Effect Of Plasma Exposure Research Articles

Effect of He Plasma Exposure on Recrystallization Behaviour and Mechanical Properties of Exposed W Surfaces—An EBSD and Nanoindentation Study

Fusion reactors are designed to operate at extremely high temperatures, which causes the plasma-facing materials to be heated to 500 °C to 1000 °C. Tungsten is one of the target design materials for the plasma-facing diverter components in Tokamak designs, such as ITER, because of its excellent high-temperature strength and creep properties. However, recrystallization due to high temperatures may be detrimental to these superior mechanical properties, while exposure to He plasma has been reported to influence the recrystallization behaviour. This influence is most likely due to the Zener effect caused by He bubbles formed near the surface, which retard the migration of grain boundaries, while at the same time modifying the surface microstructure. This paper reports a study of the effect of plasma exposure at different sample temperatures on the recrystallization behaviour of W at different annealing temperatures. The characterization after plasma exposure and annealing is pursued through a series of post-exposure annealing, followed by scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) characterization and nanoindentation to determine the mechanical properties. Here, it is shown that the hardness is closely related to the recrystallization fraction, and that the plasma exposure at a sample temperature of 300 °C slows down the recrystallization more than at higher sample temperatures of 500 °C and 800 °C. Atomic force microscopy (AFM) was subsequently used to determine any changes in pile-up height around the nanoindents, to probe any indication of changes in hardenability. However, these measurements failed to provide any clear evidence regarding this aspect of mechanical behaviour.

Plasma enhanced planar crystal growth of laser induced graphene

The effect of wettability of Polyimide (PI) surface on the crystallite size and electrical conductivity of Laser-Induced Graphene (LIG) was studied for the first time. The wettability of PI was increased by varying the scan speed of a localised Argon cold plasma pen. The surface energy of PI increases with wettability which reduces the activation energy of diffusion of graphene nuclei and improves the crystallinity of LIG. The effect of plasma exposure was studied by contact angle measurement using two liquid solvents such as water and Ethylene Glycol (EG). Raman spectra of LIG showed that the crystallite size increased by 21 % at lower CO2 laser power (0.77 W) on PI pre-treated at a lower plasma scan speed (200 mm/min) which improved the conductivity by 51.13%. This study demonstrated that increased wettability of PI surface assists in the planar growth of LIG crystallites.

Mechanical and microstructural analysis of tungsten exposed in JET deuterium plasmas

A tungsten Langmuir probe exposed in the JET divertor during the ITER-like wall campaigns (ILW) has been studied to evaluate changes in mechanical properties and microstructure. The tip of the probe that was exposed to plasma was cross-sectioned and polished for post mortem analysis. Analysis involved a comparison with a non-exposed probe to determine the effect of plasma exposure on material microstructure and mechanical properties. Visually the probe appeared to have melted and re-solidified during its time in the vessel. Secondary electron (SE) images of cross sections showed the formation of bubbles near the exposed surface that ranged from 50 µm to sub-micron sized. Electron backscatter diffraction (EBSD) revealed that the average grain size had increased from 33 µm to 570 µm. The investigation also showed that hardness had increased from 5.2 to 6.1 GPa and pop-in behaviour was supressed after exposure. This was initially attributed to the uptake of deuterium (D) but nuclear reaction analysis (NRA) indicated that no deuterium remained in the sample and hinted that some other type of defect was modifying the mechanical properties.

Positive Effect Induced by Plasma Treatment of Seeds on the Agricultural Performance of Sunflower

The need for efficient technologies to enhance productivity in agriculture strongly motivates research on plasma treatment of seeds and plants. In this study, the influence of plasma treatment on sunflower (Helianthus annuus L.) seeds was evidenced throughout the entire life span of the plants. The seeds were packed in a DBD reactor operated in air and treated in plasma for 10 min, using a sinusoidal voltage of 16 kV amplitude at 50 Hz frequency. Early growth observation of plants under laboratory conditions showed that, after a slower start, the plasma-treated seeds developed faster and produced taller seedlings with greater total mass as compared to the control samples. Results obtained from mature plants cultivated in the field revealed a positive effect of plasma exposure with respect to capitulum size, number of seeds per capitulum and mass per thousand seeds, resulting in a remarkable increase in crop yield. The plasma effect lasted for at least two weeks of seed storage; however, it was considerably affected by the sowing period.

