|Escherichia coli deactivation study controlling the atmospheric pressu..|
Escherichia coli deactivation study controlling the atmospheric pressure plasma discharge conditions
Cur. Appl. Phys. 9, 625 (2009)
Bio-applications of plasma have been widely studied in recent years. However, considering the high interests, the inactivation mechanisms of micro-organisms by plasma have not been clearly explained. The goal of this study was to find the sterilization mechanisms and define the major sterilization factors with the atmospheric pressure radio-frequency helium glow discharge. For the sterilization target the Escherichia coli was used. To begin with the sterilization study, the plasma characteristics were investigated by means of electrical and optical diagnostics. Especially, the gas temperature was controlled under 50 °C by keeping the input power less than 70 W to eliminate the thermal effects. Contribution of the UV irradiation from the plasma was studied and it turned out to be negligible. On the other hand, it was found that the sterilization was more effective up to 40% with only 0.15% oxygen addition to the helium supply gas. It indicates that the inactivation process was dominantly controlled by oxygen radicals, rather than heat or UV photons.
|Polydimethylsiloxane Microlens Arrays Fabricated Through Liquid-Phase ..|
Polydimethylsiloxane Microlens Arrays Fabricated Through Liquid-Phase Photopolymerization and Molding (2008)
(Xuefeng Zeng and, Hongrui Jiang, Wisconsin University, US)
We report on polydimethylsiloxane (PDMS) microlens arrays fabricated through liquid-phase photopolymerization and molding. The gist of this fabrication process is to form liquid menisci of variable radii of curvature at an array of apertures through pneumatic control, followed by photopolymerization under ultraviolet radiance. The resultant polymerized structures are then transferred to PDMS utilizing two molding steps. By adjusting the pneumatic pressure during the process, a single aperture array can be used to fabricate PDMS microlens arrays with variant focal lengths. The liquid menisci are formed by liquid–air interfaces that are pinned at the top edges of the apertures along hydrophobic–hydrophilic boundaries generated through surface chemical treatments. The microlens arrays are optically characterized. Variant focal lengths from 2.35 to 5.54mm and f-numbers from 1.27 to 5.88, dependent on the diameter of apertures and the applied pressure to form the liquid menisci, are achieved with this relatively simple process and match well with the physical model. Owing to the formation from the liquid–air interfaces, the surface roughness of microlenses is measured to be around 25 nm.
►소수-친수 계면 특성과 광학폴리머의 경화 특성 활용 렌즈 제작(목적)
->공정 조건 별 형상 제어 가능한 반 구형 광학 렌즈 형상 제조 가능(결과)
|The Effect of Openair® Atmospheric Plasma on the Adhesion of UV Curabl..|
The Effect of Openair® Atmospheric Plasma on the Adhesion of UV Curable Coatings to Plastics (2014) (Plasma Treat USA, Inc.)
Ultraviolet (UV) cured liquid and powder coatings provide plastic part manufacturers with a number of desirable benefits including enhanced appearance, improved performance and various process advantages. At the same time, the rapid film formation and densely cross-linked chemistry that characterize UV curable materials also increases the likelihood of adhesion failures. That these coatings are formulated with little or no solvents makes attaining adhesion even more challenging. This paper examines adhesion problems inherent in UV curable liquid and powder coatings, and explores the tradeoffs associated with popular methods to mitigate adhesion problems. We find that atmospheric plasma treatment provides an especially effective means of improving adhesion of UV cure coatings to a wide range of plastic substrates.
