Design of ultrasonic fingerprint sensor made of 1-3 piezocomposites by finite element method

In this study, the feasibility of an ultrasonic fingerprint sensor made of a 1-3 piezocomposite material was analyzed using the finite element method, and a fingerprint identification method suitable for the piezocomposite sensor was also determined. Two finite element models were constructed, one without acoustic walls and one with acoustic walls. Two methods for signal analysis were used to identify the ridges and valleys of a fingerprint: comparing (1) maximum peak amplitudes of the reflected waves from the ridges and valleys and (2) flight time differences of the same-ordered peaks. Both methods were applied to the two models. The maximum peak amplitude analysis of the model with acoustic walls showed the best performance in identifying the ridges and valleys. The efficacy of this identification scheme was illustrated using two threedimensional (3D) fingerprint models: one with concentric circles and one with several concentric semicircles and curves at two corners. Results of this work can lead to the development of more efficient and sensitive ultrasonic fingerprint sensors.