Cold atmospheric plasma deposition of antibacterial polypyrrole–silver nanocomposites on wearable electronics for prolonged performance

Abstract

Wearable electronics have become integral for monitoring physiological parameters in diverse applications, particularly in medical and military fields. e-Textiles, featuring integrated conductive threads or fabrics, offer seamless integration and comfort for prolonged contact with the body. Despite their potential, the biofouling of textile-based electrode systems by skin microbes remains a significant challenge, limiting their operational lifespan. Recent studies have highlighted the efficacy of conductive nanocomposites with antibacterial agents, such as silver nanoparticles (AgNPs), in addressing biofouling concerns. However, implementing such systems on 3D fibrous structures and textile surfaces often proves complex and inefficient. To overcome these challenges, we explored cold atmospheric plasma (CAP)-based in situ polymerization for the direct deposition of functional conductive polypyrrole–silver (PPy–Ag) nanocomposites onto conductive textile surfaces. For this process, a customized CAP deposition system was engineered, enabling precise material deposition through robotic control of the plasma jet. This process achieved direct, conformal attachment onto textile fibrous structures, ensuring uniform distribution of conductive polypyrrole and silver in the form of AgNPs throughout the polymer polypyrrole matrix without compromising fabric flexibility and breathability, which was validated through different surface electron microscopy and chemical analysis (e.g., EDX, FTIR, Raman, and XRD). Systematic studies with various precursor mixtures identified an optimized PPy–Ag composition that demonstrated stable antibacterial properties and biocompatibility against common skin microbes and epithelial cells. Systematic studies with various precursor mixtures identified an optimized PPy–Ag composition, with the precursor mixture containing 96 wt% pyrrole and 4 wt% AgNO₃ weight ratios as the optimal surface coating process, demonstrating stable antibacterial properties and biocompatibility against common skin microbes and epithelial cells respectively. As a proof of concept, the nanocomposite coating was applied to conductive carbon fabric surfaces as dry electrodes in a wearable garment for continues electrocardiography (ECG) monitoring over 10 days. Results revealed a significantly longer performance of the dry electrodes as comparable to standard gel-based Ag/AgCl electrodes (1 day) while providing less noise in ECG signal measurements from the subject, showcasing the potential of this technology for practical wearable applications. Envisioned as a groundbreaking solution, this technology opens new avenues for the scalable and effective integration of functional conductive circuits and sensors into everyday garments, ensuring prolonged and efficient performance in wearable electronics.