Tunable droplet generation with particle suspension via impact on lubricant-infused surfaces

Conventional droplet generation techniques often rely on complex nozzle-based systems that demand precise actuation, sophisticated fabrication, and suffer from clogging issues under high particle mass-loading, making them unsuitable for particle-laden applications and cost-sensitive settings. In this study, we present a passive, low-cost method to generate tunable daughter droplets through the partial rebound of a macro-droplet impacting a lubricant-infused surface (LIS). The method enables the formation of a protruded liquid column that pinches off into sister droplets without requiring external actuation. The size and outcome of the generated droplets are controlled by varying the Weber number. Systematic experiments and simulations are conducted to elucidate the retraction dynamics and pinch-off behavior. The proposed approach enables droplet generation with a wide range of volumes ranging from tens of nanoliters to microliters, well below the capillary length and high particle mass-loading (up to 30% w/w) with 5 μm particles, overcoming limitations of nozzle-based and patterned surface methods. This study introduces a novel LIS-assisted droplet generation using nonfluorinated, soot-based LIS, which enhances economic and environmental viability along with potential applications in printing, biochemical assays, and material synthesis, particularly in resource-limited environments.