2 – 10 µm Diameter Water Droplets in Mineral Oil Emulsion Production
The Small Droplet System setup is described in detail to illustrate the assembly of components along with the fluidic setup. The system is used in a test case to generate water droplets in mineral oil, an organic fluid.
By setting the pressures on the P-pumps, stable and monodisperse droplets are found to be produced over a wide range of sizes.
The experiment showed successful generation of droplets with the following specification.
• Small droplet chip used with etch depth of 5 μm and junction width of 8 μm.
• Water-in-mineral oil emulsion generated.
• Droplet sizes achieved:
- Smallest monodisperse droplet size 2.7 μm diameter
- Largest monodisperse droplet size 10.7 μm diameter.
- Largest non-monodisperse droplet size 18 μm (cover photo) diameter.
• SPAN-80 surfactant used to stabilize the emulsion.
• Test setup utilizes 2 P-Pumps, Flow sensors, Optical system, and Flow accessories such as tubing, connectors and flow resistors.
• System tested in ‘Pressure Control Mode’ varied between 0-5 bar each.
• The flow rates observed were 0 – 300 nL/min and 0 – 60 nL/min for the mineral oil and water respectively.
• Production rates varied between 26 and 1600 Hz.
• In general, larger droplets imply lower production rate and vice versa.