https://www.cnet.com/news/the-galaxy-s10s-key-feature-will-reportedly-be-ultrasonic/

It's one of the worst-kept secrets in the phone industry: Samsung is hoping to eventually sell you a phone with a fingerprint sensor that lives underneath the screen.

But how? Well, a pair of reports out of China and Korea suggest that sucker might be ultrasonic -- firing high-frequency acoustic waves through the glass that capture your fingerprint without fear of being defeated by dirt or grease.