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Despite being surrounded by it – in the stars, our TVs, our lights – few of us are aware of plasma. It is the fourth state of matter after solid, liquid and gas.
But could this unusual state of matter hold the key to solving some of the world’s greatest challenges? Exciting research at Deakin University is revealing new ways of producing plasma inside liquid and of shaping solid materials.
Plasma is partially or fully ionised gas containing electrons, positive and negative ions, excited atoms and molecules, free radicals and UV photons. Although not well known, it’s actually the major constituent of the universe, from the stars and the sun to the ionosphere of the Earth’s atmosphere.
Scientist Dr Jane Dai heads up Deakin’s Plasma Research Laboratory in the Institute for Frontier Materials. She says, ‘The outward beauty of plasma, its colour and power, can be seen in aurora and lightning (natural plasmas), while its inner beauty is that every species inside plasma can harmoniously work together to change our material world in an environmentally friendly way.’
Dr Dai is passionate about the potential of plasma to help solve the problems of our world, and her work brings different experts from around the world together. This approach has led to the development of several unique plasma technologies and their application to real-world challenges.
'Every species inside plasma can harmoniously work together to change our material world in an environmentally friendly way.'
Dr Jane Dai,
Institute for Frontier Materials, Deakin University
One of these developments by Dr Dai and her team is a new, cost-efficient way of selectively producing plasma species inside a liquid. ‘To generate plasma inside liquids has been more difficult than in a gas, as it needs much more energy. To select a required plasma species in liquid is even more difficult,’ said Dr Dai. ‘In this development, we generate gas plasma inside liquid by blowing a chosen gas through fine metal needles to produce gas bubbles directly in the liquid.’
The plasma is formed inside the bubbles when a high-voltage pulse is applied. Dr Dai explains, ‘The chosen gas gives the selected species and the bubbles being inside the liquid means that the plasma species have nowhere else to go, only to react with, and go straight into, the liquid giving high production.’
Although the science sounds complex, the solution was based on a simple childhood amusement – using a straw to blow bubbles into a drink.
‘This advance has huge potential to transform a range of fields, from agriculture, biomedicine, food processing and wastewater treatment, to fabrication of nano-materials at atmospheric pressure and near ambient temperature,’ Dr Dai says.
This technique is being used for milk sterilisation without damaging the nutrition, improving beer brewing and enhancing plant growth. However, Dr Dai is most excited about how it can change the way we power our world. Plasma treated water has now been used as an electrolyte to replace toxic chemicals in the production of nanotubes and nanoparticles for use in clean energy technologies, such as solar cells and batteries. Furthermore, using this method in a chosen liquid can be used to produce ultra-strong ‘nano-diamonds’, avoiding the high temperature and extreme pressure of current methods.
Dr Dai has always got one eye on the future – global collaboration, and sharing know-how like this, she says, will be critical to the future of plasma innovation for a better world.
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