Smaller magnets more attractive

As one leaves childhood behind, magic and mystery seem to evaporate at a disappointing rate – Santa Claus isn't real; he might even be a relative. Grand tales of why the sky is blue give way to explanations of oxygen and nitrogen scattering more of the blue portion of the sun's spectrum.

One might imagine the situation being especially dire for scientists, with all romantic notions of the universe being systematically replaced by dull equations, although appreciating the pure beauty of mathematics' ability to describe hefty chunks of the known universe might be a wishful surrogate for the childhood loss, I am often stumped in childlike-wonder at the march of scientific progress. One particular instance was the levitating frog of 1997. I understood that some physicists had devised a particularly catchy way of demonstrating the miniscule magnetic properties of water in extremely high magnetic fields through the levitation of a light, watery and accommodating frog; but really – levitating frogs are magic! Or at least magnetism remains just as magically fascinating millennia after its discovery. Around 800BC, both Chinese and Europeans stumbled upon magnetism by discovering lodestones – rocks rich in the iron oxide mineral magnetite that were magnetised in the presence of nearby lightning strikes. While physicists took a few millennia to develop explanations for the true origins of lodestones' magnetic properties, applications for magnetism date from around 100AD, with references in Chinese texts to a 'south pointer'. This device was a spoon made of lodestone that was balanced on its bowl to freely rotate and orient in the Earth's magnetic field.

Staggering range The south pointer was used for rituals rather than navigation, but compasses appeared about 900 years later, after methods for making lighter artificial magnets were devised. In the millennia since, compasses have had a profound effect on exploration and its associated cultural ramifications, and magnetism has been employed in a staggering range of applications: from early communications and electric motors to medical imaging and data storage. The arguably rapid development from magnetised ritualistic spoons to digitised Iron Maiden on an Apple iPod is laudable, but humans were beaten to the compass application long before they ever started. In 1975 a microbiologist witnessed some bacteria in marsh water performing a south-north shuffle on his microscope slide. At first he thought they were attracted to sunlight streaming in from the window, but after a quick series of tests with objects from around the office, he found they were only interested in his handheld magnet. The magnetic sensing (or magnetotactic) bacteria turned out to have tiny particles of magnetite arranged like a spine along their length. Earth's magnetic field has a downward component everywhere except on the equator, and magnetotactic bacteria use their magnetic spines to navigate down towards a safe and nourishing environment in the silt. While this discovery was fascinating enough, it was noted that the particles were single crystals of magnetite with precisely controlled nanoscale dimensions. Below a certain volume, magnetite is useless for maintaining a permanent magnetisation required for sensing direction. Billions of years ago, nature optimised magnetotactic bacteria's chemical synthesis of magnetite to be just big enough. So, not only did they invent the compass before us, but they were already practicing nanoengineering. Those smug Magnetospirillum magnetotacticum! It is at the intersection of these disciplines – physics, biology, and chemistry – that some of the most promising applications for magnetism are being developed throgh the exploitation of nanoscale engineering tools that nature has already provided. Researchers with interdisciplinary skills and facilities specifically designed for fostering interdisciplinary work have flourished over the last few years, and early commercial applications herald breakthroughs in medical imaging and diagnostics, drug delivery, cancer therapies, environmental clean-up, electronics and data storage. While many companies are currently focused on targeting magnetic nanoparticles to highlight diseased tissue for medical magnetic resonance imaging (MRI), some also promise the potential of inexpensive, globally accessible drinking water using protein-wrapped magnetite nanospheres. Indeed the potential for magnetic applications is more attractive (and magical) at the nanoscale. Nanomagnetics undertake their research and development in state-of-the-art facilities designed and constructed by leading specialist technology contractors M+W Zander FE UK. Kevin Feldman, business development director, explains that their focus from the outset of the project was to develop a solution based upon the final process requirements for nanomagnetics, not just build a cleanroom within the space available. This ensured that they benefited from the optimum facility layout and associated infrastructure, thus minimising capital expenditure for nanomagnetics at a crucial time in their business development. The project involved the design, construction and fitting out of two cleanrooms (ISO 4 / ISO 8) and offices within an existing unit located in a technology park on the outskirts of Bristol. The project was commissioned to allow Nanomagnetics to transfer their early research and development work from within Bristol University, to a commercial operation.