Plasma Exposure Time Research Articles

The Effect of DBD Plasma Activation Time on the Dyeability of Woven Polyester Fabric with Disperse Dye.

This study consists of two parts. In the first, the woven polyester fabric, after washing to remove lubricant oils, was treated with the dielectric barrier discharge (DBD) plasma at the short plasma exposure time (from 15 to 90 s). The effect of the plasma exposure time on the activation of the polyester fabric was assessed by the wicking height of the samples. The results show that the wicking height in the warp direction of the plasma-treated samples improved but was virtually unchanged in the weft direction. Meanwhile, although the tensile strength in the warp direction of the fabric was virtually unaffected despite the plasma treatment time up to 90 s, in the weft direction it increased slightly with the plasma treatment time. Scanning Electron Microscope (SEM) images and the X-ray Photoelectron Spectroscopy (XPS) spectra of the samples before and after the plasma treatment were used to explain the nature of these phenomena. Based on the results of the first part, in the second part, two levels of the plasma treatment time (30 and 60 s) were selected to study their effect on the polyester fabric dyeability with disperse dyes. The color strength (K/S) values of the dyed samples were used to evaluate the dyeability of the fabric. The SEM images of the dyed samples also showed the difference in the dyeability between the plasma-treated and untreated samples. A new feature of this study is the DBD plasma treatment condition for polyester fabrics. The first is the use of DBD plasma in air (no addition of gas). Second is the very short plasma treatment time (only 15 to 90 s); this condition will be very favorable for the deployment on an industrial scale.

Fluorine doping for improved thermoelectric properties of spark plasma sintered bismuth telluride

Bismuth-telluride (Bi2Te3) is considered to have the best thermoelectric properties at room temperature (ca. 300 K). Thus, synthesis and improvement of Bi2Te3 and its derivatives quickly and cost-effectively at favorite temperatures are of interests. Recently, doping fluorine (F) into electronic materials (e.g., FTO) has gained attention; however, it is not applied to Bi2Te3 till now. Here, our synthesis of F-doped Bi2Te3 for thermoelectric application is introduced using spark plasma sintering (SPS) for Bi2Te3 preparation and reactive ion etching (RIE, with SF6 gas) for F-doping. The exposure time of SF6 plasma is adjusted to evaluate F-doping effect on the thermoelectric properties of the samples. During characterizations, the increased electrical conductivity and the improved Seebeck coefficient of F-doped Bi2Te3 are observed. Through spectroscopic studies and DFT calculations, the main mechanism behind that improvement is unveiled. It also emphasizes the essential role of the F-doping (optimum treatment time of 40 s) in increasing the carrier concentrations as well as electrical conductivity. With increasing measurement temperature (300–510 K), F-doping raises the figure of merit of electron rich Bi2Te3 from 1.0 to 1.11 (peaked at 390 K).

Visualizing Spatiotemporal Temperature Variation for Estimating H+ aq Distribution by Pulsed Discharge Plasma Exposure

Positive pulsed discharge plasma is generated above a test liquid containing NaCl in Ar atmosphere, and H+ distribution and a temperature variation in the liquid are, respectively, visualized by colorimetric methods using methyl red (MR) and microencapsulated thermotropic liquid crystals (MTLCs). The discharges generated above the liquid containing MR and MTLCs have almost the same characteristics in the waveforms of discharge voltage and current, and the appearance of discharges. The generation of H+ and the temperature increase in the liquid are induced below the discharge area, and H+ distribution and temperature-increased area expand similarly, by the plasma exposure. The spatiotemporal measurement of temperature distribution in the liquid is also observed with MTLCs using a sheet laser. It is found that temperature increase is measured just below the extremity of the discharge and distributes in a torus form and that no temperature increase occurs below the middle of the discharge area. Since good similarity is observed between the H+ distribution and the temperature increase in the test liquid, H+ distribution probably expands in a concentric configuration from the generation area with the plasma exposure time.

