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We have seen a number of innovations in soft robotics, from a self-healing robot to a robotic hand with a very soft touch. But one limitation has been in the area of creating artificial skin that can ‘feel’ like human skin. In recent years, researchers have even been able to instil sensory perception, like touch and pressure, in artificial skin. However, while those sorts of senses will be incredibly important in engineered skin, they’ve so far been rather limited. For example, current versions can be quite sensitive to light touch, but they aren’t able to sense high pressures that could cause damage. When researchers at the Huazhong University of Science and Technology in China recently set out to fix that problem, they drew their inspiration from jellyfish.

The Atolla jellyfish can sense changes in pressure in its surroundings which could indicate the approach of a predator. In response, the jellyfish emits bright flashes of light when it senses danger based on these changes in water pressure. The researchers devised a way to mimic that response and combine visual signals with pressure sensing. The research team embedded silver nanowires within stretchy poly-dimethysiloxane (PDMS) film. This allowed the PDMS film to produce electrical signals when light pressure was applied to it. Sandwiched between two layers of PDMS, the researchers then added an additional layer embedded with phosphors – particles which light up when strong pressure is applied. This ‘sandwich’ allows artificial skin made with the PDMS film to register a much wider range of pressure than previously.

As the high pressures registered by the phosphors are around the levels that become painful to humans, a visual representation of ‘pain’ is created. Because this artificial skin can sense a range of pressure, it more closely mimics the feeling of real human skin. As the researchers point out, this capability could lead to the electronic skin becoming a potential component in human-machine interfaces and intelligent robots. What other uses might there be for a pain-sensitive artificial skin?