Plasma refers to the state of matter in which energy is continuously applied to matter from the outside to dissociate it into negative and positive charged particles. Since the state of matter is solid, liquid, gas, and plasma according to the order of energy levels, plasma is habitually called the fourth state. In addition to being in nature, plasma can also be obtained artificially. Usually an electric field is applied to the gas to accelerate the charged particles. Since the ions are heavier, they are all electrons that are accelerated. Ionization is caused by electrons colliding with heavier particles, and finally plasma is formed. Most gas discharges are accompanied by luminescence, so they are also called glow discharges. Since part of the particles generated in the glow zone can reach the non-electric field zone, plasma afterglow effect will occur. Practice has proved that plasma sterilization can be achieved in either the discharge zone or the afterglow zone. In the medium and low pressure state, the temperature of the heavier particles (neutral groups and ions) as the main mass of the plasma is at least an order of magnitude lower than that of the electrons, so this kind of plasma is called low-temperature plasma or cold plasma. When a pulsed electric field (such as corona discharge, dielectric barrier discharge, etc.) is applied, the gas temperature can even be as low as room temperature, which makes plasma sterilization more universal. Our previous article has already talked about the application of low-temperature plasma sterilization technology. Let's talk about its mechanism and advantages in detail below.

Low-temperature plasma sterilization mechanism:

As for the sterilization mechanism of low-temperature plasma, so far people have not been able to give a more satisfactory answer. According to early experiments, various hypotheses about the mechanism have emerged one after another. Throughout various hypotheses, whether it is to explore the mechanism of sterilization and disinfection from the physical or chemical aspects, there are basically the following three types in the final analysis: The large amount of ultraviolet light generated during the plasma formation directly destroys the genetic material of microorganisms; ultraviolet photons are inherent Photolysis breaks the chemical bonds of microbial molecules, and finally generates volatile compounds such as CO and CHx; through the etching effect of plasma, that is, the active substances in the plasma chemically react with the proteins and nucleic acids in the microorganisms, which can destroy microorganisms and disturb microorganisms. Survival function. Some scholars also believe that the killing effect of plasma on bacteria is the result of the above-mentioned combined forces, which can be observed from some proven bacteria survival curves. Most gases can be discharged to form plasma. In the 1970s, more inert gases such as argon and helium were used for sterilization experiments. Subsequently, some halogens including chlorine, bromine, and iodine were added to the discharge gas to enhance the sterilization and disinfection effect. With the addition of acetaldehyde vapor in the 1980s and hydrogen peroxide in the early 1990s, it has been gradually confirmed that both single gas and mixed gas can excite plasma for sterilization. Studies have shown that in a single gas, the killing effect of the gas on the bacterial spores is not the same. According to the order of the sterilization effect, they are O2, CO2, H2, Ar and N2; and using the mixed gas to excite the plasma, its sterilization and disinfection effect It is often better than a single neutral gas.

The advantages of low-temperature plasma sterilization technology:

Low-temperature plasma sterilization and disinfection technology has almost all the conditions that an ideal sterilization and disinfection method should have: Compared with high-pressure steam sterilization and dry heat sterilization, the sterilization time is short; compared with 1, 2-ethylene oxide Compared with the chemical sterilization of the main body, the operating temperature is lower; it can be widely used to sterilize a variety of materials and articles; especially after the power is cut off, the various active particles produced can disappear within a few milliseconds, so no ventilation is required. It will cause harm to the operator, and it is safe and reliable. At present, this technology has been widely used in many fields including food processing and medical hygiene at home and abroad.