Designing ultrasensitive and strechable strain sensors by tailored fragmentation of carbon-based conductors

There is an increasing demand for strain sensors with high sensitivity and high stretchability for new applications such as robotics or wearable electronics. However, for available technologies, the sensitivity of the sensors varies widely. These sensors are also highly nonlinear, making reliable measurement challenging. Here we introduce a new family of sensors composed of a cracked carbon nanotube structures embedded in an elastomer. Cracks are usually considered detrimental to the overall mechanical and electrical properties of materials. However, if these cracks can be controlled, they also have the potential for use in mechanical sensing applications. In this study, we demonstrate that strain sensors based on fragmented single-walled carbon nanotube (SWCNT) assemblies embedded in poly (dimethyl siloxane) (PDMS) can maintain their sensitivity at very high strain levels. Our strategy here is to develop a new family of sensors taking advantage of the special properties of fragmented carbon-nanoparticles based structures (papers and wires). We systematically describe how to control the fragmentation of the conductive CNT papers or wires for achieving highperformance strain sensors. This fragmentation based sensing system brings opportunities to engineer highly sensitive stretchable sensors.