Bulletin of the American Physical Society
64th Annual Gaseous Electronics Conference
Volume 56, Number 15
Monday–Friday, November 14–18, 2011; Salt Lake City, Utah
Session DT2: Plasmas in Liquids and Bio-Applications |
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Chair: Kunihide Tachibana, Osaka Electro Communication Room: 255E |
Tuesday, November 15, 2011 9:30AM - 10:00AM |
DT2.00001: Plasmas in High-Density Medium - Supercritical fluid plasma and Cryogenic plasma Invited Speaker: Recently, there has been a lot of attention to plasmas in high-density medium as novel plasmas from the views points of not only pure sciences but also various technologies. In this talk, two topics, supercritical fluid plasma and cryogenic plasma, will be discussed. First, plasmas generated in supercritical fluids (supercritical fluid plasma) provide a new reaction field that combines the high reactivity of plasmas with the unique characteristics of supercritical fluids, i.e. molecular clustering and density fluctuations near the critical point. An overview of the earliest studies on plasmas generated in supercritical fluids to recent advances in the field, including synthesis of novel nanomaterials such as highly-order diamondoid (diamond molecules), will be given. Second, continuing to thermal plasma (gas temperature Tg higher than a few thousands to millions of K) and low temperature plasma (Tg ranging from a few hundreds to thousands of K), plasma in a third range of gas temperatures (Tg lower than 300 K) is called cryogenic plasma (or cryoplasma) to distinguish it from thermal and low-temperature plasmas. In our group, the gas temperature of the plasma can be continuously controlled below room temperature (RT) down to a cryogenic temperature such as the boiling point of helium (4 K). In addition to the diagnostics, the application of cryogenic plasma to nanoporous material processing (low damage ashing of low-k materials) will be discussed. [Preview Abstract] |
Tuesday, November 15, 2011 10:00AM - 10:15AM |
DT2.00002: Streamer Initiation and Propagation in Water with the Assistance of Bubbles and Electric Field Initiated Rarefaction Wei Tian, Mark J. Kushner Mechanisms for streamer initiation and propagation are of great interest to applications of discharges in liquids. One of the possible mechanisms, bubble-assisted discharges, has received attention in view of its analogy to gas phase discharges. In this paper, we report on a computational investigation of the initiation and propagation of streamers in water with macroscopic and microscopic bubbles having contact with and in vicinity of the powered electrode. In propagation of the streamer, a phase-like transition due to highly intense electric fields is also considered. These simulations were performed using nonPDPSIM, which solves Poisson's equation and transport equations for charged species and electron temperature. The water is treated as a condensed phase plasma with an appropriate charged particle reaction mechanism. Computed results are compared to experiments for a pin-plane geometry with a gap of 400 $\mu $m and applied voltages of 20-50 kV [1]. In the bubble mechanism, our results show that electron impact ionization within bubbles and photo-ionization in liquid water both contribute to breakdown. \\[4pt] [1] K. Schoenbach, J. Kolb, S. Xiao, S. Katsuki, Y. Minamitani and R. Joshi, Plasma Sources Sci. Technol. \textbf{17, }024010 (2008). [Preview Abstract] |
Tuesday, November 15, 2011 10:15AM - 10:30AM |
DT2.00003: Nonequilibrium plasma in liquid water - dynamics of generation and quenching Yong Yang, Young Cho, Alexander Fridman, Andrey Starikovskiy In most cases, the electric breakdown of liquids is initiated by the application of high electric field on the electrode, followed by rapid propagation and branching of plasma channels. Typically plasmas are only considered to exist through the ionization of gases and typical production of plasmas in liquids has generated bubbles through heating or via cavitation and sustains the plasmas within those bubbles. The question appears: Is it possible to ionize the liquid without cracking and voids formation? To answer this question we used a pulsed power system with 32-220 kV pulse amplitude, 0.5-12 ns pulse duration, 150 ps rise time. Discharge cell had point-to-plate geometry with a tip diameter of 100 mm. These parameters allow us to observe the non-equilibrium plasma generation. The measurements were performed with the help of 4Picos ICCD camera. It was found that discharge in liquid water forms in picosecond time scale. Emission intensity increase and plasma formation took 200-300 ps. Diameter of excited region near the tip of the high-voltage electrode was $\sim $ 1 mm. After this initial stage emission rapidly decreased and plasma region becomes almost invisible in 500 ps. The absence of the emission during the rest of the pulse is explained by electrical field decrease on the boundary of conductive zone. Thus we have demonstrated possibility of formation of nonequilibrium plasma in liquid phase and investigated the dynamics of excitation and quenching of nonequilibrium plasma in liquid water. [Preview Abstract] |
