Conductive hydrogels possess promising potential as sensor materials due to their biocompatibility and mechanical flexibility, mimicking the properties of human skin. However, limitations such as lack of stretchability, hardness, and fatigue resistance hinder their sensing capabilities and durability. This study addresses these challenges by developing an extremely flexible, robust, and anti-fatigue conductive nanocomposite hydrogel.

The synthesized nanocomposite hydrogel, denoted as NIPAm_lap_GNP, was obtained through a two-step process involving free-radical polymerization. Initially, Laponite was dispersed in a solution containing gold nanoparticles (GNP) via sonication. Subsequently, NIPA monomer was added, followed by the initiation of polymerization with ammonium persulfate (APS) and N,N,N′,N′-tetramethylethylenediamine (TEMED) at room temperature, yielding a homogeneous solution.

Characterization of the resulting hydrogel composite included assessments of stretchability, toughness, and fatigue resistance using mechanical testing equipment such as a tensile meter, compression meter, and rheometer. Results revealed impressive mechanical properties, with tensile stress ranging from 50 to 60 kPa, a tensile elongation of 1300-1400%, a compressive stress of approximately 25-30 kPa, and a toughness of 27.76 MJ.m^-3. Furthermore, the hydrogel demonstrated remarkable motion sensitivity through electrochemical measurements, exhibiting a linear response to tensile strain (up to 250%) and bending finger angles (15-120°).

In conclusion, the NIPAm_lap_GNP hydrogel exhibited exceptional mechanical properties, including high stretchability and toughness, making it suitable for wearable sensor applications. The incorporation of gold nanoparticles (GNP) significantly enhanced electrical conductivity, while Laponite (Lap) increased crosslinking points and mechanical stability. This innovative nanocomposite hydrogel holds promise for various applications in flexible and conductive wearable sensors. Future research directions may explore its potential in other biomedical or electronic devices.