Research progress on new materials and properties of electronic skin

Human skin is an extraordinary organ; it comprises an integrated, stretchable network of sensors that transmits information to the brain about tactile and thermal stimuli, enabling us to safely and efficiently operate in our environment. Researchers have become interested in large-scale electronic device networks inspired by human skin, motivated by the prospect of developing devices such as autonomous smart robots and bionic prostheses. Developing electronic networks consist of flexible, stretchable, and robust devices that are compliant with large-scale implementation and integrated with multiple functionalities is a testament to the progress in developing human-skin like electronic bodies. In the fields of human physiological parameter detection and robot tactile perception, electronic skin has been commonly used as a kind of flexible tactile biomimetic sensor. Conventional electronic skin tactile sensors based on metal and semiconductor materials do not meet the requirements for stretchability and portability during actual use because of poor flexibility and wearability. Attributed to the rapid development of flexible materials, and manufacturing and sensing technologies, new materials such as polydimethylsiloxane (PDMS), carbon nanotubes, and graphene have been used to prepare or support electronic skin sensors in recent years, thus enabling electronic skin to be more similar to human skin in terms of stretchability, compressibility, and spatial resolution of touch, and other properties. Now, multi-functional integrated electronic skin devices have realized interaction with smart devices to obtain further collection and processing of human body information. This study analyzed and discussed new electronic skin materials and sensing technologies used in electronic skin, including capacitive effects, piezoelectric effects, piezoresistive effects, optical effects, and wireless antenna sensing. We focused on the recent research progress in electronic skin in terms of stretch/compressibility, biocompatibility, biodegradability, self-power, self-healing, temperature sensitivity, and multi-functional integration. Moreover, we anticipate the future research directions of new electronic skin properties and possible ways to achieve large-area, low-cost, multi-function integrated electronic skin sensor arrays.