Toxicity and virucidal activity of a neon-driven micro plasma jet on eukaryotic cells and a coronavirus.

Plasma medicine is a developing field that utilizes the effects of cold physical plasma on biological substrates for therapeutic purposes. Approved plasma technology is frequently used in clinics to treat chronic wounds and skin infections. One mode of action responsible for beneficial effects in patients is the potent antimicrobial activity of cold plasma systems, which is linked to their unique generation of a plethora of reactive oxygen and nitrogen species (ROS). During the SARS-CoV-2 pandemic, it became increasingly clear that societies need novel ways of passive and active protection from viral airway infections. Plasma technology may be suitable for superficial virus inactivation. Employing an optimized neon-driven micro plasma jet, treatment time-dependent ROS production and cytotoxic effects to different degrees were found in four different human cell lines with respect to their metabolic activity and viability. Using the murine hepatitis virus (MHV), a taxonomic relative of human coronaviruses, plasma exposure drastically reduced the number of infected murine fibroblasts by up to 3000-fold. Direct plasma contact (conductive) with the target maximized ROS production, cytotoxicity, and antiviral activity compared to non-conductive treatment with the remote gas phase only. Strikingly, antioxidant pretreatment reduced but not abrogated conductive plasma exposure effects, pointing to potential non-ROS-related mechanisms of antiviral activity. In summary, an optimized micro plasma jet showed antiviral activity and cytotoxicity in human cells, which was in part ROS-dependent. Further studies using more complex tissue models are needed to identify a safe dose-effect window of antiviral activity at modest toxicity.

DBD System Operating in Ambient Air for Surface Treatment of Polyethylene Terephthalate Films

Abstract Polymers are materials widely used in many important technologies and applications because of their optical, physical, mechanical, thermal and chemical properties. Polyethylene terephthalate (PET) foil is often used as an insulating material in printed electronics, flexible circuitry, displays, industrial applications, graphic films, or for clinical and healthcare applications. A big inconvenience of PET film is the low surface tension which also implies a low wettability, resulting in poor coating adhesion and poor printing properties. In order to eliminate this disadvantage, a surface treatment was used by means of a dielectric barrier discharge (DBD) operating in ambient air at atmospheric pressure which consisted of a high voltage AC source and two circular metal electrodes 60 mm in diameter. The paper aims are to treat two different PET film substrates designed in this work as PET 1, without thermal treatment, and PET 2 which is heat stabilized. The effect of plasma exposure was assessed by determining the water contact angle by means of an Ossila goniometer and by measuring the surface tension with a special ink. The considered foils were exposed to different DBD treatment times (0.2, 0.5, 1, 5, 10, 30 s) and the evolution of the water contact angle overtime after treatment up to 96 hours was monitored. It was found that the water contact angle of the untreated PET 1 and PET 2 was 74° and 73.5°, respectively, and after 30 s DBD treatment time it decreased to 30.9° and 30°, respectively.

Effect of Downstream Plasma Exposure on Schottky Diodes Fabricated on β-Ga2O3

The effects of downstream plasma exposure on Ga2O3 Schottky diode forward and reverse IV characteristics were investigated. Ultra-wide bandgap semiconductor β-Ga2O3 has attracted increasing attention because of the prospects for use in next generation high-power electronics. However, the Ga2O3 surface has been reported to be particularly sensitive to plasma-induced damage, which could lead to device performance degradation[1]. In our study, the plasma treatments were performed using a PIE Scientific Tergeo Plasma Cleaner with O2, N2 or CF4 discharges. The system can be operated either in immersion mode or downstream mode. The samples were exposed to fluxes of electrons, ions and neutral and an rf power of 50 W was used to generate the plasma at a pressure of 400 mTorr, with a fixed treatment time of 1 min. Ti/Au and Ni/Au metallization were employed as the Ohmic and Schottky contacts, respectively, on the test diodes. Prior to the Schottky metal deposition, the samples were treated to ozone plasma/dilute HCl solution/ozone treatments to remove surface contamination. A Schottky barrier height of 1.1 eV was obtained for the reference sample without plasma treatment, and an ideality factor of 1.001 was achieved. From the forward I-V characteristic, as illustrated in Figure 1, the diodes exposed to CF4 showed a 0.25V shift from the I-V of the reference sample due to a Schottky barrier height lowering around 13.9%, as show in Table 1. The diodes exposed with N2 and O2 plasmas showed a decrease of Schottky barrier height of 2.5 and 6.5 % with O2 or N2 treatments, respectively, as shown in Figure 2. The effect of plasma exposure on the ideality factor of diodes treated with these plasmas was minimal; 0.2% for O2 and N2, 0.3% for CF4, respectively, as shown in Figure 2. The reverse leakage currents were 0.0012, 0.0022 and 0.0048 mA/cm2 for the diodes treated with O2, and CF4, and N2 respectively, as shown in Figure 3. The effect of downstream plasma treatment on diode on-resistance and on-off ratio were also very minimal as shown in Figure 4 and 5.[1] Jiancheng Yang, Zachary Sparks, Fan Ren, Stephen J. Pearton, and Marko Tadjer, J. Vac. Sci. & Technol. B36, 061201-1-9 (2018). Figure 1

