High-Performance Organohydrogel Fibers for Wearable Thermoelectric Energy Conversion and Multifunctional Sensing

Abstract

The development of flexible and high-performance thermoelectric material is crucial for the next generation of self-powered wearable electronics. In this study, a multifunctional PVA (poly(vinyl alcohol))/CNF (cellulose nanofiber)/CNT (carbon nanotube) thermoelectric organohydrogel fiber was successfully synthesized by employing PVA as a polymer matrix, CNF and CNT as fillers, Fe2+/3+ ions as a redox pair, and DMSO (dimethyl sulfoxide)/H2O as a binary solvent. Owing to the ion-electron coupling mechanism, the electrical conductivity of the as-prepared organohydrogel fiber was significantly improved, resulting in an optimal power factor of 1.71 × 10–4 mW m–1 K–2. To solve the water-retention issue, UV-cured silicone was used to encapsulate the organohydrogel fiber. The encapsulated fiber retained 96% of its initial weight after 7 days of exposure to ambient atmosphere, demonstrating its long-term environmental stability. A wristband thermoelectric prototype was fabricated to demonstrate the performance of converting body heat. An output voltage of ∼60 mV could be generated by wearing the wristband. With the help of a voltage amplifier, an LED bulb can be successfully lighted up. With great flexibility and conductivity, the fiber can also be utilized as wearable strain sensors to monitor diverse human activities, ranging from large-scale joint movements to subtle vocal vibrations. This work provided a promising strategy for developing durable and high-performance organohydrogel fibers for wearable thermoelectric and sensing applications.