Storm warning

Issue 20 | Spring/Summer 2007

Report: Samantha Blair
Photography: Greg Ford and Melissa Di Ciero

Dr Leslie Yeo

An 80-year-old principle discovered by Albert Einstein is being applied by Monash University scientists to develop an 'electronic canary', capable of detecting tiny grains of biohazardous materials.

It is called the 'tea leaf paradox'. In 1926 Einstein noticed stirred tea leaves spun inwards and concentrated centrally at the bottom of a tea cup and reasoned it was friction that caused the leaves to spin inward, rather than a centrifugal force that would push them out.

It's a concept that has intrigued Monash engineer Dr Leslie Yeo and his colleagues at the Micro/Nanophysics Research Laboratory for some time. "A year ago we applied this idea to blood," Dr Yeo said. "We found we were able to separate red blood cells from plasma in a small device using an electrically charged probe to stimulate the liquid. The red blood cells were spun down to a central point, leaving the clear plasma fluid on top."

His discovery attracted international attention for its potential applications to develop pocket diagnostics such as on-the-spot blood tests.

Twelve months later Dr Yeo and his colleague Dr James Friend have taken the tea leaf paradox theory into the world of nanophysics, using sound waves to concentrate very small particles or micro-organisms to the point where they can be detected. They found when sound waves travelled across the surface of a drop of liquid, the sound energy leaked into the drop and created a tornado-like storm effect within it.

"The tornado causes the microbes to spin down to a point on the surface and localises them within seconds. The clustering of microbes then gives us a high enough sample concentration to measure," Dr Yeo said.

That concept has led to the design by the Micro/Nanophysics Research Laboratory of a battery powered, credit card sized sensor much like a smoke detector that can warn of much smaller concentrations of biohazardous materials.

Dr Yeo says this 'electronic canary' would have the ability to rapidly detect viral outbreaks like SARS and bird flu, or dangerous levels of deadly bacteria or chemicals released in the event of a bio-terrorism attack.

"This could mean a world of difference in a situation like a viral outbreak where detection and containment are vital or when authorities need to quickly respond to a terrorism threat involving bio-chemicals," Dr Yeo said.

"Microfluidics and nanotechnology are not just about making equipment and technology smaller and more portable, but also making it more efficient, cost effective, and accessible." It is anticipated that the disposable 'smart-card' devices would cost about 50 cents to manufacture, replace slower and larger equipment, and could be on the international market within five years.

For more information please visit the Micro/Nanophysics Research Laboratory website.