I’m just going to do a brief update today on the microfluidics project. We set out to make acrylic plastic microfluidic chips that could generate tiny droplets of water in oil. Eventually, I hope to use these droplets to make polymer particles. We can make polymer particles from a water in oil emulsion. We usually just shake the mixture vigorously to make the emulsion. But that makes all kinds of different sizes and causes other problems as well. So now we’re going to use a much more complicated method: microfluidics.

I have some experience with droplet based microfluidics. I worked on it in graduate school. It’s a simple idea. Flow oil and water through tiny tubes that merge into a single tube. This forces them to mix and they break up into little droplets. In practice, it can be pretty hard. One of the practical challenges is that it takes a stable flow rate to make homogeneous droplets. It can be a big challenge to get a stable flow. That’s especially true if your microfluidic chip is made of a stretchy material (I’m looking at you PDMS). It makes sense to move to a chip that doesn’t stretch at all like acrylic plastic.

I had a great undergraduate come in and work with me this weekend on creating droplets with an acrylic plastic microfluidic chip. I had this working a few months ago but with much bigger channels. My first success was with channels that were more like 1 mm wide. The droplets were close to 1 mm wide as well.

We set about to optimize a fabrication technique that would make smaller channels and then uses channels to make droplets. After much difficulty, we have succeeded. We are now making channels that are approximately 100 µm wide and making droplets that are approximately 50 µm wide.

If you have an application that requires non-stretching microfluidic channels, please get in touch. We can send you one.

Here are parts 1 2 3 4, and 5.