Liquid metal-based flexible and wearable thermoelectric cooling structure and cooling performance optimization

Soft wearable cooling devices using flexible thermoelectric coolers (TECs) are highly advantageous for diverse applications. However, challenges remain in low cooling capacity, short device lifetime, and limited understandings of the impact of thermoelectric component’s dimension, structure and density on their cooling capacity. Here, we addressed these issues by engineering a large-electrode flexible TEC composed of thermoelectric components embedded in a three-layer polydimethylsiloxane (PDMS) matrix interconnected with biphasic liquid metal traces (core-shell structured liquid metal nanoparticles and nickel-doped GaIn). Attributed to the larger electrodes and three-layer PDMS, the TECs significantly reduce the amount of liquid metal used, minimize the risk of leakage, lower the cost, eliminate environmental pollution, and improve product reliability and manufacturing efficiency. We further optimized the TEC structure design by finite element analysis, providing a generic TEC design kit taking into account multiple physical fields and impact factors. The demonstrated TECs offer high cooling capacity (7.4°C) and great performance stability under deformation, which outperform previously reported models that use similar materials and structures. This work represents a significant step forward in the development of flexible TECs, with promising applications in fields such as wearable devices, electronic skins, and smart textiles.