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Qualcomm announces first ultrasonic fingerprint reader: Headed to the Galaxy S10?

The 3D Sonic Sensor will live within your screen.

Tania González/CNET

After years of prototypes and fine-tuning, Qualcomm on Tuesday finally announced a fingerprint reader that uses sound to unlock your phone. Called the 3D Sonic Sensor, this technology bounces sound waves off your skin, an approach that Qualcomm claims is secure and convenient. 

Qualcomm designed the 3D Sonic Sensor to fit underneath your phone screen, giving phone-makers the ability to create in-screen fingerprint readers with this technology, rather than the in-screen optical sensors that most phone-makers with in-screen fingerprint readers use today. 

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Jessica Dolcourt/CNET

This "ultrasonic" fingerprint sensor could very well form the backbone of the in-screen fingerprint reader rumored to appear in the Galaxy S10.

In-screen fingerprint readers are a hot trend in smartphone design, because they don't take up any room on the phone face, and require less groping around than a sensor embedded on the phone's power button or back casing. Analysts at consumer research firm IHS Markit predict that 100 million phones will have in-screen fingerprint sensors by 2019.

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James Martin/CNET

"Security and biometrics have been integrating into mobile platforms at a rapid pace," Alex Katouzian, Qualcomm senior vice president of mobile technology, said Tuesday at the company's conference. "This is the future of fingerprint technology."

Here's what you need to know about Qualcomm's ultrasonic 3D Sonic Sensor.

What's an 'ultrasonic' fingerprint sensor?

The 3D Sonic Sensor fingerprint sensor developed by Qualcomm uses sound waves (this is the "sonic" part) to "read" your fingerprint when you unlock your phone. The trend these days is to embed this fingerprint sensor underneath the display so that you unlock the phone by putting your finger or thumb in the center of the screen -- it's also called an in-screen fingerprint reader -- but this type of sensor could also exist on a device's home button. CNET saw a prototype of this ultrasonic sensor in 2015.

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How exactly does a 3D Sonic Sensor work?

Qualcomm's technology generates sound waves that map your fingerprint based on the pressure reading of the sound wave bouncing off your skin. It works with wet and grimy hands, and can take a reading through metal and glass. The soundwaves can also detect your blood flow -- and would reject a print from a severed finger.

Ultrasonic versus optical fingerprint reader: How is it different?

An optical fingerprint reader -- like the one powered by component-maker Synaptics that we first saw in Vivo phones -- essentially takes a photo of your finger to determine the pattern of ridges and valleys that make your fingerprint unique. Remember, Qualcomm's approach relies on sound waves.

How is ultrasonic different to what phones like the Galaxy S9 use now?

When you put your finger on a smooth reader on a phone's back, side or home button, your fingerprint's captured by a capacitive fingerprint sensor. Yes, "capacitive" is the same term that applies to your phone's touchscreen, where your finger lets off trace amounts of electric charge for the display to sense where exactly you're touching.

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Goodbye, capacitive fingerprint reader. Hello, ultrasonic.

Angela Lang/CNET

It's the same case here. Capacitors throughout the scanner detect the placement of your finger ridges by measuring electrical charge and then matching the pattern of those charges to your registered fingers.

How secure is an ultrasonic fingerprint reader?

Qualcomm claims that its ultrasonic fingerprint sensor is powerful enough to get a reading as deep as the level of your pores when it scans your print. Conversely, hackers and security experts have used photos to trick some optical fingerprint readers. Since the ultrasonic technology is new, rigorous real-world testing by the security community are likely still to come.

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Jessica Dolcourt/CNET

What's the advantage of using this versus Face ID and other face unlocking features?

Let's start with facial recognition. Apple's Face ID uses a depth map made of 30,000 infrared dots to map your facial contours. Samsung has technology to scan your irises, and a third method takes a photo of your face. Face ID and iris scanning are considered secure enough to use for mobile payments, but the facial recognition option that's packaged in Android won't support mobile payments, and is considered a fast way to unlock the phone -- it too, has been tricked with photos.

Qualcomm's ultrasonic fingerprint reader will work with mobile payments.

Read next: What 5G really feels like

Real also: We got an early look at the ultrasonic fingerprint reader