Electrical, Thermal and Optical Diagnostics of an Atmospheric Plasma Jet System

Nwankire, Charles; Law, Victor J.; Nindrayog, Amritpal Singh; Twomey, Barry; Niemi, Kari; Milosavljević, Vladimir; Graham, W. G.; Dowling, Denis P.

doi:10.1007/s11090-010-9236-5

Cited by 46 publications

(34 citation statements)

References 35 publications

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“…The helium atmospheric plasma studies were carried out using the PlasmaStream™ (Dow Corning Plasma Solutions) system, which has been described previously [22,23]. In this system the discharge is formed using a modified PTI 100 W rf power supply, between two pin electrodes.…”

Section: Coating Depositionmentioning

confidence: 99%

“…In this system the discharge is formed using a modified PTI 100 W rf power supply, between two pin electrodes. This is a high voltage source that uses a flyback transformer, which produces a non-sinusoidal voltage waveform due to the rapid collapse of the magnetic circuit within the flyback transformer [23]. Liquid precursors are nebulised between these electrodes using a pneumatic Burgener Mira Mist nebuliser.…”

Section: Coating Depositionmentioning

confidence: 99%

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Protein adhesion on water stable atmospheric plasma deposited acrylic acid coatings

Donegan

Dowling

2013

Surface and Coatings Technology

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There is considerable interest in the application of plasma polymerised acrylic acid (ppAAc) coatings due to their ability to enhance the adhesion of cells and proteins. An issue with this coating however it its stability in water and previous studies carried out using low pressure plasmas have demonstrated that high plasma powers are required to achieve water stable coatings. In this paper the use of both helium and air atmospheric plasmas are compared for the deposition of ppAAc coatings. The deposition studies were carried out on silicon wafer substrates using the PlasmaStream TM and PlasmaTreat TM plasma jet deposition systems respectively. The coatings were characterized using contact angle, FTIR, SEM, XPS, ellipsometry and optical profilometry. While both the helium and air plasmas were successful in the deposition of ppAAc coatings, the nm thick films deposited using the PlasmaTreat system exhibited significantly higher levels of water stability, probably due to a higher level of coating cross linking. Ellipsometry measurements demonstrated only a 0.2 nm reduction in the thickness of an 18 nm thick ppAAc coating, when immersed in an aqueous buffer solution for one hour. Protein attachment studies were carried out using a flow cell system, which was monitored using a spectroscopic ellipsometer. This study was carried out with Bovine Serum Albumin (BSA), Immunoglobulin G (IgG) and Fibrinogen (Fg) proteins. In all three cases increased levels of protein adhesion was observed for the ppAAc coating, compared to that obtained on the uncoated silicon wafer substrates.Keywords: Atmospheric Plasma, Thin Film, Nano-coatings, Surface Engineering, Protein Adhesion IntroductionControlling protein adhesion is an important issue affecting many different fields including bio-processing, medical device implants, biosensors, and drug delivery devices [1,2]. When the surface of a material interacts with a biological environment one of the initial interactions is through protein adhesion [3]. Amongst the factors influencing protein adsorption, are surface chemical functionality and morphology [4]. Amongst the techniques that have been investigated to modify the surfaces of polymers prior to protein adhesion studies have been micro patterning and monomer polymerisation by free radical solution, emulsion, grafting as well as plasma processes [5][6][7][8][9]. It has been demonstrated by a number of authors that plasma techniques enable both the surface functionality and morphology to be tailored [10,11]. This makes it possible to create a surface which will inhibit or enhance the rate of protein adhesion onto a biomaterial surface, without changing the properties of the bulk material [12].One surface chemistry that has received considerable attention for cell and protein adhesion has been acrylic acid. Surfaces containing this coating have been reported in applications ranging from platelet adhesion promotion [13], RGD peptide immobilisation [14], attachment of osteoblast-like [15], fibroblast [16] and keratinocyte [17]...

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Section: Coating Depositionmentioning

confidence: 99%

Section: Coating Depositionmentioning

confidence: 99%

Protein adhesion on water stable atmospheric plasma deposited acrylic acid coatings

Donegan

Dowling

2013

Surface and Coatings Technology

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“…Studies have shown that molecular species (OH, N 2 , N 2 + , NO, and NO 2 ) as well as atomic species (metastable He, H, and O) are abundant in an AP helium LTP [60,61]. For peptides having intra-chain disulfide bonds, one major product after the nanoESI plume interacting with LTP were ions corresponding to the addition of O and H to the intact peptide ([M + nH + OH] n•+ ) [58,59].…”

