Preparation of Dual-Network Conductive Hydrogels As Wearable Flexible Strain Sensors Using One-Pot Method and Soaking Strategy

Conductive hydrogel-based flexible strain sensors have gradually attracted the attention of scientific researchers in recent years. They are capable of converting invisible mechanical stimulus signals into visible electrical signals and have excellent biocompatibility and good electrical conductivity, which also provide the basis for the development of flexible electronic devices. Nowadays, conductive hydrogel, as the core component of flexible sensors, puts forward higher requirements for sensitivity, fast response, and cycle stability to adapt to human activity detection and health monitoring. In this paper, acrylamide (AM), cellulose nanocrystals (CNC), and sodium alginate (SA) were used as raw materials to prepare PAM/CNC/SA double network hydrogel by in situ free radical polymerization. Soaked in the CaCl₂ solution, a PAM/CNC/SA-Ca²⁺ double-network conductive hydrogel is formed. The results show that the addition of CNC can significantly improve the mechanical properties of the hydrogel. In addition, the introduction of the Ca²⁺ ion has a certain positive effect on the conductivity of the hydrogel. At the same time, the conductive hydrogel has good strain sensitivity (gauge factor up to 16.63). Therefore, conductive hydrogels have potential application value and broad application prospects in the field of flexible sensors.