I just picked up a Vivo phone, laid my thumb on its screen and voila: I unlocked it. That might not sound like much, but titans like Apple and Samsung have reportedly struggled to squeeze fingerprint sensors beneath their own displays. And yet here I am, with a prototype phone from a company most have never heard of, touching a finger to glass and watching a phone come to life.
What's really impressive is how conceptually elegant this setup is. The whole thing is made possible by a Synaptic CMOS sensor -- which is basically just a very tiny camera -- laminated to the back of an OLED panel. (LCDs are a no-go because of their backlights.) The light from the OLED display itself illuminates your fingerprint, which the sensor "sees" and checks against the print stored on the phone. Of course, none of this will matter to the people who actually try it. Aside from the fact that you can't actually see the sensor, it works just like you'd expect it to.