While smartwatches are convenient, there is a limit to their functionality due to their small interfaces. Enter LumiWatch. 

The CMU team collaborated with ASU Tech to reveal the first fully-functional and self-contained projection smartwatch implementation in a research paper presented at CHI 2018. 

By using shallow-angle projection to project the display onto the wearer's forearm, the LumiWatch offers more than 5 times the interactive surface area of a typical smartwatch display. A 1-D depth-sensing array monitors finger tracking for input, and their 15 lumen projector output is bright enough to be seen while wearing the watch outside. To prevent inadvertent touches on the arm, the interface requires a 'swipe to unlock' mechanism. 

For more information and to download the research paper, visit the project website.  

Link to Project
LumiWatch: On-Arm Projected Graphics and Touch Input