A series of apparent iPhone 8 leaks still haven’t answered one of the biggest questions about this year’s flagship iPhone: will the fingerprint sensor be embedded into the display?

We know that Apple has numerous patents for this type of embedded fingerprint technology, and it also appears clear that the display will occupy almost the entire front face of the device, but some claimed leaks do show a fingerprint sensor on the back of the case. I’ve discussed a third option, where a Touch Bar element appears to be part of the display, and a patent published today raises a fourth possibility …

The patent, with the rather dry-sounding title ‘Finger biometric sensor assembly including direct bonding interface and related methods,’ describes a method of embedding a fingerprint reader into a button. One of the drawings (above) seemingly shows it as part of the power button.

The patent itself is a technical one dealing primarily with the bonding material used between the sensor itself and the outer layer.

A finger biometric sensor assembly may include a finger biometric sensor integrated circuit (IC) die having a finger sensing area and a cover layer aligned with the finger sensing area. The finger biometric sensor may also include a direct bonding interface between the finger biometric sensor IC die and the cover layer.

The direct bonding interface may be a hydrophilic direct bonding interface, for example. Alternatively, the direct bonding interface may be a hydrophobic direct bonding interface. The direct bonding interface may include silicon oxynitride. The direct bonding interface may include silicon oxide, for example.

It describes how the outer layer of the button might comprise an extremely thin piece of glass or sapphire.

The patent does make the point that embedding the fingerprint reader into a button on the top of the device is merely one possible example – but does seemingly refer to it as a preferred option.

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein

We have seen claimed prototypes and and renders of a design featuring a Touch ID sensor embedded in the rear of the casing, but most of you agree with my view that this would be an unlikely approach. The majority of purported leaks do not show the sensor.

The idea of a Touch ID sensor embedded into the power button has always seemed unlikely, due to the technology Apple uses. Although slim fingerprint readers exist, these currently require you to roll your fingertip across the sensor rather than simply touching it. However, this patent suggests that Apple may have solved this problem, allowing a narrow strip of fingerprint to be read simply by pressing down on the button.

Would this approach work for you? As ever, let us know your thoughts in the comments.

Via Patently Apple

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Ben Lovejoy

Ben Lovejoy is a British technology writer and EU Editor for 9to5Mac. He’s known for his op-eds and diary pieces, exploring his experience of Apple products over time, for a more rounded review. He also writes fiction, with two technothriller novels, a couple of SF shorts and a rom-com!

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