Imagine a tiny mechanical machine, complete with miniature valves, switches, pumps and motors all operating together on a nanoscale size – too small for the eyes to see. This is the dream of University of Melbourne chemist Associate Professor Paul Mulvaney.

Associate Professor Mulvaney was recently awarded an ARC Federation Fellow to complete his research into the new field of molecular mechanics, which could one day lead to the creation of tiny portable devices that could be used in smart clothing, optical devices, health monitors, disease detectors and environmental transponders.

Associate Professor Mulvaney takes his inspiration from nature.

“At the heart of every living organism is an essential, practical skill that mankind has not yet managed to re-create. It is very simply the ability to convert chemical energy on a microscopic scale into mechanical motion,” he says.

For example, some bacteria - one of the most basic forms of life - have a tiny whip-like tail only 25 nanometres in width (for comparison: a human hair is about 20,000 nm wide), which is fuelled by chemicals and capable of spinning at 15,000 revolutions per minute.

Scientists have not even come close to creating something so tiny and powerful.

“At present we have no way of mimicking what happens so often in nature. We don't know how to store chemical or electrical energy and covert it into mechanical energy on tiny scales. This is the fundamental blockage to nanotechnology research,” Associate Professor Mulvaney says.

The conversion of one form of energy to other types is what drives many man-made machines. For example, the basic principle of a steam engine's operation involves the burning of coal – converting chemical energy (contained in the coal) into heat energy. The heat energy produces steam, which is then changed to mechanical energy by a generator.

Achieving this on a tiny scale has not yet been possible.

Associate Professor Mulvaney says the past decade has seen some significant advances in the field of nano- science and technology. For example, nanoscale optics and electronics have come a long way, but active mechanical devices, such as rotors, pumps, valves, relays, and regulators, lag far behind.

“It is currently impossible to build a working, moving nanoscale machine that would even closely resemble the actions of for example, the bacterium-tail. Even if we could make sub-micron rotors and cogs, we would have no way to turn them on autonomously,” Associate Professor Mulvaney says.

“Yet, even the simplest living cells and their organelles have been doing this for millions of years.”

Associate Professor Mulvaney's research is geared towards finding out how these tiny cells manage to convert chemical energy directly into nanoscale mechanical energy. Finding this out will open a whole new area of research, enabling scientists to start building tiny machines capable of probing, mending and delivering information in biological systems.

But, Associate Professor Mulvaney explains, building these devices is not as simple as scaling down conventional mechanical structures. Cells tend to work and respond differently when broken down to the nanoscale level, so nanoscale engines and motors will need to be built from the ground up with completely different design rules. The nanoscale machines will be based on molecular assembly and chemical synthesis as well as classical physics.

Also, while mimicry of biological systems will help the researchers to identify the ground-rules in nanomechanical systems, Associate Professor Mulvaney will also endeavour to outline new approaches for research into nanomechanics and to develop methods for creating functional nanomechanical devices.

“Research into these issues will have an immediate impact on Australia's capacity to construct sensors, smart clothing, optical devices, environmental transponders, and medical devices,” he says.

Associate Professor Mulvaney is a co-director of the University's Centre for Nanoscale Science and Technology (CNST). CNST is currently overseeing construction of an $8 million facility that will provide world-class electron microscopy, nanofabrication, atomic imaging and molecular analysis – technologies essential for work on a nanoscale level.

Associate Professor Mulvaney is currently working in Germany, but is happy to arrange interviews via email.

More information about this article:

Elaine Mulcahy
Media Promotions Officer
emulcahy@unimelb.edu.au
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Associate Professor Paul Mulvaney
Chemistry
mulvaney@unimelb.edu.au