From The Editors Technology

Your Arm Can Now Become the Touch-Sensitive User Interface for a New Projector Smartwatch

A team of researchers at the Carnegie Mellon University has developed a revolutionary smartwatch prototype that has made it possible to use your arm as the user interface for the device.

LumiWatch incorporates a 15-lumen scanned-laser projector, a ten-element sensor array, a Qualcomm 1.2 GHz quad-core CPU running Android 5.1, 768 MB of RAM, 4GB flash memory and a 740 mAh lithium-ion battery, along with Bluetooth and Wi-Fi capability, and uses up to 40 square cm on your arm as a touch screen for all that swiping; and poking; and tapping; to operate the prototype.

Sounds good, doesn’t it?

Want to be among the first to have it?

The answer to that is expected to be in the affirmative by most people, particularly the young but be aware that there’s a decent wait ahead before the technology translates to a consumer-ready device.

The final shape the LumiWatch takes might well turn out to be worth the wait in the end.

We have seen how mobile phones evolved into smartphones and smartphones into even smarter devices.

We also witnessed how, in order to accommodate the increasing number of features and functionality, the size of the devices grew over the years to a point where smartphones became like mini tablets.

However, the same can’t be said about wearable devices like the smartwatch, for instance, since it never could afford that luxury and had to work within certain limitations, as far as size went.

Considering the fact that even the smallest of smartphones would look ridiculously large strapped to the wrist, there was never much scope for major improvements.

Even if smartwatch manufacturers, somehow, did find a way to cram a world of features and functionality into the tiny screen space of the smartwatch, it would be outrageously impractical, considering the size of the average human finger in relation to a smartwatch screen.

So, it was a stalemate of sorts until LumiWatch happened – thanks to the efforts of the Carnegie Mellon University researchers – which now gives them 40 of real estate on the device-wearers arm to incorporate as many features as they’d like and give smartphone makers a thing, or, two to worry about.

In a paper entitled titled “LumiWatch: On-Arm Projected Graphics and Touch Input,” the researchers wrote:

“Although obstacles remain for practical adoption, we believe our work demonstrates the first functional projection smartwatch system and constitutes a significant advance in the state of the art.”

So what are these obstacles the researchers are referring to?

Now, the fact that LumiWatch is restricted in having its own display in the desired size specifications, it creates one, instead, by projecting a 1024×600-pixel image on borrowed space, which in this case is the arm or the back of the wearer’s hand.

As they are not the ideal surface for projecting images from an angle as low as the wearer’s wrist, distortion and warping are bound to happen.

Also, everyone wears a watch a little differently, plus wrists can be thick or slim, as can the fingers of different users, which was a calibration issue that needed solving.

Well, the creators of LumiWatch found a way to work around those hurdles by using the “swipe to unlock” gesture.

So, when the user swipes to the left to unlock the device, the integrated sensors detect the motion and track the user’s swiping finger to calibrate its shape and size and optimize the angle of projection, thereby minimizing the distortion.


While the prototype appears to have solved most of the issues to make it a workable unit, there are still some wrinkles remaining that need ironing out – the size of the device is one of them.

With dimensions measuring 50x 41 x 17mm (2 x 1.6 x 0.66 inches), the LumiWatch is considerably larger than the 42.5 x 36.4 x 11.4mm Apple Watch Series Three, which in inches works out to 1.67×1.43×0.45.

According to the researchers’, the prototype should cost somewhere around the $600 price point.

The idea of having a virtual keyboard on your arm may sound like a pie in the sky, but LumiWatch has brought the pie down to a reachable height, it seems.

Speaking to Digital Trends, head of FIG Chris Harrison described the LumiWatch as an “entire computer with battery that lasts a day, plus a projector for on-skin graphics, as well as a custom depth sensor that allows us to track touch input on the skin,” saying that “the computational difference between a smartphone and a smartwatch is very small.”

He said that “the big difference is the screen. Smartwatches have yet to gain traction in large part because the interface are so meager you can’t do much with them. If we can solve that problem – give smartwatches big screens – we might be able to make them first-class devices.”

Talking about the LumiWatch’s chances of becoming a reality, Harrison told Digital Trends, “We collaborated on this proof-of-concept hardware with ASU Tech, a consumer electronics OEM in China.”

“They are well positioned to take this to the market. Beyond that, I can’t say much more,” he said.

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