Tuesday, November 15, 2011 10:30AM - 10:45AM |
DT2.00004: Synthesis of Water-Soluble Gold Nanoparticles Covered with DNA Using Gas-Liquid Interfacial Plasma Toshiro Kaneko, Qiang Chen, Rikizo Hatakeyama Water-soluble gold nanoparticles (AuNPs) covered with DNA are desired for the application to a novel DNA delivery system. A gas-liquid interfacial discharge plasma (GLIDP) in association with DNA is used for the rapid synthesis of a DNA-AuNP conjugate, where the synthesis is free from the elaborate reaction control usually required in conventional methods. Moreover, the size and morphology of the AuNPs are simply tuned by varying the concentration and type of DNA which acts as a stabilizer through conjugating on the AuNPs. The DNA conjugation prevents the AuNPs from a further coalescence, resulting in the formation of small-sized AuNPs. These small-sized DNA-AuNP conjugates are encapsulated into carbon nanotubes which work as a capsule for the delivery to a diseased part. [Preview Abstract] |
Tuesday, November 15, 2011 10:45AM - 11:00AM |
DT2.00005: STUDENT AWARD FINALIST: Plasma Acid: A Chemically and Physically Metastable Substance Natalie Shainsky, Danil Dobrynin, Utku Ercan, Suresh Joshi, Ari Brooks, Haifeng Ji, Gregory Fridman, Young Cho, Alexander Fridman, Gennady Friedman Non-thermal atmospheric pressure dielectric barrier discharge applied to the surface of a liquid creates a chemically and physically metastable substance. The properties and lifetime of the substance depend on the treatment conditions such as gas atmosphere and liquid medium used, treatment dose, and other parameters. When deionized water is used, the metastable substance becomes a strong oxidizer. We show that direct exposure of deionized water to neutral and charged species produced in plasma creates a strong oxidizer and acidic substance in this water which, for the lack of a better term, we termed \textit{plasma acid}. Plasma acid can remain stable for relatively long time and its oxidizing power may be linked to the significant lowering of its pH. We report experiments that demonstrate plasma acid's metastability. We also show that observed pH of as low as 2.0 cannot be completely accounted for by the production of nitric acid; and that the conjugate base derived from superoxide is at least partly responsible for both, lowering of the pH and increase in the oxidizing power of the solution. [Preview Abstract] |
Tuesday, November 15, 2011 11:00AM - 11:15AM |
DT2.00006: Plasma chemistry simulation of surface microdischarge in humid air for wound healing David Graves, Yukinori Sakiyama, Marat Orazov, Gregor Morfill Controlling fluxes of reactive oxygen species and reactive nitrogen species (RONS) created in humid air plasma is important for biomedical applications of surface micro-discharges (SMD). We report results from a well-mixed, dual-zone model that couples a plasma region with a reaction-transport region, and incorporates about 50 charged and neutral species coupled through about 500 elementary reactions. Dominant species in dry air are O3, NO2, and N2O5, while HNO3 and H2O2 approach similar densities in humid air. Finally, we report initial results from coupling the plasma chemistry model to a transient, one-dimensional wound-healing model. Wound-healing models, based on a reaction-diffusion description of cell dynamics, describe the spatial and temporal variations of chemo-attractants, blood vessels, fibroblasts and the extracellular matrix. [Preview Abstract] |
Tuesday, November 15, 2011 11:15AM - 11:30AM |
DT2.00007: Evaluation of Penicillium digitatum sterilization using non-equilibrium atmospheric pressure plasma by terahertz time-domain spectroscopy Takehiro Hiraoka, Noboru Ebizuka, Keigo Takeda, Takayuki Ohta, Hiroki Kondo, Kenji Ishikawa, Kodo Kawase, Masafumi Ito, Makoto Sekine, Masaru Hori Recently, the plasma sterilization has attracted much attention as a new sterilization technique that takes the place of spraying agricultural chemicals. The conventional methods for sterilization evaluation, was demanded to culture the samples for several days after plasma treatment. Then, we focused on Terahertz time-domain spectroscopy (THz-TDS). At the THz region, vibrational modes of biological molecules and fingerprint spectra of biologically-relevant molecules were also observed. In this study, our purpose was measurement of the fingerprint spectrum of the Penicillium digitatum (PD) spore and establishment of sterilization method by THz-TDS. The sample was 40mg/ml PD spore suspensions which dropped on cover glass. The atmospheric pressure plasma generated under the conditions which Ar gas flow was 3slm, and alternating voltage of 6kV was applied. The samples were exposed the plasma from 10mm distance for 10 minutes. We could obtain the fingerprint spectrum of the PD spore from 0.5 to 0.9THz. This result indicated the possibility of in-situ evaluation for PD sterilization using THz-TDS. [Preview Abstract] |
Tuesday, November 15, 2011 11:30AM - 11:45AM |
