Paralysed woman's thoughts control robotic armShe was implanted with two sensors - each four millimetres by four millimetres - in the motor cortex of her brain. A hundred tiny needles on each sensor pick up the electrical activity from about 200 individual brain cells. "The way that neurons communicate with each other is by how fast they fire pulses, it's a little bit akin to listening to a Geiger counter click, and it's that property that we
