Scientists have figured out how to give robots a sense of touch nearly as sensitive as that of humans. They have created an electronic skin that can distinguish extremely subtle texture differences far beyond the capabilities of current robotic sensing devices. One area where the technology would be useful is in surgery.
The new robotic skin is truly a laboratory marvel. It is a very thin film, 1,000 times thinner than a sheet of paper. The film is a sandwich of alternating layers of microscopic particles of gold and cadmium sulphide, which conduct electricity. Each of these conducting layers is separated by a nonconducting plastic layer.
When an electric current is sent through the film, conductivity increases at the pressure points, causing the microscopic particles to glow. The higher the pressure, the brighter the glow.
The work comes from University of Nebraska chemical engineer Ravi Saraf and a graduate student, who published their research in the journal Science. Saraf told interviewers that a fine sense of touch would dramatically enhance robotic capabilities.
"For example, by touch the robot could quickly tell if the object is smooth or has sharp edges, a property that an optical system would taker longer with much more computing power," said Ravi Saraf. "If a robot has a touch sensation, this would allow the robot to maneuver in the dark like a blind person."
Saraf says his electronic skin can sense spacing between textural ridges as close as 40 microns, or 40,000's parts of a millimeter, less than one-third the width of a human hair. This is 50 times finer than current touch technologies. It can also resolve textural heights as low as five microns, comparable to the two micron resolution of the human finger.
For demonstration purposes, the researcher pressed a U.S. one cent coin against the film. The image lighted up in the shape of some of the letters in the word "Liberty" on the penny. It also distinguished some of the wrinkles in the clothing of Abraham Lincoln, the 19th century U.S. president portrayed on it.
Saraf says the technology could benefit medicine. Surgeons currently use their own sense of touch to detect tumors or gallstones, which are harder than normal tissue. But robots could take over the function with the thin film wrapped around the end of mechanical fingers. Saraf says the robot digits could be attached to an endoscope, a camera with a light used to peer inside body cavities.
"Having this device on the endoscope can allow one to image both the area where the surgeon is performing and superimpose the texture of the tissue, such as the hardness of the tissue," he said. "That way, the surgeon can determine if the tissue is cancer or not."
Saraf says a practical robotic touch system could be designed in a few years if their is enough interest and funding.