It seems to be a capacitive touch sensor, just like Apple's new Touch ID technology works in the iPhone 5s, so barring any patent issues, HTC will be sporting the second handset with that technology when it announces the One Max later on in the year...Source: http://www.phonearena.com/news/HTC-One-Max-rooted-fingerprint-sensor-proves-accurate-camera-features-leak_id47614
