Integrated Microwave Atmospheric Plasma Source (IMAPlaS): thermal and spectroscopic properties and antimicrobial effect onB. atrophaeusspores

Abstract

The Integrated Microwave Atmospheric Plasma Source (IMAPlaS) operating with a microwave resonator at 2.45 GHz driven by a solid-state transistor oscillator generates a core plasma of high temperature (T > 1000 K), therefore producing reactive species such as NO very effectively. The effluent of the plasma source is much colder, which enables direct treatment of thermolabile materials or even living tissue. In this study the source was operated with argon, helium and nitrogen with gas flow rates between 0.3 and 1.0 slm. Depending on working gas and distance, axial gas temperatures between 30 and 250 • C were determined in front of the nozzle. Reactive species were identified by emission spectroscopy in the spectral range from vacuum ultraviolet to near infrared. The irradiance in the ultraviolet range was also measured. Using B. atrophaeus spores to test antimicrobial efficiency, we determined log 10 -reduction rates of up to a factor of 4.

Gas-liquid interfacial plasmas producing reactive species for cell membrane permeabilization

“…Researchers in the plasma life science field make and use various kinds of APPJs that differ in electrode configuration, excitation frequency (pulsed DC, ( 45 ) LF (~kHz), ( 46 ) RF (~MHz), ( 47 , 48 ) microwaves (~GHz) ( 49 ) ) and working gas (He, Ar, O 2 , N 2 , H 2 O). The choice of electrode, frequency, and working gas dictates the electron density and temperature, and the gas temperature of the generated plasma in the gas phase region, resulting in changes in the density of the excited particles such as metastable He * and Ar * , and various kinds of reactive species such as • OH, H 2 O 2 , HO 2 and NO x .…”

The quality by design approach for optimization of slayer exciter based low power portable atmospheric plasma jet on bactericidal efficacy of Pseudomonas aeruginosa

“…Numerous studies have recently been conducted on various plasma jet designs such as, dual-electrode plasma jet [15,16], dielectric barrier discharge (DBD) plasma jet [14,[17][18][19][20][21][22], and single electrode plasma jet [23][24][25][26] for their microbicidal efficacy. The dualelectrode plasma jet design is less explored than other designs as the plasma jet intensity is majorly dependent on the electrode spacing and applied voltage.…”

“…Further, the device output has high frequencies in RF and microwave range, leading to reduce power consumption. The single electrode plasma jet is subclassified into two types, namely, single electrode DBD type jet [23,24] and single bare electrode plasma jet [25,26]. Single electrode DBD type jet requires a high AC power supply of 300 W (due to the presence of a dielectric layer) and a high carrier gas flow rate of 2-5 L/min [23,24].…”

“…In addition, the plasma intensity is dependent on the dielectric strength and operating output frequency. On the other hand, single bare electrode plasma jets require an input voltage source of 280-300 V and operates in the output frequency range of 13 MHz-2.5 GHz with a gas flow of 0.3-1 L/min [25,26].…”

Characterization of a novel microwave plasma sheet source operated at atmospheric pressure

“…Thus, microwave atmospheric plasma has gained ground in this field. It was used for the sterilization [25][26][27][28], cleaning [29,30] and activation [31] of material surfaces as well as the modification of nanofibers [32], silicon, polymer and wood [33] surface properties. An important prospect in the field of surface modification is chemical vapor deposition [34,35] and plasma polymerization [36,37].…”