Main image of article Windows Locked? Ask Wireless, Battery-free System
Anyone like myself who has a nasty habit of leaving their windows unlocked might want to take a look at a sensor system currently under development by Fraunhofer Institute for Integrated Circuits in Germany. It’s Window Sentinel System uses a 3D magnetic field sensor that is described as being roughly the same size as a fingernail. This sensor is placed in the inner frame of the window and a sliding magnet goes on the bottom of the sash. The two communicate and the sensor can detect whether the window has been locked, based on the angle and position of the magnet. Apparently, it’s accurate enough to differentiate between a locked window from one that has been closed but left unlocked. And, more importantly, it can detect if tampering has occurred. The folks at Fraunhofer Institute have really thought their system through. The frame also features an embedded microcontroller and radio unit, which permits status reports to be transmitted as far as 66 to 98 feet. The transmissions are received by an Internet-connected base station, which can be anything from a smart phone to a computer.
The system is powered with the help of solar cells incorporated into the window frame and a thermoelectric generator. Although the Fraunhofer Institute has put a lot of thought into its window sensor system, one thing it doesn’t do is lock the windows once the error is discovered.

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