Watchful windows

Watchful windows

  10:20:00 PM    Science Lover

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New light-sensitive sensor technology could enable your windows to detect intruders and sound an alarm

Ever had that sinking feeling that someone is sneaking around in front of your window, probably trying to break in? With new technology crafted by researchers in Germany, windows and doors might soon be able to detect whether there’s suspicious activity outside your house, and accordingly, sound an alarm.

A novel motion sensor developed by the Fraunhofer Institutes for Applied Polymer Research (IAP) in Potsdam-Golm enables window panes and glass doors to detect movements, thanks to a special coating.

If anything changes in front of a pane, or someone sneaks up to it, an alarm is soon sounded.

“The glass is coated with a fluorescent material,” explains IAP group manager Dr Burkhard Elling. “The coating contains nanoparticles that convert light falling on the window into fluorescent radiation.”

How it works

The principle is as follows: The invisible light of an ultraviolet (UV) lamp “illuminates” the window panes, and generates fluorescent radiation in the coating. Sensors in the edges of the window detect this radiation, and thus keep a tab on activities.

A single sensor can perform simple applications: For example, if someone steps into the light of the lamp, less light reaches the coating and less fluorescent radiation is produced – thus triggering the sensor.

If several sensors are installed on all four sides of the window frame, conclusions can be drawn from the data as to how fast and in what direction an object is moving. Its size, too, can be estimated by the sensors.

The invisible light of a UV lamp ‘illuminates’ the window panes and generates fluorescent radiation in the coating. This radiation is detected by sensors in the edges of the window

“This is especially useful in warding off false alarms. For instance, by setting a threshold for the alarm, moving objects that are the size of birds do not set off any sirens,” Elling says.

Likewise, the smart sensors do not react to light from passing cars, as the researchers have developed a software application that can interpret different light signals. This enables the system to easily distinguish between a UV lamp and the slowly changing light from a passing headlight.

“The system has further advantages: For one, it does not infringe on anybody’s personal rights, as it only detects the change in radiation, and not who triggered it,” Elling points out.

“It is also cost-efficient, because the coating can be sprayed onto the windows by airbrush or glued on as a film,” he adds.

A demonstrator system has already been made, and the boffins are aiming to market it at places such as museums.

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