I can’t find the original article, but Derek Lowe (famously of the Things I Won’t Work With column about exciting chemistry) published a series of articles on t

I can’t find the original article, but Derek Lowe (famously of the Things I Won’t Work With column about exciting chemistry) published a series of articles on the topic around 2021 - 2022. I did find an interview with Derek Lowe where they talk a bit on the topic, it I haven’t listened through all of it to see if they discuss microfluidics: https://www.earwolf.com/episode/where-oh-where-is-the-covid-19-vaccine-with-derek-lowe/ https://www.earwolf.com/episode/where-oh-where-is-the-covid-... EDIT: found it! Here’s the write up where Derek Lowe discusses microfluidics devices that ended up being the bottleneck to producing the original COVID vaccines: https://www.science.org/content/blog-post/myths-vaccine-manufacturing https://www.science.org/content/blog-post/myths-vaccine-manu... From the article (there’s more than this): Ah, but now we get back to Step Four. As Neubert says, "Welcome to the bottleneck!" Turning a mixture of mRNA and a set of lipids into a well-defined mix of solid nanoparticles with consistent mRNA encapsulation, well, that's the hard part. Moderna appears to be doing this step in-house, although details are scarce, and Pfizer/BioNTech seems to be doing this in Kalamazoo, MI and probably in Europe as well. Everyone is almost certainly having to use some sort of specially-built microfluidics device to get this to happen - I would be extremely surprised to find that it would be feasible without such technology. Microfluidics (a hot area of research for some years now) involves liquid flow through very small channels, allowing for precise mixing and timing on a very small scale. Liquids behave quite differently on that scale than they do when you pour them out of drums or pump them into reactors (which is what we're used to in more traditional drug manufacturing). That's the whole idea. My own guess as to what such a Vaccine Machine involves is a large number of very small reaction chambers, running in parallel, that have equally small and very precisely controlled flows of the mRNA and the various lipid components heading into them. You will have to control the flow rates, the concentrations, the temperature, and who knows what else, and you can be sure that the channel sizes and the size and shape of the mixing chambers are critical as well.