At the last CES in January 2020 OnePlus unveiled a concept phone designed in collaboration with McLaren. It had colour-shifting glass on the rear which could darken to hide the cameras, much like the electrochromic roof glass in McLaren’s 720S Spider.

The two companies are no longer partners, but OnePlus has announced a new experimental phone: the 8T Concept.

This takes the colour-shifting theme even further with a rear glass panel that can change from a dark blue to light silver.

It’s controlled electronically using a colour-changing film that contains metal oxide in glass. OnePlus says that the valence state of the metal ions varies when different voltages are applied.

Aside from the cool factor, the company says there are actual uses for the technology when combined with others such as a mmWave radar module. Millimetre wave is the high-frequency portion of 5G tech and can perceive, image, locate, and track objects.

The suggestion is that you could use hands-free gestures to answer or reject a call and that the colour could pulse to indicate an incoming call – or other notifications.

The 8T Concept wouldn’t be unique in offering hands-free gestures as that’s been available on phones (that you can actually buy) for a long while now, including the Huawei Mate 30 Pro.

OnePlus is adamant that the only reason to bring new technology such as ECMF (Electronic Colour, Material and Finish) is to deliver a better user experience, and that the colour-changing glass in the 8T Concept is there to create a more natural interaction between users and the device.

It would be easy, though, to call it a gimmick, as with the Concept One's invisible cameras. Even the other potential benefit of being a biofeedback device - the colour changing in response to a user breathing in and out – seems unlikely to be enough to persuade anyone to pick a phone with ECMF unless it was also better than rivals in performance, battery life, camera quality and price.

Not that you can buy the 8T Concept. It’s exactly that: a concept. We had imagined the colour-shifting glass from the Concept One, below, would make it into a future OnePlus phone, but that hasn’t happened yet and there’s every chance this will remain a concept as well.

OnePlus 8T Concept

You can, however, buy a OnePlus 8T, which is one of the best flagship phones of 2020. Better still that it's half the price of some flagships.

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