Touched by a Robot

Even though humans develop a sense of touch before other senses, it has been very difficult to create a similar mechanism for robots. This makes some elements of manual dexterity very hard to duplicate, because robots receive no sensory information about how their hand relates to the item being handled. Instead, they must look at what they're doing and interpret it through visual information.

That may now change. A thin, flexible film has been developed that can replicate the sensitivity in the human finger. Ravi Saraf and his team from the University of Nebraska, Lincoln, announced their findings in Science. There are also articles on the topic in Nature and Scientific American.

The film, about 100 nanometers thick (typical office paper is about 1,000 times thicker), is built of alternating layers of gold and cadmium sulphide nanoparticles, separated by insulating sheets of 2 or 3 nanometer thick polymers. A current flows through the film so that the stress of pressing it against a surface creates distortions among the layers. The current can more easily flow past the insulating layers under such distortions, allowing the current to hit the cadmium sulphide - which then glow in relation to the stress (and therefore current) involved. By observing the light, they can measure the amount of pressure felt by the film.

This research is actually materials science rather than robotics, but the applications to robots are obvious. The research was motivated in an attempt to detect small malignant growths which cannot be observed with current monitoring devices. Unfortunately, this film doesn't appear to have the resolution necessary for such an application. Such a monitoring system will have to wait for some other innovation . . . for now, we'll take what we can get.

Related Article:

• Robotic Ants & Snakes
• "Android Science"
• Robots & Robotics

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