The sensor, as it turns out, is the latest
ultrasonic fingerprint sensor from Qualcomm that now works through OLED display stacks up to 1.2 mm thick, up to 0.8 mm of cover glass, or up to 0.65 mm of aluminum (an increase from 0.4 mm for both glass or metal).
It is not yet mentioned how the technology exactly works but we can get an idea
from the Samsung patent where they used 12 pressure point
sensors sandwiched between cover glass and display panel where the scanner passes
ultrasonic signals through an OLED to read the contours of a
fingerprint without making direct contact.