Microwave Plasma Assisted Sol‐Gel Synthesis of TiO2 Photocatalyst for DC Plasma Jet Driven Degradation of Methylene Blue

AbstractA new microwave plasma assisted sol‐gel (MPAS) technique was adopted to produce Titanium dioxide (TiO2) photocatalyst by using pure and mixed stabilizers. The crystalline phases, composition, bandgap energy and surface morphology of TiO2 were studied through SEM, XRD, FT‐IR, UV‐Visible spectroscopy and photoluminescence spectroscopy. The average particle size of MPAS synthesized TiO2 nanoparticles remained smaller than the simple sol‐gel method while bandgap energy increased by 40 %. The rutile content and crystallinity of nanoparticles were also found higher in MPAS synthesized TiO2 than the simple sol‐gel method. The type of stabilizer only effected the particle size but not the phase transformations of TiO2 nanoparticles. TiO2 photocatalyst with band gap of 3.06 eV was used to degrade methylene blue dye in water under the exposure of open atmosphere argon plasma jet. UV radiation intensity of the plasma jet at a distance of 2 cm was 576 μW/cm2, which reduced to 149 μW/cm2 at 10 cm. The plasma jet produced some highly reactive species and UV radiations. The reactive species reacted with dye molecules while UV radiations promoted the activity of TiO2. The dye degradation efficiency of the process, under the combined effect of reactive species and TiO2 activity, reached to 95 % after 30 min of plasma exposure time.

Post-synthesis plasma processing and activation of TiO2 photocatalyst for the removal of synthetic dyes from industrial wastewater

In this study, TiO2 nanopowders were prepared by combining the surfactant assisted sol–gel method with microwave plasma calcination. Plasma calcination was performed just for 20–30 min for reducing the calcination time and ensuring the energy efficient synthesis of photocatalyst. The mixed anatase–rutile phased TiO2 nanoparticles were obtained under these synthesis conditions. The band gap energy of the photocatalyst decreased by 40% on microwave plasma calcination. The surfactants were found to be ineffective on phase transformations of synthesized TiO2. FTIR analysis confirmed the absorption of O–Ti–O band stretching between 415 and 420 cm−1. The hydroxyl bands (OH) were observed to be less stretched after plasma calcination. The conventionally calcined HA–Ti, NA–Ti and MS–Ti samples showed band gap energies of 5.09 eV, 4.88 eV and 5.06 eV, respectively. The band gap energy of plasma calcined MTHA–Ti, MTNNA–Ti and MTMS–Ti samples was calculated about 4.92 eV, 3.11 eV and 4.96 eV, respectively. The combined effect of photocatalyst, plasma reactive species and UV radiations promoted the degradation efficiency of the methylene blue dye. Under DC plasma jet exposure, the maximum degradation efficiency of 95% was achieved after 30 min of plasma exposure time. The catalyst retained about 93–95% degradation efficiency after five cycles of dye degradation.

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.

Quantitative evaluation of hydrogen retention of solid tin after exposure to hydrogen plasma

In this study, the hydrogen retention properties of solid tin exposed to DC glow plasma were investigated using thermal desorption spectroscopy. The measurements were performed by varying the plasma exposure time from 0 (no exposure) to 40 min. The resulting retained hydrogen from the ion fluence of the plasma was quantified as ~10−3. The retained hydrogen increased with the exposure time.

