Cephalopods inspire artificial skin for bioelectronic devices

The new skin, developed in a Penn State University-led collaboration, mimics the elasticity and the neurologic functions of cephalopod skin, which octopuses, squids and cuttlefish use to sense and respond to their surroundings.

Led by Cunjiang Yu, Dorothy Quiggle Career Development Associate Professor of Engineering Science and Mechanics and Biomedical Engineering, the team published its findings on June 1 in the Proceedings of the National Academy of Sciences.  

According to Penn State, cephalopod skin is a soft organ that can endure complex deformations, such as expanding, contracting, bending and twisting. It also possesses cognitive sense-and-respond functions that enable the skin to sense light, react and camouflage its wearer.

Artificial skins with these physical or cognitive capabilities have existed previously, but until now none has simultaneously exhibited both qualities, which is the combination needed for advanced, artificially intelligent bioelectronic skin devices.   

“Although several artificial camouflage skin devices have been recently developed, they lack critical noncentralised neuromorphic processing and cognition capabilities, and materials with such capabilities lack robust mechanical properties,” Yu said in a statement. “Our recently developed soft synaptic devices have achieved brain-inspired computing and artificial nervous systems that are sensitive to touch and light that retain these neuromorphic functions when biaxially stretched.”   

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To simultaneously achieve smartness and stretchability, the researchers constructed synaptic transistors entirely from elastomeric materials. These rubbery semiconductors operate in a similar way to neural connections, exchanging critical messages for system-wide needs, impervious to physical changes in the system’s structure.

According to Yu, the key to creating a soft skin device with cognitive and stretching capabilities was using elastomeric rubbery materials for every component. This approach resulted in a device that can successfully exhibit and maintain neurological synaptic behaviours, such as image sensing and memorisation, even when stretched, twisted and poked 30 per cent beyond a natural resting state.   

“With the recent surge of smart skin devices, implementing neuromorphic functions into these devices opens the door for a future direction toward more powerful biomimetics,” Yu said. “This methodology for implementing cognitive functions into smart skin devices could be extrapolated into many other areas, including neuromorphic computing wearables, artificial organs, soft neurorobotics and skin prosthetics for next-generation intelligent systems.”