Insights on the Atmospheric-Pressure Plasma-Induced Free-Radical Polymerization of Allyl Ether Cyclic Carbonate Liquid Layers.

Plasma-induced free-radical polymerizations rely on the formation of radical species to initiate polymerization, leading to some extent of monomer fragmentation. In this work, the plasma-induced polymerization of an allyl ether-substituted six-membered cyclic carbonate (A6CC) is demonstrated and emphasizes the retention of the cyclic carbonate moieties. Taking advantage of the low polymerization tendency of allyl monomers, the characterization of the oligomeric species is studied to obtain insights into the effect of plasma exposure on inducing free-radical polymerization. In less than 5 min of plasma exposure, a monomer conversion close to 90% is obtained. The molecular analysis of the oligomers by gel permeation chromatography coupled with high-resolution mass spectrometry (GPC-HRMS) further confirms the high preservation of the cyclic structure and, based on the detected end groups, points to hydrogen abstraction as the main contributor to the initiation and termination of polymer chain growth. These results demonstrate that the elaboration of surfaces functionalized with cyclic carbonates could be readily elaborated by atmospheric-pressure plasmas, for instance, by copolymerization.

Effects of Downstream Plasma Exposure on β-Ga2O3 Rectifiers

The effects of downstream plasma exposure with O2, N2 or CF4 discharges on Si-doped Ga2O3 Schottky diode forward and reverse current-voltage characteristics were investigated. The samples were exposed to discharges with rf power of 50 W plasma at a pressure of 400 mTorr and a fixed treatment time of 1 min to simulate dielectric layer removal, photoresist ashing or surface cleaning steps. Schottky contacts were deposited through a shadow mask after exposure to avoid any changes to the surface. A Schottky barrier height of 1.1 eV was obtained for the reference sample without plasma treatment, with an ideality factor of 1.0. The diodes exposed to CF4 showed a 0.25 V shift from the I–V of the reference sample due to a Schottky barrier height lowering around 14%. The diodes showed a decrease of Schottky barrier height of 2.5 and 6.5% with O2 or N2 treatments, respectively. The effect of plasma exposure on the ideality factor of diodes treated with these plasmas was minimal; 0.2% for O2 and N2, 0.3% for CF4, respectively. The reverse leakage currents were 1.2, 2.2 and 4.8 μA cm−2 for the diodes treated with O2, and CF4, and N2 respectively. The effect of downstream plasma treatment on diode on-resistance and on-off ratio were also minimal. The changes observed are much less than caused by exposure to hydrogen-containing plasmas and indicate that downstream plasma stripping of films from Ga2O3 during device processing is a relatively benign approach.

Regulatory Action of Plasma from Patients with Obesity and Diabetes towards Muscle Cells Differentiation and Bioenergetics Revealed by the C2C12 Cell Model and MicroRNA Analysis.

Obesity and type 2 diabetes mellitus (T2DM) are often combined and pathologically affect many tissues due to changes in circulating bioactive molecules. In this work, we evaluated the effect of blood plasma from obese (OB) patients or from obese patients comorbid with diabetes (OBD) on skeletal muscle function and metabolic state. We employed the mouse myoblasts C2C12 differentiation model to test the regulatory effect of plasma exposure at several levels: (1) cell morphology; (2) functional activity of mitochondria; (3) expression levels of several mitochondria regulators, i.e., Atgl, Pgc1b, and miR-378a-3p. Existing databases were used to computationally predict and analyze mir-378a-3p potential targets. We show that short-term exposure to OB or OBD patients’ plasma is sufficient to affect C2C12 properties. In fact, the expression of genes that regulate skeletal muscle differentiation and growth was downregulated in both OB- and OBD-treated cells, maximal mitochondrial respiration rate was downregulated in the OBD group, while in the OB group, a metabolic switch to glycolysis was detected. These alterations correlated with a decrease in ATGL and Pgc1b expression in the OB group and with an increase of miR-378a-3p levels in the OBD group.

