Plasma Immersion Research Articles

Degree of Wettability and Aging of PVC and PET Polymers Treated by Plasma Immersion or Deposition

The wettability, aging characteristics, and optical transmittance in the visible region following Plasma Immersion (PI) or Plasma Immersion Ion Implantation (PIII) treatment of polymers were studied. In addition, structural and chemical modifications of the polymers were examined. The polymers investigated were white Polyvinyl chloride (PVC) and Polyethylene terephthalate (PET). Initially, plasmas of nitrogen (N2) were employed, aiming to produce hydrophilic surfaces. In contrast, sulfur hexafluoride (SF6) plasma treatments produce high surface fluorination, which tends to increase hydrophobicity. Isopropyl alcohol (IPA) was mixed with SF6 or N2 to deposit a series of organic films. Aging effects over 30 days on the contact angle, q, were measured for the polymer surfaces. Conventional plasma immersion (PI) tended to decrease of θ for N2 plasma treatments, with or without IPA, and to increase θ values ​​for samples immersed in IPA/SF6 plasma. The highest value of θ was 140º for IPA/SF6 plasma treatments, while the smallest θ was 20º for N2 or IPA/N2 treatments. There was an ideal condition under which θ was stable upon aging. The results obtained suggest the developed treatment enables the preparation of polymers with distinct wettability properties depending of the nature of the plasma with overall reasonable aging stability. Moreover, the opaque character of these materials makes them interesting for the production of bags, boxes, bottles, food packaging, among others.

Deep Level Reduction in 4H-SiC Treated by Plasma Immersion

The carbon vacancy (VC) is a lifetime-killer defect that hinders the correct functionality of 4H-SiC bipolar devices. Until now, different methods based on carbon interstitial injection, have been proposed, in order to reduce its concentration. However, if on one hand these methods effectively reduce the VC concentration in the epilayer, on the other they cannot prevent the re-generation of VC occurring during the manufacture of a p-i-n diode, e.g., p+ implantation and activation. In the following contribution, we employ PIII of B for the formation of the anode for a p-i-n diode. We show that by PIII, it is possible to simultaneously form a p+n junction with a low concentration of VC in the drift layer.

Development of tropoelastin-functionalized anisotropic PCL scaffolds for musculoskeletal tissue engineering.

The highly organized extracellular matrix (ECM) of musculoskeletal tissues, encompassing tendons, ligaments and muscles, is structurally anisotropic, hierarchical and multi-compartmental. These features collectively contribute to their unique function. Previous studies have investigated the effect of tissue-engineered scaffold anisotropy on cell morphology and organization for musculoskeletal tissue repair and regeneration, but the hierarchical arrangement of ECM and compartmentalization are not typically replicated. Here, we present a method for multi-compartmental scaffold design that allows for physical mimicry of the spatial architecture of musculoskeletal tissue in regenerative medicine. This design is based on an ECM-inspired macromolecule scaffold. Polycaprolactone (PCL) scaffolds were fabricated with aligned fibers by electrospinning and mechanical stretching, and then surface-functionalized with the cell-supporting ECM protein molecule, tropoelastin (TE). TE was attached using two alternative methods that allowed for either physisorption or covalent attachment, where the latter was achieved by plasma ion immersion implantation (PIII). Aligned fibers stimulated cell elongation and improved cell alignment, in contrast to randomly oriented fibers. TE coatings bound by physisorption or covalently following 200 s PIII treatment promoted fibroblast proliferation. This represents the first cytocompatibility assessment of novel PIII-treated TE-coated PCL scaffolds. To demonstrate their versatility, these 2D anisotropic PCL scaffolds were assembled into 3D hierarchical constructs with an internally compartmentalized structure to mimic the structure of musculoskeletal tissue.

