%0 Journal Article
%T Formation of Tunable, Emulsion Micro-Droplets Utilizing Flow-Focusing Channels and a Normally-Closed Micro-Valve
%A Jung-Hao Wang
%A Gwo-Bin Lee
%J Micromachines
%D 2013
%I MDPI AG
%R 10.3390/mi4030306
%X A mono-dispersed emulsion is of great significance in many chemical, biomedical and industrial applications. The current study reports a new microfluidic chip capable of forming tunable micro-droplets in liquids for emulsification applications. It can precisely generate size-tunable, uniform droplets using flow-focusing channels and a normally-closed valve, which is opened by a pneumatic suction force. Experimental data showed that micro-droplets with a diameter ranging from several to tens of micrometers could be precisely generated with a high uniformity. The droplet size is experimentally found to be dependent on the velocity of the dispersed-phase liquid, which is controlled by the deflection of the suction membrane. Emulsions with droplet sizes ranging from 5.5 to 55 ¦Ìm are successfully observed. The variation in droplet sizes is from 3.8% to 2.5%. The micro-droplets have a uniform size and droplets smaller than those reported in previous studies are possible with this approach. This new microfluidic device can be promising for emulsification and other related applications.
%K microfluidics
%K emulsification
%K normally-closed valve
%K suction force
%U http://www.mdpi.com/2072-666X/4/3/306