London, May 10 : Chinese researchers have reported the successful development of "plasma needles," i.e. luminous jets of ionised gas, which when put to use, can revolutionise dental treatment and other medical uses.
Plasma is a cloud of gas broken down into a melange of free electrons and ions, which under atmospheric pressure and temperature may increase its temperature to thousands of degrees Celsius.
However, recently physicists have created "plasma needles" that are cold enough to touch but may prove fatal to bacteria.
Now, Chinese researchers have created a device that generates cold plasma and can also measure the flow of electrons inside it. This may aid in uncovering new insights into the nature of such plasmas so they can be enhanced for biomedical use. Still, the researchers are trying to work out the best way to control cold plasma.
XinPei Lu at Huazhong University of Science and Technology, China said that majority of plasma plumes created till date have been only millimetres long, or tens of degrees hotter than room temperature, and unsuitable for medical use.
But, the latest device created by their team generates a useful 4cm long room-temperature plasma plume that one can touch safely with a bare finger.
Consisting of a high-voltage wire electrode inside a quartz tube, this new plasma plume is encased in a syringe, which can be used to channel nitrogen or helium gas. A luminous needle of plasma is created when fragments of voltage are applied to the electrode. One can also vary the length of the plume by changing the gas, its flow rate, and the applied voltage.
Lu claimed that ultimately the device could be used in a number of applications, including sterilising medical instruments, and killing dental bacteria.
"We are focusing on dental hygiene applications, such as treating teeth cavities (caused by bacteria like Streptococcus mutans) and root canals," New Scientist quoted him, as saying.
It has been shown earlier that oxygen, ozone and hydroxide radicals generated by such plasma can kill bacteria.
According to John Goree of The University of Iowa, US, Lu's device has a feature that could lead to better understanding of what is happening inside the plasma, which could even help them for peak bacteria-killing performance.
He said that monitoring the flow of electrons in a plasma is the usual way to get a handle on conditions inside, but it is difficult to measure small, cold plasmas, because they contain few electrons compared to larger and hotter plasmas.
It is possible for the Chinese group to measure electron flow by powering their device using short electrical pulses, which could help tune them for peak bacteria-killing performance.