Effect of plasma ion immersion implantation on physiochemical and biological properties of silk towards creating a versatile biomaterial platform

Silk biomaterials are widely used in tissue engineering applications due to their mechanical tuneability, processability and low immunogenic response. However, due to the lack of cell binding sites, further modification is typically required to optimize silk biomaterials towards a specific biomedical application. Plasma immersion ion implantation (PIII) is a surface modification technique that can covalently attach a wide range of bioactive molecules onto silk surfaces to trigger desirable biological responses. However, the effect of PIII treatment on the surface and bulk properties of silk biomaterials remains largely unknown. Therefore, the aim of this study is to investigate PIII-treated silk (PIII-silk) biomaterials towards their use as a platform for biomedical applications. Silk films with or without PIII treatment were examined to determine changes to the surface and bulk properties, including the chemical, mechanical, degradation properties, and the in vivo immune response. PIII treatment of silk was found to alter surface chemistry with densification of the silk surface layer and the introduction of oxygen and nitrogen functional groups. This then resulted in a significant increase in surface stiffness but also led to minor changes in tensile properties of clinically relevant silk formats and minor differences in in vitro degradation properties. Following PIII treatment, there was a significant increase in HCAEC adhesion on PIII-silk compared to untreated silk but no significant differences in fibrous encapsulation and macrophage response when implanted in vivo in a subcutaneous mouse model. Together, these results show that PIII treatment of silk minimally compromises the bulk properties and can be used to promote cellular interactions as well as a means of reagent-free, covalent immobilization of biomolecules.

Combined platelet-rich plasma and cold water immersion treatment minimize the damage following a skeletal muscle stretch injury in rats

The skeletal muscle stretch injuries are commonly observed in sports. In order to stimulate tissue healing, the platelet-rich plasma (PRP) and cold water immersion (CWI) are widely used in clinical practice. This study investigated the effects of isolated or combined PRP and/or CWI on the oxidative damage determined by a stretch injury induced in gastrocnemius muscle of rats. PRP and CWI are applied immediately after the injury, and the biochemical analysis was performed after 1, 3, 5, or 7 days. The levels of o thiobarbituric acid reactive substances and oxidized dichlorofluorescein were significantly increased, both in skeletal muscle tissue and erythrocytes preparations, and the combined PRP and CWI minimized these parameters. Moreover, combined PRP and CWI were more effective than the isolated treatments to increase catalase activity, also the ratio of reduced/oxidized glutathione, and the non-protein thiols (-SH) group levels. In conclusion, we could infer that the combination of these regular treatments used in an isolated form shows a great potential for treatments of muscular injuries.

A surface-engineered multifunctional TiO2 based nano-layer simultaneously elevates the corrosion resistance, osteoconductivity and antimicrobial property of a magnesium alloy

Magnesium biometals exhibit great potentials for orthopeadic applications owing to their biodegradability, bioactive effects and satisfactory mechanical properties. However, rapid corrosion of Mg implants in vivo combined with large amount of hydrogen gas evolution is harmful to bone healing process which seriously confines their clinical applications. Enlightened by the superior biocompatibility and corrosion resistance of passive titanium oxide layer automatically formed on titanium alloy, we employ the Ti and O dual plasma ion immersion implantation (PIII) technique to construct a multifunctional TiO2 based nano-layer on ZK60 magnesium substrates for enhanced corrosion resistance, osteoconductivity and antimicrobial activity. The constructed nano-layer (TiO2/MgO) can effectively suppress degradation rate of ZK60 substrates in vitro and still maintain 94% implant volume after post-surgery eight weeks. In animal study, a large amount of bony tissue with increased bone mineral density and trabecular thickness is formed around the PIII treated group in post-operation eight weeks. Moreover, the newly formed bone in the PIII treated group is well mineralized and its mechanical property almost restores to the level of that of surrounding mature bone. Surprisingly, a remarkable killing ratio of 99.31% against S. aureus can be found on the PIII treated sample under ultra-violet (UV) irradiation which mainly attributes to the oxidative stress induced by the reactive oxygen species (ROS). We believe that this multifunctional TiO2 based nano-layer not only controls the degradation of magnesium implant, but also regulates its implant-to-bone integration effectively. Statement of significanceRapid corrosion of magnesium implants is the major issue for orthopaedic applications. Inspired by the biocompatibility and corrosion resistance of passive titanium oxide layer automatically formed on titanium alloy, we construct a multifunctional TiO2/MgO nanolayer on magnesium substrates to simultaneously achieve superior corrosion resistance, satisfactory osteoconductivity in rat intramedullary bone defect model and excellent antimicrobial activity against S. aureus under UV irradiation. The current findings suggest that the specific TiO2/MgO nano-layer on magnesium surface can achieve the three objectives aforementioned and we believe this study can demonstrate the potential of biodegradable metals for future clinical applications.

