Window sensors have long been a part of security systems, but since they all rely on wires so they can be constantly monitored, there's the potential for them to be compromised. That's not the case with these new wireless sensors that are invisible when installed, and don't even require an outside power source.
Developed at the Fraunhofer Institute for Integrated Circuits IIS, the new sensors are built around the institute's HallinOne 3D magnetic field sensor which is already in use in other consumer products. A magnet embedded in the bottom of the window is detected by the fingernail-sized 3D sensor built into its frame. It's sophisticated enough to determine both the position and angle of the magnet, so it can tell if a window has been left just slightly open, or even if it's been properly locked. And to keep it powered a thermoelectric generator, also embedded in the window frame, converts heat into electricity -- while a small solar cell harvests sunlight from outside.
The system also uses a clever nodal RF system to wirelessly transmit status information to a base station. Every single window has a small radio unit and microcontroller built-in so that they can talk to each other, passing along data to the next if they're out of range of the base station. And while all the hardware is only available as bulky prototypes at the moment, by the end of the year it will be refined and ready for mass production so you can hopefully expect to see security systems employing this technology as early as next year. [Fraunhofer]