Title: Diamagnetic levitation for studies of fluids and granules in weightless conditions, and for interdisciplinary science
Funder: Engineering and Physical Sciences Research Council

Abstract: How do objects behave when they are weightless? This is a question that has fascinated generations of scientists and captured the imagination of the general public. To address this question of fundamental importance for space travel, experiments are performed in space-craft, orbiting the Earth, or in free-fall. Diamagnetic levitation (DL) is a promising technique that uses a powerful magnetic field generated by an electromagnet, to simulate the weightless conditions in orbit, on the Earth. It allows diamagnetic materials, such as water and biological organisms, to levitate above the magnet. These materials are repelled from the magnetic field, but too weakly to notice ordinarily, unlike iron for example, which is strongly attracted to the field. Just as the centrifugal force balances the weight of an orbiting spaceship, the diamagnetic force opposes the force of gravity on a levitated object, so that it floats as though in space. In 1863, Plateau was inspired to experiment on a spinning drop of oil, floated in an alcohol mixture, to model the Earth's shape. He recognised that surface tension, holding the drop together, could model the action of gravity holding a planet or star together. It was later realised that the surface tension of an electrically-charged drop could also model the forces binding nucleons inside an atomic nucleus. I will use DL to study what Plateau couldn't: a drop suspended freely in space. I will investigate the possibility of using this drop to discover clues to the behaviour of both astronomical objects and the atomic nucleus. By studying vibrations of the drop, I will also obtain its surface tension. This non-contact measurement technique will enable the study of very reactive liquids and supercooled liquids.I will also study how levitated 'rain' drops vibrate, distort and shatter in electric fields, which influences the behaviour of electrical storms, and image the spray of small droplets that issue from the drop upon break-up. The latter process is important in extracting biological molecules from liquids for analysis, winning John Fenn a Nobel Prize in 2002, and revolutionising the search for new medicinal drugs.Granular materials are everywhere, from asteroids to cornflakes. Understanding the dynamics of the granules is important in many industries, e.g. food and pharmaceutics, and in studying many natural processes, e.g. landslides. In zero-gravity, granules are always suspended in the liquid. Vibrating the liquid causes granules to move and self-organise into three-dimensional patterns, caused by the motion of the liquid around the grains. I will perform experiments on levitated granules to investigate the interactions between the grains and the liquid; such knowledge should ultimately lead to significant improvements in the control and exploitation of granular materials on Earth and in space. By collaborating with other researchers, I will also explore how DL can be applied to a broader range of topics. I will use it to obtain precise measurements of the magnetisation of biological tissues in a strong magnetic field, fundamentally important for medical magnetic resonance imaging. In conventional methods, the magnetisation of the sample container introduces significant uncertainty into the measurement. Since a levitated sample does not require a container, we avoid this complication. I will study the nucleation and growth of bubbles in levitating gas-saturated liquids, directly benefitting our understanding of, e.g. decompression sickness ('the bends') in SCUBA accidents. By levitating the liquid, we can observe the growing bubble without it detaching from its nucleation site and floating away. I will also investigate how a strong magnetic field can be used to construct a mesh of hollow tubular protein structures in levitating solutions, which could form templates for nano-scale electric circuits or 'scaffolds' for cell growth.


Research activity codes: 1.3 CHEMICAL AND PHYSICAL SCIENCES
Health categories: GENERIC HEALTH RELEVANCE