Designing "Supermetalphobic" Surfaces that Greatly Repel Liquid Metal by Femtosecond Laser Processing: Does the Surface Chemistry or Microstructure Play a Crucial Role?

It is demonstrated that the wettability of liquid metal (LM) on a substrate is very different from the water wettability. Superhydrophobic and superhydrophilic silicon and polydimethylsiloxane surfaces, respectively, are obtained by femtosecond laser processing and proper chemical modification. All of the structured surfaces have excellent LM repellence, that is, supermetalphobicity, in spite of superhydrophobicity or superhydrophilicity. The experimental comparison and contact model analysis reveal that surface microstructure actually plays a crucial role in endowing a surface with supermetalphobicity while surface chemistry has a little influence on the formation of supermetalphobicity, because the liquid/solid contact is replaced by a solid/solid contact mode for a LM droplet on a textured substrate. It is believed that the established principle for creating supermetalphobic surfaces will enable to accelerate the application progress of LM materials in flexible circuits and liquid robots.