Experimental study of the sensitivity of a porous silicon ring resonator sensor using continuous in-flow measurements

A highly sensitive photonic sensor based on a porous silicon ring resonator was developed and experimentally characterized. The photonic sensing structure was fabricated by exploiting a porous silicon double layer, where the top layer of a low porosity was used to form photonic elements by e-beam lithography and the bottom layer of a high porosity was used to confine light in the vertical direction. The sensing performance of the ring resonator sensor based on porous silicon was compared for the different resonances within the analyzed wavelength range both for transverse-electric and transverse-magnetic polarizations. We determined that a sensitivity up to 439 nm/RIU for low refractive index changes can be achieved depending on the optical field distribution given by each resonance/polarization

ФОРМИРОВАНИЕ КРЕМНИЕВЫХ НАНОНИТЕЙ МЕТОДОМ МЕТАЛЛ-СТИМУЛИРОВАННОГО ХИМИЧЕСКОГО ТРАВЛЕНИЯ И ИССЛЕДОВАНИЕ ИХ ОПТИЧЕСКИХ СВОЙСТВ

The results of study and development of silicon nanowires (SiNWs) formation by metal-assisted chemical etching (MACE) are introduced. Linear dependence of SiNWs length from etching time is established. Total and mirror reflectance spectra, Raman scattering spectra of SiNWs and photoluminescence (PL) spectra are studied. Si band broadening and shifting to short-wave region in Raman spectra with increasing of etching time are revealed.Представлены результаты исследования особенностей формирования и оптических свойств кремниевых нанонитей (КН), формируемых методом металл-стимулированного химического травления (МСХТ) монокристаллического кремния дырочного и электронного типа проводимости. Установлено, что с увеличением времени химического травления длина КН линейно возрастает. Исследованы спектры полного и зеркального инфракрасного (ИК) отражения, спектры комбинационного рассеяния (КР) света сформированных КН, а также спектры фотолюминесценции (ФЛ). Выявлено, что полоса кремния в спектре КР с увеличением времени химического травления расширяется и сдвигается в коротковолновую область

Surface Enhanced Raman Spectroscopy of Lactoferrin Adsorbed on Silvered Porous Silicon Covered with Graphene

We registered surface enhanced Raman scattering (SERS) spectra of the human lactoferrin molecules adsorbed on a silvered porous silicon (por-Si) from 106–1018 M solutions. It was found that the por-Si template causes a negative surface potential of silver particles and their chemical resistivity to oxidation. These properties provided to attract positively charged lactoferrin molecules and prevent their interaction with metallic particles upon 473 nm laser excitation. The SERS spectra of lactoferrin adsorbed from 106 M solution were rather weak but a decrease of the concentration to 10-10 M led to an enormous growth of the SERS signal. This effect took place as oligomers of lactoferrin were broken down to monomeric units while its concentration was reduced. Oligomers are too large for a uniform overlap with electromagnetic field from silver particles. They cannot provide an intensive SERS signal from the top part of the molecules in contrast to monomers that can be completely covered by the electromagnetic field. The SERS spectra of lactoferrin at the 10-14 and 10-16 M concentrations were less intensive and started to change due to increasing contribution from the laser burned molecules. To prevent overheating the analyte molecules on the silvered por-Si were protected with graphene, which allowed the detection of lactoferrin adsorbed from the 10-18 M solution

Historique des techniques de génie biologique appliquées aux cours d'eau

International audienceLes végétaux vivants sont utilisés depuis fort longtemps, partout dans le monde, pour l'aménagement d'ouvrages de lutte contre l'érosion des terres. Florissant en France au XIXe siècle, le génie biologique connaît un regain d'intérêt en Europe depuis les années 30. Cet article répertorie, à partir d'une riche bibliographie, les différents types d'aménagements réalisés dans le passé, dans les cours d'eau et sur leurs berges, principalement en Europe. Depuis les barrages en fascines ou clayonnages jusqu'à l'enherbement des berges en briquettes de gazon, en passant par les gabions en osier, de nombreuses techniques, simples ou combinées, sont proposées. Aujourd'hui, les ouvrages associent de plus en plus des matériaux modernes (géotextiles par exemple), parfois synthétiques, aux végétaux

FORMATION OF SILICON NANOWIRES BY METAL-ASSISTED CHEMICAL ETCHING AND STUDY OF ITS OPTICAL PROPERTIES

The results of study and development of silicon nanowires (SiNWs) formation by metal-assisted chemical etching (MACE) are introduced. Linear dependence of SiNWs length from etching time is established. Total and mirror reflectance spectra, Raman scattering spectra of SiNWs and photoluminescence (PL) spectra are studied. Si band broadening and shifting to short-wave region in Raman spectra with increasing of etching time are revealed

La contamination historique aux PCB et aux HAP du bassin versant du lac du Bourget : quel impact sur la ressource en eau ?

International audienc

Nanostructured Metal Films Formed onto Porous Silicon Template

The review reports results of our research work on nanostructured metal films on porous silicon. Principal steps of the techniques allowing fabrication of metal films completely inheriting morphological pattern of different types of porous silicon are presented. It is shown, that imprinting of the nanostructured pattern to metal films by means of porous silicon template opens their new structural, optical, mechanical and electrical properties, which can be successfully applied in nanoelectronics and biomedicine, particularly including devices based on superconductivity effect, SERS analysis with picomolar sensitivity and transdermal drug delivery by electroporation

Nitrogen-doped twisted graphene grown on copper by atmospheric pressure CVD from decane precursor

We present Raman studies of graphene films grown on copper foil by atmospheric pressure CVD with n-decane as a precursor, a mixture of nitrogen and hydrogen as the carrier gas, under different hydrogen flow rates. A novel approach for the processing of the Raman spectroscopy data was employed. It was found that in particular cases, the various parameters of the Raman spectra can be assigned to fractions of the films with different thicknesses. In particular, such quantities as the full width at half maximum of the 2D peak and the position of the 2D graphene band were successfully applied for the elaborated approach. Both the G- and 2D-band positions of single layer fractions were blue-shifted, which could be associated with the nitrogen doping of studied films. The XPS study revealed the characteristics of incorporated nitrogen, which was found to have a binding energy around 402 eV. Moreover, based on the statistical analysis of spectral parameters and the observation of a G-resonance, the twisted nature of the double-layer fraction of graphene grown with a lower hydrogen feeding rate was demonstrated. The impact of the varied hydrogen flow rate on the structural properties of graphene and the nitrogen concentration is also discussed