A droplet splitter: Simple, controlled and efficient droplet splitting using superhydrophobic pyramid structures

Abstract

Droplet splitting technology presents considerable potential for advancing applications in sample encapsulation, manipulation, chemical reaction control, and precision measurement systems. However, existing methodologies frequently encounter limitations related to complex operation and high cost. To address the need for controllable, high-precision, and cost-efficient droplet splitting, this study combines three-dimensional printing technology with superhydrophobic surface modification to fabricate pyramid microstructures with customized splitting functionalities. The pyramidal sharp edges act as “fluidic blades” to split droplets through the synergistic interaction of edge-induced capillary forces and inertial forces generated at the liquid film periphery during spreading dynamics. Upon penetration by the pyramid apex, the droplet forms an annular liquid ring that subsequently fragments into sub-droplets, enabling programmable splitting. A comprehensive experimental and computational framework was developed to investigate splitting dynamics, force distribution patterns, and geometric dependence of pyramid structures on splitting performance. Results indicate that increased Weber numbers, larger droplet volumes, and reduced pyramid apex angles markedly improve splitting controllability. Additionally, six- and 12-sided pyramid-based splitting/collection devices were engineered to demonstrate practical implementations, including on-demand droplet splitting and liquid marble synthesis. This work establishes a scalable, low-cost platform for precision droplet manipulation with significant implications for microfluidic devices and lab-on-a-chip technologies.