3D Printed Gelatin Methacrylate Hydrogel-Based Wearable Thermoelectric Generators

The present study focuses on the utilization of a hydrogel consisting of gelatin methacrylate (GelMA) and polyvinyl alcohol (PVA) as a matrix for hosting the redox couple Fe(CN)63-/4-. The hydrogel exhibits a discernable thermopower (Src) of 3 mV K-1. The beneficial effect of the hydrogel microstructure on the mechanical robustness is demonstrated by small-angle X-ray scattering (SAXS). Moreover, the hydrogel is used to construct a 3D printed thermoelectric generator (TEG) consisting of eight p-type thermoelectric legs, which exhibits commendable thermoelectric properties, including an open-circuit voltage of 64 mV and a power density of 4.0 mW m-2 under a temperature gradient (Delta T) of 2.5 K. These findings demonstrate that 3D printing both enhances the quality of the interface between the hydrogel and electrode and provides a promising method for a more facile TEG fabrication process with the potential for further applications in low-grade waste heat harvesting. The fabrication of wearable thermoelectric generators (TEGs) constitutes the main challenge in the development of thermo-electrochemical cells (TECs). In this work, this issue is addressed through 3D printable hydrogels. Moreover, the TEG device shows a moderate power density approximate to 4.0 mW m-2 under Delta T = 2.5 K. The results highlight the potential of the 3D printing technique in hydrogel-based TEGs. image