3D Printed Gelatin Methacrylate Hydrogel‐Based Wearable Thermoelectric Generators

Abstract 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)₆^3−/4−. The hydrogel exhibits a discernable thermopower (S_rc) 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 (ΔT) 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.