Magnetically Responsive Superhydrophobic Surfaces with Droplet Manipulation Capability

The precise control of tiny droplets has always been a complex problem to be solved. The magnetically responsive superhydrophobic surfaces, which can be controlled for droplet manipulation by an external magnetic field, have attracted attention because of its characteristics such as easy operation, rapid response, remote control, and simple process. Herein, a magnetically responsive superhydrophobic surface is designed and prepared by a two-step spraying process. The precise control of microdroplets on the prepared surface is carried out, and the droplet control can be quickly achieved through noncontact control in various ways including active, multidirectional, and antigravity. On this basis, the ideal surface model is established to analyze the droplet control mechanism. In addition, the transport effects of different types of droplets, including water droplets and saline, are investigated. The durability evaluation experiment including droplet-repeated control, friction, tape stripping, and scratch test shows that the surface has certain durability. This magnetically responsive superhydrophobic surfaces can meet requirements of biological experiments and provide a new idea for low-loss droplet transport and microfluidic chip.