Ultrasonic 3D fingerprint scanner developed by researchers from the University of California

Low-cost 3D fingerprint scanner for smartphones

Researchers have developed an innovative 3D fingerprint scanner that could be used in smartphones and other devices to improve security.

The device uses an ultrasonic sensor that can image a thicker layer of the skin than a regular 2D scanner common on some of today’s gadgets, including the iPhone 6.

Instead of creating a flat 2D image, the 3D scanner can thus measure the structure of the outer layer of the finger’s skin in a more complex manner, capturing the depth of the ridges and bumps.

Experts believe 3D biometrics could provide an increased level of security compared to the current 2D devices, which can be spoofed easily with a printed image of the fingerprint.

The new device, described in the latest issue of the journal Applied Physics Letters, was created by a team of engineers at the University of California led by professor David A Horsley.

“Ultrasound images are collected in the same way that medical ultrasound is conducted,” Horsley explained. “Transducers on the chip’s surface emit a pulse of ultrasound and these same transducers receive echoes returning from the ridges and valleys of your fingerprint’s surface.”

The basis for the ultrasound sensor is an array of MEMS ultrasound devices with highly uniform characteristics and therefore very similar frequency response characteristics.

To fabricate their imager, the group employed existing microelectromechanical systems (MEMS) technology, which smartphones rely on for such functions as microphones and directional orientation. They used a modified version of the manufacturing process used to make the MEMS accelerometer and gyroscope found in the iPhone and many other consumer electronics devices.

“Our chip is fabricated from two wafers: a MEMS wafer that contains the ultrasound transducers and a CMOS wafer that contains the signal processing circuitry,” explained Horsley.

“Because we were able to use low-cost, high-volume manufacturing processes that produce hundreds of millions of MEMS sensors for consumer electronics each year, our ultrasound chips can be manufactured at an extremely low cost.”

The imager is powered by a 1.8-Volt power supply, using a power-efficient charge pump on an application-specific integrated circuit.

“Using low-voltage integrated circuits will reduce the cost of our sensor and open up myriad new applications where the cost, size, and power consumption of existing ultrasound sensors are currently prohibitive,” Horsley said.

The researchers believe their device can find its way into many other applications including low cost ultra-sound systems for medical diagnostics and personal health monitoring.

The device, though, is not the first 3D capable fingerprint scanner developed. At the Mobile World Congress in Barcelona this year, chip maker Qualcomm unveiled a similar smartphone-ready system dubbed the Snapdragon.

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