'Plasma needle' could replace the dentist's drill

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Zeeya Merali
03 July 2006

MANY of us would go to great lengths to avoid the dentist's drill. Sticking a needle with a flaming plasma tip into your mouth may not at first strike you as much of an improvement on conventional dentistry. However, the plasma needle, which is cold and painless to the touch, could be just the panacea we have been waiting for.

The needle's creator, physicist Eva Stoffels-Adamowicz, who is based at the Eindhoven University of Technology in the Netherlands, says it could also be used to painlessly remove cancerous tissue.

Stoffels-Adamowicz came up with the idea for the needle while working with low-pressure plasmas, which are created in a vacuum. In order for the plasma to be used on people, she and her colleagues developed a plasma needle that works in air. The needle is a 50-millimetre-long tungsten wire housed in a quartz tube filled with gas. Driving a voltage through the needle generates a small plasma spark at its tip "like a children's sparkler", explains Stoffels-Adamowicz.

She and her colleagues have used the needle to generate a nitric oxide plasma, by flushing helium gas and air into the tube. The helium helps the plasma to form efficiently from air at low energies, although at this stage the researchers are unsure why. This could have medical applications because the body uses nitric oxide to fight infection and inflammation. The team found that when the nitric oxide plasma is produced using small amounts of energy and applied in short bursts, it can kill bacteria while leaving other living cells unharmed (Plasma Sources Science and Technology, vol 15, p 501).

Nitric oxide is also involved in cell messaging, so it can be used to trigger programmed cell death. Using higher-energy doses of plasma, in longer bursts, the team was able to target certain living cells and cauterise the tissue while leaving surrounding cells undamaged. "The plasma needle could be used to excise tumours or skin cancers," says Stoffels-Adamowicz. "It's surgery without cutting."

Plasma physicist Bill Graham at Queen's University Belfast, UK, is also developing medical treatments using plasma and thinks the team's development could have several uses. "The real innovation of the plasma needle is that it works in air, opening up the possibility of using plasma in new realms, like in the mouth, or in certain places inside the body."
Stoffels-Adamowicz's team are already working on a method to generate a plasma that can be sent down blood vessels via a catheter. They think that plasma therapy could one day be used to help clear blocked arteries, although it is likely to be used in dentistry much sooner, allowing Stoffels-Adamowicz to avoid the dreaded drill. "Until then, I just hope that I don't get toothache," she says.

From issue 2558 of New Scientist magazine, 03 July 2006, page 32