Ultrasonic Fingerprint Sensor For Smartphone Security

Fingerprint sensors are a nifty way to unlock smartphones. Unfortunately, they can also be tricked with a forged print, as was shown with the iPhone 5s and iPhone 6. But a new technology developed in California could change that.

A team led by David Horsley, professor of mechanical and aerospace engineering at the University of California, Davis, has developed a new ultra-safe, ultrasonic sensor.
"Our ultrasonic fingerprint sensors have the ability to measure a three-dimensional, volumetric image of the finger surface and the tissues beneath the surface – making fingerprint sensors more robust and secure," says Horsley. 

The sensor uses similar technology to medical ultrasound imagers. Transducers on the tiny sensor’s surface send out ultrasound pulses, which bounce off the fingerprint’s ridges and valleys before returning to the transducers. Using ultrasound means that the sensor can penetrate a thin layer of tissue near the finger’s surface, making the technology much more difficult to trick.

The chip itself is made from two wafers bonded together: a ‘complementary metal-oxide-semiconductor’ (CMOS) wafer and a microelectromechanical systems (MEMS) wafer. The CMOS wafer contains the circuitry for processing the signals, while the MEMS wafer contains the transducers.

Besides the security advantages, the researchers say that these chips will be extremely cheap to make.

“We were able to use low-cost, high-volume manufacturing processes that produce hundreds of millions of MEMS sensors for consumer electronics each year,” says Horsley.

So look out for these sensors on a smartphone near you…