Smartwatches are a promising new platform, but their small size makes even basic actions cumbersome. Hence, there is a great need for approaches to allow human input to escape the small physical confines of the device. We propose using tiny projectors integrated into the smartwatch to render icons on the user’s skin. These icons can be made touch sensitive, significantly expanding the interactive region without increasing device size.
Gierad Laput, Robert Xiao, Xiang 'Anthony' Chen, Scott E. Hudson, and Chris Harrison. 2014. Skin buttons: cheap, small, low-powered and clickable fixed-icon laser projectors. In Proceedings of the 27th annual ACM symposium on User interface software and technology (UIST '14). ACM, New York, NY, USA, 389-394. DOI=http://dx.doi.org/10.1145/2642918.2647356