Flexible Sensors Make Robot Skin

By Roland Piquepaille

In recent years, lots of efforts have been made to give robots the ability to hear and see. But what about the sense of touch? Unlike us, robots don't have sensitive skin. But this is about to change. By using organic, or plastic, field-effect transistors as pressure sensors deposited on a flexible material, researchers at the University of Tokyo have created an artificial skin which will give robots the sense of touch. The prototype has a density of 16 sensors per square centimeter, far from the 1,500 of our fingertips. When this density increases and when the problem of the reliability of this kind of transistors is solved, the researchers say this artificial skin will also be used for car seats or gym carpets. Expect to see them in four or five years. Read more...

Here are selected excerpts from the Technology Research News article.

Researchers from the University of Tokyo have devised pressure-sensor arrays that promise to give objects like rugs and robots the equivalent of one aspect of skin -- pressure sensitivity.

The researchers' pressure sensor arrays are built from inexpensive organic, or plastic, transistors on a flexible material. This allows for dense arrays that can be used over large areas.

The arrays could be used in pressure-sensitive coverings in hospitals, homes, gyms and cars to monitor people's health and performance, and eventually as skin that would give robots the means to interact more sensitively with their surroundings, said Takao Someya, an associate professor of electrical engineering at the University of Tokyo.

The sensor skin works even when rolled around a cylinder as small as 4 millimeters in diameter, said Someya. The researchers' prototype is an eight-centimeter-square sheet containing a 32-by-32 array of organic sensors -- a density of 16 sensors per square centimeter. In contrast, humans have 1,500 pressure sensors per square centimeter in the fingertips, though far fewer in most other places.

Here is a picture of a robotic hand using organic transistors as pressure sensors. (Credit: Takao Someya)

And what are possible applications?

The active-matrix design allows the arrays to be smart enough to enable specific sensors at certain feedback points to, for instance, monitor the heart and breathing rate of a hospital patient who has fallen to the floor, said Someya. The skin could measure whether an elderly patient is just taking a rest, or needs help, he said.

The skin could also be used in car seats to monitor drivers' mental and physical conditions, Someya said. "Our large-area pressure [sensing abilities] would be helpful" in obtaining information through drivers seats, he said.

And, of course, we'll see home robots able to pick an egg in the fridge.

The research work has been published by the Proceedings of the National Academy of Sciences on July 6, 2004, under the title "A large-area, flexible pressure sensor matrix with organic field-effect transistors for artificial skin applications." Here is a link to the abstract.

PNAS, Volume 101, Issue 27, pp. 9966-9970, July 6, 2004

Sources: Eric Smalley, Technology Research News, September 22/29, 2004; and various websites