Magnetically Controllable Isotropic/Anisotropic Slippery Surface for Flexible Droplet Manipulation.

Controllable wetting surfaces play a significant role in numerous applications such as smart liquid manipulation, lab-on-a-chip, drug delivery, liquid robot, and so on. A novel type of magnetically controllable isotropic/anisotropic slippery surface was prepared by femtosecond laser ablation. The slippery liquid-infused porous surface (SLIPS) can be switched between an isotropic smooth state and an anisotropic groove state by the magnetic field. The relationship between the sliding property of the SLIPS and the magnetic flux density, water droplet volume, microgroove width, and microgroove height are systematically studied. Passively flexible movement on the isotropic SLIPS and actively directional movement on the anisotropic SLIPS of water droplets were realized. This work provides a fresh understanding of the controllable isotropic/anisotropic SLIPS and reveals great potential in versatile applications which are related to magnetically controllable smart liquid manipulation.