Abstract
A novel microfluidic device was designed and fabricated to overcome size dependence of droplet on microchannel (MC) dimension with microchannels having three inlet channels. The microchannels have rectangular cross-section with a depth of about 5 micrometers. A viscous stream (i. e., the dispersed phase) flowed centrally between two inviscid streams (i. e., the continuous phase). Increasing the flow rate ratio of the side flow to the central flow (Fs / Fc) resulted in the reduction in the width of the central flow and flow instability. As the width of the central flow was narrowed down below a critical breakup width, the breakup of the viscous liquid sheet occurred and droplets with the diameters smaller than channel size were formed. The effect of channel configuration on the narrowing down and the breakup of the central flow is presented. With this microfluidic system, it is possible to observe real-time process of droplet formation and precisely control droplet size. This approach shows promise for the applications of such as microemulsification and precision fluid microdispersing.
