Highly Sensitive and Stretchable Strain Sensors Based on Conductive Elastomer Composites

Flexible strain sensors are essential for applications in surgical robots, wearable electronics, and soft electronic skin. However, it remains challenging to realize materials that combine both high sensitivity and large stretchability. The gauge factor (GF), which quantifies resistance changes under strain, is often low in highly stretchable polymers, because their conductive pathways remain intact during deformation. Here, we present conductive elastomer composites that integrate movable cross-links with carbon-based conductive fillers to overcome this trade-off. Among the four designed systems, γ-cyclodextrin–containing P1–CD⊃P2/KB achieved the best balance between mechanical and electrical performance. Systematic optimization of molecular weight, γ-cyclodextrin content, and Ketjenblack loading yielded an optimal composition, P1–CD⊃P2/KB (86k, 0.62, 10), which exhibited an ultrahigh GF of 1500 ± 100 together with a fracture strain of 300%. This conductive elastomer composite also demonstrated excellent durability and recyclability, maintaining stable performance over 500 stretch–release cycles and enabling precise motion sensing in a robotic hand. These findings highlight the potential of movable cross-linked elastomer composites as next-generation strain sensors for wearable devices and humanoid robotics.