Investigation of the effect of non-thermal plasma on increasing the shelf life of fresh-cut pears

Purpose: Fresh-cut fruits are one of the most popular products. Pear is a highly putrefying fruit that is susceptible to mechanical damage, decay and physiological disorders during storage. Reducing post­ harvest losses of agricultural products with a view to increasing food security and preventing the loss of capital is one of the major issues facing societies. Research Method: Non-thermal plasma is under research for fruits preservation, especially fresh-cut fruits and vegetables. This study investigates the effects of plasma exposure to delay color changes of fresh-cut pears. Findings: Different treatments for the time of plasma exposure and types of packaging were studied. The results showed that; the parameter a*, L*, Chroma and browning index (BI) was significant at 5% level due to different treatments, but the plasma effect on b*, ΔE, h* and YI were not significant at 5% level. Furthermore, the best acceptability is the direct exposure for two-minutes. Research Limitations: No limitations were founded. Originality/Value: It can be concluded that using non-thermal plasma can be considered as a new approach to increasing the durability and shelf life of fresh-cut pears. In addition, plasma exposure is one of the nondestructive processes that does not have any side effects on the products and can significantly obstruct microorganisms and delayed degradation, discoloration.

Surface Analysis of TMCTS-Based SiOC(H) Low-k Dielectrics in Post-Etch Strip of ACL Hardmask.

The miniaturization of devices requires the introduction of a high aspect ratio through patterning in the Damascene copper interconnect process. The high aspect ratio etch process employs hardmasks, such as amorphous carbon, that can withstand high-powered plasma exposure. When an etch hardmask is removed after patterning, the properties of the underlying film can be altered by the effect of plasma exposure during the strip process. In this study, surface properties of SiOC(H) are investigated after an amorphous carbon strip with O2/Ar plasma. Since the low-k film of SiOC(H) structure shows characteristics according to the Si-O internal bonding structure, the Si-O bonding ratio of the ring, network and cage structure was analyzed through Fourier-transform infrared (FT-IR) analysis to measure changes in thin film properties. X-ray photoelectron spectroscopy (XPS) was also used to add reliability to the SiOC(H) film structure. In addition, the end point of the strip process was obtained using an optical emission spectroscopy sensor and variations in thin film characteristics over the plasma exposure time were analyzed. These results revealed the structural modification of the SiCO(H) thin film in the post-etch strip of the amorphous carbon layer (ACL) hardmask.

Treatment Effect Modeling for FTIR Signals Subject to Multiple Sources of Uncertainties

Fourier-transform infrared spectroscopy (FTIR) is a widely adopted technique for characterizing the chemical composition in many physical and chemical analyses. However, FTIR spectra are subject to multiple sources of uncertainty, and thus the analysis of them relies on domain experts and can only lead to qualitative conclusions. This study aims to analyze the effect of a certain treatment on FTIR spectra subject to two commonly observed uncertainties, the offset shift and the multiplicative error. Due to these uncertainties, the pre-exposure FTIR spectra are modeled according to the physical understanding of the uncertainty--observed spectra can be viewed as translating and stretchering an underlying template signal, and the post-exposure FTIR spectra are modeled as the translated and stretchered template signal plus an extra functional treatment effect. To provide engineering interpretation, the treatment effect is modeled as the product of the pattern of modification and its corresponding magnitude. A two-step parameter estimation algorithm is developed to estimate the underlying template signal, the pattern of modification, and the magnitude of modification at various treatment strengths. The effectiveness of the proposed method is validated in a simulation study. Furtherly, in a real case study, the proposed method is used to investigate the effect of plasma exposure on the FTIR spectra. As a result, the proposed method effectively identifies the pattern of modification under uncertainties in the manufacturing environment, which matches the knowledge of the affected chemical components by the plasma treatment. And the recovered magnitude of modification provides guidance in selecting the control parameter of the plasma treatment.

