Samsung Galaxy S10 to go ultrasonic? Here's an early look at its likely fingerprint reader

Qualcomm shows off a prototype fingerprint reader that's tucked underneath the display and potentially headed to Samsung's early 2019 flagship smartphone. The technology is the same as that teased by DJ Koh, the head of Samsung's mobile business, at an event in China this week. And while Qualcomm declined to comment on any specifics phones using the technology, and Samsung remains mum on what will show up in the Galaxy S10, any phone embracing ultrasonic waves to read a fingerprint will have to work with Qualcomm.

Embedding the fingerprint reader underneath the glass represents the next step in how we verify our identities and log in to our smartphones. It's also a convenient fit with the trend toward eliminating physical home buttons and enlarging the frame around the display. The more full-sized display has forced phone makers to move the reader to the back of the phone or, in Apple's iPhone X, gotten rid of it entirely in favor of a facial recognition system.

Both the Vivo and Huawei phones use optical technology to scan the fingerprint through the display, a different technique than that employed by Qualcomm. Regardless of the technology, in-screen fingerprint readers are expected to show up in a big way next year. Consumer research firm IHS Markit predicts that 100 million phones will have in-screen fingerprint sensors by 2019.

How does it work?

Qualcomm uses sound waves to generate a map of your fingerprint, with the wave of pressure bouncing off the contours of your skin.

Ultrasonic technology offers a few advantages, said Gordon Thomas, director of product management for Qualcomm. It can read a finger even if it's wet, since the waves can pass through the liquid. He touts a 1 percent rejection rate, as well as a lag time of 250 milliseconds, comparable to traditional capacitive fingerprint readers on home buttons found on the iPhone 8 or the Galaxy S9.

The sensor itself is 0.15 millimeter, so it doesn't add much thickness to the phone. It can also work through glass or metal. In fact, a version of this technology is out there with the Huawei Honor 10, but the company chose to place the fingerprint reader in the glass chin below the display.

Last, the ultrasonic waves can also be used to track blood flow and heart rate.