Applications of plasma in surface processing and film deposition

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Plasma transporting in flexible tube

Transported plasmas through capillary tubes operating at atmospheric pressure have received considerable attention recently for both their fundamental physics and practical applications [112-114]. These plasmas have great potential to be used in medical applications such as endoscopy due to their excellent flexibility and capability to deliver reactive chemical species to a target [115-117]. This is an interesting point because the plasma bullets emerge the tube, with a sufficient reduced electric field at the tip. There also exist a few publications dealing with the development of new non thermal atmospheric pressure plasma sources allowing for plasma delivery. Such a potentiality will for sure open up new opportunities for plasma technology in both clinical applications and medical device disinfection.
A lot of effort has been made to devise plasma jet systems capable of guiding active species far from the source, where a localized treatment at atmospheric pressure can be achieved. Several groups [118-120] have reported propagation of plasma into flexible plastic tubes with different lengths and thicknesses. Usually most authors ignite He or Ne plasmas, which reportedly propagate into bended plastic tubes [121] with a length up to 2 m [118]. Plasmas from argon and argon–nitrogen mixtures could only propagate short distances inside flexible plastic pipes [22,122].
In our knowledge, Robert et al. [119] developed a first version of low temperature plasma, ‘plasma gun’, traveling through capillary tube (Fig.I-21). They used a compact nanosecond dielectric barrier discharge inside capillaries of diameter ranging from 200μm to 4mm flushed with neon or helium. They found that the plasma bullets propagate at speeds up to 5×108 cm s−1 over distances of a few tens of centimeters and exit from the capillary tube as a streamer discharge. A few centimeters downstream of the DBD source, the IW (Ionization Wave) appears to be electronically isolated from the high-voltage source.

Plasma jet array

For most of the plasma jet devices, the plasma jets cover only a few square millimeters, which make them difficult for large-scale applications, such as surface coating, deposition, cleaning, and medicine [129]. To overcome this challenge, several researchers have considered the use of plasma jet arrays consisting of many individual jets placed within close proximity of each other; clearly, such structures have the potential to greatly enhance the scale of surface treatment over that of a single plasma jet [130-134]. Several cold-plasma jet array devices of scalable 1-D and 2-D arrays have been designed by different groups [135-139]. Ma et al have developed arrays of microchannels embedded in polymer producing micro-jets having a channel diameter of 340μm and extending almost 4mm into air [140]. These plasmas are capable of a direct production of reactive species near large scale 3-D objects with a tight control of plasma stability, which are generated with capillary–ring electrode configuration or with a downstream ground electrode.

Application of cold atmospheric plasma in medicine

The sensitivity to heat of biomedical samples narrows the choice of non-thermal plasmas. There are many types of plasmas that can be generated under ambient pressure and temperature conditions suitable for treatment of sensitive samples. The motivation is to develop new medical techniques, as plasma offers some possibilities for inducing desired processes with minimum damage to the living tissue [146-148].
Plasmas became commercially available for medical use in the 1990s. Studies investigating the interaction of plasma with living cells have shown eradication of pathogens [20,54], blood coagulation [39,149], tissue sterilization [39,150], and the ablation of cultured liver cancer cells [151].

Applications of plasma in surface processing and film deposition

Surface processing and coating by cold atmospheric plasmas are among the most intensively studied technologies during the last decade. Dependent on several plasma parameters like energy input, pressure, working gas composition, addition of primer substances, etc., as well as the nature of the substrate, a variety of chemical-reaction based interactions with materials can be enhanced or even enabled by plasma application. These interactions are etching or ablation, thin dielectric film deposition, chemical and/or physical surface modification, activation or functionalization (see Fig.I-29) are basic processes which are used not only in several industrial applications but also for processing of surfaces, materials or devices intended for medical application. At the end of the 1960s, plasma was applied to improve the biocompatibility or biofunctionality of materials, which are supposed to be in direct contact with biological systems.
Up to now, a wide range of plasma-based surface treatment techniques has been developed and a number of which has been commercialized. These treatment techniques are plasma sputtering and etching, plasma implantation, plasma deposition, plasma polymerization, plasma spraying, and many more. These processes and techniques can be based both on low-pressure as well as atmospheric-pressure plasmas [190].