► 폴리머 기판에 대기압 플라즈마 처리 후 UV 레진의 접착 강도 평가(목적)
-> 다양한 기판에서 표면 처리 이후 접착 강도 향상 확인(결과)
|Improving the Electrical Properties of Zinc Tin Oxide Thin Film Transi..|
Improving the Electrical Properties of Zinc Tin Oxide Thin Film Transistors Using Atmospheric Plasma Treatment (Published June 9, 2011)
* 결과 : AP Ar Plasma Treatment → ZTO TFT 특성 개선
|Coplanar amorphous-indium-gallium-zinc-oxide thin film transistor with..|
Coplanar amorphous-indium-gallium-zinc-oxide thin film transistor with He plasma treated heavily doped layer (published online 17 January 2014)
* Annealing – O2 분위기 1 시간 처리 (RT~300℃)[Plasma Treatment]1. IGZO Resistivity (Initial – RT)– Plasma 처리 후 감소– 2.98 Ω*cm (미처리) à 9*10-3 Ω*cm (Ar)2. Plasma 별 Resistivity (Initial – RT)– He Plasma 가 가장 작음 (2.79*10-3 Ω*cm)3. Annealing Temp.– 상승할수록 Resistivity 증가 (4 방식)– He Plasma Resistivity ↓ (7.92*10-2 Ω*cm at 300℃)* 결과 : He Plasma Treatment → IGZO Resistivity 감소
|Electrochemical migration of Ag nanoink patterns controlled by|
Electrochemical migration of Ag nanoink patterns controlled by
atmospheric-pressure plasma, Microelectronic Engineering, 106, 27 (2013)
Highly contrasting surface energies were induced on polyimide (PI) substrates using atmospheric-pressure plasma (APP) to allow precise printing of Ag electrodes that showed mitigated electrochemical migration (ECM). The substrate surface was made uniformly hydrophobic via APP tetraethyl orthosilicate (TEOS) polymerization. Selected areas were then made hydrophilic via oxygen APP applied through a patterned metal mask. Ag nanoink was then inkjet-printed onto the hydrophilic portions and sintered for 30 min at various temperatures ranging from 100 to 250 °C. The resulting Ag patterned electrodes were of the desired dimensions and showed sharp edges. The Ag ECM dendrites deposited at the cathode took ca. 39% longer than in similar patterns printed on pristine substrates. The contrasting surface-energies induced by the plasma allowed precise control of the Ag electrodes’ edges, which led to reduce ECM.
|Effects of plasma polymerized acrylic acid film on the adhesion of Ag ..|
Effects of plasma polymerized acrylic acid film on the adhesion of Ag tracks screen-printed on polyimide
The Journal of Adhesion, 88:1–13, (2012)
The adhesion of conductive patterns printed on polymer substrates is an indispensible issue for the commercialization of printable and flexible electronic devices. Plasma treatment has been widely used to improve the interfacial adhesion between a metal and a flexible polymer substrate. This study aims to investigate the influence of a polymerized acrylic acid layer coated by atmospheric-pressure plasma (APP) on the adhesion of a screen-printed silver (Ag)/polyimide (PI) system. The acidic oxygen-containing functional groups were incorporated onto a PI film by plasma polymerization of acrylic acid and, on it, the conductive tracks were constructed with a Ag nanopaste via screen printing. The Ag tracks were sintered at various temperatures ranging from 150 to 300°C for 30 min in air. The adhesion was evaluated by a roll-type 90% peel test. The peel strength of the screen-printed Ag/PI system with the acrylic acid film approximately quadrupled. To understand this adhesion enhancement, field emission scanning microscopy (FE-SEM), atomic force microscopy (AFM), contact angle analyzer, and X-ray photoelectron spectroscopy (XPS) were utilized. It was confirmed from these analyses that a hydrophilic film was formed due to the plasma polymerization process, and the carbon-oxygen (C–0)and carbonyl (C=0) bonds increased at the interfacial surface. Under the optimized conditions, a maximum adhesion of 245.5 N/m was obtained, and the stronger adhesion with the acrylic acid coating influenced the improvement in the flexibility of the film.
