This introductory review on plasma health care is intended to provide the interested reader with a summary of the current status of this emerging field, its scope, and its broad interdisciplinary approach, ranging from plasma physics, chemistry and technology, to microbiology, biochemistry, biophysics, medicine and hygiene. Apart from the basic plasma processes and the restrictions and requirements set by international health standards, the review focuses on plasma interaction with prokaryotic cells (bacteria), eukaryotic cells (mammalian cells), cell membranes, DNA etc. In so doing, some of the unfamiliar terminology—an unavoidable by-product of interdisciplinary research—is covered and explained. Plasma health care may provide a fast and efficient new path for effective hospital (and other public buildings) hygiene— helping to prevent and contain diseases that are continuously gaining ground as resistance of pathogens to antibiotics grows. The delivery of medically active 'substances' at the molecular or ionic level is another exciting topic of research through effects on cell walls (permeabilization), cell excitation (paracrine action) and the introduction of reactive species into cell cytoplasm. Electric fields, charging of surfaces, current flows etc can also affect tissue in a controlled way. The field is young and hopes are high. It is fitting to cover the beginnings in New Journal of Physics, since it is the physics (and non- equilibrium chemistry) of room temperature atmospheric pressure plasmas that have made this development of plasma health care possible.

/pdf/plasma-medicine-an-introductory-review-16ncxlrbef.pdf

Plasma medicine: an introductory review

Laser-induced breakdown spectroscopy (LIBS) has become a very popular analytical method in the last decade in view of some of its unique features such as applicability to any type of sample, practically no sample preparation, remote sensing capability, and speed of analysis The technique has a remarkably wide applicability in many fields, and the number of applications is still growing From an analytical point of view, the quantitative aspects of LIBS may be considered its Achilles' heel, first due to the complex nature of the laser–sample interaction processes, which depend upon both the laser characteristics and the sample material properties, and second due to the plasma–particle interaction processes, which are space and time dependent Together, these may cause undesirable matrix effects Ways of alleviating these problems rely upon the description of the plasma excitation-ionization processes through the use of classical equilibrium relations and therefore on the assumption that the laser-induced 

Laser-Induced Breakdown Spectroscopy (LIBS), Part I: Review of Basic Diagnostics and Plasma–Particle Interactions: Still-Challenging Issues Within the Analytical Plasma Community

Plasmas for medicine

Nonthermal plasma (NTP) is electrically energized matter and is composed of highly reactive species including gas molecules, charged particles in the form of positive ions, negative ions, free radicals, electrons and quanta of electromagnetic radiation (photons) at near-room temperature. NTP technology is an emerging nonthermal technology with potential applications for sterilization in the food industries. An upsurge in the research activities for plasma-based inactivation of food-borne pathogens is evident in recent years. These studies have shown that NTP can be used for the surface decontamination of raw produce including; dried nuts and packaging materials. This paper reviews the action of plasma agents on the microbial classes and describes proven and potential applications in food processing. Novel developments in the technology and a future outlook for the application to foods are discussed.

/pdf/nonthermal-plasma-inactivation-of-food-borne-pathogens-42he42en6a.pdf

Nonthermal Plasma Inactivation of Food-Borne Pathogens

Thanks to their portability and the non-equilibrium character of the discharges, microplasmas are finding application in many scientific disciplines. Although microplasma research has traditionally been application driven, microplasmas represent a new realm in plasma physics that still is not fully understood. This paper reviews existing microplasma sources and discusses charged particle kinetics in various microdischarges. The non-equilibrium character highlighted in this manuscript raises concerns about the accuracy of fluid models and should trigger further kinetic studies of high-pressure microdischarges. Finally, an outlook is presented on the biomedical application of microplasmas.

Microplasmas: sources, particle kinetics, and biomedical applications

The inactivation of bacteria and biomolecules using plasma discharges were investigated within the European project BIODECON. The goal of the project was to identify and isolate inactivation mechanisms by combining dedicated beam experiments with especially designed plasma reactors. The plasma reactors are based on a fully computer-controlled, low-pressure inductively-coupled plasma (ICP). Four of these reactors were built and distributed among the consortium, thereby ensuring comparability of the results between the teams. Based on this combinedeffort,theroleofUVlight,ofchemicalsputtering(i.e.thecombinedimpactofneutrals and ions), and of thermal effects on bacteria such as Bacillus atrophaeus, Aspergillus niger ,a s well as on biomolecules such as LPS, Lipid A, BSA and prions have been evaluated. The particle fluxes emerging from the plasmas are quantified by using mass spectrometry, Langmuir probe measurements, retarding field measurements and optical emission spectroscopy. The effects of the plasma onthe biologicalsystems are evaluatedusingatomic force microscopy, ellipsometry, electrophoresis, specially-designed western blot tests, and animal models. A quantitative analysis of the plasma discharges and the thorough study of their effect on biological systems led to the identification of the different mechanisms operating during the decontamination process.OurresultsconfirmtheroleofUVinthe200‐250nmrangefortheinactivationofmicroorganisms and a large variability of results observed between different strains of the same species. Moreover, we also demonstrate the role of chemical sputtering corresponding to the synergism between ion bombardment of a surface with the simultaneous reaction of active species such as O, O2 or H. Finally, we show that plasma processes can be efficient against different micro-organisms, bacteria and fungi, pyrogens, model proteins and prions. The effect of matrices is described, and consequences for any future industrial implementation are discussed.

