A compact and low-cost motion detector based on a light-sensitive protein bacteriorhodopsin is fabricated. We show that a single photocell, which is masked with a pattern, can detect the speed and direction of a moving light without complex software algorithms. When light scans the patterned sensing area, the edges of each pattern produce polarity-reversed photocurrents depending on the light bar's speed and direction. Owing to the asymmetry of the pattern, we can detect two or four directions of the moving light. We intend to exploit this unique property in gestural manipulation with a laser pointer or fingers for remote control systems.

doi: 10.1016/j.synthmet.2016.10.020