Would you like to reduce the size of your home security system? Like something on the order of magnitude of motion detectors that can fit on a postage stamp? These tiny rectangular sensors are actually powerful passive infrared (PIR) detectors that can be easily slipped into an area where their larger PIR brethren couldn't even dream of fitting.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.