Magneto-responsive wettability-switchable surfaces for in-situ large distance droplets capturing-releasing-bouncing

In this paper, superhydrophobic magnetically responsive micro-plate arrays (SMMAs) with reverse switching wettability were studied for in-situ capturing, releasing, and directional bouncing of droplets over a large distance. A novel method for producing superhydrophobic pattern on one side surface of the micro-plates by laser texturing at 90 degree bending state, created water contact angle of 151°, a rolling angle of < 10°, and a maximum surface adhesion force of 35.5 μN. Reversible switching between droplets (volume 5–40 μL) capturing with high adhesion force (high surface energy) and droplet releasing with low adhesion force were achieved spontaneously. The instantaneous response of the SMMAs to magnetic field provided a guarantee for the directional bouncing of droplets in long distance. Droplets transportation up to 40 μL, directional bouncing of 5 μL droplets with a vertical bounce height of 4.5 mm and a horizontal bounce distance of 24.7 mm have been achieved. This work provides a novel approach for flexible droplets manipulation and multifunctional operation of droplets for non-contact, remote-driven and non-destructive reagent transfer applications.