There are now a number of materials designed to give robots or prostheses a sense of touch. And while most of them are thin and skin-like, a new alternative takes the form of a spongey foam – and it combines several desirable qualities.
Designed by scientists at the National University of Singapore, the experimental material is known as artificially innervated foam, or AiFoam. It consists of a "highly elastic" Teflon-like fluoropolymer mixed with a surfactant and microscopic metal particles, with cylindrical electrodes embedded beneath its surface.
The fluoropolymer can stretch by 230 percent without breaking, while the surfactant – which reduces the surface tension of the material – allows cuts within it to heal when heated. In the foam's current form, cuts heal by 70 percent after four days of being heated to 70 ºC (158 ºF), although those figures may improve as the technology is developed further.
The addition of the metal microparticles gives the material proximity-sensing capabilities (when an electrical current is run through it), allowing it to sense the presence and movements of nearby capacitive objects such as human fingers. According to the university, this type of proximity-sensing technology is more reliable than others that are instead based on light, and which are more likely to produce false positive or erroneous negative readings when tasked with detecting the presence of humans.
Finally, when the AiFoam does make actual contact with an object, the electrodes allow it to sense both the amount of pressure and the direction in which it's being applied. This capability could help robots to better understand the intentions of users, plus it may help robotic or prosthetic hands to adjust their grip on objects that are slipping out of their grasp.
A paper on the research, which is being led by Asst. Prof. Benjamin Tee, has been published in the journal Nature Communications. The capabilities of AiFoam are demonstrated in the following video.
Source: National University of Singapore