Ever since the Pixel 6 series switched to an in-display fingerprint sensor, users have complained that unlocking performance has deteriorated compared to the Pixel Imprint sensor. Over the years, performance has improved, but the Pixel 9 series is rumored to be even better thanks to an ultrasonic fingerprint sensor.
According to Android Authority, the Pixel 9 and 9 Pro will feature an ultrasonic fingerprint sensor, specifically the Qualcomm 3D Sonic Gen 2. The Pixel 9 Pro Fold version will keep its side sensor built into the power button. The inaudible sound waves «will read the depressions and protrusions of the finger» and create a «reproduction of the scanned fingerprint». This sensor is used in Samsung Galaxy S24 Ultra.
This component (QFS4008) was introduced in early 2021 with a surface size of 8×8 mm. The first-generation scanner had dimensions of 4×9 mm. So, the surface area is increased by 77%, which makes it easier to place your finger while storing (1.7 times) more biometric data. It is also said to be «faster compared to older solutions when fingers are wet».
In comparison, optical fingerprint sensors work by emitting bright light and essentially taking a picture of the surface of the finger. Google’s first implementation in the Pixel 6 was not very effective, especially when using screen protection solutions. The company responded to complaints with a new sensor in the 6a model.
Source: 9to5google