https://wccftech.com/qualcomm-3d-sonic-max-ultrasonic-fingerprint-reader/

Qualcomm’s first under-display fingerprint reader, the 3D Sonic Sensor, didn’t exactly live up to its hype. Unlike optical fingerprint sensors that use light for taking an image of the fingerprint, the chipmaker used ultrasound to create 3D impressions. However, security, speed, inaccuracy issues plagued these sensors, to which Qualcomm apparently has the solution in the form of its 3D Sonic Max, the next generation of under-display fingerprint technology.

According to Qualcomm, the 3D Sonic Max is 17 times larger than its predecessor and measures 20mm x 30mm, which means the area of the display that will recognize your fingerprint will be much larger. Thanks to this bigger authentication surface area, it will also be possible to scan two fingerprints simultaneously, which will result in improved overall security. Moreover, a larger sensor will also be able to capture more information, which will theoretically make it harder to spoof the process.