Dear Leon,

I have worked with different kinds of silicon oil (sf 10, sf 50, sf 100, 1000, FC40) and without any surfactant I could make stable droplets. The question is this: what are you going to do after droplet generation? store them for a long time or transfer them to another chip for some reactions or you wanna do reactions in the chip right after droplet generation or ... . The other thing is your limit in the application. If you need to have either oil or water without surfactant then it differs to search water soluble surfactant or oil soluble. Normally for the first one people use tween 20 or 80 and for the latter they use span 80. SDS and CTAB are also soluble in water but as I said it depends on what you are gonna do after droplet generation. If you make it more clear what you want to do as an application we may help more. Good luck.

there are lot of food grade emulsifiers available. I will suggest you to check with the emulsifiers manufactures. they can guide you better.

Dear Leon,

You can try Hexadecane + 2% w/v SPAN 80 or Light mineral oil + 2%SPAN 80 which should be both biocompatible and relatively cheap. 2% is what I usually use but depending on your inner phase viscosity you can adapt it.

Best,

Romain

I suggest you buy a blue can of Nivea Cream (the old one!) and check the formula (INCI names) at the back side.

The first and more succesfull water in oil emulsion ever.

Mineral oil plus span 80 and silicone oils were commonly used prior to commercialization of the fluorocarbon based oils and surfactants. If you plan on working with cells the fluorocarbon oils are probably going to still be the best bet. We purchase hfe 7500 in large quantities and are able to get it for around 500 USD for 4 liters. We use picosurf surfactant from sphere fluidics are are able to dilute down to as low as 0.1 wt% and still get stable drops.

Thank you all for your answers!

I have succesfully made stable aqeous (PBS) droplets in mineral oil/hexadexane/squalene in the presence of SPAN80 (2,3,4%).

The next step is to measure drop stability and monodispersity. I was intending to do image analysis with imageJ or Mipar. Any suggestions which program works best for determination of size distribution, monodispersity etc.?

To answer your question @Ali, my goal is to have a sorting mechanism for droplet sorting (based of fluorescence for example), so yes the drops should be stable over some period of time for incubation/cultivation of cells within, have enough oxygen within and than have them reinjected on a chip where sorting occurs.

@Joseph, my main goal is to not use fluorooils and surfactants because my work is connected to industry, where, in theory, they will use great amounts of reagents so the price is a big factor. I undestand that fluorocarbon oils are better, and I would also use them in a lab scale experiments, but as I said the main goal for implementation in industry is reducing the costs while still getting effective system.

Thank you all again.

Its around three years that I have been using DMV (Droplet morphometry and velocimetry) (https://pubs.rsc.org/en/content/articlehtml/2013/lc/c3lc50074h) to measure the size, speed and CV (coefficient of variation) of droplets. I am happy with that. The other tool or software that you can use is ADM (Automated droplet measurement) (Article Automated droplet measurement (ADM): an enhanced video proce...

@Ali

Yes, I've come across this software too and it looks interesting. But I have written a request to obtain it and didn't receive an answer. Where did you get this software?

@Leon

I did the same thing and got the DMV. Or I think easily you can download ADM and use that.

hi leon,

i was also use mineral oil adding 2%wt span 80 as continuous phase and water as disperse phase to make w/o droplet. but, the droplet were gradually black after 1h. do you know how to solve it?

Leon Ostanek Jurina based on your experience with mineral oils., do you consider mineral oil/water is as good as fluorocarbon oil/water systems for cell cultivation/viability ? Please share your experience.

Joseph de Rutte I would also like to hear your say on this :)

Hi Feng, sorry to hear that you are experiencing problems, but I didn't have any like the ones you mentioned. All droplets (2%-4% SPAN) were stable, even after several days at 37°C.

Sahana, to answer your question. I didn't get to that part of experiment to acctually measure cell viability, but I think that in comparisson to mineral oil system the fluorocarbons are still superior based on oxygen sollubility and diffusion, which are important for cells when cultivating.

Leon Ostanek Jurina Thank you for your valuable input

hi leon, thank you for your reply. i have solve my question.