Those traffic loop sensors embedded at stop lights to detect the presence of a car have always provided fodder for vehicular snake oil vendors: I've seen products promising to eliminate red lights ONCE AND FOR ALL by ingeniously fooling a mysterious (but gullible, apparently) system hidden below the pavement. While false promises abound, this patent for bicycles seems to be more on the legit side, and could result in more carefree whizzing through intersections than previously allowed.
The systems work by detecting the shift in inductance caused by a huge metal object being in the vicinity of a charged loop of wire embedded in the road, thus knowing when someone is waiting for a light change. Bikes, naturally, have a hard time tripping these sensors, which are calibrated to avoid false positives by smaller objects. This sensor, then, emits a signal which fools the sensors at the press of a button. Carry on, cyclists, carry on. [Plan Bravo via BBG]