Ariane 5 technology turns the lights on

ESA - Technology Transfer - Ariane 5 technology turns the lights on

A company called Sensitive Object has developed and patented
ReverSys technology that uses one accelerometer to capture the
accoustic pattern of any rigid surface, and then uses Time-Reversed
Lamb Waves to calculate the precise location of any finger-tap, on
that surface.
The result is that you can use everyday household objects,
blackboards, etc., as input devices to control other devices via
computer.