The Verge:

LG Innotek today joins Fingerprint Cards in announcing a fingerprint module that can be integrated under the same glass cover as a phone’s display, obviating the need for a button. This will allow smartphone makers to have truly seamless designs while still offering the now-mandatory fingerprint authentication — and both companies expect devices with this new technology before the end of the year.

And:

LG Innotek points out that waterproofing a smartphone becomes significantly easier without a discrete button for the fingerprint reader. Plus the sensor itself is less susceptible to being scratched if it sits under the same tough cover glass as the display. Fingerprint readers have to be particularly robust, by microelectronics standards, because they sit on the exterior of a device.

Imagine if your phone knew who was holding your phone, no matter where your finger made contact. This tech is likely coming to Android. It will be interesting to see if Apple responds in some way.