A full characterization of plasma polymerized biofunctional films requires the use of multi-analytical approaches to determine the chemical composition, topography and potential interaction mechanisms of such films with biomolecules and cells. In this work we aim at underlining the versatility of ion-based techniques to contribute to the chemical characterization of plasma polymerized surfaces. The simultaneous use of energy recoil detection (ERD) and Rutherford backscattering (RBS) spectroscopies with incident He ions is an example of this versatility. Performing sequential measurements and the use of correlating computing tools for ERD-RBS interpretation allows providing in-depth concentration profiles of light elements, including namely hydrogen. More accurate analysis of light elements in polymer films can be increased by looking for particular ions with resonant backscattering responses (i.e., non-Rutherford Scattering). In particular, proton beams of 1.765 MeV are used to increase the detection of C and N, and particular incidence and detector angles to diminish the Si substrate contribution. These analytical tools have been applied to allylamine films and multi-layers crosslinked in a capacitive plasma onto both Si and porous Si substrates.

The 4d → 4f Fano resonances for various rare earth doped GaN thin films (RE = Gd, Er, Yb) were investigated using synchrotron photoemission spectroscopy. The resonant photoemission Fano profiles show that the major Gd and Er rare earth 4f weight is at about 5–6 eV below the valence band maximum, similar to the 4f weights in the valence band of many other rare earth doped semiconductors. For Yb, there is very little resonant enhancement of the valence band of Yb doped GaN, consistent with a largely 4f14 occupancy.

Chemical composition and topography of titanium surface are important factors to improve osteointegration. Surfaces with different roughness and chemical composition respond differently when in a biologic environment. In this work, calcium incorporation to Al2O3 sandblasted titanium surfaces has been achieved by Plasma Immersion Ion Implantation and Deposition (PIIID). Granulated calcium was sublimated by an electron beam at the same time as negative pulses (5 kV, 30 µs and 400 Hz) were applied to titanium samples immersed in argon DC plasmas. During the ON time of the pulses, positive ions in the plasma were implanted on the surface while between the pulses the surface was covered by a metallic calcium layer. Modified surfaces were characterized before and after soaking the samples in simulated body fluid (SBF), to evaluate the effect of the treatments on the titanium bioactivity. Morphology, composition and chemical structure were evaluated by scanning electron microscopy, energy dispersive and infrared absorption spectroscopies, respectively. Selected sample was also characterized by X-ray photoelectron spectroscopy. The results have shown that the concentrations of calcium and phosphorus, after the immersion in SBF, were larger on the plasma treated titanium samples if compared to the as-received material. Those elements can be present on the surface forming bioactive species such as CaTiO3, CaCO3 and hydroxyapatite (HA).

This paper proposes a general applicable algorithm for the optimization of the current density distribution in the electrochemical cells using the insulating shields during the electroplating process. The innovative aspect is that the position of the insulating shield is displaced over a number of predefined time steps convecting its surface proportional with and in the direction of a well chosen rate provided by a genetic algorithm. The aim of this method is to develop a systematic modification of the insulating shield position in order to get a more uniform distribution of the current density, hence a more uniform deposited layer at the cathode. As the displacement of the insulating shield is performed with the Level Set Method, the re-meshing of the computational domain with finite elements is not required anymore. Finally an example related to the optimization of the current density distribution in the vicinity of a singularity (incident angle between the electrode and insulator = 180°), using an insulating shield, will be presented.

Cold plasma processes for surface engineering of biomaterials and biomedical devices are traditionally performed at low pressure; more and more, though, surface modification plasma processes at atmospheric pressure are also gaining popularity. This short review is aimed to list briefly atmospheric pressure plasma processes reported, in the last decade, for adapting the surface of materials to the best interactions with cells, bacteria and biomolecules.

The biocompatibility of polystyrene (PS) samples has been improved by treatment with weakly ionized highly non-equilibrium oxygen plasma. Samples were exposed to plasma for 30 s for which they have received a dose of ions of 4.5 × 1017 m−2 and a neutral oxygen atom dose of 3 × 10−23 m−2. Both untreated and plasma-treated samples were tested for biocompatibility according to the same procedure. Proliferation of human mammary epithelial cells (HMECs) on samples revealed a dramatically improved biocompatibility of polystyrene treated by oxygen plasma. The HMECs were deposited on all samples and incubated for 1, 2 and 6 days. MTT test revealed about two times higher activity of cell enzymes after 48 h incubation. The activity for plasma-treated samples remained much higher than for untreated samples even after 6 days of incubation when the samples were already covered with a dense film of HMECs.

Nonthermal plasma created in a catalyst-packed bed reactor was applied to the conversion of carbon oxides (CO and CO2) into methane. The methanation was performed over a Ni/alumina catalyst with the molar ratios of H2/CO and H2/CO2 at 3.0 and 4.0, respectively. The present work focused on the effect of nickel loading (0–12.5 wt.%) on the methanation rate over the temperature range of 200–300 °C. The applied voltage for creating nonthermal plasma was 6.4–10.3 kV (operating frequency: 1 kHz). For both CO and CO2, the behavior of the methanation in the plasma-catalytic reactor greatly depended on the applied voltage, resulting in higher conversion efficiencies at higher voltages. There was optimal nickel content of 2.5–5.0 wt.% where the plasma effect on the methanation rate was maximized. It is believed that the plasma created in the catalytic reactor can change the rate-determining step by accelerating the dissociation of carbon oxides adsorbed on the catalyst surface.

