Impact of Dynamic Tip-Surface Interactions on Microdroplet Formation via Fluid Force Microscopy

The emergence of FluidFM technology has presented a novel opportunity for selective aspiration and distribution of liquids at the sub-micron scale. However, precise control over droplet generation volume remains a challenging issue. This study investigates the impact of dynamic parameters between the tip and surface on droplet formation. Initially, we establish a finite element model to simulate the process from the formation of a liquid bridge between the hollow cantilever probe and the substrate to the rupture resulting in droplet formation. Additionally, we propose an image-based method for quantifying droplet volume. Subsequently, we construct a comprehensive experimental framework to delve into the influence of these parameters on microdroplet formation by monitoring the dynamic interaction parameters between the probe tip and the liquid surface. Finally, we optimize the parameters during the droplet generation process, enabling the formation of uniform arrays of microdroplets under controlled experimental conditions. Our study provides a reference for automation parameters of serial experiments and improves experimental throughput.