Generation of Single, Monodisperse Compound Droplets

TL;DR

This paper demonstrates a method for generating single, monodisperse compound droplets using a piezoelectric device, and studies how water pressure influences droplet composition and oil layer thickness.

Contribution

It introduces a novel apparatus and method for controlled production of monodisperse compound droplets and analyzes the effect of water pressure on droplet structure.

Findings

Increasing water pressure reduces oil layer thickness in droplets.

The apparatus reliably produces single compound droplets.

Pressure pulse controls droplet ejection and composition.

Abstract

The generation of single, monodisperse compound droplets is shown in these fluid dynamics videos. In an apparatus designed to produce single compound droplets, a piezoelectric diaphragm generates a pressure pulse from a voltage waveform input to eject a droplet. In the method presented, oil is allowed to flow into the water nozzle with the pressure pulse ejecting both fluids as a compound droplet. Experiments were performed to demonstrate how changes in water pressure affect compound droplet compositions. It was found that increasing the water pressure decreased the thickness of the compound droplet's oil layer.