A Puncture-Resistant and Self-Healing Conductive Gel for Multifunctional Electronic Skin

Significance 

Wearable flexible bionic tactile sensor, also known as electronic skin, has a wide range of applications in artificial intelligence and other fields like the development of wearable devices and human-machine interaction systems. To date, various sensing devices have been developed by incorporating functional moieties into polymer substrates. The conformability and compliance of the resulting flexible electronics have been achieved by designing skin-like materials capable of mimicking the natural phenomena of skills, such as self-healing capabilities. Despite the good progress in developing electronic skins, two critical issues that are yet to be fully addressed still restrict their practical applications.

First, electronic skins should have the ability to perceive multiple external stimuli like friction and temperature to mimic the functions of human skin effectively. Second, mechanical damage of the electronic skins caused by various injuries is possible during their long-term application. Thus, like human skins, electronic skins should possess good cut- and puncture resistance as well as self-healing abilities after mechanical damages. However, due to the complexity involved in the lamination and integration of different sensors, the fabrication of multifunctional skins remains a big challenge. Additionally, most polymer substrates used in fabricating electronic skins are highly susceptible to mechanical forces due to their fragile and soft nature.

Currently, multifunctional sensors are integrated within a flexible matrix to effectively imitate multisensory perception of human skin. Despite the significant research efforts, effective and economical strategies for the fabrication of multifunctional electronic skin with superior performance are still lacking. This can be attributed to several factors, including unstable uniformity and structural properties, the heterogeneous nature of their structures, and the tradeoff effects between toughness, flexibility and self-healing abilities. Therefore, more studies on the preparation of multifunctional skins with self-healing abilities are necessary.

To this note, a team of researchers from Nanjing University: Mr. Ke-Xin Hou, Mr. Shu-Peng Zhao, Dr. Da-Peng Wang, Dr. Pei-Chen Zhao, Professor Cheng-Hui Li and Professor Jing-Lin Zuo used a combination of flexible sodium methallyl sulfonate functionalized poly(thioctic acid) polymer network and rigid conductive polyaniline combined through ionic bonds to synthesize a solvent-free polymer conductive gel for fabricating multifunctional electronic skin with superior performance. The work is currently published in the research journal, Advanced Functional Materials.

The research team findings showed that the polymer hybrid gel exhibited a modulus akin to that of human skin. Besides, it showed excellent properties, including good flexibility, excellent toughness, cut- and puncture resistance, notch-insensitivity as well as fast self-healing ability. Moreover, the conductive gel converted the strain and temperature changes into electrical signals, which improved its multifunctional sensing performance. The remarkable multifunctional sensing performance was attributed to the synergistic effects of the ionic and hydrogen bonds owing to the benefits of incorporating the polyaniline. Furthermore, it was reported that flexible electronic skin sensors based on the fabricated conductive gel are highly sensitive to strain and temperature changes and can thus be used to detect various human psychological signals like temperature, breath and the movement of local joints with improved accuracy.

In a nutshell, Nanjing University scientists successfully synthesized a conductive gel with improved juncture-resistance and self-healing properties for potential use in fabricating multifunctional electronic skin. The gel had several advantages, such as similar modulus to the human skin and improved electrical conductivity. The proposed strategy takes advantage of the synergistic effects between the ionic and hydrogen bonds to realize skin-like materials with superior properties. It is flexible and can be extended to other flexible materials used in fabricating wearable devices. In a statement to Advances in Engineering, the authors stated explained the realization of their newly developed multifunctional sensing system will contribute to the fabrication of multifunctional electronic skin sensors with superior performance.

Reference

Hou, K., Zhao, S., Wang, D., Zhao, P., Li, C., & Zuo, J. (2021). A Puncture‐Resistant and Self‐Healing Conductive Gel for Multifunctional Electronic SkinAdvanced Functional Materials, 31(49), 2107006.

Go To Advanced Functional Materials

Check Also

Powering Entire Cities through Urban Photovoltaics - Advances in Engineering

Powering Entire Cities through Urban Photovoltaics