An actuatable ionogel thermoelectric fiber with aligned mesogens-induced thermopower for four-dimensional dynamically adaptive heat harvesting.

Thermoelectric (TE) ionogel have emerged as promising materials for harvesting low-grade heat owing to their flexibility and giant thermopower. However, current high-performance TE ionogel requires multi-component systems, resulting in trade-offs between TE performance, mechanics, and ion leakage risk. Moreover, the humidity-dependent thermopower and two-dimensional device architectures restrict their practical applications. Here, a thermally actuated TE ionogel fiber is designed by tailoring the interactions between liquid crystal elastomer (LCE) network and ionic liquid. Fine tuning the mesogen orientation of LCE network ensures ~3-fold thermopower boost (25.8 mV K) and ~30-fold electrical conductivity boom (21.5 mS m) at low humidity (<30% RH). Furthermore, an actuatable gripper-structured TE device can be successfully integrated, which could four-dimensional dynamically adapt to complex-geometry heat source and enable decoupled recognition of size/shapes and temperatures of the heat source. The design concepts of actuatable thermoelectrics pave ways for their commercial successes in smart wearables and soft robots.