2025/03/26 by Mathieu Oléron, Oléron, Mathieu, Grégoire Clement +11
Agricultural and Biological Sciences · Engineering · #Classical Physics (physics.class-ph) #Electrowetting and Microfluidic Technologies #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Heat Transfer #Plant Surface Properties and Treatments
paper · pdf · doi:10.48550/arxiv.2504.01976
openalex publication_date 2025/03/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Droplet generation under steady conditions is a common microfluidic method for producing biphasic systems. However, this process works only over a limited range of imposed pressure: beyond a critical value, a stable liquid jet can instead form. Furthermore, for a given geometry the pressure conditions set both the generation rate of droplets and their volume. Here, we report on-demand droplet production using a positive pressure pulse to the dispersed-phase inlet of a flow-focusing geometry. This strategy enables confined droplet generation within and beyond the pressure range observed under steady conditions, and decouples volume and production rate. In particular, elongated plugs not possible under steady conditions may be formed when the maximal pressure during the pulse reaches the jet regime. The measured volume of droplets-on-demand, as well as the onset of droplet generation are both captured with a simple model that considers hydraulic resistances. This work provides a strategy and design rules for processes that require individual droplets or elongated plugs in a simple microfluidic chip design.