Apple seems to be working on a fingerprint acoustic imaging technology, which enables the creation of a full-screen Touch ID. This will allow the company to offer Touch ID to iPhone without the need to integrate the sensor into the home button. In addition, Apple will be able to maintain the full-screen design of the front of its devices.
On iPhone X, Apple replaced the Touch ID with the Face ID that uses the TrueDepth camera series. Although this has allowed the company to offer an edge-to-edge screen, the Touch ID is better and safer.
In the patent filed with the US Patent and Trademark Office, Apple describes an acoustic imaging system used on a whole surface. This system uses a combination of acoustic transducers to vibrate a surface in a specific way that can effectively turn the entire screen into a fingerprint reader.
Apple has filed another patent named “Acoustic Imaging System for spatial waveform scrambling“, which is relatively similar except that it provides more details about the installation of the inverter.
In this patent Apple reports that the object being detected is a finger and the entrance surface is made of glass, sapphire or metal.