Ash Waste Utilization via Direct Current Arc Plasma with Production of SiC and AlN

Ash accumulation is a relevant problem due to the widespread use of coal-fired power plants and a very limited number of ash utilization technologies. Plasma processing of ash is a promising method of ash valorization for production of various useful products, which is limited by high energy consumption. In the current study, a mixture of waste ash from power plant and black carbon was processed using an original direct current plasma arc experimental setup in ambient air which allows lower energy consumption due to the absence of the vacuuming system. Four types of samples at different plasma exposure times were produced and together with the initial ash were studied by thermal analysis, X-ray diffractometry and scanning electron microscopy. The X-ray diffraction analysis identified the resulting phases of graphite, silicon carbide, and aluminum nitride in the synthesis products; at the same time, at the arc discharge energy increased from 26 to 105 kJ, the intensities of the maxima that correspond to metal and nonmetal oxides in the composition of the initial ash decreased to nearly zero. To remove graphite, the processed samples were annealed at 750 °C in air and studied. It was found that the applied approach made it possible to obtain a mixture of silicon carbide and aluminum nitride powders in direct current arc plasma initiated in ambient air, which reduced the energy consumption for ash processing by electric arc.

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.

Surface characterization of plasma-modified low density polyethylene by attenuated total reflectance fourier-transform infrared (ATR-FTIR) spectroscopy combined with chemometrics

Atomic layer deposition (ALD) on polymer substrates often requires a modification of the polymer surface properties. Plasma-enhanced ALD (PE-ALD) process is capable of establishing improved coating/substrate adhesion and layer properties by a plasma pre-treatment prior to the layer deposition. Low density polyethylene (LDPE) films were plasma treated using different gases (N2, O2, and N2+O2 mixture) for various exposure times. A novel method was proposed to reveal the chemical changes in the surface region of LDPE films with attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy combined with multivariate analysis. The loading plots of principal component analysis (PCA) revealed the formation of polar functional groups on the surface of LDPE films, as a result of plasma pre-treatment. PCA was also able to explore the differences and similarities in the chemical modifications of LDPE originated from different plasma gas and exposure time.

Multi-effects of atmospheric He/CF4 plasma jet treatment on the surface properties of epoxy resin

Surface fluorination by low-temperature plasma treatment is proved to be a useful method to improve surface electrical strength of insulating materials. The electrical performances of modified materials deeply depend on the operation parameters during surface modification. It is necessary to find out the physical and chemical changes on the surface properties of modified materials systematically combined with different parameters. In this paper, an atmospheric pressure plasma jet (APPJ) fed with He/CF4 mixtures is utilized for treatment of epoxy resin (EP). The surface properties of modified epoxy resin are evaluated by the water contact angle (WCA), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results show that the He/CF4 APPJ has multi-effects on the surface properties of epoxy resin. It means that some different changes are found under different operation parameters. The multi-effects are mainly caused by the various physical and chemical processes in the interface between plasma and material surface, and they can be adjusted by changing the plasma exposure time, the applied voltage and the CF4 volume fraction. The results can offer an evidence for the mechanisms of the enhanced surface electrical strength using plasma-based surface fluorination.

Atomic layer deposition of LiF using LiN(SiMe3)2 and SF6 plasma.

Lithium fluoride films were prepared by atomic layer deposition (ALD) using a new route in which LiN(SiMe3)2 is used as a precursor and SF6 plasma as a coreactant. Conformal LiF films were deposited at 150 °C at a growth rate of ∼0.4 Å per cycle. All deposited films were polycrystalline and slightly lithium-rich with a composition of LiF0.8, independently of the plasma conditions (e.g. exposure time, pressure and power). The levels of H, C, N, O, Si, and S were all <1 at%. Spectroscopic ellipsometry measurements were carried out over the wavelength range of 140-2480 nm and showed a refractive index of 1.37 at 633 nm for films deposited using 1 s plasma exposure time. We conclude that short plasma exposures are preferred, since a prolonged exposure time leads to an increase in optical absorption and lower growth per cycle values. Furthermore, mass spectrometry measurements revealed the formation of SiMe3F species during both half-cycles, originating from the reaction between the precursor ligands and fluorine species present either at the surface or in the plasma. Moreover, the SF6 plasma step led to the formation of fluorocarbon species, suggesting that dissociation and recombination in the plasma takes place. Overall, this work demonstrates that SF6 plasma offers a promising alternative to other coreactants for ALD of high purity lithium fluoride.

