Controlling liquid landscape with 3D-printed spines: A tool for micromanipulation

Manipulation of floating objects, whether solid or liquid, spanning from microscopic to mesoscopic sizes, is crucial in various microfluidics and microfabrication applications. While capillary menisci naturally self-assemble and transport floating particles, their shapes and sizes are limited by the properties of the fluid and the objects involved. We herein introduce an innovative and versatile method that harnesses the superposition of capillary menisci to curve liquid interfaces without size limit. By using 3D-printed spines piercing the interface, we can finely adjust height gradients across the liquid surface to create any liquid topography at low cost. Thus, our method becomes a powerful tool for manipulating floating objects of all sizes. Combining experimental demonstrations and theoretical modeling, we study the liquid elevation created by specific spine dispositions and the three-dimensional manipulation of submillimetric particles. Multiple examples showcase the method's potential applications, including sorting and capturing particles, which could pave the way for cleaning fluid interfaces.