Effect of sliding discharge on proliferation and death of brain microvessel endothelial cells in vitro

The dose-dependent effects of plasma exposure to a unipolar nanosecond sliding discharge over the surface of the culture medium in a closed plate on the cells of cerebral endothelium in vitro were studied. Using a 24-well plate, the surface plasma energy density of one pulse was 360 μJ/cm2 at a pulse frequency of 100 Hz. It has been shown that in the creeping discharge plasma there is an active excitation of air molecules, the formation of positive nitrogen and oxygen ions, and the formation of carbon monoxide. In the dose density range of 0-32 J/cm2, the dose-dependent effects were assessed in the 4-12 h post-radiation period. Cell death was analyzed with an assessment of the total number of cells, necrotic cells, cells in apoptosis (phosphatidylserine externalization, internucleosomal DNA fragmentation) and their proliferative activity (Ki67-immunopositive cells). A preliminary assessment of subtle dose-dependent effects indicates the peculiarities of the effect of small doses.

Thermographic investigation of the effect of plasma exposure on the surface of a MAST upgrade divertor tile in Magnum-PSI

One of the issues faced by future fusion devices will be high divertor target heat loads. Alternative divertors can promote detachment, flux expansion and dissipation mechanisms to mitigate these heat loads. They have been investigated in several devices including TCV and DIII-D, and will be investigated on MAST-U. To evaluate their effectiveness, accurate target heat flux and power balance measurements are required in these machines. Infrared (IR) thermography is a widely used technique to determine the target heat flux, but is susceptible to surface effects and emissivity in carbon-walled machines. In this work, the effect of plasma exposure on graphite is assessed to understand what may happen in MAST-U. A sample of fine grain graphite, as used on MAST-U, is exposed to 30min plasma exposures, with density n e = 6 × 1018 m−3 and temperature T e = 0.08 eV as measured by Thomson scattering. During these pulses, the temperature is measured by a medium wave IR camera and is seen to decrease by ≈ 70 °C over the course of 3h of plasma exposure. Pyrometer measurements suggest that the IR camera data is affected by a change in the surface emissivity. Profilometry confirms erosion of graphite at the tile centre to a depth of ≈ 100 µm , and a larger region of deposition further out, amounting to ≈ 40 µm of material. • A graphite tile from MAST-U was exposed to plasma in Magnum-PSI. • Apparent temperature decrease of 70°C was reported over the course of 3h. • Multiwavelength pyrometry confirms that temperature did not actually decrease. • Apparent change was caused by lower emissivity. • Surface topology reveals lower emissivity caused by erosion of tile surface.

Nonthermal plasma treatment of polymers modulates biological fouling but can cause material embrittlement

Plasma-based treatment is a prevalent strategy to alter biological response and enhance biomaterial coating quality at the surfaces of biomedical devices and implants, especially polymeric materials. Plasma, an ionized gas, is often thought to have negligible effects on the bulk properties of prosthetic substrates given that it alters the surface chemistry on only the outermost few nanometers of material. However, no studies to date have systematically explored the effects of plasma exposure on both the surface and bulk properties of a biomaterial. This work examines the time-dependent effects of a nonthermal plasma on the surface and bulk (i.e. mechanical) properties of polymeric implants, specifically polypropylene surgical meshes and sutures. Findings suggest that plasma exposure improved resistance to fibrinogen adsorption and Escherichia coli attachment, and promoted mammalian fibroblast attachment, although increased duration of exposure resulted in a state of diminishing returns. At the same time, it was observed that plasma exposure can be detrimental to the material properties of individual filaments (i.e. sutures), as well as the structural characteristics of knitted meshes, with longer exposures resulting in further embrittlement and larger changes in anisotropic behavior. Though there are few guidelines regarding appropriate mechanical properties of surgical textiles, the results from this investigation imply that there are ultimate exposure limits for plasma-based treatments of polymeric implant materials when structural properties must be preserved, and that the effects of a plasma on a given biomaterial should be examined carefully before translation to a clinical scenario.

In vitro endothelial hyperpermeability occurs early following traumatic hemorrhagic shock.

