Hi! After weeks of testing we get control of the drop size, by put oil pump vertical and adjust the oil flow rate. However, we found the drop size becomes crazily deviated when trying to get drop smaller than the channel size. The chip adopt classical "+" geometry. We have 2 chip: diameter 70um and 80um. Both hard to get drop
Is the goal to get oil drops or are you producing particles with polymer and use of solvent in disperse phase (oil phase)? Dependent on the application, several parameters can be adjusted to obtain the desired particle size.
I'm using the acrylamide/water solution for bead, and surfactant and crosslinker in oil. so it is trying to get water drop in size smaller than channel diameter
Hi,
The increasing capillary number leads to having smaller droplets. For water droplet inside oil generation, you can have smaller droplet if you increase Oil flow rate/pressure and viscosity or decrease interfacial tension between the two fluids.
Note that, its better to generate droplets in squeezing or dripping regime to have less size deviation, otherwise in the jet regime the droplet size polydispersity increases.
Thanks Ali Kalantarifard That's what we are trying to do. we are trying to generate in dripping regime for drops smaller than the diameter of channel, by increasing oil flow rate. Yet we see great increase in deviation. Is it our only way to switch to chips with smaller channel?
Regards!
Indeed, making smaller channel is the easiest way but if you prefer not to do that I suggest using long flexible tubing for supplying fluids to the chip. This way you will damp flow rate fluctuations due to the syringe pump. Also, you can try the pressure pump as a flow source which has lower fluctuations. There are some studies about how to generate monodisperse droplets.
Article Damping hydrodynamic fluctuations in microfluidic systems
Article Theoretical and experimental limits of monodisperse droplet generation
I hope you find these papers useful and it works for you.
Another suggestion: If you can reduce your acrylamide concentration, your final particle will be (much) smaller.
- Badges
- Science topic
- Similar topics
- Engineering
- Thermal Engineering
- Thermofluid
- Fluid Mechanics