Simulating the human body's ion transmission mechanism, bionic skin can heal itself

A piece of soft material was cut by a knife and left at room temperature for one hour. After testing, its mechanical properties could be restored to 91% of its original state... Recently, the bio-based polymer materials team of the Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences In cooperation with the scientific research teams of Hanyang University and Chungnam University in South Korea, a "super-sensitive and self-repairing ionic skin" was developed. Relevant papers were published online in "Nature Communications".

"This research result simulates an ion signal transmission system similar to biological tactile cells, controlling the ion distribution inside the ion conductor according to changes in force, and maximizing tactile perception." Corresponding author of the paper, Associate Researcher Ying Wu Bin of the Ningbo Institute of Materials, Chinese Academy of Sciences Introduction, it is very meaningful that it proposes a new concept of ionic skin technology that simultaneously restores wound and tactile functions, which can be used for human prosthetic skin or robot skin, especially for human-machine interfaces in the field of wearable medical care.

Inspired by the sensing structure of human skin, domestic and foreign scientists have previously developed several types of ionic skins with ion transmission mechanisms, and have applied them to mechanical devices such as remote controls and sensors. The materials in question, while possessing high immunity to interference, excellent spatial resolution, and responsiveness to static and dynamic stimuli, are susceptible to continuous wear, causing unintended mechanical damage that results in functional disruption or reduced device life.

Design concept of ionic skin: action potential stimulation generated by ion dynamics and bond exchange effect of dynamic disulfide bonds simulate the external force sensing and self-healing functions of human skin. Photo courtesy of the scientific research team

Is it possible to give ionic skin the ability to self-repair by referring to human skin, thereby ensuring the stability and service life of the corresponding equipment?

Ying Wubin introduced that the market size of electronic skin in 2021 will be US$6.3 billion, and the market is expected to have a compound annual growth rate of 21.1%. Ion skin is the next generation of electronic skin, which is still in the research and development stage.

In this study, based on the mechanical stimulation response principle of tactile cells and simulating the self-healing function and biological ion signal transmission mechanism of real human skin, the joint team designed and synthesized a new type of tactile membrane containing dynamic disulfide bond functional groups and chlorine substituents. Thermoplastic polyurethane material.

On this basis, they used ionic liquid as the signal transmission medium, filled it with this thermoplastic polyurethane material, and developed a new ionic conductor. They used silver nanowires as flexible electrodes and polyurethane as packaging materials to assemble a target ionic skin. .

"Dynamic disulfide bonds have a bond exchange effect, which can be carried out even at room temperature. When the material is damaged, the bond exchange effect will bring the molecular chains closer and allow them to stack back together again, which will also show a self-healing phenomenon macroscopically. , the sensitive tactile function can also be restored as the wound heals." Ying Wubin introduced that changing the reversible ion dipole interaction between the chlorine substituent and the ionic liquid can effectively increase the difference between the immediate capacitance and the initial capacitance. value, thereby improving sensitivity.

"This work is an advancement of the previous 'simulated muscle' work, which is closer to the human body's sensing mechanism and one step closer to a flexible human-machine interface." Ying Wubin introduced.

Previously, the bio-based polymer materials team of the Ningbo Institute of Materials, Chinese Academy of Sciences has developed a new type of polyurethane (DA-PU) material, namely "simulation muscle", which is suitable for use as an elastic matrix for stretchable electronic products, ensuring that electronic devices can be used in complex It can still work stably in any environment. However, the "simulated muscle" does not use an ion transport mechanism, but an electron transport mechanism. There is a mismatch between electrons and ions in the human body, and its application in the human body is limited.