Visible to the public Wideband material detection for spoof resistance in GHz ultrasonic fingerprint sensing

TitleWideband material detection for spoof resistance in GHz ultrasonic fingerprint sensing
Publication TypeConference Paper
Year of Publication2017
AuthorsKuo, J., Lal, A.
Conference Name2017 IEEE International Ultrasonics Symposium (IUS)
KeywordsAcoustic Fingerprints, Acoustics, backside silicon interface, biological tissues, biomedical ultrasonics, capacitive sensing approaches, capacitive sensors, chirp modulation, composability, conventional optical sensing approaches, elastic impedance, fake 3D printed plastic finger, fingerprint identification, fingerprint imaging, Fingerprint recognition, Fingers, Frequency response, GHz ultrasonic fingerprint sensing, Human Behavior, imaged material, Impedance, impedance mismatch, material detection, Microwave photonics, pubcrawl, pulse echo impedance imaging, reflectometry, Resiliency, Resonant frequency, spoof resistance, Transducers, ultrasonic fingerprint reader, ultrasonic imaging, ultrasonic materials testing, ultrasonic reflection, ultrasonic sensors, ultrasonic transducers, ultrasound reflectometry, wideband RF chirp signal
AbstractOne of the primary motivations for using ultrasound reflectometry for fingerprint imaging is the promise of increased spoof resistance over conventional optical or capacitive sensing approaches due to the ability for ultrasound to determine the elastic impedance of the imaged material. A fake 3D printed plastic finger can therefore be easily distinguished from a real finger. However, ultrasonic sensors are still vulnerable to materials that are similar in impedance to tissue, such as water or rubber. Previously we demonstrated an ultrasonic fingerprint reader operating with 1.3GHz ultrasound based on pulse echo impedance imaging on the backside silicon interface. In this work, we utilize the large bandwidth of these sensors to differentiate between a finger and materials with similar impedances using the frequency response of elastic impedance obtained by transducer excitation with a wideband RF chirp signal. The reflected signal is a strong function of impedance mismatch and absorption [Hoople 2015].
Citation Keykuo_wideband_2017