A functionalized TiO2/Mg2TiO4 nano-layer on biodegradable magnesium implant enables superior bone-implant integration and bacterial disinfection

Rapid corrosion of biodegradable magnesium alloys under in vivo condition is a major concern for clinical applications. Inspired by the stability and biocompatibility of titanium oxide (TiO2) passive layer, a functionalized TiO2/Mg2TiO4 nano-layer has been constructed on the surface of WE43 magnesium implant by using plasma ion immersion implantation (PIII) technique. The customized nano-layer not only enhances corrosion resistance of Mg substrates significantly, but also elevates the osteoblastic differentiation capability in vitro due to the controlled release of magnesium ions. In the animal study, the increase of new bone formation adjacent to the PIII-treated magnesium substrate is 175% higher at post-operation 12 weeks, whereas the growth of new bone on titanium control and untreated magnesium substrate are only 97% and 29%, respectively. In addition, its Young's modulus can be restored to about 82% as compared with the surrounding matured bone. Furthermore, this specific TiO2/Mg2TiO4 layer even exhibits photoactive bacteria disinfection capability when irradiated by ultraviolet light which is attributed to the intracellular reactive oxygen species (ROS) production. With all these constructive observations, it is believed that the TiO2/Mg2TiO4 nano-layer on magnesium implants can significantly promote new bone formation and suppress bacterial infection, while the degradation behavior can be controlled simultaneously.

Plasma processing of PDMS based spinal implants for covalent protein immobilization, cell attachment and spreading.

PDMS is widely used for prosthetic device manufacture. Conventional ion implantation is not a suitable treatment to enhance the biocompatibility of poly dimethyl siloxane (PDMS) due to its propensity to generate a brittle silicon oxide surface layer which cracks and delaminates. To overcome this limitation, we have developed new plasma based processes to balance the etching of carbon with implantation of carbon from the plasma source. When this carbon was implanted from the plasma phase it resulted in a surface that was structurally similar and intermixed with the underlying PDMS material and not susceptible to delamination. The enrichment in surface carbon allowed the formation of carbon based radicals that are not present in conventional plasma ion immersion implantation (PIII) treated PDMS. This imparts the PDMS surfaces with covalent protein binding capacity that is not observed on PIII treated PDMS. The change in surface energy preserved the function of bound biomolecules and enhanced the attachment of MG63 osteosarcoma cells compared to the native surface. The attached cells, an osteoblast interaction model, showed increased spreading on the treated over untreated surfaces. The carbon-dependency for these beneficial covalent protein and cell linkage properties was tested by incorporating carbon from a different source. To this end, a second surface was produced where carbon etching was balanced against implantation from a thin carbon-based polymer coating. This had similar protein and cell-binding properties to the surfaces generated with carbon inclusion in the plasma phase, thus highlighting the importance of balancing carbon etching and deposition. Additionally, the two effects of protein linkage and bioactivity could be combined where the cell response was further enhanced by covalently tethering a biomolecule coating, as exemplified here with the cell adhesive protein tropoelastin. Providing a balanced carbon source in the plasma phase is applicable to prosthetic device fabrication as illustrated using a 3-dimensional PDMS balloon prosthesis for spinal implant applications. Consequently, this study lays the groundwork for effective treatments of PDMS to selectively recruit cells to implantable PDMS fabricated biodevices.

Effect of plasma ion immersion treatment on the structure and phase state of the TiNi alloy for medical implantants

In this paper we present the results of studying the structure and phase composition of the medical alloy Ti-50.9 at. % Ni processed by method of plasma ion-immersion implantation (PIIID) by Si ions. TEM\\EDS\\XPS analyses were used. After ion-plasma treatment, a separate amorphous layer is formed on the TiNi sample surface, containing Si. It is found that diffusion transformations in TiNi during PIID occur. The aging in the bulk of samples takes place with the separation of coherent Ti3Ni4 precipitation. After cooling in the alloy a B2→R martensitic transformation is realized.