A dielectric barrier discharge (DBD) has been successfully applied to studying, both theoretically and experimentally, phenol degradation in waste water aqueous solutions. A coaxial reactor was selected where the liquid waste constitutes a part of the internal electrode itself, the liquid solution flowing up inside the hollow internal electrode impelled by a submersible pump. Thus, the solution falls by gravity on the external surface of the internal electrode. The DBD gas flows in parallel to the surface of the liquid. The cold plasma was generated from Ar-O2 mixture and O2 pure with the inclusion of moisture from the same solution. Two power supplies were compared delivering potentials up to 23 kV at 1.5 kHz, and up to 12 kV at 15.6 kHz respectively. The initial concentration of phenol was around 5 × 10−3 mol/L and efficiencies up to 99% were obtained after 1 h of treatment. Finally, a simplified kinetics model was developed where the temporal evolution of the compounds generated in the phenol degradation process was analyzed. Hydroquinone, catechol and resorcinol were obtained as byproducts and H2O, CO2 and some light carboxylic acids as final products.

We performed electron microscopy analysis of carbon tiles dismantled from the toroidal limiter of the Tore Supra tokamak. The tile top surfaces are either eroded, or covered with deposits, depending on ion flux. On the contrary, the tile gap surfaces are covered with deposits whatever the region of the limiter. We analyzed both the topography and the microstructure of gap deposits. Deposits are tip-shaped and deposition is significant only down to ~1 mm, due to the limited penetration of ions. The direction of tips results from the combination of the ion speed along the magnetic lines and the drift associated to the local electric fields. The microstructure of deposits reveals the presence of graphitic species, such as onion-like nanoparticles, and our results therefore show that deposition results from local plasma chemistry similar to what is observed for cold plasmas.

The development of a new passive wireless pressure sensor, based on an electromagnetic transduction approach, is reported. The sensing element is a flexible high resistivity silicon membrane located above a coplanar quarter-wavelength resonator. The comprehensive coverage of the physical bases is beyond the scope of this paper. For the remote extraction of the applied pressure value, the passive pressure sensor is connected to a broadband horn antenna via a coaxial delay line. When interrogated by a frequency modulated continuous wave radar, the level of the backscattered signal changes versus the pressure applied to the proof body. Through this interrogation principle, the sensor provides load impedance that is reflected back to the radar reader: the measured dynamic is about 0.8 dBm/bar. This completely passive and wireless pressure telemetry micro-sensor has been designed, fabricated and characterized, thereby eliminating the need for contact, signal processing circuits, and power supplies needed by conventional active sensors.

Ellipsometry is used as a technique to determine glass temperature transitions of isotactic Poly(methyl methacrylate) (iPMMA) ultra-thin films and isolated chains deposited on a silicon wafer surface. The importance of systematically probing the samples at different wavelengths is pointed out in this work since for a similar thin film, slope changes in delta are more or less pronounced according to the wavelength used. The technique performed on iPMMA thin films and isolated globular chains, deposited on Piranha treated surfaces, reveals the presence of multiple transitions, whereas films of comparable thicknesses deposited on HF treated silicon wafers show only one transition. The results confirm the assumptions of a layered structure yielding specific Tg(h) which depends on depth location, which is in good agreement with recent theories of glass transitions in confined polymers, and emphasize the influence of polymer-substrate interactions and chain disentanglement.

In the last decade, surface plasmon resonance (SPR) has become a very sensitive technique for real-time detection of chemical and biochemical targets in many application areas. Considering the important needs for analyzing biomolecular reactions through automated and miniaturized components, optical fiber sensors based on the SPR effects are presently considered as an alternative in the development of microsensors. In the present work, a microfluidic system associated with an optical fiber SPR sensor is developed and evaluated to monitor in real-time the sensitivity of optical fiber sensor to each kinetic reaction occurring at the surface. From the kinetic parameters obtained by our experimental measurements and then implemented in the numerical model, modeling allows us to demonstrate the potential of SPR optical fiber sensors for biological analysis.

A gravimetric surface acoustic wave (SAW) biosensor, based on the biotin-streptavidin and antistreptavidin-streptavidin recognitions, has been carried out. A network analyser and a pulse excitation technique were used to monitor both amplitude and phase changes. The SAW biosensor presented a total selective recognition of streptavidin-antistreptavidin and HRPstreptavidin-antistreptavidin. The presence of HRP (Horseradish peroxidase) affects neither the selectivity nor the sensitivity (of order of 0.25°/nM) of the biosensor, nevertheless, it causes a reduction of binding kinetics by a factor ranging between 2 to 5, as well as a diminution of antistreptavidin saturation concentration (of 40%). Results showed that equilibrium constants can be different, depending on evaluation method (from saturation values or from linear part of the output signal variation according to solution concentration).