Samsung's Newest Phones Read Your Fingerprints With Ultrasonic Sound Waves (cnet.com)

An anonymous reader quotes CNET: The Galaxy S10's in-screen fingerprint scanner may look just like the one on the OnePlus 6T, but don't be fooled. Samsung's flagship Galaxy S10 and S10 Plus are the first phones to use Qualcomm's ultrasonic in-screen fingerprint technology, which uses sound waves to read your print.

Related to ultrasound in a doctor's office, this "3D Sonic Sensor" technology works by bouncing sound waves off your skin. It'll capture your details through water, lotion and grease, at night or in bright daylight. Qualcomm also claims it's faster and much more secure than the optical fingerprint sensor you've seen in other phones before this. That's because the ultrasonic reader takes a 3D capture of all the ridges and valleys that make up your skin, compared to a 2D image -- basically a photo -- that an optical reader captures using light, not sound waves.

Comments

How does it work?

[goombah99]

Anyone know how it gets the resolution it needs? Even ultrasonics have long wavelengths. It would have to be extremely high frequency to image the finger. But perhaps they use some sort of channeled time domain reflectometry or near field methods to get the lateral resolution.
Still it's not obvious what they mean from the description

Re:How does it work?

[Pinky's Brain]

It doesn't need to penetrate or cross much air, at 10 MHz ultrasonic has a wavelength of 34 microns.

Re:How does it work?

[LynnwoodRooster]

Interferometry. A 1 MHz wavelength is human tissue is about 1.5mm. A decent interferometric system can discriminate down to 3 degrees without an issue, which would be around 12.5 microns. Which is about half the height of a fingerprint ridge. So it seems pretty simple, since you can get presence/absence of a pattern over an area.

Re:How does it work?

[hankwang]

Unlikely. An interferometer typically has subwavelength depth resolution, but much coarser lateral resolution.

Re:How does it work?

[hankwang]

I found a paper on an ultrasonic fingerprint sensor: https://www.researchgate.net/p... . It's probrably not the exact technology that qualcomm uses (this one doesn't handle 2 mm of display and touch screen on top of the sensor). But it does mention an essential concept: the sensor is an array of transducers; a cluster of nearby transducers sends an ultrasonic pulse (14 MHz carrier, ) with delays such that the wave is focused at some distance from the transducer, somewhere inside the skin (so that it's harder to fake).

Presumably, one could do many pixels in parallel, if there is enough data bandwidth and signal processing capacity to handle entire waveforms for each pixel.

I'm afraid to use these

[Anonymous Coward]

I play guitar and my thumb and index are shredded on both hands, the callouses seem to flake off and change all the time. I think I'd end up never being able to unlock my phone.

Not all of them

[sremick]

The feature is notably missing from the S10e, the only one of the three of them that is a reasonable size. Even my S7 is a bit too big, making one-handed use awkward and difficult. The S10e is larger still, but the other two are just ridiculous.

I really wish Samsung wasn't participating in this infuriation game of seeing who can make the largest phone. They're either marketing to people 6'10" with hands the size of my feet, or morons who like looking like fools holding tablets to their heads to talk. I'm neither a giant nor a douchebag, so I'm left with sub-par, handicapped phones to choose from.

Re:Not all of them

[epine]

I'm neither a giant nor a douchebag, so I'm left with sub-par, handicapped phones to choose from.

Well, I'm both, and it's an awesome way to express my disdain over the spine-rupturing kitchen-counter height convention established in the dwarf-like 1950s (as optimized for female physiology, due to yet another patriarchal conspiracy).

Now I just need to find myself a phone that looks like a 4" thick Boos board (without which I cannot function on my feet in any normal kitchen).

Maybe works better for older people

[SuperKendall]

As people age, fingerprints get vary hard for machines to read - I wonder if this approach will work better, it sounds like it.

Seems like a nice advancement for that tech, although I still prefer FaceID to even a faster fingerprint scanner (especially in winter).

Just use your nipple...

[willy_me]

So long as your lover is not a sadist, you should be fine. Search Google, found YouTube