Journal
LAB ON A CHIP
Volume 12, Issue 8, Pages 1540-1547Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/c2lc21197a
Keywords
-
Categories
Funding
- Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration [DE-AC04-94AL85000]
- Sandia National Laboratories
- Directorate For Engineering
- Div Of Chem, Bioeng, Env, & Transp Sys [1066904] Funding Source: National Science Foundation
Ask authors/readers for more resources
A thin flow-focusing microfluidic channel is evaluated for generating monodisperse liquid droplets. The microfluidic device is used in its native state, which is hydrophilic, or treated with OTS to make it hydrophobic. Having both hydrophilic and hydrophobic surfaces allows for creation of both oil-in-water and water-in-oil emulsions, facilitating a large parameter study of viscosity ratios (droplet fluid/continuous fluid) ranging from 0.05 to 96 and flow rate ratios (droplet fluid/continuous fluid) ranging from 0.01 to 2 in one geometry. The hydrophilic chip provides a partially-wetting surface (contact angle less than 90 degrees) for the inner fluid. This surface, combined with the unusually thin channel height, promotes a flow regime where the inner fluid wets the top and bottom of the channel in the orifice and a stable jet is formed. Through confocal microscopy, this fluid stabilization is shown to be highly influenced by the contact angle of the liquids in the channel. Non-wetting jets undergo breakup and produce drops when the jet is comparable to or smaller than the channel thickness. In contrast, partially-wetting jets undergo breakup only when they are much smaller than the channel thickness. Drop sizes are found to scale with a modified capillary number based on the total flow rate regardless of wetting behavior.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available