BARCELONA, Spain—At Mobile World Congress, Qualcomm is showing off Sense ID, a new technology that brings ultrasonic fingerprint scanning to mobile devices. The main advantage of ultrasonic fingerprint scanning is that because it uses sound waves, it doesn’t require direct contact with your finger. This means the ultrasonic sensor can be underneath the device’s front cover glass or potentially underneath the display itself.
While digital fingerprint sensors have been around for years, they were popularized in the mobile space by the iPhone 5S with Touch ID. The Touch ID sensor, along with the various other fingerprint sensors that have appeared in smartphones over the last couple of years, are all based on capacitive technology. Capacitive sensors work in much the same way as a touchscreen. When you place your finger on the reader, the pattern of ridges, whorls, and minutiae points create electrical circuits that can be read and recorded. This method works just fine, but it has limitations. Your finger needs to be in direct contact with the sensor, and if you have contaminants (water, lotion, dirt) on your finger, it may not work.
Because ultrasonic fingerprint recognition uses high-frequency sound waves, it can penetrate through a variety of obstacles: the aforementioned contaminants, glass, metal, plastic, and more. In theory, ultrasonic scanners can also penetrate a lot deeper into your finger’s dermal layers than capacitive, which means it’s possible to extract more biometric data. The ultrasonic waves are produced by a piezoelectric transducer, much like ultrasonic medical imaging devices. (Qualcomm isn’t releasing much in the way of technical details right now, so we don’t know exactly how deep Sense ID will be able to penetrate. You probably won’t be using it to scan any internal organs… not yet, anyway.)
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