**5. Multiscale micro/nanostructured wick structure for two-phase heat spreaders**

Sintering a porous microstructure on the inner surface of the vapor chamber to form a wick structure is the most common way in the fabrication of a vapor chamber. Researchers tried to use various kinds of porous microstructure to enhance the thermal performance of the vapor chamber, while little research was focused on growing a nanostructure on the porous microstructure to form a multiscale micro/nanostructured wick structure for enhancing the thermal performance before 2010. However, the nanostructure can enlarge the area of thin-film evaporation, increase the nucleation sites for boiling and improve the backflow ability of the wick structure without changing the microstructure [27, 28]. Thus, the authors investigated the effect of the multiscale micro/nanostructured wick structure on several types of two-phase heat spreaders.
