HCNT/AgNPs/PVA/PAM hydrogel-based flexible pressure sensor for physiological monitoring

Flexible wearable devices for health monitoring require continuous wear throughout the day, making flexible pressure sensors a critical component that has attracted significant attention. Polyacrylamide (PAM) and polyvinyl alcohol (PVA) were used as hydrogel substrate materials to fabricate wearable devices with on-the-go wearability. Helical carbon nanotubes (HCNTs) were employed as conductive fillers, with silver nanoparticles (AgNPs) deposited on their surface to enhance conductivity. The conductive HCNT/AgNPs fillers bonded with the PVA/PAM substrate via metal–hydrogen bonds, metal complexes, and Ag–O bonds. This bonding enhanced the binding strength of the gel and accelerated polymerization. Pressure sensors packaged within the hydrogel exhibited high sensitivity of 0.118 kPa^–1 to minor deformations and high sensitivity of 0.0141 kPa^–1 to regular deformations, providing a flexible pressure sensor with high sensitivity and fast response. This innovation delivers a highly sensitive and fast-responding flexible pressure sensor, paving the way for advanced flexible wearable electronic devices.