Constructing Electronic/Ionic‐Conductive Hydrogel with Soft Compliance and High Conductivity as Flexible Strain Sensor

Flexible sensors are garnering substantial interests for various promising applications, including medical electronics, environmental monitoring, and wearable devices. Developing a flexible sensor with high compliance, high sensitivity, and high reliability through the construction of a novel composite conductive hydrogel based on the synergistic enhancement effect of conductive polymers and metal ions is a remarkable achievement. Herein, an electronic/ionic‐conductive double network hydrogel (polypyrrole (PPy)/carboxymethyl cellulose (CMC)‐Al 3+ /polyvinyl alcohol (PVA)) with soft compliance, highly conductivity, and stability is presented. Moreover, owing to the synergistic reinforcement effect of the relatively immobilized “islands” of PPy particles and large amounts of movable “bridges” of aluminum ions (Al 3+ ) within the double network hydrogel, the as‐optimized PPy/CMC‐Al 3+ /PVA composite gels exhibit excellent conductivity ( σ = 3.47 ± 0.25 S m −1 ) and mechanical properties (E = 18.53 ± 0.67 kPa). Furthermore, it has been developed as strain sensors with relatively high linear sensitivity (gauge factor = 2.58) within a broad linearity range (0–400%). It can also be served as a monitoring devices for subtle physiological signals emanating from various parts of the human body. The robust sensor has great potential to be developed as wearable electronic devices and applied in healthcare monitoring fields.