Structural evolution of thermal annealed Si(0 0 1) surface layers fabricated by plasma immersion He+ implantation

Abstract Structural evolution in Si(0 0 1) surface layers after high-dose (D = 5 × 1017 cm–2) low-energy (2 and 5 keV) plasma immersion He+ ion implantation (He+ PIII) and subsequent annealing at 853 and 1073 K was studied by complementary structural sensitive methods (TEM, XRR, RBS, and AFM). Formation of a three-layer structure (amorphous a-SiOx sublayer at the surface, amorphous a-Si sublayer with large size helium-filled bubbles, and heavily damaged crystalline c-Si sublayer containing small-size bubbles and Si nanocrystallites) was observed for both implantation energies. This three-layer structure is retained after annealing. It was shown that the thickness of the oxide sublayer does not depend on implantation energy and does not change after annealing. This amorphous oxide sublayer together with dense top part of the a-Si sublayer forms a cap layer with a thickness of 15 nm that can be considered as a protective layer for the sublayers containing He-filled bubbles and Si nanocrystallites. The Si nanocrystallites were revealed at the boundary of the a-Si and the c-Si sublayers both in as-implanted at 5 keV and annealed samples.

Preparation and characterization of copper thin film obtained by metal plasma immersion ion implantation and deposition

Copper thin film was obtained by metal plasma ion immersion implantation and deposition (MePIIID). The film structure was characterized by grazing incidence X-ray diffraction whereas its thickness and surface topography were evaluated by field emission scanning electron microscopy and atomic force microscopy, respectively. Rutherford backscattering spectroscopy and X-ray photoelectron spectroscopy were used to evaluate the film chemical states. Electrochemical quartz crystal microbalance (EQCM) analysis coupled to potentiodynamic polarization was employed to investigate the dissolution behavior of the MePIIID deposited layer. The copper film presented a crystalline character and its surface chemical state was mainly comprised of Cu2O. EQCM measurements provided good basis for estimating the thickness reduction and anodic dissolution rate of the as-deposited layer, proving to be a valuable tool for developing and evaluating copper-based MePIIID films for electronic applications.

Improved Multiprotein Microcontact Printing on Plasma Immersion Ion Implanted Polystyrene.

Multiprotein micropatterning allows the creation of complex, controlled microenvironments for single cells that can be used for the study of the localized effects of various proteins and signals on cell survival, development, and functions. To enable analysis of cell interactions with microprinted proteins, the multiprotein micropattern must have low cross-contamination and high long-term stability in a cell culture medium. To achieve this, we employed an optimized plasma ion immersion implantation (PIII) treatment to provide polystyrene (PS) with the ability to covalently immobilize proteins on contact while retaining sufficient transparency and suitable surface properties for contact printing and retention of protein activity. The quality and long-term stability of the micropatterns on untreated and PIII treated PS were compared with those on glass using confocal microscopy. The protein micropattern on the PIII treated PS was more uniform and had a significantly higher contrast that was not affected by long-term incubation in cell culture media because the proteins were covalently bonded to PIII treated PS. The immunostaining of mouse pancreatic β cells interacting with E-cadherin and fibronectin striped surfaces showed phosphorylated paxillin concentrated on cell edges over the fibronectin stripes. This indicates that multiprotein micropatterns printed on PIII treated PS can be used for high-resolution studies of local influence on cell morphology and protein production.

Plasma-Immersion Formation of High-Intensity Ion Beams

For the first time, the possibility of forming high-intensity beams of low-energy metal and gas ions is demonstrated experimentally. The use of a hybrid system for ion-beam formation including plasmaimmersion extraction and ion acceleration and their subsequent ballistic focusing in an equipotential space with neutralization of the space charge of the beam made possible the pulse-periodic formation of titanium and nitrogen ion beams with an ion-current density of more than 1 A/cm2 and a pulsed power density of 2.6 kW/cm2.

