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International audience; Nanocomposite thin films, composed of monometallic Au and Ag, and bimetallic AuAg nanoparticles, dispersed in a CuO matrix were prepared, characterised and tested for Localized Surface Plasmon Resonance (LSPR) sensing. The films were deposited by reactive magnetron sputtering, followed by a post-deposition thermal annealing to modify the size and shape of the nanoparticles distribution within the oxide matrix. Regarding the main results of the monometallic systems, the Au:CuO films showed LSPR bands from 800 nm to 650 nm, which reveal a progressive narrowing and a continuous blue-shift with increasing temperature (400–700 °C). The Ag:CuO films evidenced plasmonic bands at about 400 nm for temperatures of 500 °C and above. The bimetallic system, Au-Ag:CuO, showed LSPR bands in the range between those of the corresponding monometallic systems, due to the presence of Ag enriched AuAg alloy nanoparticles, taking part of Janus-like structures in some cases. In terms of LSPR sensing, Au:CuO films revealed the highest values of refractive index sensitivity since the nanoparticles are more exposed to the surrounding environment.

International audience; AbstractIn this work, a versatile method is proposed to increase the sensitivity of optical sensors based on the localized surface plasmon resonance (LSPR) phenomenon. It combines a physical deposition method with the oblique angle deposition technique, allowing the preparation of plasmonic thin films with tailored porosity. Thin films of Au–TiO2 were deposited by reactive magnetron sputtering in a 3D nanostructure (zigzag growth), at different incidence angles (0°„α„80°), followed by in-air thermal annealing at 400°C to induce the growth of the Au nanoparticles. The roughness and surface porosity suffered a gradual increment by increasing the incidence angle. The resulting porous zigzag nanostructures that were obtained also decreased the principal refractive indexes (RIs) of the matrix and favoured the diffusion of Au through grain boundaries, originating broader nanoparticle size distributions. The transmittance minimum of the LSPR band appeared at around 600nm, leading to a red-shift to about 626nm for the highest incidence angle α=80°, due to the presence of larger (scattering) nanoparticles. It is demonstrated that zigzag nanostructures can enhance adsorption sites for LSPR sensing by tailoring the porosity of the thin films. Atmosphere controlled transmittance-LSPR measurements showed that the RI sensitivity of the films is improved for higher incidence angles.

"Available online 20 September 2017.", Nanomaterials based on Localized Surface Plasmon Resonance (LSPR) phenomena are revealing to be an important solution for several applications, namely those of optical biosensing. The main reasons are mostly related to their high sensitivity, with label-free detection, and to the simplified optical systems that can be implemented. For the present work, the optical sensing capabilities were tailored by optimizing LSPR absorption bands of nanocomposite Au/TiO 2 thin films. These were grown by reactive DC magnetron sputtering. The main deposition parameters changed were the number of Au pellets placed in the Ti target, the deposition time, and DC current applied to the Ti-Au target. Furthermore, the Au NPs clustering, a key feature to have biosensing responses, was induced by several post-deposition in-air annealing treatments at different temperatures, and investigated via SEM analysis. Results showed that the Au/TiO2 thin films with a relatively low thickness (∼100 nm), revealing concentrations of Au close to 13 at.%, and annealed at temperatures above 600 °C, had the most well-defined LSPR absorption band and thus, the most promising characteristics to be explored as optical sensors. The NPs formation studies revealed an incomplete aggregation at 300 and 500 ⁰C and well-defined spheroidal NPs for higher temperatures. Plasma treatment with Ar led to a gradual blue-shift of the LSPR absorption band, which demonstrates the sensitivity of the films to changes in the dielectric environment surrounding the NPs (essential for optical sensing applications) and the exposure of the Au nanoparticles (crucial for a higher sensitivity)., This research was sponsored by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013 and FCT Project 9471 - Reforçar a Investigação, o Desenvolvimento Tecnológico e a Inovação (Projeto 9471-RIDTI), comparticipado pelo Fundo Comunitário Europeu FEDER and with reference PTDC/FIS-NAN/1154/2014. Joel Borges also acknowledges FCT for his Post-Doc Grant SFRH/BPD/117010/2016 and Marco S. Rodrigues acknowledges his PhD-Grant from FCT with reference SFRH/BD/118684/2016. Paulo Pedrosa acknowledges the support by the region of Franche-Comté in cooperation with the Labex ACTION program (contract ANR-11-LABX-01-01) and also the MIMENTO Platform of the RENATECH network., info:eu-repo/semantics/publishedVersion

International audience; Inclined, zigzag and spiral TiAg films were prepared by glancing angle co-deposition, using two distinct Ti and Ag targets with a particle incident angle of 80° and Ag contents ranging from 20 to 75 at%. The effect of increasing Ag incorporation and columnar architecture change on the morphological, structural and electrical properties of the films was investigated. It is shown that inclined columnar features (β = 47°) with high porosity were obtained for 20 at% Ag, with the column angle sharply decreasing (β = 21°) for 50 at% Ag, and steeply increasing afterwards until β = 37° for the film with 75 at% Ag. The sputtered films exhibit a rather well-crystallized structure for Ag contents ≥50 at%, with a TiAg (111) preferential growth. No significant oxidation was detected in all films, except for the one with 20 at% Ag, after two 298–473–298 K temperature cycles in air. The calculated temperature coefficient of resistivity (TCR) values vary between 1.4 and 5.5 × 10−4 K−1. Nano-sculptured spiral films exhibit consistently higher resistivity (ρ = 1.5 × 10−6 Ω m) and TCR values (2.9 × 10−4 K−1) than the inclined one with the same Ag content (ρ = 1.2 × 10−6 Ω m and TCR = 2.0 × 10−4 K−1). No significant changes are observed in the zigzag films concerning these properties. The effective anisotropy A eff at 473 K changes from 1.3 to 1.7 for the inclined films. Spiral films exhibit an almost completely isotropic behavior with A eff = 1.1. Ag-rich TiAg core + shell Janus-like columns were obtained with increasing Ag concentrations.