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Table of contents :

General Introduction
Chapter I: State of the Art
I-1) Definition of plasma
I-2) Classification of Plasma
I-3) Atmospheric pressure plasma sources
I-3-1) Direct current (DC)
I-3-2) Alternating current (AC) discharges
I-3-3) Radio-frequency plasmas (RF)
I-3-4) Microwave (MW) discharge
I-4) Dielectric Barrier Discharge (DBD) plasmas
I-5) Ionization waves and streamers
I-6) Structures and composition of plasma jets
I-6-1) Dielectric-free electrode (DFE) jets
I-6-2) Dielectric barrier discharge (DBD) jets
I-6-3) DBD-like jets
I-6-4) Single electrode (SE) jets
I-7) Guided ionization waves–plasma bullets
I-8) Effect of discharge parameters on plasma jet
I-8-1) Pulse frequency
I-8-2) Rise time of pulse voltage
I-8-3) Pulse width
I-8-4) Voltage polarity
I-8-5) Diameter of the tube
I-8-6) Applied voltage amplitude
I-9) Plasma transporting in flexible tube
I-10) Plasma jet array
I-11) Application of cold atmospheric plasma in medicine
I-11-1) Plasma decontamination
I-11-2) Cancer therapy
I-12) Applications of plasma in surface processing and film deposition
I-12-1) Surface activation and treatment
I-12-2) Deposition of films
Chapter II: Experimental Setup and methods
II-1) Power Supply
II-2) Surface processing and film deposition methods
II-2-1) Plasma reactor
II-2-2) Surface treatment method
II-2-3) Plasma Polymerization method
II-3) Coating and surface characterization methods
II-3-1) Fourier Transform Infrared Spectroscopy (FTIR)
II-3-2) Field Emission Scanning Electron Microscopy (FESEM)
II-3-3) X-Ray Photoelectron Spectroscopy (XPS)
II-3-4) Water Contact Angle (WCA) Measurement
II-3-5) Atomic Force Microscopy (AFM)
II-4) Biological techniques and methods
II-4-1) Cell treatment
II-4-1-1) Plasma reactor
II-4-1-2) Cancer Cell culture
II-4-1-3) Fibroblast culture
II-4-1-4) Apoptosis detection
II-4-2) Bacteria treatment
II-4-2-1) Plasma reactor
II-4-2-2) Bacteria Sample Preparation
II-5) Plasma characterization methods
II-5-1) Optical Emission Spectroscopy (OES)
II-5-2) Electrical measurements
Chapter III: The influence of different parameters and configurations on transporting discharge .
III-1) Introduction
III-2) Effect of waveforms on the transporting discharge
III-3) Effect of the tube diameter on transporting discharge
III-4) Light Intensity Measurement
III-5) Effect of gas mixture on discharge transporting
III-6) Optical Emission Spectroscopy
III-6-1) Effect of additive gas (O2 or Ar)
III-6-2) Influence of He flow rate
III-7) Effect of electrode structure
III-7-1) Propagation velocity inside the tube
III-8) Transporting discharge arrays
III-8-1) Two dimensional configurations of arrays
III-8-2) Characterization of arrays
III-9) Bacteria Decontamination
III-9-1) Single jet configuration
III-9-2) Multijet arrays configuration
III-10) Cell treatment
III-10-1) Cancer Cell treatment
III-10-2) Apoptotic analysis
III-10-3) Fibroblast treatment
III-11) Conclusion
Chapter IV: Surface treatment and thin film deposition in an atmospheric pressure transported discharge
IV-1) Introduction
IV-2) Film deposition by transporting plasma
IV-2-1) Deposition of thin SiOx films
IV-2-2) Influence of Process Parameters on the SiOx film
IV-2-3) Fabrication of thin SiOx films inside a Fluorinated Ethylene Propylene (FEP) tube
IV-2-4) Deposition of thin PEG films
IV-2-5) Cell adhesion on plasma polymerized coatings
IV-2-6) Deposition of thin PEG films on the inner wall of tube
IV-3) Surface modification by transporting plasma
IV-3-1) Surface modification of UHMWPE films
IV-3-1-1) Transporting discharge inside the FEP tube
IV-3-1-2) Transporting discharge inside the HDPE tube
IV-3-2) Inner wall modification of a HDPE tube
IV-4) Conclusion
General Conclusion
References

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