Born from the imagination of British and French scientists and engineers, this skin is able to detect touch and pressure, and it could eventually be used in everyday devices such as the shell of a smartphone or the touchpad of a computer.

nanofils in silicium

The idea of tickle your smartphone may sound crazy, but it may soon become a reality. A group of researchers from the University of Bristol in England, as well as Télécom Paris and the University of the Sorbonne,  have just unveiled Skin-On, a touch interface that looks like human skin. This artificial skin is able to detect touch, rotational pressure, multi-touch, stretching, caressing, tickling and twisting pinches.

Researchers imagine using artificial skin to replace the shell of smartphones, smartwatch bracelets, or the touchpad on laptops. It could replace a knobby pinching it, a joystick by simply pressing with the finger, and it could even detect in which hand a user holds his smartphone to offer a side menu accessible with the thumb.

New ways to interact with virtual objects

The skin is created by casting a layer of colored silicone on a mold to obtain the texture of the skin. The researchers then designed an electrode grid on top using a conductive stretchable wire. They then finished with a thickness of silicone to mimic the hypodermis, which fixes the electrodes in place and forms a soft layer under the skin that deforms under pressure.

Such an interface could more easily transmit clues about the user’s emotional state, for example during a conversation: squeezing the device to indicate anger, tapping the back for fun, etc. It would also allow new interactions with applications, such as stroking a virtual animal.

Artificial skin as sensitive as human skin

A polymer incorporating a very dense network of nanowires combining silicon and gold mimics the elasticity and sensory capacities of human skin. Mounted on a prosthesis, such an artificial epidermis could give amputees a new sense of touch, provided that they can relay this mass of information to the brain…

Limb prostheses have made considerable progress in recent years, particularly in the field of thought control via neural interfaces. Restoring the sense of touch is one of the other major challenges that researchers are trying to address. And in this field, the most promising path lies in the creation of an artificial skin capable of reproducing the sensitivity of the human epidermis. An idea that now seems within reach… This is evidenced by the work of a team of researchers from Seoul National University (South Korea), the North American University of Wisconsin-Madison and MC10, who designed a biometric stamp. Together, they have developed an artificial skin as sensitive and elastic as human skin.

In an article published in Nature Communications magazine, the group describes in detail how they managed to achieve this level of accuracy. This artificial skin is composed of a transparent polymer, polydimethylsiloxane, in which silicon and gold nanowires circulate. They form a very dense network, capable of detecting pressure, temperature, stretching, and humidity. The silicon is arranged in a spiral to support stretching without breaking. To increase realism, resistors heat the texture so that it provides a contact close to the temperature of human skin.

400 sensors per square millimeter

The researchers used motion-capture by filming a hand to observe how the skin moves. They then varied the layers to obtain a different elasticity according to the areas of the hand. This sensory system is connected to a network of electrodes that can stimulate the nerves to which a prosthesis with this skin would be connected. As a result, with 400 sensors per square millimeter, the sense of touch produced by this artificial epidermis is equivalent to that of a human hand. While this advance offers very promising prospects for the evolution of limb prostheses, the greatest challenge now is to create a stimulation interface that can restore this sensory information to the brain with all the nuances that make human touch so complex. Several experiments have already been carried out in this field.

Last year, Futura-Sciences published an article on the work of Case Western Reserve University in Cleveland (United States) on a neural interface capable of producing a sense of touch via a prosthesis. Igor Spetic, the volunteer who tested this equipment, was able to experience realistic sensations such as those that occur when he hits a steel ball, the tip of a pen, sandpaper or cotton ball. But at the time, Professor Dustin Tyler, who led this project, recognized that it would take at least another decade to develop a perfectly viable sensitive prosthesis. One of the main obstacles concerns the material part of the stimulation module that must be miniaturized in order to be integrated into the prosthesis. As far as this artificial skin is concerned, for the moment it has only been tested on rodents. Researchers say they want to extend their tests to larger animals so that they can study their effects more accurately.

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