In a new research published in ACS Applied Materials & Interfaces, the researchers reported the development of a jellyfish-inspired electronic skin that glows when the pressure against it is high enough to potentially cause an injury.

Electronic-skin technologies for prosthetics and robots can detect the slightest touch or breeze. But oddly, the sensors that make this possible do not respond effectively to a harmful blow. An electronic skin that can mimic the full range of biological skin's sensitivity has great potential to transform prosthetics and robotics. Current technologies are very sensitive, but only within a narrow range of weak pressures.

Under high pressures that could cause damage, the electronic skins' sensitivity fades. To address this shortcoming, Bin Hu and colleagues at the Huazhong University of Science and Technology turned to the Atolla jellyfish for inspiration. This bioluminescent, deep-sea creature can feel changes in environmental pressure and flashes dramatically when it senses danger.

Building on the idea of a visual warning in response to a physical threat, the researchers combined electric and optical systems in a novel electronic skin to detect both slight and high-force pressures. The research team embedded two layers of stretchy, poly-dimethysiloxane, or PDMS, the film with silver nanowires. These layers produce an electrical signal in response to slight pressures, such as those created by a breeze or contact with a leaf.

Sandwiched in between the silver nanowire electrodes is a PDMS layer embedded with phosphors. This layer kicks in and glows with growing intensity as the physical force increases. The researchers say this approach more closely copies the wide range of pressures the human skin can feel.

A dual-mode e-skin, which is able to quantify and map the static and dynamic pressures through electrical and optical sensing. By integrating the capacitive and luminescent sensing modes into a monolithic device via a simple and scalable fabrication process, the functions of the mechanoreceptors and nociceptors in the biological skin can be mimicked.

Surface-microstructured dielectric layer induces highly sensitive capacitance change in low-pressure regime, which is used to sense the gentle tactile as mechanoreceptor. While the notable change in visualized luminescent intensity in high-pressure regime acts as nociceptor to warn the injurious mechanical stimuli.

The two sensing modes with complementary sensitive ranges provide a reliable response to different levels of pressure, and mechanical robust and stretchable properties of the e-skins show their great potential towards the realistic applications in human-machine interfaces and intelligent robots.