Proof-of-concept interface design from Figlab uses light-projected touch-sensitive icons around your wrist, and is also low-cost and low-energy - video embedded below:
We present Skin Buttons, tiny laser 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. We show a proof-of-concept device and demonstrate example applications. These “skin buttons” can have high touch accuracy and recognizability, while being low cost and power-efficient.