Researchers at the National Electronics and Computer Technology Center in Pathumthani, Thailand, led by Sarun Sumriddetchkajorn, have developed an optical touch-activated switch to replace mechanical switches for use by disabled people. They described the device in the March issue of Optical Engineering.The switch operates based on total internal reflection in a Dove prism. When a finger is applied lightly to the surface of the device, the light beam traveling through the prism is redirected to a photodetector, converted into an electrical current and fed to a circuit. The switch can be made more or less sensitive to accommodate the needs of the individual, and the team plans to implement the concept to control electrical appliances such as computers, cell phones and doorbells.