Remote plasma enhanced atomic layer deposition of titanium nitride film using metal organic precursor (C12H23N3Ti) and N2 plasma

Deposition of titanium nitride (TiN) thin films has been studied by remote plasma enhanced atomic layer deposition (PEALD) using MAP Ti (Mecaro Advanced Precursor-C12H23N3Ti) precursor and nitrogen plasma. Consequently, it was possible to use a temperature window of 275–325 °C, lower than the window required by other TiN films using TiCl4 precursor and NH3 gas. The auger electron spectroscopy (AES) analysis showed that as plasma power and plasma exposure times increase, impurity content decreases and TiN film deposited at plasma power of 400 W and exposure time of 35 s has lower impurity content than films deposited by other methods such as metal organic chemical vapor deposition (MOCVD). For TiN thin film deposited at 300 °C, plasma power of 400 W, and plasma exposure time of 35 s, the X-ray diffraction (XRD) analysis showed crystallinity and resistivity of approximately 320μΩcm. Atomic force microscopy (AFM) measurements determined a TiN film surface roughness of under 0.5 nm. TEM (transmission electron microscope) analysis showed 98% step coverage.

Degradation of cefixime antibiotic in water by atmospheric plasma bubbles: Performance, degradation pathways and toxicity evaluation

• Underwater plasma bubbles were used to degrade cefixime in water. • Complete cefixime degradation with high-energy yield of 1.5 g/kWh. • Degradation of cefixime was conducted by reactive species, especially short-lived OH radicals. • Degradation pathways of cefixime were proposed by intermediates identified by LCMS. • Plasma treatment leads to the loss of antibacterial activity and cytotoxicity of cefixime. Excessive use and indiscriminate discharge of antibiotics inevitably lead to their accumulation in the environment, posing significant ecological and physiological risks. Non-thermal plasma (NTP) is receiving increasing attention as a sustainable technology for the efficient breakdown of these antibiotics as well as other contaminants. However, implementation of NTP technology still faces several hurdles, particularly the maximization of the reactive plasma effects and the practical scaling approaches. In this study, we generated NTP inside forming bubbles with enlarged gas-liquid interfacial areas for efficient delivery of reactive plasma species to target cefixime antibiotic molecules in aqueous solution. The degradation of cefixime was largely dependent on the different number of microholes, air flow rate, discharge power, plasma exposure time and solution properties. Results show that a high-performance degradation was achieved in the 10-microhole reactor with an energy yield of 1.5 g/kWh, after 30 min of plasma treatment. Based on LC-MS analysis, an NTP-initiated cefixime degradation pathway was proposed. Cytotoxicity studies demonstrated that the antibiotic activity of cefixime was effectively and wholly deactivated by the plasma process, and that no toxic effects of the 30 min-treated water were observed toward human cell lines. Furthermore, considering that air was employed as the inducer gas, which results in the formation of reactive nitrogen species in the water, the treated water was able to enhance seedling growth, further contributing to the societal and economic benefits of this plasma-based antibiotic degradation strategy.

Surface Functionalization of a Polyurethane Surface via Radio-Frequency Cold Plasma Treatment Using Different Gases

Herein, the surface treatment of polyurethane (PU) films via air, O2, N2, Ar, and their mixtures were tested. The treatment was performed to incorporate new polar functionalities on the polymer surface and achieve improved hydrophilic characteristics. The PU films were subjected to RF low-temperature plasma treatment. It was found that plasma treatment immensely enhanced the hydrophilic surface properties of the PU films in comparison with those of the pristine samples; the maximum plasma effect occurred for the PU sample in the presence of air plasma with treatment time of 180 s at nominal power of 80 W. The surface topography was also found to vary with plasma exposure time and the type of gas being used due to the reactivity of the gaseous media. Roughness analysis revealed that at higher treatment times, the etching/degradation of the surface became more pronounced. Surface chemistry studies revealed increased O2 and N2 elemental groups on the surface upon exposure to O2, N2, air, and Ar. Additionally, the aging study revealed that samples treated in the presence of air and Ar were more stable in comparison to those of the other gases for both the contact angle and peel test measurements.

