Highly stretchable conductors and piezocapacitive strain gauges based on simple contact-transfer patterning of carbon nanotube forests

Three-dimensionally interconnected carbon nanotubes (CNTs) in a vertically aligned CNT (vCNT) forest are potentially desirable for retaining their electrical functionality under various elastic deformations after being incorporated into elastomeric materials. Here, we report a class of highly stretchable and reliable elastic conductors based on the elastomer-infiltrated vCNT forest with micro-patternability enabled by a facile and accurate contact-transfer patterning approach. The stretchable conductors show electrical and mechanical robustness over a wide range of tensile strains of up to ∼450% and fully-stabilized response characteristics after some pre-conditioning. In addition, the electrical performance of the stretchable conductors is also found to be fairly retained without significant degradation in response to other types of elastic deformations such as bending, twisting, and folding. In this way, we demonstrate a piezocapacitive strain gauge that can measure large tensile strains as high as ∼150% with superior linearity, sustainability, and reversibility of the resultant capacitive responses. We show that the strain gauges can be used to monitor large-scale static and dynamic motions of human parts in real time.