Artificial skin could sense objects without touching them

The artificial skin developed by researchers from the Nanyang Technological University in Singapore could be able to identify objects it has not yet touched. 

The team demonstrated that the artificial skin could be used in a variety of applications, including the manipulation of virtual game characters, navigation of electronic maps, and scrolling through electronic documents.

“Human skin has to touch something to tell it what is there,” said researcher Yifan Wang. “Human skin can only tell the softness or hardness of an object. We wanted our artificial skin to have more functions.”

Even without touching an object, Wang and his colleagues´ artificial skin can sense if it is close by and can also discern some clues about the type of material it is made of.

“We can tell whether it’s a piece of metal, plastic… or some biological material,” he said.

The skin was made from two outer layers of conductive fabric coated with nickel to serve as electrodes. The layers surround a porous sponge soaked in ionic liquid, which is a salt in a liquid state that acts as a conduit for electricity.

The two layers act as a capacitor, storing electrical energy in an electric field.

The sensing performance of the capacitor, which Wang claims is between 10 and 100 times more sensitive than a standard capacitor, means it is also able to detect very small changes in the electric field around the skin, allowing it to sense when objects are near.

Moreover, those subtle changes can help it identify what type of material a nearby object is made of.

The researchers tested the skin and demonstrated that it was able to classify a series of objects brought near it as being either polymer, metal or skin, indicated by specific changes in the capacitor’s measurements.

“The process is relatively simple. As the component comes close to contact, it enters the edges of the electric field of the capacitive structure,” said researcher Jonathan Aitken at the University of Sheffield, UK.

At the moment, the skin relies on machine learning techniques to identify how the object it detects compares with data on known materials.

Eventually, Wang said the skin could be used on a robotic finger to allow factory robots to better understand which objects to pick up and which to leave without having to grasp them, as well as being useful for prostheses.

“The work could lead to next-generation robotic perception technologies superior to existing tactile sensors,” Wang said. 

The researchers published their findings in the journal Small.