Ultrasonic fingerprint sensing
Capture d'empreintes digitales à ultrasons

Each time the sound speed varies, for instance at an interface between two materials, a reflection/transmission occurs (the same as light). An ultrasonic wave is sent, and an echo is received later, depending on the sound speed. One problem is the multiple echoes.

Ultra-sound fingerprint reading was not common in the past, and required quite a big device with mechanical parts, and was quite expensive. Moreover, it took a few seconds to grab an image, and was not suited for large production volumes at low cost. Its main advantage is the possibility to read the derma, the sub-surface of the skin, rather than only the surface.

Several companies are working to make small solid-state ultrasonic sensors, and production started with UltraScan/Qualcomm in 2016.

In 2017, there is a big hype because ultrasound sensors may solve the "in-display" problem for smartphone makers, as they want to propose an edge-to-edge displays, and moreover, it looks more natural to put your fingerprint directly on the screen. (Fingerprint sensors on the back are less expensive, but this position is not natural although some people like that).

ultrasonic sensing

Products

Ultrascan > 2013 > Qualcomm

Ultrascan

CrossMatch >> Sonavation

Sonavation MEMS

UC Berkeley Swarm lab >> Invensense


BEFS (Cammsys)


Fingerprint Cards


Silead

Reseach & Development

Optel

Optel Optel fingerprint

University of Windsor [Canada]


Cornell University + Intel / Geegah / A*STAR


Tsinghua university


North Carolina State University / Goodix


Nanjing University of Aeronautics and Astronautics


Some other ultrasonic fingerprint sensor studies

Tessonics