Smartwatches are an emerging computational form factor, made commercially viable by recent advances in miniaturization and battery technology. However, because they are small and our fingers are relatively large, their interfaces tend to be simplistic. Touchscreen smartwatches allow the watch face to be used for a multitude of interfaces, providing flexibility that physical buttons cannot, but suffer from lack of tactile feedback and finger occlusion. These issues would be partially mitigated if we could simply provide more space for interaction. However, simply making smartwatches larger is not an option, as this would make them more obtrusive. Thus one possible approach is to appropriate surface area around the watch for interaction.
To achieve this, we created low cost, very small projectors that can render a fixed image onto the skin at an oblique angle. These properties make them suitable for inclusion into smartwatches, where they can extend the interactive area beyond the small screen. For example, a notification icon could be projected for missed calls or new messages. Infrared proximity sensors work in concert with these projectors to enable touch sensitivity. For example, tapping a pulsating text message icon could allow users to quickly jump to that message. In addition to providing a projection surface, the skin also provides useful tactile feedback.
Laput, G., Xiao, R., Chen, X., Hudson, S. and Harrison, C. 2014. Skin Buttons: Cheap, Small, Low-Power and Clickable Fixed-Icon Laser Projections. In Proceedings of the 27th Annual ACM Symposium on User interface Software and Technology (Honolulu, Hawaii, October 5 – 8, 2014). UIST ’14. ACM, New York, NY. 389-394.