Traditional fingerprint readers are made out of silicon and are not transparent. Recently, work has been done to put them behind a screen, but this is a new approach.
It uses JDI’s Pixel Eyes tech, which builds the capacitive touch sensor into the LCD panel. The company has improved the sensitivity to the point where it can detect the ridges of your fingerprints. All this is built into the glass substrate, which is highly transparent.
So there’s no need to put it behind the screen to achieve the same functionality as the Synaptics sensor used in the vivo X20.
The sensor unveiled today measures 8 x 8mm (160 x 160px, 508dpi) and should start shipping commercially by March next year. JDI will make both larger and smaller sensors too and wants to make flexible sensors in the future.
source:https://www.gsmarena.com