Investigation of microstructure and properties of ultrathin graded ZrNx self-assembled diffusion barrier in deep nano-vias prepared by plasma ion immersion implantation

Ultrathin graded ZrNx self-assembled diffusion barriers with controllable stoichiometry was prepared in Cu/p-SiOC:H interfaces by plasma immersion ion implantation (PIII) with dynamic regulation of implantation fluence. The fundamental relationship between the implantation fluence of N+ and the stoichiometry and thereby the electrical properties of the ZrNx barrier was established. The optimized fluence of a graded ZrN thin film with gradually decreased Zr valence was obtained with the best electrical performance as well. The Cu/p-SiOC:H integration is thermally stable up to 500°C due to the synergistic effect of Cu3Ge and ZrNx layers. Accordingly, the PIII process was verified in a 100-nm-thick Cu dual-damascene interconnect, in which the ZrNx diffusion barrier of 1nm thick was successfully self-assembled on the sidewall without barrier layer on the via bottom. In this case, the via resistance was reduced by approximately 50% in comparison with Ta/TaN barrier. Considering the results in this study, ultrathin ZrNx conformal diffusion barrier can be adopted in the sub–14nm technology node.

Nanoscale Layer Transfer by Hydrogen Ion-Cut Processing: A Brief Review Through Recent U.S. Patents.

A hydrogen-based Ion-Cut layer-transfer technique, the so-called Ion-Cut or Smart-Cut processing, has been used in transferring a semiconductor membrane onto a desired substrate to reveal unique characteristics on a nanoscale size and to build functional electronic and photonic devices that are used for specific purposes. For example, the sub-100 nm thick silicon membrane transferred onto an insulator became a key substrate for fabricating nanoscale integrated circuit (IC) devices. Recent U.S. patents have exhibited integration of various thinning approaches requiring precision of a few nanometers in fabricating large-area semiconductor nanomembranes, especially for silicon. This paper reviews published patents and work on fabricating sub-100 nm silicon membranes with welldefined features without a chemical-mechanical polishing (CMP) thinning process. This included material analysis leads to ultraprecision thickness in the sub-100 nm region. This paper combines an analysis of peer-reviewed articles and issued patents using focused review keywords of hydrogen implantation, wafer bonding, and layer splitting. The quality of selected patents was appraised based on the authors' 20-year research experience in the field of ultrathin silicon layer-transfer technology. The paper covered more than 10 U.S. patents that have been filed on hydrogen-based Ion-Cut layer-transfer techniques. These patents described approaches for inserting hydrogen ions to split at a well-defined location and then transfer the as-split silicon membrane at the nanoscale thickness onto a desired substrate. Hydrogen-trap sites, implantation energy, and interface of the distinct doped regions could define the layer-split location. The insertion of high-dose hydrogen ions could be thoroughly achieved by ion implantation, plasma ion immersion implantation (PIII), plasma diffusion, and electrolysis. The article concludes with the discussion of the patent-orientated review of layer-transfer techniques and makes some concrete suggestions for manufacturing the FDSOI substrate, the key material technology to fabricate nanoscale microelectronics for applications in artificial intelligence for "Industry 4.0."

The effects of oxygen plasma implantation on bipolar resistive-switching properties of copper nitride thin films

Copper nitride (CuxN) thin films were prepared by plasma ion immersion implantation (PIII) then post-processed with oxygen plasma implantation at a voltage of −1.5kV. The resistive-switching properties of the CuxN:O-based RRAM devices were studied with different oxygen implantation time from 0 to 20min. The memory cells processed with oxygen plasma implantation for 5min showed longest endurance performances, largest resistance window and highest yield. Linear fitting results of the electrical measurements indicated the formation of copper oxide (CuO) is benefit for prolonged cycle life of the CuxN based RRAM devices, while increasing Cu2O species will lead to severe performance degradation.

Stabilization of the GeO2/Ge Interface by Nitrogen Incorporation in a One-Step NO Thermal Oxynitridation.

The thermal instability of GeO2/Ge structures lasts as a barrier against the development of Ge-based metal-oxide-semiconductor devices. In the present work, stabilization was achieved through the incorporation of nitrogen into the oxide layer by thermally growing GeOxNy films in NO. With this approach, a stable layer is obtained in a single step as opposed to other nitridation techniques (like plasma immersion) which require additional processing. Significant reduction of GeO desorption from the surface and a strong barrier against additional substrate oxidation were obtained by the insertion of a small amount of nitrogen content (N/O ≈ 10%). Nuclear reaction analysis and profiling showed that nitrogen incorporation and removal occur simultaneously during film growth, yielding N to be distributed throughout the whole film, without accumulation in any particular region. Both the oxidation barrier and the lower GeO desorption rate are explained by a reduction of vacancy diffusivity inside the dielectric. This is not caused by the densification of the oxide, but is a consequence of nitrogen blockage of oxygen vacancy diffusion paths.

