As we know, human skin is natural barrier for human being to protect the body from external substance invasion, and also biological multifunctional sensors perceiving pressure, temperature, proximity, pain, smell, friction, texture of objects, etc. [4,12,13] Admittedly, human skin also has its intrinsic drawbacks like inaccurate and indirect discernment of relative humidity which needs to be perceived by the cooperation of mechanoreceptor and thermoreceptor. [14,15] Thus, e-skin should be not only limited to imitating the structure and multifunctional sensing capabilities of human skin, but also be able to develop more excellent traits beyond the human skin. [14,16] Considering the exploitation and employment of numerous materials, versatile structures and the integration of various mechanisms and manufacturing methods, the real future e-skins would surpass human skin in most aspects and show new characteristics such as transduction of other stimuli like light, sound, and even magnetism. [17][18][19] The delicate design and integration of multifunctional flexible sensors may overcome the current shortcomings and offer new insight into the forthcoming era of omnipotent stretchable and bendable electronics.Basically, flexibility is a trait for contours with zero-Gaussian curvature, while stretchability is necessary for conformal and entire covering surfaces with non-zero Gaussian curvature when the flexible sensors are attached to irregular 3-dimensionally curvilinear human skin. [20] Thus, stretchable sensors are supposed to be flexible. In the beginning of flexible sensors, most of the elemental sensing parts were created by combining inherently inorganic and rigid active materials (e.g., Si and Au) with soft substrates via special shape designs which are partly flexible to some extent. [20][21][22][23] Nonetheless, it is far from perfect for practical use if attaching these electronic devices on arbitrarily curved human skin and robot surfaces. Actually, commercial wearables are supposed to gradually take the sense of human scale and aesthetic into consideration, i.e., they are expected to be mechanically conformal, user-comfortable, environment-friendly, biocompatible, transparent, etc. [24,25] Consequently, all-flexible/stretchable sensors mainly consisting of organic active materials and/or metal nanowires are springing up. [26] Among various signals existing in nature, forces, temperature, and humidity play essential and vital roles in our normal Multiresponsive flexile sensors with strain, temperature, humidity, and other sensing abilities serving as real electronic skin (e-skin) have manifested great application potential in flexible electronics, artificial intelligence (AI), and Internet of Things (IoT). Although numerous flexible sensors with sole sensing function have already been reported since the concept of e-skin, that mimics the sensing features of human skin, was proposed about a decade ago, the ones with more sensing capacities as new emergences are urgently demanded. However, highly integrated a...
