Polymeric fibres are incredibly useful in the healthcare field for numerous reasons. Their uses include everything from biosensors to tissue engineering for wound healing patches. However, the process for making fibres has traditionally produced low yields, which means scaling up for manufacture has been impossible.
In response to this, Professor Mohan Edirisinghe OBE from UCL Mechanical Engineering developed a process for mass producing polymeric fibres using pressurised gyration, or suppression gyration. As well as the team in his lab, Professor Edirisinghe has collaborated with academics and universities across Europe, the USA, India and China for the research with the help of significant UKRI funding.
Harnessing pressurised gyration
“It’s a bit like candy floss,” Professor Edirisinghe says. “When you spin the candy floss, you get lots of nice sugary things coming out. Except in our rotating pot we have a polymer solution and controlled pressure, and we get floss-like fibres coming out in high yield.”
The rotating pots Professor Edirisinghe and his team have developed apply pressure and rotation simultaneously to get the desired results. The pressure applied can be immense – three times atmospheric pressure. And the speed can go up to an incredible tens of thousands of RPM. Combined with the polymer solution, the result is high yields of fibres that have a variety of important uses. Pressure and speed are carefully used to control the fibre diameter at all scales, and additions can be made to the pot simply like making a cocktail to functionalise the fibres. In fact a functional layer can be deliberately created at the fibre surface by using core-sheath pressurised gyration.
“My mission is to manufacture,” explains Professor Edirisinghe. “Manufacturing is different from making, because making is only a start and is usually on a very small scale. Often when you extend it to bigger quantities, your process is not that attractive because of reproducibility issues. If you want to be attractive to industry and patients in the healthcare sector, you’ve got to demonstrate that you can do it on a bigger scale.”
Putting the process to good use
Now that there is a process to produce high yields of polymeric fibres, the positive knock-on effect to many sectors is significant. As well as healthcare applications, these fibres can be used in filters and environmental controls. The scalability of the concept has huge potential too. “It’s a vessel,” Professor Edirisinghe says. “So you can simply use a bigger vessel if you want a higher quantity.”
Professor Edirisinghe works on manufacturing solutions mostly for the healthcare sector, and he was awarded an OBE in 2021 for his contribution to biomedical engineering. However, he is also applying some of the concepts he has created to other contexts. For example, he has also used pressurised gyration to create fibres from natural materials and waste, and he is currently collaborating with Edinburgh Napier University to use cow-dung to extract carbon nanofibrils which are then made fibrous. Professor Edirisinghe says that this kind of solution can make an impact in parts of the world with a high level of dairy farming. “For example, in Scotland, the prominent dairy industry can create a high carbon footprint, as larger animals have a notable impact on the environment,” Professor Edirisinghe explains. Putting some of the animal waste to good use could go some way towards maximising the products of large animals.
Professor Edirisinghe and team were recently invited to publish a featured review paper about his work, 'Developments in Pressurized Gyration for the Mass Production of Polymeric Fibers', featured in Advanced Science News. His team has produced 54 papers on the subject as a whole in the last decade since the invention of this manufacturing technology in 2013, and Professor Edirisinghe also recently edited a Special Issue on sustainability which further develops applications of pressurised gyration in a sustainable and environmentally-friendly way.
The last three UCL Mechanical Engineering PhD successes of 45 in total from the Edirisinghe Lab have involved important advances of pressurised gyration research.
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