Plasma in your TV and as a potential antibiotic

Published 04 May 2012
A recent article in the Sydney Morning Herald described how Chinese and Australian scientists have collaborated to make plasma torch that can kill bacteria. (

Well-Being Australia chairman, Mark Tronson, knew about plasma TV screens and also about blood plasma, but he wondered how these things were related to antibiotics. He asked some of his scientifically-educated acquaintances to explain it, and in this comment article he shares their knowledge with you.

The word 'plasma' comes from an ancient Greek word meaning 'to spread thinly'. In medicine, it refers to the thin, watery part of the blood. However, the meaning in the above article comes from physics, where it refers to a substance-without-form that consists of tiny positively charged and negatively charged particles (ions) floating around freely. It is not a solid, not a liquid and not a gas (all of which have electrically neutral atoms or molecules), but a different, diffuse type of matter.

Plasmas exist in outer space, around stars, where there is almost no atmosphere.

To make this type of plasma, there needs to be an input of energy to force some electrons to jump away from the atoms to which they are attached. They then ionise some other molecules and atoms as they try to find a positive particle to combine with. In space, this energy comes from the nuclear energy created by the 'burning' of the stars. On Earth, we need to supply heat, light or electricity.

Here on Earth, we also need to remove most of the air before we can make a plasma. Fluorescent tubes and neon signs are examples of everyday uses of this form of matter; they are made when air is evacuated from a glass tube (which has electrodes sealed into it), then small amounts of gases such as mercury vapour or neon are put inside. When an electric current is turned on, a plasma is formed and some of the electrically charged ions formed from these gases react with the phosphorescent coating on the glass to produce light.

Closer to home

Inside your plasma TV screen, something similar happens on a miniature scale. Each little pixel has three small containers, each containing a tiny electrode and one of three different gases that flouresce blue, red or green when the energy released from their ions hits the glass screen. The electronics and software inside the TV are designed to cause particular 'packets of gas' to 'fire', depending on which digital signal representing the original picture is sent to them. Thus each pixel makes a little plasma that makes a small part of the overall picture. (

The new bacteria-killing device described above is designed to allow the charged particles of the plasma to be emitted as a beam like a torch, rather than to make coloured pictures or light. It is based on an invention published by a Russian scientist several years ago, which was able to kill disease-forming bugs on raw chicken. Subsequently, a similar gadget was used to successfully treat infected wounds.

The improvements that the Australian and Chinese scientists have made enables this new 'torch' to keep to a low enough temperature to be safely touched by the skin, and also to use only a small amount of power so it can be powered by a battery. The stream of positive and negative ions, however, is still strong enough to react with the molecules on the surface of the bacteria, zapping them dead.

As cited in the 'Science Now' website: Making the device truly portable is a big advance, says Michael Keidar, a plasma physicist at George Washington University in Washington, D.C. "Operating cold plasma in air is challenging, [and] it seems like they were able to make it work," he says. "This is a purely technical issue that was solved." (

Another discovery

Another advantage of this latest equipment is that it can kill 'biofilms'. These are mats of bacteria that stick together, such as those that form in the lungs in some types of pneumonia or bronchitis, that are difficult to kill with conventional antibiotics because of the dense film of mucus they make. (

Mark Tronson notes that this is only the beginning. So far, this has only been demonstrated in a laboratory. It will take maybe five years to do all the tests to prove it is safe for use in human beings; he understands that there is no 'instant magic bullet' that can make fundamental science and engineering discoveries into practical applications.

He says that there are many places in the Bible where 'slow and steady' approach is advocated; for example Ecclesiastes 7:8 "The end of a matter is better than its beginning, and patience is better than pride."

Scientific and medical research works like this: piece by piece, building up better and better innovations on the basis of previous work. The best scientists rely on patience, not pride; and the outcome is improvement in our lives and health.


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