, and a PC. The scanner was successfully applied to monitoring the deep-layer pattern 1500 μm below the surface of an artificial finger module, as well as the surface fingerprint pattern, with an axial resolution of 123 μm. The Hilbert transform and 50x interpolation were performed on the received ultrasound data to enhance the axial and lateral resolutions, respectively. B-mode and C-mode imaging and a contour plot were presented for the surface fingerprint and the deep-layer pattern. © 2019 Institute of Electronics and Information Engineers. All rights reserved.11Nscopuskc