REACH into your wallet and find a coin. Without looking, could you identify the picture embossed on the coin's surface just by feeling it with your fingertip? Most people would struggle, but they would still far outstrip today's robots, which could not even identify the object as a coin.

Roboticists have long hoped to build a device with the touch sensitivity of a human hand. Now a team at the University of Nebraska-Lincoln has gone a stage further by building a simple, flexible sensor that can create highly detailed images of surfaces through touch alone (Science, vol 312, p 1501).

The sensor could be used in robotic surgery, for example, to allow a surgeon operating an endoscope to "feel" masses such as gallstones or detect precisely where healthy tissue ends and cancerous tissue begins. "A surgeon would press on cancer tissue and tell what it is by its hardness," says ...