Effect of non-oxidative plasma treatments on the surface properties of poly(p-phenylene terephthalamide) (PPTA) and poly(p-phenylene benzobisoxazole) (PBO) fibres as measured by inverse gas chromatography

It has been shown in previous works that the interfacial adhesion in PPTA- and PBO-epoxy composites can be improved by modifying the surface properties of these high-performance fibres upon exposure to non-oxidative plasma treatments. In this work, the effects developed on both types of polymer surface were examined as a function of treatment gas nature (He or N2) and exposure time (one or four minutes) using inverse gas chromatography at infinite dilution (IGC). From the adsorption of n-alkanes, it has been proved that non-oxidative plasma treatments led to energetically heterogeneous surfaces in the case of PPTA, and to low-energy surfaces in the case of PBO. Nevertheless, it was proved with the 1-min plasma treatments (either under helium or under nitrogen) that chemical reactivity was enhanced on the PBO surface. Such a behaviour was ascribed to the presence of low-molecular weight oxidized materials. The mechanisms involved in surface activation of PPTA were not equivalent under He or N2 exposure. Nitrogen plasma exposure led to a PPTA surface that is chemically reactive as a result of polarity enhancement. Helium plasma-treated PPTA surface was characterized by the presence of branched arrangements that intensified the number of chemical contacts onto reactive sites. Finally, for both fibre sets, if the purpose is to enhance the chemical surface reactivity, it makes no sense to increase the plasma exposure time from 1 to 4 min.

Reversible synthesis of GO: Role of differential bond structure transformation in fine-tuning photodetector response

The controlled modification of graphene’s electronic band structure poses serious challenges. In the present work, we study the effect of sp 2 cluster size variation on the electronic band gap and photoconductive properties of reduced graphene oxide (RGO). This is achieved by performing reversible functionalization of RGO with oxygen species. The reversible functionalization of RGO results in its partial transformation to graphene oxide (GO) so that the size of the sp 2 clusters within the sp 3 matrix varies, thereby affecting the π-π* band structure and photoconductive properties. The study reveals: (1) incremental creation/elimination of oxygenated surface bonds’ related energy states within the π-π* band; (2) customized tuning of the sp 2/sp 3 ratio; (3) the presence/absence of oxygenated states impacts the optical transition processes both from band-to-band and oxygenated states; and (4) the incremental addition/depletion of surface states in a tunable manner directly influences the carrier transport in the photoconductive device. Experiments show a two-stage transformation of RGO electronic properties with changing oxygen functionalities: oxidation (Stage I) and decomposition or erosion (Stage II). Sp 2 cluster size variation induced bandgap change was analyzed by Raman and photoluminescence studies, indicating the possibility for photodetection in a specific band encompassing NIR to UV, depending on the sp 2/sp 3 ratio. Energy-dispersive x-ray spectroscopy and Fourier transform infrared studies confirm the surface oxygenation/de-oxygenation during plasma treatment, and XRD confirms partial transformation of RGO to GO and its amorphization at higher plasma exposure times. In addition, the photodetector performance is optimized in terms of carrier generation-recombination and carrier-lattice scattering. Thus, manipulating better photoconductive response is possible through suitable handling of the parameters involved in the plasma treatment process. This is the first study on the influence of the sp 2/sp 3 ratio-induced lattice structure evolution on photodetection.

