Bioinspired Superwettability Surface Strategies for Condensation Heat Transfer.

Along with the development of miniaturization, integration, and high power of electronic chips in the 5G and artificial intelligence era and their urgent need for technologies enabled to solve high heat flux dissipation in limited space, investigating bioinspired extreme superwettability surfaces with high-efficiency condensation heat transfer (CHT) performance has attracted great interest in academic and industrial communities. Compared with filmwise condensation of flat hydrophilic surfaces featured with continuous liquid films, dropwise condensation of flat hydrophobic surfaces is a more efficient type of energy transport way. However, discrete condensate drops can only shed off the hydrophobic flat surfaces under gravity until their sizes reach the capillary length of liquid, e.g., 2.7 mm for water. Clearly, these millimeter-sized large drops are adverse to efficient CHT because they have not only a large thermal resistance but also a slow renewal frequency. In principle, more efficient CHT can be achieved by engineering micro/nanostructure surfaces with extreme superwettability to obtain more circularly released nucleation sites and timely removal of condensate at smaller sizes. Inspired from nature, great breakthrough has been made in high-efficiency CHT proofs of concept based on various bioinspired superwettability surfaces, including condensate microdrop-jumping superhydrophobic surfaces mimicking cicada wings, superhydrophobic hybrid surfaces mimicking desert beetles, and superhydrophilic surfaces mimicking plant leaves. In this Perspective, we briefly summarize their latest progress and respective issues. Based on this, we envision the possible challenges and development trends of superwettability micro/nanostructure surfaces in the near future, especially emphasizing their practical application in high-performance phase-change devices for chip cooling.