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.

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.

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).