Ultrasonic Biometric Authentication System with Contact Gesture Sensing

The Qualcomm Technologies® Fingerprint Sensor based on piezoelectric ultrasound technology has achieved great success in commercialization. Here, we presented the concept of contact gesture sensing with the Quacomm fingerprint sensor system. Based on levels of detected contact force, two different algorithms are developed to sense the gesture. With light touch and swipe, 2D FFT with radon transform followed by normalized cross-correlation is used to identify the rotation and translation. With heavy touch and swipe, the wavelet transform is used to estimate the localized deformation, and further to identify the shear-induced gesture based on fingerprint images.