|Adhesion characteristics of silver tracks screen-printed on polyimide ..|
Adhesion characteristics of silver tracks screen-printed on polyimide with an environmental reliability test
Journal of Nanoscience and Nanotechnology, 12, 5769 (2012)
Printable and flexible electronics are increasingly being used in numerous applications that are miniaturized, multi-functional and lightweight. Simultaneously, reliability issues of the printed and flexible electronic devices are getting more attention. The adhesion of screen-printed silver (Ag) tracks on a polyimide (PI) film was investigated after two kinds of the environmental reliability test: a constant-temperature storage test, and a steady-state temperature and humidity storage test. Atmospheric-pressure plasma (APP) was adopted on the PI film surface to improve the poor adhesion derived from the inherent hydrophobicity. The Ag tracks constructed via screen printing were sintered at 250 degrees C for 30 min in air using a box-type muffle furnace. Some samples were exposed under 85 degrees C and 85% relative humidity (RH) for various durations (24, 72, 168 and 500 h), and others were aged at 85 degrees C with same durations to compare the influence of moisture on the adhesion. The adhesion of the screen-printed Ag tracks was evaluated by a roll-type 90 degrees peel test. The peel strength of the screen-printed Ag tracks decreased by 76.74% and 69.88% after 500 h run of the 85 degrees C/85% RH test, and the aging test, respectively. The weakest adhesion was 4.98 gf/mm after the 500 h run of the 85 degrees C/85% RH test. To demonstrate these experimental results, the microstructural evolution and chemical bonding states of the interfacial surfaces were characterized using a field emission scanning electron microscope (FE-SEM), and X-ray photoelectron spectroscope (XPS), respectively.
|Surface modification of PDMS by atmospheric-pressure plasma-enhanced c..|
Surface modification of PDMS by atmospheric-pressure plasma-enhanced
Sensors and Actuators B 162, 425 (2012)
Atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD) offers several benefits such as simplicity, high productivity, and versatility. An AP-PECVD-based method is proposed in this study to modify hydrophobic PDMS (polydimethylsiloxane) surfaces towards a long-lasting hydrophilic character. To enhance the sustainability of the hydrophilicity, two kinds of layers were sequentially deposited by AP-PECVD on the surface of a PDMS block (TEOS-O2/CH4/PDMS). A hydrocarbon layer was first coated on the bare PDMS surface using CH4 as the reactant, and then, a hydrophilic SiOx layer was deposited using tetraethyl orthosilicate and oxygen (TEOS-O2). The highly cross-linked hydrocarbon layer acted as a physical barrier layer (PBL) between the bare PDMS surface and the hydrophilic layer. To confirm that the PBL suppresses the hydrophobic recovery of the modified PDMS surface with double layer, a single-layer-coated PDMS sample (TEOS-O2/PDMS) without the PBL was prepared by AP-PECVD using TEOS-O2. The surface characteristics were determined by static contact angle measurements, surface roughness measurements, and surface chemical composition/chemical bonding determination and compared with those of modified PDMS surface with double layer. The surface morphology of TEOS-O2/PDMS degraded seriously by the diffusion of PDMS oligomers to the hydrophilic layer, but that of TEOS-O2/CH4/PDMS was sustained for a long time. Thus, TEOS-O2/CH4/PDMS had the lowest contact angle, almost 0°, and showed long-lasting surface hydrophilicity, with almost no change in the contact angle for 28 days. Thus, this proposed method is confirmed to be well suited for use in applications that require stable hydrophilic surface property in PDMS.
|Inactivation of listeria monocytogenes inoculated on disposable plasti..|
Inactivation of listeria monocytogenes inoculated on disposable plastic tray-aluminum foil-and paper cub by atmospheric pressure plasma
Food Control 21, 1182 (2010)
The objective of this study was to investigate the effect of atmospheric pressure plasma (APP) on Listeria monocytogenes inoculated onto disposable food containers including disposable plastic trays, aluminum foil, and paper cups. The parameters considered in APP processing were input power (75, 100, 125, and 150 W) and exposure time (60, 90, and 120 s). The bacterial reduction in the disposable plastic trays, aluminum foil, and paper cups was associated with increased input power and exposure time of APP. The D10 values were calculated as 49.3, 47.7, 36.2, and 17.9 s in disposable plastic trays, 133, 111, 76.9, and 31.6 s in aluminum foil and 526, 65.8, 51.8, and 41.7 s in paper cups at 75, 100, 125, and 150 W of input power, respectively. There were no viable cells detected after 90 and 120 s of APP treatment at 150 W in disposable plastic trays. However, only three decimal reductions of viable cells were achieved in aluminum foil and paper cups at 150 W for 120 s. These results demonstrate that APP treatment is effective for inactivation of L. monocytogenes and applicable for disposable food containers. However, the type of material is crucial and appropriate treatment conditions should be considered for achieving satisfactory inactivation level.