Quaternary Ammonium Chitosan-Based Antimicrobial and Conductive Composite Hydrogel for Flexible Wearable Strain Sensors

Conductive hydrogel-based flexible wearable sensors are considered one of the best candidates for next-generation flexible wearable devices due to their flexibility, stretchability, and biocompatibility. However, most of the conventional conductive hydrogels do not possess antimicrobial properties, limiting their application in emerging flexible wearable devices. To address this issue, we successfully developed an antimicrobial and conductive composite hydrogel (QCS-PVA-C-MWCNTs) by the freeze–thawing method, which mainly consists of poly(vinyl alcohol) (PVA), antimicrobial chitosan modified by dimethyloctadecyl-(3-trimethoxysilylpropyl) ammonium chloride (TSA) (QCS), and hydroxylated multiwalled carbon nanotubes (C-MWCNTs). QCS-PVA-C-MWCNTs hydrogels exhibit excellent mechanical properties with high stretchability, excellent self-healing ability (<1 h), and reproducible adhesion performance. QCS-PVA-C-MWCNTs hydrogel-based flexible wearable sensors accurately and quickly monitor human activity (e.g., finger flexion, elbow flexion, mouth opening, and saying “thank you”). The conductivity of QCS-PVA-C-MWCNTs3 hydrogel is ∼7.4 S·m–1, and it also features a fast response (<0.24 s) and high stability (up to 5000 cycles). Moreover, QCS-PVA-C-MWCNTs hydrogels can effectively inhibit the growth of both Escherichia coli (>99.3%) and Staphylococcus aureus (>99.8%) bacterial strains. We envision that this work broadens the avenues for designing multifunctional chitosan-based hydrogels with a wide range of applications in human-computer interaction, sports training, and personal healthcare.