German scientists have come up with a new coating that turns normal window panes into sensitive detectors that can spot suspicious movements.

The coating, developed by the Fraunhofer Institute for Applied Polymer Research, contains nanoparticles that convert light into fluorescent radiation.

The window is illuminated by a discreet ultraviolet (UV) lamp, causing the coating to fluoresce. This radiation is picked up a sensor in the window frame that can trigger an alarm if the light is interrupted by an intruder.

Bird-brained idea

If multiple sensors are used, the system can calculate how fast and in what direction an object is moving. Its size can also be estimated so that birds, for instance, do not sound the alarm.

Researchers also wrote a software application that enables the system to distinguish between the frequency of the UV lamp and the slowly changing light from passing headlights.

The Institute already has a working demonstration system using the new nanotech coating, which can be sprayed onto the windows by airbrush or glued on as a film.