An anonymous reader writes: British engineers have created the first muscle stimulating microchip small enough that several can be implanted in a person's spinal canal. In addition to providing enough stimulation to, say, let users pedal a stationary bicycle, they could also be used for thing like stimulating bladder muscles to help overcome incontinence. Their breakthrough is that the devices package everything into one tiny unit. Lasers cut tiny electrodes from platinum foil, which are then folded into a 3D shape that looks like the pages of a book. These pages, in turn, wrap around the nerve roots.