Section: Formation Of Peptide Sulfinyl Radical Ions Radical Attack Ofmentioning

confidence: 99%

Gas-Phase Peptide Sulfinyl Radical Ions: Formation and Unimolecular Dissociation

Tan

Xia

2012

J. Am. Soc. Mass Spectrom.

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A variety of peptide sulfinyl radical (RSO•) ions with a well-defined radical site at the cysteine side chain were formed at atmospheric pressure (AP), sampled into a mass spectrometer, and investigated via collision-induced dissociation (CID). The radical ion formation was based on AP reactions between oxidative radicals and peptide ions containing single inter-chain disulfide bond or free thiol group generated from nanoelectrospray ionization (nanoESI). The radical induced reactions allowed large flexibility in forming peptide radical ions independent of ion polarity (protonated or deprotonated) or charge state (singly or multiply charged). More than 20 peptide sulfinyl radical ions in either positive or negative ion mode were subjected to low energy collisional activation on a triple-quadrupole/linear ion trap mass spectrometer. The competition between radical-and charge-directed fragmentation pathways was largely affected by the presence of mobile protons. For peptide sulfinyl radical ions with reduced proton mobility (i.e., singly protonated, containing basic amino acid residues), loss of 62 Da (CH 2 SO), a radicalinitiated dissociation channel, was dominant. For systems with mobile protons, this channel was suppressed, while charge-directed amide bond cleavages were preferred. The polarity of charge was found to significantly alter the radical-initiated dissociation channels, which might be related to the difference in stability of the product ions in different ion charge polarities.

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“…The high value of Q-factor (~200) also implies that the energy loss is low and the loss mechanism is decoupled from discharge. The latter observation is contra to Draft for submission to PSST 6 flyback power supplies and drive circuits that have frequency agile impedance matching [12,27]. The authors have also noticed that when the APPJ nozzle under goes cleaning maintenance and or when the electrical cabling to the nozzle is upgraded the PWM drive frequency and harmonics can be reduced.…”

Section: Resultsmentioning

confidence: 99%

Evaluation of the sensitivity of electro-acoustic measurements for process monitoring and control of an atmospheric pressure plasma jet system

Law

O’Neill

Dowling

2011

Plasma Sources Sci. Technol.

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Abstract:The development of non-invasive process diagnostic techniques for the control of atmospheric plasmas is a critical issue for the wider adoption of this technology. This paper evaluates the use of a frequency-domain deconvolution of an electro-acoustic emission as a means to monitor and control the plasma formed using an atmospheric pressure plasma jet (APPJ) system. The air plasma system investigated was formed using a PlasmaTreat™ OpenAir applicator. Change in the electro-acoustic signal with changes in substrate type (ceramic, steel, polymer). APPJ nozzle to substrate distance and substrate feature size were monitored. The decoding of the electro-acoustic emission yields three sub dataset that are described three separate emission mechanisms. The three emissions are associated with: the power supply fundamental drive frequency and its harmonics; the APPJ nozzle longitudinal mode acoustic emission and its odd overtones, and the acoustic surface reflection that is produced by the impedance mismatch between the discharge and the surface.Incorporating this knowledge into a LabVIEW a program facilitated the continuous deconvolution of the electro-acoustic data. This enabled the use of specific frequency band test limits to control the process the APPJ treatment process which is sensitive to both plasma processing conditions and substrate type and features.PAC Codes: 52.40. Hf, 52.77.Fv, 43.60.Vx Keywords: atmospheric plasma, electrical harmonics, acoustic overtones, surface location, fault detection.Draft for submission to PSST 2 IntroductionWith the increased use of atmospheric plasma systems in applications ranging from polymer surface activation to coating deposition [1,2] there is a growing need for the development of non-invasive insitu process monitoring techniques. This paper evaluates the use of electro-acoustic technique as a means of achieving this process monitoring of an atmospheric plasma jet system. Since the late 1990s the acoustic emission from laboratory scale atmospheric pressure plasma jet (APPJ) systems [3,4], and optical-acoustic studies of plasma welding process [5] have been reported. Following these reports acoustic metrology has been used in the monitoring of anomalous arc discharge in plasma processing equipment plasma [6], plasma and laser welding [7, 8 and 9], and plasma anodizing [10].More recently plasma acoustic emission metrology has been demonstrated on industrial scale APP reel-to-reel systems [11,12] and APPJ [13], all of which [11 -13] have used helium as the working gas.Experimental observations with physics based interpretation [3, 4, 5 and 6]; time series analysis [7, 8, and 9], neural network analysis [10], and multivariate analysis [11, 12 and 13] have been used to investigate the plasma acoustic emission in an attempt to isolate the specific origin of acoustic emission. In all case it has been observed that the emission signal is complex with parts of the signal associated with specific sources. Eller and Valdivia [14] have developed a multiple frequency ap...

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Electrical, Thermal and Optical Diagnostics of an Atmospheric Plasma Jet System

Cited by 46 publications

References 35 publications

Protein adhesion on water stable atmospheric plasma deposited acrylic acid coatings

Protein adhesion on water stable atmospheric plasma deposited acrylic acid coatings

Gas-Phase Peptide Sulfinyl Radical Ions: Formation and Unimolecular Dissociation

Evaluation of the sensitivity of electro-acoustic measurements for process monitoring and control of an atmospheric pressure plasma jet system

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