Capacitive Microfabricated Ultrasonic Transducers for Biometric Applications

Two capacitive micro-fabricated ultrasonic transducers (cMUT) are evaluated for application in biometric recognition. Both transducers are 192 elements linear arrays, fabricated using the Reverse Process™ previously reported by some of the authors, and allow broadband operation at a center frequency of 12 MHz. The transducers have different pitches and acoustic lenses to allow different resolutions and focal lengths. 3D images of biometric characteristics such as palmprint and fingerprint are obtained by moving the transducer along the elevation direction and acquiring the B-scan for each scan step using a commercial ultrasound scanner; the main features of the proposed technique, also compared with conventional techniques, are presented and discussed