Although it may be handy to have sensors in your windows that remind you if you've left them open, running electrical wiring to all those sensors (or regularly changing their batteries) could be a hassle. A new window-monitoring radio sensor chip, however, gets all the power it needs from the sun.
Developed at Germany's Fraunhofer Institute for Microelectronic Circuits and Systems, the tiny chip is designed to be mounted on the window's aluminum frame, between the panes of glass. Its top surface is covered by a solar cell, and it can store enough power during daylight hours to operate throughout the night.
Using an integrated accelerometer and magnetometer, the chip is able to detect when the window has been opened, and by how much. If the window has been left open "too long" (such as once everyone has left the house for the day, or once the temperature has dropped significantly) it sends a radio signal to a base station in the home. That station in turn alerts the homeowner.
Additionally, if it detects movements that are unique to a locked window being forced open, it will signal the base station to sound an alarm.
The chip will be on display at the BAU trade fair in Munich, from January 19 to 24. Fraunhofer previously developed a similar system, in which the window sensor is powered both by a solar cell and a thermoelectric generator.