A Polypyrrole/Carbon Nanotube Based Hydrogel Sensor With High Sensitivity for Strain Detection

ABSTRACT Conductive hydrogels hold significant promise in the fields of flexible electronics and smart sensing applications owing to their outstanding stretchability and electrical conductivity. In this study, a dual‐network hydrogel based on polyacrylamide (PAAM) and sodium alginate (SA) networks was constructed to fabricate highly sensitive strain sensors. Carbon nanotubes (CNTs) were incorporated into the hydrogel system, and polypyrrole (PPy) nanoparticles were synthesized using SA as a soft template. During preparing process, ultrasonic oscillation was employed to facilitate the uniform distribution of PPy in the hydrogel matrix, and then a CNTs–PPy conductive pathway was formed, thereby enhancing the conductivity and sensitivity of the hydrogel. The prepared PAAM–SA–CNTs–PPy hydrogel exhibits high electrical conductivity (4.84 S/m), superior mechanical properties (including a tensile strength of 683.5 kPa at 812%), high toughness, good self‐healing, and adhesion properties. The assembled strain sensors demonstrate high sensing capability, a wide measurement range (the gauge factor of 2.67 for 0%–400% strain and the gauge factor of 5.25 for 400%–800% strain), rapid response times (126 ms), and good stability. The developed hydrogel‐based conductive strain sensor has the potential to be excellent candidates as wearable sensing devices for monitoring human movements.