Researchers from Carnegie Mellon University and ASU Tech have prototyped a ‘one-of-its-kind’ smartwatch as a proof-of-concept study, that can turn your hand or arm into a touchscreen. Named as ‘LumiWatch’, this watch contains a 15-lumen pico-projector, that uses the wearer’s hand to expand the watch’s display area, conveniently increasing the watch usable area up to 5 times a typical watch’s interface area.


According to the white paper presented at Special Interest Group on Computer-Human Interaction conference in Canada, named ‘LumiWatch: On-Arm Projected Graphics and Touch Input’, This self-container smartwatch contains a logic board, projector, depth sensor, metal enclosure, and 740 mAh, 3.8 V (2.8 Wh) lithium battery. The logic board itself is designed around a Qualcomm APQ8026 chip, which runs on 768 MB of RAM and has 4 GB of flash memory, 1.2 GHz quad-core CPU, 450 MHz GPU, inertial measurement unit (IMU), ambient light sensor, Bluetooth 4.0 and WiFi controller. It runs on Android 5.1. With a dimension of 50mm*41mm*17mm, it is pretty bulky and bigger than Apple watch series 3.

The custom-made 15-lumen pico-projector can project a 1024*600-pixel image at 60Hz, with the 39º×22.5º field of view, on an area of 40 cm², with the help of red, blue and green lasers and a pair of MEMS mirrors operating in a raster-scan mode, making it quite visible in broad daylight too. The virtual touch area is monitored by 1D depth-sensing array, that determines the distance within 25º cone, by emitting a pulsed infrared ray, and has a touch tracking frame rate of 27.5 Hz. This helps in avoiding distortion arising due to not so flat surface of the arm, by optimizing the angle of projection, based on the user’s finger movement, after the watch is activated by swiping left.

LumiWatch: On-Arm Projected Graphics and Touch Input


LumiWatch can register continuous user finger movement within 1cm of the skin surface and can last up to 1 hour of the continuous display, and one full day, with average usage. It uses scanned laser design, instead of other small-form-factor design LCoS or DLP, because all light source is directed towards the projector, reducing the risk of light getting absorbed or redirected by the object. The watch is restricted to maximum 65ºC for internal components before it switches off the projector and the aluminum casing assists in reducing the heat dissipation form projector and logic board.


LumiWatch is expected to be priced around $600, once in production, though it still has to be seen, what its practical applications could be. While this looks promising, but this is not the first time, the projector technology was attempted. In February, Haier launched Asu smartwatch, which projected tiny screen into the user’s arm. Ritot wearable band and Cicret bracelet also provided similar functionalities.

Read more about it, on the official website of Human-Computer Interaction Institute

Read the official white paper here