Alan Turing is best known for cracking the German Enigma machine during World War II and developing the foundations of modern computer science (along with his namesake test). But one of the man's final contributions to science—a chemistry paper he published just two years before he died—is .
Turing’s paper, published in 1952, addresses a strange principle of chemistry: In certain rare conditions, two chemicals that are mixed together can spontaneously separate and create a unique striped pattern, commonly called a "Turing pattern." These can be seen in the markings on different animals, the structures of certain plants, and even the construction patterns of some insect hives.
The key feature of these structures is that researchers can precisely manipulate their shape, size, and components to create specific properties. In this new study, a group of researchers used some chemicals called polyamides to create a membrane that lets water through while blocking salt. What's more, the Turing structures in the membrane allow it to overcome a fundamental limitation of these types of water filters.
Let's say you're trying to turn saltwater into fresh water. The basic problem is that while it's not terribly difficult to build a filter that blocks nearly all salt, such a filter also makes it difficult for water to get through. In other words, you can purify salt water very well, but not quickly. At the other end of the spectrum, a filter that lets a lot of water through will also let a lot of salt through.
Pretty much every desalination filter has to live somewhere on spectrum between "not good at removing salt" and "not good at producing fresh water," which is why desalination is so hard. This new filter designed using Turing structures could help to solve this problem by producing a filter that lets lots of water through while blocking nearly all salt.
This new type of filter is still in the early stages of development, and it’ll be a while before this new filter can begin purifying salt water at a large scale. Once that happens, Alan Turing’s insight could help millions of people find fresh water—60 years after he published it.