Antibacterial, self-adhesive guar gum/polyvinyl alcohol/tannic acid conductive hydrogels for flexible strain sensors

In this research, a multifunctional strain sensor with antibacterial properties and self-adhesion capabilities was developed using guar gum (GG), polyvinyl alcohol (PVA), and tannic acid (TA). The incorporation of TA into GG-PVA hydrogel-based strain sensors was investigated to evaluate its effects on mechanical and electrical properties, self-adhesion, and antibacterial activities. The anti-bacterial activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were enhanced with the increasing content of TA. The adhesive strength was observed in the range of 1.20 ± 0.10 kPa to 5.05 ± 0.23 kPa, and the values tended to increase as TA content increased. The tensile strength significantly increased by up to 86.66% when 1.5% TA was incorporated into the hydrogel, followed by a slight increase with the addition of TA at higher contents. Consequently, the hydrogel strain sensor with 1.5% TA was selected to evaluate its sensing capability for limb movement. The sample exhibited reproducibility and stability of the signals during repeated movements. These properties highlight the potential of strain sensors with multifunctional capabilities for applications in wearable electronic devices.