Abstract
In nature, fluid manipulations are ubiquitous in organisms, and they are crucial for many of their vital activities. Therefore, this process has also attracted widescale research attention. However, despite significant advances in fluid transportation research over the past few decades, it is still hugely challenging to achieve efficient and nondestructive droplet transportation owing to contamination effects and controllability problems in liquid transportation applications. To this end, inspired by the motile microcilia of micro‐organisms, the superhydrophobicity of lotus leaves, the underwater superoleophobicity of filefish skin, and pigeons' migration behavior, a novel manipulation strategy is developed for droplets motion. Specifically, herein, a superwettable magnetic microcilia array surface with a structure that is switchable by an external magnetic field is constructed for droplet manipulation. It is found that under external magnetic fields, the superhydrophobic magnetic microcilia array surface can continuously and directionally manipulate the water droplets in air and that the underwater superoleophobic magnetic microcilia array surface can control the oil droplets underwater. This work demonstrates that the nondestructive droplet transportation mechanism can be used for liquid transportation, droplet reactions, and micropipeline transmission, thus opening up an avenue for practical applications of droplet manipulation using intelligent microstructure surfaces.
Highlights
Inspired by micro-organisms’ motile cilia, “self-cleaning” lotus leaves, and pigeons’ migration behaviors, we demonstrate a strategy to manipulate directional water droplet movement on a superhydrophobic magnetic microcilia array (MMA) surface with low adhesion, which was prepared via template and a superhydrophobic nanosilica-n-hexane solution immersion method
By comparing the MMA surface morphologies before (Figure 1b) and after hydrophobic modification (Figure 1c), we demonstrate the existence of microscale structures on the MMA surface, while micro/nano hierarchical structures are formed on the superhydrophobic MMA surface
Comparing the unmodified MMA surface with the MMA surface modified with DA (2.0 mg mL−1) solution (Figure 6b) and the MMA surface modified with the mixture of DA (2.0 mg mL−1) and TEOS (6.0 mg mL−1) solution (Figure 6c), we demonstrate that the MMA surface is successfully converted from underwater
Summary
To be able to control the transport direction of water droplets, an MMA surface was first fabricated using template technology;[17a] afterward, the surface was immersed in a solution of hydrophobic fumed nanosilica in n-hexane to obtain a superhydrophobic MMA surface (Figure 1a). Based on the Cassie equation,[19] surface hydrophobicity is enhanced owing to the increase in surface micro/nanoscale hierarchical structures, resulting in the MMA surface becoming superhydrophobic. The microcilia transform from the fully upright to the clustered morphology when a magnet is placed below the superhydrophobic MMA surface (magnetic field intensity of about 0.37 T) (Figure 1e). Enhancing the magnetic field results in only a small increase of the adhesion force between the superhydrophobic MMA surface and the water droplets (Figure 1f,g), indicating that the superhydrophobic MMA surface has low-adhesion characteristics. It is easy to advance and retreat the droplets along the superhydrophobic MMA surface at the concave points under the magnetic field
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
