Answer: Your temperature.
In case someone tries to get into your phone using an artificial fingerprint, researchers have developed fingerprint-scanning technology that can check for natural body heat. Created by scientists from South Korea’s Samsung Display Center at Ulsan National Institute of Science and Technology, this sensor adds an additional layer of security to biometrics by checking the pressure and temperature of the finger using it.
This new sensor is also transparent, which means it could be placed directly beneath the screen. Current fingerprint sensors are opaque and therefore must be placed somewhere besides a device’s display, like under the home button or on the back. You will still have to use a traditional thermometer to check if you have a fever — this tech is designed only to detect average temperatures of human skin.