Joy Jiang received the B.S. degree in mechanical engineering from University of Rochester in 2013 and the M.S. degree in electrical engineering from the University of California, Berkeley in 2015. Currently she is a Graduate Student Researcher in the Berkeley Sensor and Actuator Center (BSAC) at the University of California, Berkeley, pursuing her Ph.D. in mechanical engineering. Her research interests include MEMS sensors and actuators for acoustic sensors applications. She is a recipient of the Outstanding Student Paper Award at the IEEE MEMS 2016 Conference.
Novel Ultrasonic Fingerprint Sensor Based on High-Frequency Piezoelectric Micromachined Ultrasonic Transducers (PMUTs) [BPN628]
This project presents the first MEMS ultrasonic fingerprint sensor with the capability to image epidermis and dermis layer fingerprints. The sensor is based on a piezoelectric micromachined ultrasonic transducer (PMUT) array that is bonded at wafer-level to complementary metal oxide semiconductor (CMOS) signal processing electronics to produce a pulse-echo ultrasonic imager on a chip. To meet the 500 DPI standard for consumer fingerprint sensors, the PMUT pitch was reduced by approximately a factor of two relative to an earlier design. We conducted a systematic design study of the individual PMUT and array to achieve this scaling while maintaining a high fill-factor. The resulting 110X56 PMUT array, composed of 30um X 43um rectangular PMUTs achieved a 51.7% fill-factor, three times greater than that of the previous design. Together with the custom CMOS ASIC, the sensor chieves 2 uV/Pa sensitivity, 19 kPa peak-to-peak pressure output, 75 um lateral resolution, and 150 um axial resolution in a 4.6 mm X 3.2 mm image.