Strain-Isolation Bridge Structure to Improve Stretchability of Highly Sensitive Strain Sensors

Increasing interests of stretchable strain sensors due to their important applications in skin electronics, soft robotics, and wearable systems require the capability of detecting subtle strain and large stretched deformation, but this remains a challenge. A new strategy based on a simple bridge-like structure design, replacing previous sophisticated mechanics designs or advanced low-dimension materials (carbon-nanotubes, graphene, metal nanowires etc.), is demonstrated to disperse the applied strain effectively and prevent the conductive layer from unexpected destruction; thus the obtained graphite sensor increases its stretchability up to 123% while maintaining its high gauge factors more than 1000. This strain isolation effect as the underlying mechanism is verified by both experiments and numerical simulations. Furthermore, a biaxial bridge strain sensor with reconstructed crack-network, fabricated by a simple multistep prestretching method, shows an isotropic strain sensing behavior that has potential applications on detecting complex human motions. The proposed strategy can be easily extended to other conductive materials and stretchable substrates, which can thus serve as a new facile yet efficient way for high-performance wearable electronics.