ELI5- How can my phone screen be a screen and read my fingerprint?


So I remember seeing it explained how the phone screen can tell when you’re touching it. Something about how the conductivity of your finger causes the screen to react to its presence. Makes sense. How exactly does it do all of that, but also be able to distinguish between such details as fingerprints?

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Most underscreen fingerprint readers are ultrasonic readers. It sends ultrasonic waves out to scan your finger to determine if it’s a match. They are capable of scanning through glass and/or aluminum which is why they work through your display, which usually has both in it.