Google is introducing a new feature to its Pixel phones with the release of Android 16 DP2. The “Screen-off fingerprint unlock” option allows users to access their phone’s fingerprint sensor even when the screen is completely turned off.
This feature appears to be exclusive to the Pixel 9 series, as it was not found in Settings on other devices, including the Pixel 8 Pro. However, experts believe that this is due to the new ultrasonic fingerprint sensor used in these devices, which eliminates the need for light to activate the sensor.
The practical advantage of this feature is that it reduces the jarring effect caused by the optical sensors when they are turned on in a dark environment. This is especially beneficial for users who don’t use always-on display (AOD) settings.
To access this new setting, users must have Android 16 Developer Preview 2 installed and navigate to Settings > Security & privacy > Device unlock > Face & Fingerprint Unlock > Fingerprint Unlock.
Source: https://9to5google.com/2024/12/19/android-16-pixel-9-fingerprint-sensor-screen-off