Fatigue‐Resistant Conducting Polymer Hydrogels as Strain Sensor for Underwater Robotics

Abstract Conducting polymer hydrogels are widely used as strain sensors in light of their distinct skin‐like softness, strain sensitivity, and environmental adaptiveness in the fields of wearable devices, soft robots, and human‐machine interface. However, the mechanical and electrical properties of existing conducting polymer hydrogels, especially fatigue‐resistance and sensing robustness during long‐term application, are unsatisfactory, which severely hamper their practical utilities. Herein, a strategy to fabricate conducting polymer hydrogels with anisotropic structures and mechanics is presented through a combined freeze‐casting and salting‐out process. The as‐fabricated conducting polymer hydrogels exhibit high fatigue threshold (>300 J m −2 ), low Young's modulus (≈100 kPa), as well as long‐term strain sensing robustness (over 10 000 cycles). Such superior performance enables their application as strain sensors to monitor the real‐time movement of underwater robotics. The design and fabrication strategy for conducting polymer hydrogels reported in this study may open up an enticing avenue for functional soft materials in soft electronics and robotics.