MRSA（耐甲氧西林金黄色葡萄球菌） (methicillin-resistant Staphylococcus Aureus) and other drug-resistant bacteria could face annihilation（歼灭，湮灭） as low-temperature plasma¹（等离子体） prototype devices have been developed to offer safe, quick, easy and unfailing（无尽的，无穷的） bactericidal cocktails². Two prototype devices have been developed: one for efficient disinfection（消毒） of healthy skin (e.g. hands and feet) in hospitals and public spaces where bacteria can pose a lethal³（致命的） threat; and another to shoot bacteria-killing agents into infested⁴ chronic⁵ wounds and enable a quicker healing process.

Two papers published today, Thursday 26 November, as part of a selection of papers on Plasma Medicine in New Journal of Physics (co-owned by the Institute of Physics and German Physical Society), demonstrate how far the design of equipment to harness the bacteria-killing power of low-temperature plasma has come.

Plasma, oft（常常） called the fourth state of matter after solid, liquid and gas, is defined by its ionized state（电离态）. In space, stars are made up of high-energy plasma and, on Earth, it is researchers in high-energy plasma that are making significant strides towards limitless energy from nuclear fusion⁶（核子融合）. The high energy of plasma stems from（源于） some atoms or molecules⁷ in a gas being stripped of their electrons, resulting in a mix of ionized and neutral species.

Also on Earth, scientists have been working on low-temperature and atmospheric-pressure plasma and have found applications in a range of industries, from plastic bag production to the manufacturing of streetlamps and semiconductor⁸（半导体） circuits.

In a low-temperature plasma, unlike its high-temperature counterparts, the temperature of ions and neutral particles（中性粒子） stays low. The 'recipe' for producing such plasmas is simple: the fraction（分数，小部分） of atoms (molecules) that are ionized – and therefore are hot – is so low that collisions with cold neutral atoms (molecules) quickly reduce their temperature again. The analogy of adding a drop of hot water to a bucket of cold water gives a sense of how low-temperature plasma physicists⁹ are able to create plasmas without dramatically increasing the temperature of the overall molecules.

In medicine, low-temperature plasma is already used for the sterilization¹⁰（消毒，灭菌） of surgical¹¹ instruments as plasma works at the atomic level and is able to reach all surfaces, even the interior of hollow needle ends. Its ability to disinfect is due to the generation of biologically active bactericidal agents, such as free radicals¹² and UV light, which can be delivered to specific locations. It is research into how and why these biologically active agents are generated that has led to the construction of medically invaluable¹³ devices.