DT2.00008: Eradication of Bacterial Biofilms Using Atmospheric Pressure Non-Thermal Plasmas Mahmoud Yousef Alkawareek, Brendan Gilmore, Sean Gorman, Qais Algwari, William Graham, Deborah O'Connell Bacterial biofilms are ubiquitous in natural and clinical settings and form a major health risk. Biofilms are recognised to be the predominant mode of bacterial growth, and are an immunological challenge compared to planktonic bacteria of the same species. Eradication of biofilms with atmospheric pressure plasma jets is investigated. Cold non-equilibrium plasmas, operated at ambient atmospheric pressure and temperature, are efficient sources for controlled energy transport through highly reactive neutrals (e.g. ROS, RNS), charged particles (ions and electrons), UV radiation, and electro-magnetic fields. A focused panel of clinically significant biofilms, including Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Bacillus cereus, are exposed to various plasma jet configurations operated in helium and oxygen mixtures. Viability of surviving cells was determined using both standard plate counting method and XTT viability assay. These are correlated with measurements and simulations of relevant reactive plasma species. [Preview Abstract] |
Tuesday, November 15, 2011 11:45AM - 12:00PM |
DT2.00009: Bactericial effect of a non-thermal plasma needle against \textit{Enterococcus faecalis} biofilms Chunqi Jiang, C. Schaudinn, D.E. Jaramillo, P.P. Sedghizadeh, P. Webster, J.W. Costerton Up to 3 cm long submillimeter-in-scale plasma needle was generated in ambient atmosphere for root canal disinfection. Powered with 1-2 kHz, multi-kilovolt nanosecond electric pulses, this He/(1{\%})O$_{2}$ plasma jet consists of ionization fronts propagating at speeds of the order of 10$^{7}$ cm/s. Plasma treatment of \textit{Enterococcus} \textit{faecalis} biofilms on hydroxyapatite (HA) discs for 5 min resulted in severe damage of the bacterial cells and sterilized HA surfaces of more than 3 mm in diameter, observed by the scanning electron microscopy. With a curing dielectric microtube placed 1 cm or less below the nozzle, the plasma jet entered even at a sharp angle and followed the curvature of the tube, and reached the bottom of the tube. The bactericidal effect of the plasma needle against \textit{E. faecalis} biofilm grown on the inner surfaces of the tube was demonstrated. However, the bactericidal effect weakens or diminishes for the bacteria grown deeper in the tube, indicating improvement of the plasma treatment scheme is needed. Mechanisms of the plasma bactericidal effects are discussed. [Preview Abstract] |
Tuesday, November 15, 2011 12:00PM - 12:15PM |
DT2.00010: Investigation of ambient air species diffusion into the effluent of an atmospheric pressure plasma jet by measurements and modeling Ansgar Schmidt-Bleker, Stephan Reuter, J\"orn Winter, Hartmut Lange, Klaus-Dieter Weltmann The diffusion of ambient air species into the effluent of a cold atmospheric pressure plasma (CAP) jet operated with pure argon is quantified using both experimental methods and theoretical estimations by a convection-diffusion approach. In the effluent of CAP jets operated in ambient air, reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated. ROS and RNS are believed to play a central role in biomedical applications of low temperature atmospheric pressure plasmas. The inflow of atmospheric oxygen is determined by a novel absorption technique in the VUV spectral range, where emission originating from within the discharge is used as light source. An analytic expression for the estimation of the on-axis density of ambient species was obtained assuming a stationary drift-diffusion equation and is compared to complete numerical results. The easy to use expression correlates well with the experimental results obtained. [Preview Abstract] |
Tuesday, November 15, 2011 12:15PM - 12:30PM |
DT2.00011: Cell Internal Treatable Microplasma Jets in Cancer Therapies Jae Young Kim, Yanzhang Wei, Jinhua Li, Sung-O Kim We developed a 15-$\mu $m-sized, single-cellular-level, and cell-manipulatable microplasma jet device with a microcapillary glass tip and described its potential in physical cancer therapies. The microcapillary tip is a funnel shaped glass tube and its nozzle has an inner diameter of 15 $\mu $m and an outer diameter of 20 $\mu $m with 20\r{ } capillary angle. The electrical and optical properties of this plasma jet and apoptosis results of cultured murine B16F0 melanoma tumor cells and CL.7 fibroblast cells treated with the plasma jets were described. In spite of the small inner diameter and the low gas flow rate of the microplasma jet device, the generated plasma jets are stable enough to treat tumor cells. The microplasma jet was observed inducing apoptosis in cultured murine melanoma tumor cells in a dose-dependent manner. Furthermore, the percentage of apoptotic cells of murine melanoma tumor cells induced by this plasma device was approximately 2.5 times bigger than that of murine fibroblast cells as indicated by an Annex V-FITC method. This highly precise plasma medicine, which enables new directed cancer therapies, can be combined with current cell manipulation and cell culturing technologies without much difficulty. [Preview Abstract] |
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