Recently, Chen Tao and Xiao Peng, researchers of the Intelligent Polymer Materials Team of the Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, realized the efficient integration of touch and pain perception of bionic electronic skin by building a suspended double-layer sensing structure, providing new possibilities for material applications in human-computer interaction, intelligent prosthetics and other fields. The relevant papers have been published in the international academic journal Advanced Materials. "We have cleverly designed a suspended three-dimensional deformation contact perception structure by imitating the human tactile pain perception dual-mode mechanism. While achieving ultra sensitive tactile perception, we also endow flexible electronic devices with adjustable threshold pain perception functions, providing new ideas for the integration of tactile perception structures in biomimetic electronic skin." Xiao Peng, one of the corresponding authors of the article and a researcher at the Chinese Academy of Sciences Ningbo Institute of Materials Technology and Engineering, said. Sensor materials that can enhance the human-computer interaction experience and experience the function and structure of human skin have become a research hotspot, as they can perceive different external stimuli such as pressure, strain, temperature, humidity, etc. Biomimetic electronic skin is one of them. "Biomimetic electronic skin can convert external stimuli such as deformation and temperature into electrical signals and deliver them to data processing terminals." Zhou Wei, the first author of the paper and a doctor from the Chinese Academy of Sciences Ningbo Institute of Materials Technology and Engineering, told the Science and Technology Daily that in recent years, bionic electronic skin has received increasing attention and has shown broad application prospects in robot perception, intelligent artificial limbs, medical monitoring and other fields. Biomimetic electronic skin can attach to the surface of robots, endowing them with tactile perception, which can improve the robot's operational ability and enhance the human-machine interaction experience. This material can also be applied to prosthetic limb manufacturing, helping users perceive external information such as pressure, temperature, and vibration. When the biomimetic electronic skin is attached to the surface of the human body, it can also obtain real-time physiological parameters such as heart rate, blood pressure, and body temperature, and continuously and uninterrupted health monitoring Zhou Wei said. The suspended double-layer perception structure has stronger information acquisition ability. In order to mimic the perception ability of human skin, biomimetic electronic skin materials need to maintain both sensitivity and flexibility, as well as stability and reliability. In this latest study, the research team innovatively constructed a suspended double-layer sensing structural material, achieving efficient integration of touch perception mediated by mechanical thresholds. "This achievement can be understood from two aspects: material composition and device structure." Zhou Wei told reporters that in terms of material composition, the research team used graphene nanosheets as sensing and electrode materials, leveraging their strong conductivity and flexibility. Based on the water gas interface assembly strategy, graphene assembled thin films were prepared. "By combining graphene assembled films with ultra-thin elastomer films and microstructure elastic substrates, the stability of the composite material during the pain perception process can be ensured." Zhou Wei said. In terms of device structure, researchers have constructed a suspended double-layer structure. This structure mainly consists of a suspended elastic thin film on the upper layer and a microstructure elastic substrate on the lower layer. The material adopts piezoresistive tactile sensing technology. The three-dimensional deformation and mechanical contact response behavior of suspended elastic films are key to achieving tactile sensation Zhou Wei told reporters that when the elastic thin film undergoes deformation, the current in the material decreases, resulting in tactile sensation; When the upper suspended elastic film and the lower substrate make mechanical contact, the current in the material will increase in the opposite direction, resulting in pain sensation. With the help of double-layer contact interface and reverse mutation of current, biomimetic electronic skin completes the dynamic transition from tactile perception to pain perception. This study shows that this suspended double-layer structure can distinguish dynamic displacement of 20 microns and recognize tactile information as low as 0.02 pascals. "Even under 5200 cycles of contact separation stimulation, the material can maintain stable and reliable tenderness response performance, exhibiting high sensitivity and excellent stability." Zhou Wei said. "By introducing pain signals, this suspended double-layer sensing structure can greatly enhance the ability of a single tactile sensor to obtain information and improve its interaction performance with the environment." Zhou Wei introduced that the team conducted experiments on attaching the biomimetic electronic skin to the surface of the robotic arm. The results show that this can achieve real-time response and self-protection to mechanical stimuli, improving the safety and efficiency of human-computer interaction. In the "Guiding Opinions on the Innovation and Development of Humanoid Robots" issued by the Ministry of Industry and Information Technology, technological innovation promotes the development of biomimetic skin. The key product and component research column mentions the development of high-resolution and multi-point contact detection capable biomimetic electronic skin. The related industries are in a critical period from research and development to industrialization, and technological exploration is an important prerequisite and foundation for the future industry to break through bottlenecks and flourish. In recent years, biomimetic materials, as an important research topic in the field of materials science, have developed rapidly and made significant progress in material technology, sensing technology, system integration, and other areas. A series of materials with high conductivity and mechanical flexibility, such as carbon nanotubes, graphene, and metal nanowires, can achieve efficient electrical signal transmission while maintaining the softness and stretchability of biomimetic electronic skin. The application of nanoscale sensors enables biomimetic electronic skin to perceive extremely small pressures and vibrations, providing precise tactile perception Zhou Wei introduced that some biomimetic electronic skins integrate self powered systems, utilizing piezoelectric or frictional effects to achieve energy self-sufficiency. Some biomimetic electronic skins also integrate wireless communication modules, which can transmit data to external devices in real time. By incorporating an intelligent control unit, the bionic electronic skin can also process and analyze sensing data, performing more complex feedback control tasks. From a technical perspective, biomimetic electronic skins have features such as portability, intelligence, self-healing, and multimodal perception. In Zhou Wei's view, improving the durability, stability, and biocompatibility of sensors is currently the focus of research on biomimetic electronic skin. For example, how to keep materials stable in high temperature, high humidity, and corrosive environments? How to perform real-time and low-power signal processing and data transmission? How to solve the problem of biocompatibility when applied in the fields of healthcare and human-computer interaction? Through continuous technological innovation and interdisciplinary cooperation, bionic electronic skin research is expected to overcome these challenges and achieve wider and deeper applications in the future Zhou Wei said. (Lai Xin She)