The United States Patent and Trademark Office (USPTO) on Tuesday granted Apple a patent for acoustic fingerprint imaging technology that could work beneath a display and replace its current Touch ID fingerprint reader.

Apple’s U.S. Patent No. 9,747,488 for an “Active sensing element for acoustic imaging systems” details a fingerprint imaging system using acoustic elements to read fingerprints without requiring physical contact between your skin and the sensor.

Ultrasonic piezoelectric transducers arranged in a pattern beneath a display send out an acoustic pulse toward the top substrate surface, which is then reflected off a finger touching the top surface of the substrate. The transducer array reads the reflected acoustic waves and turns the signals into an image of your fingerprint.

According to Apple, the system is based on so-called acoustic boundary relying on acoustic impedance mismatch between the top surface and the portion of object engaging it. For example, a ridge of a fingerprint may present a different acoustic boundary when touching the substrate than a valley of a fingerprint.

Accordingly, a ridge of a fingerprint may reflect the acoustic pulse differently than a valley of a fingerprint. In other words, a ridge of a fingerprint produces a different acoustic output than a valley of a fingerprint, allowing the sensing elements to turn electrical signals into pixels.

It’s unclear if today’s patent grant means that Apple has already implemented an acoustic fingerprint reader in its upcoming iPhone 8. The rumors have suggested that Apple’s in-screen solution is not yet ready for prime time. Still, this patent could be implemented in a one of subsequent iPhone models.

First filed for in August 2015, the invention credits Apple engineers Mohammad Yeke Yazdandoost, Giovanni Gozzini and Jean-Marie Bussat as its inventors.