Double-network PEDOT:PSS xerogel fibers with high stretchability and electrical stability for wearable strain sensing

Conductive polymer xerogels provide a promising route toward mechanically stable and water-independent alternatives to conventional hydrogels for wearable bioelectronics. However, achieving high stretchability, mechanical robustness, and stable electrical performance in xerogel fibers remains challenging. Here, we develop highly stretchable and conductive double-network PEDOT:PSS xerogel fibers fabricated through freeze–thaw-induced physical crosslinking of poly vinyl alcohol (PVA) followed by borax-mediated crosslink formation. The resulting fibers exhibit enhanced network integrity and mechanical robustness, enabling tensile strength up to ∼16 MPa and elongation at break exceeding 1100% at an optimized borax concentration, while maintaining stable electrical conductivity (∼0.8 S m^-1). The fibers display reproducible strain-dependent resistance changes with gauge factors up to ∼19 at high strain. When integrated as wearable sensors, the xerogel fibers enable reliable real-time monitoring of human motion, including finger, wrist, and elbow movements. This double-network xerogel strategy provides a simple and scalable approach to engineering mechanically robust conductive fibers for next-generation wearable sensing and bioelectronic applications.

Mechanical and electrical tests were performed using a Mach-1 V500csst MA009 mechanical tester (Biomomentum Inc., Canada). Uniaxial tensile tests were performed on xerogel fibers to evaluate their mechanical response, using a constant crosshead speed of 30 mm min 1. For xerogel fibers, a custom

double-needle tensile mounting approach was used to enable reliable handling of small-diameter filaments (Fig. S1). Briefly, two syringe needle tips were positioned facing each other on the bench and separated by a predefined gauge gap of B10 mm. The xerogel fiber was carefully threaded through

both needle tips, and a single drop of cyanoacrylate adhesive was applied within the plastic cavity of each needle to immobilize the filament ends. The two needle tips were then seated onto a double-needle tip holder assembly (provided by Biomomentum Inc., Canada) designed for the Mach-1 tester. A 70 N load cell was used for these experiments. The holders were mounted coaxially, facing each other at the center of the testing chamber, and the double-needle assembly was firmly inserted onto the holders to establish a stable tensile configuration for fiber testing.

Electrical conductivity measurements were carried out using a tailored tensile grip with electrodes (model MA068) made by Biomomentum Inc., interfaced with a source measure unit (B2902A, Agilent). For all electrical measurements, copper tape was used to tab the xerogel fibers at both ends to ensure stable electrical contact between the sample and the electrodes. The electrical resistance of the samples was measured using the source measure unit during the test.