While Apple and Samsung race to be the first company to perfect a fingerprint scanner that resides under a smartphone's display, a Chinese company called Vivo has already done it. 

Vivo is launching the technology jointly with Qualcomm at Mobile World Congress Shanghai on Wednesday, but Vivo shared key details, images and video exclusively with Mashable prior to the announcement. 

First, let's look at why this is important. The trend that dominated the smartphone market this year was making the screen as big as it can possibly be, with companies such as Samsung, LG and newcomer Essential launching phones with ultra-wide screens that cover most of their front side. 

All of these new phones have a drawback: To accommodate the huge screen in the front, the design could not accommodate a physical home button. As a consequence, the fingerprint scanner — a staple feature of flagship phones — needs to move somewhere else, usually to the back of the phone. 

Apple's upcoming iPhone 8, however, is widely rumored to have none of that. Instead, the fingerprint scanner is said to be embedded directly into the screen. Samsung has reportedly tried to use a similar fingerprint sensor in its Galaxy S8 flagship, but could just not make it work reliably in time for its spring release.

The sensor that works through glass... and even metal

Enter Vivo. The Chinese company's solution, called Vivo Under Display, is a fingerprint sensor that can be placed under glass, an OLED screen, or even aluminum(!), making it completely invisible and unobtrusive. 

Vivo's sensor is an ultrasonic one, which is not new; in fact, Qualcomm already has an ultrasonic fingerprint sensor that's built into some phones, like the Xiaomi Mi 5s. It works by emitting ultrasonic sound waves which penetrate the skin of your finger and capture a precise, 3D image of your fingerprint. 

However, Vivo's sensor can penetrate glass, aluminum, and OLED deeper — the company claims — than any similar technology out there. More precisely, Vivo Under Display can penetrate 1.3mm of OLED, 525μm of aluminum or 800μm of glass. For comparison, Qualcomm's previous technology could only penetrate 400μm of glass, and capacitive scanners only go up to 300μm. 

This should be enough for a phone manufacturer to place the sensor under the display — a more elegant solution than placing it, well, anywhere else. And there are other benefits: For example, Vivo's new fingerprint sensor is not affected by ambient light and it will work with wet fingers and sweat marks. The company is also working on a variant that also works underwater. 

Before you get too excited, keep in mind we haven't tried the technology ourselves. Vivo supplied us with a video (the same one that recently leaked) and new imagery of the technology. From what we can see, it seems to work effortlessly; perhaps a tad slower than the newest breed of standard fingerprint sensors, but still fast enough to be usable. 

There's a caveat, though. This launch is only a proof of concept; Vivo has not announced an actual product that sports the new sensor yet, although a Vivo spokesperson said the company plans to integrate it into its devices in the future.

A glimpse of the future

Even looked at cautiously, Vivo's announcement is important, as it shows us where smartphones are headed, and it may give us a glimpse of what could turn out to be the most distinguishing feature of Apple's upcoming iPhone 8. While it doesn't appear Apple will use Vivo's solution, Apple is expected to use similar technology in its upcoming iPhone, but it will be built in-house. 

UPDATE: June 28, 2017, 8:23 a.m. CEST The article was slightly modified to make it clearer what information comes from Vivo and what's based on other sources.

As for Samsung, there are conflicting reports on whether the company will have this feature in its upcoming Galaxy Note 8. From what we've heard from Vivo, it appears Samsung won't use Vivo's technology either (reports say Samsung is working with Synaptics on an under-the-display fingerprint scanner).  

Still, after all the reports on how tough it is to actually make this technology work, and with all the back-and-forth on whether Apple will perfect under-the-screen fingerprint tech in time for the iPhone 8, it's a big deal to see Vivo's Under Display Sensor in action. We'll reserve our final judgement until we can actually try it out on a production phone, but it's a good indication that fingerprint sensors will soon be pretty much invisible.