Galaxy S10 goes 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 upcoming flagship phone.

Roger Cheng Former Executive Editor / Head of News
Roger Cheng (he/him/his) was the executive editor in charge of CNET News, managing everything from daily breaking news to in-depth investigative packages. Prior to this, he was on the telecommunications beat and wrote for Dow Jones Newswires and The Wall Street Journal for nearly a decade and got his start writing and laying out pages at a local paper in Southern California. He's a devoted Trojan alum and thinks sleep is the perfect -- if unattainable -- hobby for a parent.
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Roger Cheng
4 min read

Qualcomm had an early version of its ultrasonic fingerprint reader set up for a demonstration. It's so early, the smartphone on the right is a dummy unit set up with just the reader. The phone on the left actually registers the scan. 

Tania Gonzalez/CNET

I place my thumb on the display of a dummy smartphone. A tiny, imperceptible wave of pressure shoots out of the device and maps the ridges and valleys of my finger, verifying my identity.

In an instant, another phone that's connected to the dummy flickers to life as the home page appears.

It's a sunny summer day in July, and I'm standing in a conference room in the heart of Qualcomm's San Diego headquarters, trying out an early -- and very rough -- prototype of the company's ultrasonic fingerprint reader, which Qualcomm says will show up in smartphones this year.

Watch this: An early look at the ultrasonic fingerprint reader likely headed to Galaxy S10

The technology is the same as that teased by DJ Koh, the head of Samsung's mobile business, at an event in China last year. 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.


Hey, even the head of Samsung's mobile business, DJ Koh, is a fan of ultrasonic technology. 

James Martin/CNET

Putting the fingerprint reader under the display was once considered a holy grail technology -- largely because it failed to materialize after years of rumors. But they're starting to pop up: the OnePlus 6T has a fingerprint reader under its display has put a reader into its special-edition Porsche Design Huawei Mate RS phone.

Both the OnePlus 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 this year.

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.


The Huawei Honor 10 features Qualcomm's ultrasound fingerprint reader, but embedded underneath the glass chin below the display. 

Andrew Hoyle/CNET

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

The alternative in-screen optical readers are built by the likes of Synaptics and Goodix. Instead of sound, they use light waves to map the fingerprint, but they can be thrown off by different lighting conditions and by water. Goodix's technology powers the Mate RS, while Synaptics and Goodix are also in Vivo and Xiaomi phones.

"We already have reliable high-performing solutions in multiple smartphones at retail today," Synaptics spokesman David Hurd said in response to Qualcomm's suggestion that its technology is superior.

A spokesman for Goodix couldn't be reached for comment.

So where are ultrasonic smartphones?

Qualcomm introduced this fingerprint technology last June, but few smartphones have publicly embraced it.

That's because the ultrasonic waves will work only through flexible OLED displays, according to Gordon. Phones more commonly used what's known as rigid OLED, which has air gaps that prevent pressure waves from going through.

The Honor 10, for instance, had to place the reader in the glass section below because it wouldn't work through the display.


Did I mention the demonstration unit was really rough?

Tania Gonzalez/CNET

It's so difficult to obtain a flexible OLED display for a demo unit that Qualcomm doesn't even have a working prototype, which is why its engineers had to pair up a dummy phone with another smartphone for my demonstration.

There are only two companies using flexible OLED displays on a wide scale: Apple and Samsung. Given Apple's legal battles with Qualcomm, it's an unlikely customer.

Which brings us back to Samsung.

The Korean tech giant uses the right display technology, and could use another gee-whiz feature when touting its 10th anniversary Galaxy S smartphone.

Talk about making waves. 

The story first published on July 18 at 5 a.m. PT. 
Correction on July 18 at 8:15 a.m. PT: This story initially misstated the thickness of the sensor. It's also been updated to note that rigid OLED displays have air gaps. 

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