BACKGROUND:Endothelial hyperpermeability is suggested to play a role in the development of microcirculatory perfusion disturbances and organ failure following hemorrhagic shock, but evidence is limited.OBJECTIVE:To study the effect of plasma from traumatic hemorrhagic shock patients on in vitro endothelial barrier function.METHODS:Plasma from traumatic hemorrhagic shock patients was obtained at the emergency department (ED), the intensive care unit (ICU), 24 h after ICU admission and from controls (n = 8). Sublingual microcirculatory perfusion was measured using incident dark field videomicroscopy at matching time points. Using electric cell-substrate impedance sensing, the effects of plasma exposure on in vitro endothelial barrier function of human endothelial cells were assessed.RESULTS:Plasma from traumatic hemorrhagic shock patients collected at ED admission induced a 19% loss of in vitro endothelial resistance compared to plasma from controls (p < 0.001). This loss was due to reduced cell-cell contacts (p < 0.01). Plasma withdrawn at later time points did not affect endothelial barrier function (p > 0.99). Interestingly, in vitro endothelial resistance showed a positive association with in vivo microcirculatory perfusion (r = 0.56, p < 0.01).CONCLUSIONS:Plasma from traumatic hemorrhagic shock patients obtained following ED admission, but not at later stages, induced in vitro endothelial hyperpermeability. This coincided with in vivo microcirculatory perfusion disturbances.

Understanding hydrogen retention in damaged tungsten using experimentally-guided models of complex multispecies evolution

Fuel retention in plasma facing tungsten components is a critical phenomenon affecting the mechanical integrity and radiological safety of fusion reactors. It is known that hydrogen can become trapped in small defect clusters, internal surfaces, dislocations, and/or impurities, and so it is common practice to seed W subsurfaces with irradiation defects in an attempt to precondition the system to absorb hydrogen. The amount of H can later be tallied by performing careful thermal desorption tests where released temperature peaks are mapped to specific binding energies of hydrogen to defect clusters and/or microstructural features of the material. While this provides useful information about the potential trapping processes, modeling can play an important role in elucidating the detailed microscopic mechanisms that lead to hydrogen retention in damaged tungsten. In this paper, we develop a detailed kinetic model of hydrogen penetration and trapping inspired by recent experiments combining ion irradiation, hydrogen plasma exposure, and thermal desorption. We use the stochastic cluster dynamics method to solve the system of coupled partial differential equations representing the mean field description of the multispecies system. The model resolves the spatial distribution of defects and hydrogen clusters during the three processes carried out experimentally and is parameterized with information from atomistic calculations. We find that the calculated thermal desorption spectra are broadly characterized by three H emission regions: (i) a low temperature one where dislocations are the main contributors to the release peaks; (ii) an intermediate one governed by hydrogen release from small overpressurized clusters with multiple overlapping peaks, and (iii) a high temperature one defined by clean isolated emission peaks from large underpressurized bubbles. These three temperature intervals are seen to largely correlate with the depth at which the clusters are found. The relevance of the ‘super abundant’ vacancy mechanism is assessed, finding that its main role is to transfer more clusters from the intermediate to the high temperature regions as its relevance increases. We find this picture to be in very good agreement with the experiments, adding confidence to the predictive potential of the models and their useto understand irradiation damage and plasma exposure effects in plasma facing components.

Non-thermal plasma effects on structural and optical properties of Cd doped ZnO thin films

Undoped ZnO and Cd doped ZnO thin films were deposited utilizing chemical spray pyrolysis. The effects of non-thermal plasma on the structural and optical properties were studied. XRD patterns indicate that all the deposited films were polycrystalline hexagonal structure, but the preferred orientation of un doped ZnO was (002), while for doped samples were orientated along (101). The effect of plasma exposure on crystal size, transmittance, absorption edge and optical energy gap were investigated. Results illustrate that the crystal size, transmittance and optical energy gap were decreased when doped samples exposure to plasma.

Effect of DC micro-plasma treatment on bacteria in its vegetative bacteria

Argon gas plasma consists of discharge pattern of micro hollow cathode. The pattern is used to inactivate the two main kinds of bacteria. The Culture of Escherichia Coli (gram positive) and Staphylococcus aureus (gram negative) are subjected to the plasma exposure. The micro-plasma jet (MPJ) discharge was generated in the voltage range of 2-10 kV with an operating current of 20-35 mA. Under such conditions, a MPJ of approximately 1 cm visible length was produced. The power efficiency of this device was approximately 80%. The efficacy of MPJ to inactivate the bacteria is determined by observing colony forming unit (CFU) counts before and after plasma exposure. The Colony counter is used here to find the CFU/plate. The effect of plasma exposure is observed by varying the time at 15, 30, 60, 90, 120, 150 and 180 seconds. An efficient reduction in CFU is observed after plasma exposure, particularly for 120 seconds. Approximate 50% decay of both cultures is observed after treatment time of 120 seconds.