Highly Sensitive and Multimodal All-Carbon Skin Sensors Capable of Simultaneously Detecting Tactile and Biological Stimuli

Recently, design of a stretchable artificial skin with heterogeneous multi-stimuli responses as well as high sensitivity is strongly desired to emulate human skin. In particular, the effective incorporation of chemical or biological detection with tactile sensing in a single device is a challenging task for implementing an artificial skin platform beyond human skin, whereas this has not hitherto been explored in a precise and cost-effective manner. Thus, in response to the ongoing challenges for skin sensors, a rational design of sensing materials and device architecture is strongly required. In this work, we describe the highly sensitive, wearable, and multi-stimuli responsive “all-carbon” skin sensors based on hierarchically engineered elastic carbon nanotube fabrics (i.e. carbon nanotube microyarn), which is capable of detecting heterogeneous external subtle stimuli in a single pixel. In particular, effective multimodal output electric signals can be manipulated as a change of resistance or capacitance under mechanical deformations (including pressure and flexion), touch, temperature, humidity variation, which physiologically enables the communication of feelings and emotions through skin-to-skin contact similar to that of human skin. Moreover, each pixel in our sensor skin can detect and even discern input signals derived from versatile chemical fluids with different dipole moments or pH. This implies the implementation of artificial all-carbon skin sensors incorporated with an electronic nose or tongue beyond the multimodality of human skin as a new platform. We believe that a stretchable, artificial all-carbon skin suggested by us will be an effective way to implement human-interactive smart robots capable of recognizing the robot-human-environment interface and to enable in-situ human monitoring capable of effectively detecting some biological markers as well as tactile stimuli.