Frictionless magnetic fluids offer industry potential Magnetic fluids capable of transporting and protecting valuable particles have been developed by EU-funded researchers. The findings could create new possibilities in areas as diverse as healthcare, crop protection and shipping. Fundamental Research © Tyler Olson/Shutterstock.com Magnets, which exert force at distance, are used in numerous products and services, from household appliances to industrial machinery. One application with huge untapped potential is in the displacement of material at the nanoscale and microscale. “I was interested in the possibility of placing particles or a liquid within a magnetic liquid, and then controlling the flow with external magnets,” says MAMI project coordinator Bernard Doudin from the University of Strasbourg in France. “Our idea was that this ferrofluid would help to overcome certain issues in fluid dynamics.” Benefits of ferrofluids For example, pumping fluids through hard-walled tubes – especially at very small scale – can damage biological objects that might be being carried. “People in hydrodynamics will tell you that things really become challenging when you go below the 0.1-millimetre scale,” adds Doudin. Ferrofluids could help to reduce friction and shear, because particles in need of protection would be contained in a fluid. To examine the possibilities of ferrofluids in more detail, the MAMI project brought together physicists, biologists and chemists. “I’m a physicist, and my speciality is in magnets,” explains Doudin. “We also had expertise in hydrodynamics, microfluidics and applied life sciences. We wanted to see, for example, the potential of ferrofluids in transporting blood cells.” MAMI, which was supported by the Marie Skłodowska-Curie Actions programme, also helped to train early-stage researchers across all these disciplines. The focus was very much on identifying potential for industrial applications. Life sciences and crop protection Some of the applications identified by the project have demonstrated real promise. “Pumping blood externally through tubes is troublesome, because it can destroy cells,” remarks Doudin. “If blood cells flow within a liquid rather than a solid tube, then there is much less friction and therefore much less stress on the cells.” Another identified application was crop protection. The MAMI project established the basis for understanding how a magnetic field can influence the properties of water. “We hope this can help us clarify how magnetised sprays are more efficient for treating crops,” he says. “We have some initial understanding of why this works, though more research and applications to complete testing are needed. It’s one of the mysteries of magnetism.” Further improving the efficient use of pesticides would benefit the environment and save farmers money. Frictionless motion The fact that particles flowing within a liquid create almost no friction opens up a new world of possibilities. “A great deal of energy is wasted on fighting against friction,” notes Doudin. “When you drive your car for example, you are fighting against the friction of the air, and of the road.” Eliminating friction could therefore save enormous amounts of energy. While the MAMI project worked on small-scale prototypes, the potential for developing hydrophobic and stable ferrofluidic coatings for boats was identified. The challenge now would be to scale this up, to provide the shipping industry with a viable energy-saving technology. “The MAMI project was quite broad, and we made some interesting discoveries,” concludes Doudin. “The next stage will be to build on those early-stage proof-of-principle concepts, and to develop tools and technologies that have real societal impact.” Keywords MAMI, magnetic, magnets, fluid, ferrofluids, healthcare, nanoscale