Nanomodified Peek Dental Implants: Bioactive Composites and Surface Modification-A Review.

Purpose. The aim of this review is to summarize and evaluate the relevant literature regarding the different ways how polyetheretherketone (PEEK) can be modified to overcome its limited bioactivity, and thereby making it suitable as a dental implant material. Study Selection. An electronic literature search was conducted via the PubMed and Google Scholar databases using the keywords “PEEK dental implants,” “nano,” “osseointegration,” “surface treatment,” and “modification.” A total of 16 in vivo and in vitro studies were found suitable to be included in this review. Results. There are many viable methods to increase the bioactivity of PEEK. Most methods focus on increasing the surface roughness, increasing the hydrophilicity and coating osseoconductive materials. Conclusion. There are many ways in which PEEK can be modified at a nanometer level to overcome its limited bioactivity. Melt-blending with bioactive nanoparticles can be used to produce bioactive nanocomposites, while spin-coating, gas plasma etching, electron beam, and plasma-ion immersion implantation can be used to modify the surface of PEEK implants in order to make them more bioactive. However, more animal studies are needed before these implants can be deemed suitable to be used as dental implants.

Surface morphology of RF plasma immersion H+ ion implanted and oxidized Si(100) surface

The surface morphology of p-Si(100) wafers after RF plasma immersion (PII) H+ ion implantation into a shallow Si surface layer and after subsequent thermal oxidation was studied by atomic-force microscopic (AFM) imaging. After PII implantation of hydrogen ions with an energy of 2 keV and fluences ranging from 1013 cm−2 to 1015 cm−2 the Si wafers were oxidized in dry O2 at temperatures ranging from 700 °C to 800 °C. From the analysis of the AFM images, the surface amplitude parameters were evaluated and considered in terms of the technological conditions. The amplitude parameters showed a clear dependence on the H+ dose and the oxidation temperature, with the tendency of increasing with the increase of both the H+ ion fluence and the oxidation temperature. The implantation causes surface roughening, changing the RMS roughness value from 0.15 nm (typical for a polished Si(100) surface) to the highest value 0.6 nm for the H+ fluence of 1015 ions/cm2. Oxidation of the H+ implanted Si region, as the oxide is growing inward into Si, levels away the pits created by implants and results in a smoother surface, although keeping the RMS values larger than 0.2 nm.

Cell surface antigen profiling using a novel type of antibody array immobilised to plasma ion-implanted polycarbonate.

To identify and sort out subpopulations of cells from more complex and heterogeneous assemblies of cells is important for many biomedical applications, and the development of cost- and labour-efficient techniques to accomplish this is warranted. In this report, we have developed a novel array-based platform to discriminate cellular populations based on differences in cell surface antigen expressions. These cell capture microarrays were produced through covalent immobilisation of CD antibodies to plasma ion immersion implantation-treated polycarbonate (PIII-PC), which offers the advantage of a transparent matrix, allowing direct light microscopy visualisation of captured cells. The functionality of the PIII-PC array was validated using several cell types, resulting in unique surface antigen expression profiles. PIII-PC results were compatible with flow cytometry, nitrocellulose cell capture arrays and immunofluorescent staining, indicating that the technique is robust. We report on the use of this PIII-PC cluster of differentiation (CD) antibody array to gain new insights into neural differentiation of mouse embryonic stem (ES) cells and into the consequences of genetic targeting of the Notch signalling pathway, a key signalling mechanism for most cellular differentiation processes. Specifically, we identify CD98 as a novel marker for neural precursors and polarised expression of CD9 in the apical domain of ES cell-derived neural rosettes. We further identify expression of CD9 in hitherto uncharacterised non-neural cells and enrichment of CD49e- and CD117-positive cells in Notch signalling-deficient ES cell differentiations. In conclusion, this work demonstrates that covalent immobilisation of antibody arrays to the PIII-PC surface provides faithful cell surface antigen data in a cost- and labour-efficient manner. This may be used to facilitate high throughput identification and standardisation of more precise marker profiles during stem cell differentiation and in various genetic and disease contexts.