Flexible microfluidic electrocaloric cooling capillary tube with giant specific device cooling power density

The microfluidic cooling system is one of the most promising micro-cooling solutions for chip-scale thermal management, in which the regeneration of flowing cryogenic liquid is a key limitation. Thanks to its high efficiency and ease of minimization, electrocaloric (EC) cooling is regarded as a feasible solution. However, there is no existing EC cooling device that offers a continuous sub-ambient liquid media. Here, we fabricated a self-standing flexible EC capillary tube with a maximum temperature drop of 3.53 K by coaxial wet-spinning technology. The self-encapsulating property of the EC tube reduces the volume of inactive substances. Thus, the highest specific device cooling power density of 702.1 mW cm−3 among all the reported EC devices was realized in the EC capillary tube. The EC cooling capillary tube opens up a unique way to apply EC technology to the thermal management of the micro-electromechanical system, such as the cooling of the lab-on-chip systems.