Generation of Water Droplet in Fluorocarbon Using Electrostatic Atomization

Droplet-based micro-reactor systems have been investigated by many researchers and used in bioengineering and micro total analytical systems (μTAS). In these applications, individual water droplets in oil perform as micro-reactors. Generally, a magnetic stirrer and a homogenizer have been used to produce water droplets in oil. For these studies, fluorocarbon oil is an attractive candidate for the droplet-based system because of its very low solubility in water, and very low solubility of water in them. However, it is more difficult to generate W/F (water-in-fluorocarbon oil ) emulsion for a reason of the stability of fluorocarbon oils compare with other common oils. Here we conducted W/F droplet formation using the electrostatic method. Electrostatic atomization was used to produce charged water droplets into fluorocarbon oil. Our method can control the size of water droplets by adjusting the applied DC voltage. The generated water droplets were stable without a surfactant due to electrical charge. Moreover, the generated droplets kept their shape and position until fluorocarbon oil evaporated. Therefore, W/F emulsion was highly expected for an application in micro total analytical systems.