Remote Droplet Manipulation on Self-Healing Thermally Activated Magnetic Slippery Surfaces

Manipulation of discrete droplets is a paramount procedure in a broad spectrum of disciplines from digital microfluidics to energy and water systems. In these applications, droplet manipulation is required for mass or energy transport in various physical and chemical interactions. The discrete droplet manipulation enables developments of integrated microfluidic platforms without the use of conventional pumps, valves, or channels. A variety of approaches are developed for droplet manipulation. In these approaches, either the solid surface characteristics or droplet properties are tuned to control the droplet motion. However, drawbacks such as custom fabrication of the solid surface (e.g., embodiment of actuators in the solid and physical or chemical modification), limited application for high viscous fluids, fixed functionalities, and enhanced friction by the solid substrate have impeded their widespread implementation. Here, a new self-healing surface called magnetic slippery surface (MAGSS) is reported for remote and controlled droplet manipulation with exceptional droplet mobility and a wide range of functionalities (e.g., transportation, guidance, removal, and merging of droplets). This surface allows droplet manipulation in a channel-free configuration independent of viscosity of the droplet. This study envisions that MAGSS emerges as a disruptive platform for energy systems (e.g., condensation), miniature reactors, microfluidics devices, and medical bioassays.