Orbital electrowetting for versatile droplet maneuvering on slippery surfaces

Abstract

Contactless, spatiotemporal droplet maneuvering plays a critical role in a wide array of applications, including drug delivery, microfluidics, and water harvesting. Despite considerable advancements, challenges persist in the precise transportation, splitting, controlled steering, and functional adaptability of droplets when manipulated by electrical means. Here, we propose the use of orbital electrowetting (OEW) on slippery surfaces to enable versatile droplet maneuvering under a variety of conditions. The asymmetric electrowetting force that is generated allows highly efficient droplet manipulation on these surfaces. Our results demonstrate that droplets can be split, merged, and steered with exceptional flexibility, precision, and high velocity, even against gravity. Additionally, the OEW technique facilitates the manipulation of droplets across different compositions, volumes, and arrays in complex environments, leaving no residue. This novel droplet maneuvering mechanism and control strategy are poised to impact a range of applications, from chemical reactions and self-cleaning to efficient condensation and water harvesting.