Effect of a non-thermal atmospheric pressure plasma jet on four different yeasts

Non-thermal atmospheric pressure plasmas are known to be an effective method for the inactivation of microorganisms. However, yeasts have proved to be more resistant to provided treatments. We investigated the influence of an Argon plasma jet on the inactivation of four different yeasts; Saccharomyces cerevisiae, Schizosaccharomyces pombe, Candida parapsilosis and Magnusiomyces magnusii. Results from direct plasma treatment on the yeasts in distilled water, as the most effective technique we found, are presented here. The surviving yeasts after 5, 7, and 10 min plasma exposures were evaluated visually and quantitatively. Quantitative results showed strong reductions in the survival rates after the plasma treatment. The longest plasma exposure time yielded the least survival. Moreover, how long the inactivations lasted was evaluated by assessing the treated samples after 1 h and again after 2 h. The survival rates were further decreased within these storage times. In the 10 min treated-2 h stored samples, the rates dropped to 5% or even below, depending on the yeast species. High concentrations of reactive oxygen and nitrogen species in the plasma-air-water interacting system were detected by optical emission spectroscopy of the plasma jet and also by measuring concentrations of H2O2, NO2 − and NO3 − in plasma activated water (as the surrounding liquid for the yeasts). The conductivity and pH of the treated water was measured as well. The level of the conductivity increased along with the decrease in pH. Synergistic effects of these chemical reactive species in acidified water resulted in the yeast inactivation.

Impact of Ar+ bombardment of 4H–SiC substrates on Schottky diode barrier heights

In this paper, we investigate the impact of plasma power and plasma exposure time on the Schottky barrier height (SBH) and the ideality factor of silicon carbide (SiC) Schottky diodes. N-doped 4H–SiC Schottky diodes with molybdenum nitride (MoN) top metallization are fabricated. The plasma power PISE is varied from 0 up to 300 W at a constant plasma time of 300 s. High resolution transmission electron microscopy is performed showing a ~6 nm thin amorphous layer formed at the MoN/4H–SiC interfaces after ion bombardment. Current-Voltage-Temperature measurements are conducted in a wide temperature range from 50 K up to 500 K. SBHs are extracted using standard techniques, showing a significant influence of PISE on the SBH. A SBH of about 1 V is measured for diodes without ion pretreatment (PISE = 0 W). The highest SBH of 1.1 V is extracted for the diode with PISE = 50 W, followed by a continuous decrease of the SBH at higher plasma powers. At a PISE = 300 W, a SBH of 1.02 V is obtained, which is close to the SBH at PISE = 0 W. These results show that, ion bombardment increases the SBH. However, similar SBHs can be obtained by optimizing the plasma power when ion bombardment is required. Additionally, the plasma time is varied from 0 s up to 420 s by simultaneously holding the plasma power constant at 300 W. The activation energy of the investigated Schottky diodes is extracted from Arrhenius plots obtained at different voltages from −1 to −5 V. These results are in good agreement SBH evaluation. The influence of ion bombardment on SBH homogeneity on wafer level is presented. It is shown that the standard deviation of SBH on 4-inch wafers can be reduced by a factor of 2.7 when ion bombardment is used, compared to diodes fabricated without ion bombardment.

Effect of dielectric barrier discharge plasma jet on bactericidal and human dermal fibroblasts adult cells: In vitro contaminated wound healing model

Commercial dielectric barrier discharge plasma jet (DBDPJ) with helium gas was used as a handy cold atmospheric pressure plasma tool to study the DBDPJ effects on contaminated wound healing. The contaminated wound was modeled into three parts: bacteria as the contaminant origin, bacterial biofilm as the simulated bacterial contaminant layer on the wound, and the wound cells. The bacteria were Staphylococcus aureus and Pseudomonas aeruginosa and the wound cells were human dermal fibroblasts adult (HDFa) cell. DBDPJ treatments were carried out on the three model parts respectively to study the DBDPJ effects on bactericidal and wound cell survival as functions of the plasma conditions including the plasma dissipated power and exposure time and the role played by the plasma radical species. The results demonstrated that DBDPJ could effectively kill the bacteria without significant side effect on the HDFa cell. Optimal plasma conditions were determined and are ready for clinical uses.