Inactivation of Bacteria and Biomolecules by Low-Pressure Plasma Discharges

A double inductively coupled low pressure plasma for sterilization of bio-medical materials is introduced. It is developed for homogeneous treatment of three-dimensional objects. The short treatment times and low temperatures allow the sterilization of heat sensitive materials like ultra-high-molecular-weight-polyethylene or polyvinyl chloride. Using a non-toxic atmosphere reduces the total process time in comparision with common methods. Langmuir probe measurements are presented to show the difference between ICP- and CCP-mode discharges, the spatial homogeneity and the influence on the sterilization efficiency. To know more about the sterilization mechanisms optical emission is measured and correlated with sterilization results.

https://iopscience.iop.org/article/10.1088/0022-3727/40/14/008/pdf

A double inductively coupled plasma for sterilization of medical devices

We report on relative and absolute intensity calibrations of a modern broadband echelle spectrometer (type ESA 3000? trademark of LLA Instruments GmbH, Berlin) for use in the diagnostics of low-temperature plasma. This type of device measures simultaneously complete emission spectra in the spectral range from 200 to 800 nm with a spectral resolution of several picometres by using more than 90 spectral orders, causing a strongly structured efficiency function. The assumptions and approximations entering the calibration procedure under these conditions are discussed in section 3. For coping with the strongly structured efficiency function a continuum light source is needed, which covers the entire spectral range. Furthermore, the variation of its intensity must be low enough to ensure that neither statistical errors perturb the calibration in regions with low photon flux and/or low efficiency, nor local memory overflow in regions with high photon flux or high efficiency. In our case this requires that during calibration over the whole spectral range of the spectrometer the counts per pixel in one measurement vary at highest by a factor 10 to 12. Usual broadband light sources do not meet this latter requirement. We, therefore, use an uncalibrated 'composite' source, an adjustable combination of a standard tungsten strip lamp and a deuterium lamp, and calibrate the spectrometer in a two-step process against the tungsten strip lamp and well-known rovibrational intensity distributions in the emission spectra of NO and N2. We adjust the composite source in a way to produce a perturbation-free first approximation of an (uncalibrated) efficiency function, which is then corrected and thus calibrated by comparison with the (secondary) standards mentioned above. For absolute calibration we use the tungsten strip lamp. The uncertainty attained in this way for the relative calibration depends on the wavelength and varies between 5% and 10%. For the absolute calibration we obtained an uncertainty of 12%. We further discuss problems caused by the non-uniform spectral efficiency and dispersion of the spectrometer, which complicate the calibration procedure.

http://iopscience.iop.org/article/10.1088/0957-0233/18/5/019/pdf

Relative and absolute intensity calibrations of a modern broadband echelle spectrometer

The identification of sterilization agents is mandatory to achieve sterilization mechanisms in low-pressure discharges. A detailed account of each agent is required for improvements, development and establishment of plasma sterilization as an alternative to traditional sterilization processes. Sterilization agents are VUV and UV radiation, photodesorption producing volatile species and etching of spore coat and membrane. This work focuses on VUV and UV radiation as a sterilization agent of Bacillus atrophaeus spores. Four wavelength ranges are distinguished: the emission spectra above 300 nm, above 235 nm, above 112 nm and a full emission spectrum including active species. The range from 235 up to 300 nm without active species is identified to be the most capable for sterilizing Bacillus atrophaeus spores.

https://iopscience.iop.org/article/10.1088/0022-3727/40/19/019/pdf

H Halfmann

Papers

Inactivation of Bacteria and Biomolecules by Low-Pressure Plasma Discharges

A double inductively coupled plasma for sterilization of medical devices

Relative and absolute intensity calibrations of a modern broadband echelle spectrometer

Identification of the most efficient VUV/UV radiation for plasma based inactivation of Bacillus atrophaeus spores

Low-Pressure Microwave Plasma Sterilization of Polyethylene Terephthalate Bottles