Fabrication of a highly sensitive pressure sensor based on Arabic gum polyacrylic acid nano-composite hydrogel enhanced with RGO/AgNPs

Stretchable and flexible pressure sensors have attracted significant interest in a wide range of applications, including smart robots and health monitoring. However, many current materials lack the needed combination of flexibility, strength, and electrical conductivity. This study aimed to develop a nanocomposite hydrogel for a pressure sensor with enhanced mechanical and electrical properties. The sensor was fabricated by incorporating silver nanoparticles (AgNPs), and reduced graphene oxide (RGO) into Arabic gum (AG) polyacrylic acid hydrogel (PAA), resulting in a more flexible and conductive polymer that features a relatively fast response time, quick recovery time, and a high sensitivity to pressure changes and human motion for high-performance sensing. The hydrogel synthesis involved <i>in situ</i> polymerization of AA and AG, followed by physical crosslinking between polymer carbonyl groups and Fe³⁺ in the presence of AgNPs and RGO, which were produced using ascorbic acid as a green reducing agent. In addition, the sensing behaviour was evaluated under different loading geometric tips-one with a square cross-section and the other shaped like a pyramid. The nanocomposite hydrogel demonstrates high sensitivity (0.136-1.832) kPa^-1 and rapid response and recovery times (28-32 ms/62-502 ms) in a low detection range (1.15-5.77) kPa. Different techniques, including Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Fourier Transform Infrared Spectroscopy (FT-IR), and X-ray Diffraction (XRD), were implemented to characterize the physicochemical properties of the nanocomposite hydrogel, while the mechanical properties of the sensor surface were investigated using nanoindentation analysis. The results showed that the nanocomposite hydrogel is a promising candidate for the next generation of flexible and wearable pressure sensing devices.