Three-Dimensional Multifunctional Magnetically Responsive Liquid Manipulator Fabricated by Femtosecond Laser Writing and Soft Transfer

Abstract

Nature-inspired magnetically-responsive intelligent topography surfaces have attracted considerable attention owing to their controllable droplet manipulation abilities. However, it’s still challenging for magnetically-responsive surfaces to realize three-dimensional (3D) droplet/multi-droplet transport in both horizontal and vertical directions. Additionally, the droplet horizontal propulsion speed needs to be improved. In this work, a 3D droplet/multi-droplet transport strategy based on magnetically-responsive microplates array (MMA) actuated by spatially varying and periodic magnetic field is proposed. The modified superhydrophobic surface can transport droplets rapidly both in horizontal and vertical directions, and even realize against-gravity upslope propulsion. The rapid horizontal droplet propulsion (~58.6 mm/s) is ascribed to the abrupt inversion of the modified surface induced by the specific magnetic field. Furthermore, the non-magnetically-responsive microplates (NMMs)/MMA composite surface is constructed to realize 3D multi-droplet manipulation. The implementations of MMA in manipulation of continuous fluids and liquid metal are further demonstrated, providing a valuable platform for microfluidic applications.