Electrostatic Water Droplet Formation in Oil in Microchannel System

Abstract

We have investigated that a droplet-based microreactor system, such as Lab-on-a-chip, especially for using no mechanical pump. In this paper, a method to produce water droplets in oil electrically was experimented. Electrostatic atomization was studied to inject charged water droplets into oil in a microchannel system. When a negative DC voltage (–7 kV) was applied to Milli-Q water phase of microchannel, Taylor cone was formed at an interface between the water and rapeseed oil, and the water droplets were injected into oil. A diameter of the produced droplets was characterized to 10.7 ± 3.8 μm. When Milli-Q water replaced to 50% glycerol that was 6 times higher viscous liquid, the produced droplets were with 6.7 ± 2 μm. Since the electrostatic atomization, in principle, produces charged droplets into oil, the produced droplets will be manipulated using electric force.