A pioneer in nanotechnology, he designed and built the world's smallest motor in response to a challenge issued by physicist Richard Feynman in 1959. It was so tiny, it could only be seen with the use of a microscope. It looked like a grain of black grit, but when you squinted down the microscope you could make out a tiny, exquisite assembly of posts, plates and wires. It was an electromagnetic motor, made from magnets and coils of wire, and was less than half a millimetre across. The wires were just 1/80th of a millimetre wide, which is thinner than a human hair.