Prefilled Thumbtack-Shaped Micropillar Array for Liquid Metal Spreading on Intrinsically Nonwetting Surfaces

Liquid metals have emerged as advanced engineering materials in the electronics and energy industries due to their exceptional electrical conductivity, thermal conductivity, and flowability. However, high-surface-tension liquid metals exhibit poor wettability and are hard to spread on conventional solid substrates, which limits their applications. To address this issue, this work develops a surface featuring a triangular array of thumbtack-shaped micropillars. The interpillar gaps are filled with liquid metal via the vacuum-filling method. This prefilled microstructured substrate (PFMS) improves liquid metal wetting properties. The apparent contact angle (ACA) of the liquid metal changed from 140 to below 20°. The PFMS demonstrates good stability against oscillation or inversion. It can be refilled by direct injection onto its surface. For flowing liquids, experiments confirmed that the PFMS requires significantly lower flow rates compared to flat substrates to form uniform liquid metal films. The film maintains complete coverage, even under significant fluctuations induced by turbulence. Furthermore, the PFMS-based film flow exhibits sustained spreading properties, even in the face of strong magnetic resistance in extreme electromagnetic environments. These results validate the application potential of this PFMS.