Nanoengineered surfaces for microfluidic-based thermal management devices

Microfluidic systems offer compact and efficient thermal management strategies. In this work, we investigate novel nanostructured surfaces to control fluidic behavior and enhance heat dissipation in microfluidic systems. We fabricated silicon nanopillars ranging from 200 nm to 800 nm in diameter and heights of approximately 5 μm. In the presence of notches on the pillars, the liquid separates into multiple layers of liquid films. The thicknesses of the liquid layers subsequently increase as the film propagates, which is determined by the specific position and geometry of the notches. In the presence of asymmetric nanopillars, where the pillars have deflection angles ranging from 0-50 degrees, directional spreading of water droplets can be achieved. The liquid spreads only in the direction of the pillar deflection and becomes pinned on the opposite interface. We performed detailed measurements and developed models to predict the behavior based on pillar geometries. These studies provide insight into the complex liquid-nanostructure interactions, which show great potential to design nanostructures to achieve high flux thermal management solutions.