Several plasma treatments using argon, oxygen, and nitrogen are studied in order to increase the interfacial adhesion of the polyurethane/Ag:TiN system to be used as biopotential electrodes. The optimized plasma treatments conditions (100 W, 15 min, regardless of the gas) promote a steep decrease of the water contact angle values. The observed chemical and topographic alterations translate into excellent polyurethane/Ag:TiN interfacial adhesion of the plasma treated samples. The in-service validation of the proposed Ag:TiN-coated PU multipin electrodes is performed by acquiring EEG signals in parallel with the standard wet Ag/AgCl electrodes. No considerable differences are found in terms of shape, amplitude, and spectral characteristics of the signals when comparing reference wet and dry electrodes., This research is partially sponsored by FEDER funds through the program COMPETE – Programa Operacional Factores de Competitividade and by national funds through FCT – Fundação para a Ciência e a Tecnologia, under the projects PEst-C/EME/UI0285/2011, PTDC/SAU-ENB/116850/2010, PTDC/CTM-NAN/112574/2009 and Programa Pessoa 2012/2013 Cooperação Portugal/França, Project no. 27306UA Porous architectures in GRAded CERamic thin films for biosensors - GRACER. The authors would also like to acknowledge CEMUP for SEM analysis and Yantai Wanhua Polyurethanes Co., Ltd for providing the thermoplastic polyurethane pellets. P. Pedrosa acknowledges FCT for the Ph.D. grant SFRH/BD/70035/2010. P. Fiedler acknowledges the German Federal Ministry of Education and Research project – 03IPT605A. P. Pedrosa and P. Fiedler both acknowledge FP7-People Marie Curie IAPP project 610950 (ANDREA) and German Academic Exchange Services for the Germany/Portugal bi-lateral project – D/57036536.

International audience; Pure Vthin films weredcsputteredwithdifferentpressures(0.4and0.6Pa)andparticleincidentanglesα of 0°, 20° and 85°, byusingtheGLancingAngleDeposition(GLAD)technique.Thesputtered films werecharacterizedregardingtheirelectricalresistivitybehaviourinatmosphericpressureandin-vacuumconditions asafunctionoftemperature(40–550 °C), inordertocontroltheoxidationprocess.Aimingatcomprehending theoxidationbehaviourofthesamples,extensivemorphologicalandstructuralstudieswereperformedontheas-depositedandannealedsamples.Mainresultsshowthat,inoppositiontoannealing inair,thecolumnarnanostructuresarepreservedinvacuumconditions,keepingmetallic-likeelectrical properties.

International audience; In the present work, Agy:TiNx thin films,obtained by reactive DC magnetron sputtering, withdecreasing [N]/[Ti] atomic ratios (from 1 to 0.1) and afixed amount of Ag pellets placed in the erosion zone of apure Ti target, were studied envisaging their application asbiopotential electrodes. The strongly under-stoichiometricsamples, [N]/[Ti] = 0.1 and 10 at.% Ag; [N]/[Ti] = 0.2and 8 at.% Ag, were found to be composed of a N-dopedhcp-Ti structure, with possible formation of TiAg or Ti2Agintermetallics. These samples exhibit high electrical resistivityvalues and low hardness and reduced modulus. In theset of samples indexed to a transition zone, [N]/[Ti] = 0.3and 15 at.% Ag; [N]/[Ti] = 0.7 and 32 at.% Ag, a hcp-Tito fcc-TiN phase transformation took place, giving rise to adisaggregated N-deficient TiN matrix. It correlates with thehigh resistivity values as well as the higher hardness andreduced modulus values that were obtained. The lastidentified zone comprised the stoichiometric Ag:TiNxsample—[N]/[Ti] = 1 and 20 at.% Ag. Extensive metallicAg segregation was detected, contributing to a significantdecrease of the resistivity and hardness values.

This review adresses the application of concentrations and ratios of nutrients (nitrogen and phosphorus) in the diagnosis of eutrophication in natural waters. We present a brief history of eutrophication and considerations on eutrophicating elements. The use of ratios in the diagnosis of eutrophication has limitations, since there are other parameters that prevent the proliferation of phytoplankton even under optimal nutrient conditions. Assays are used to identify the nutrient limitation to phytoplankton growth, while the trophic state index is used to assess the state of nutritional enrichment of an aquatic ecosystem. This work highlights the importance of the diagnostic study of eutrophication in natural waters subjected to the human impact, and suggests actions to improve their conditions, such as protection of riparian areas, terracing of agricultural areas, use of the required amount of fertilizer, and treatment of effluents from sewage to reduce the loads of N and P for lotic environments. Esta revisão aborda a aplicação das concentrações e proporções de nutrientes (nitrogênio e fósforo) no diagnóstico da eutrofização em águas naturais. Foi realizado um breve histórico sobre a eutrofização e considerações sobre os elementos eutrofizantes. O uso das razões no diagnóstico da eutrofização apresenta limitações, uma vez que existem outros parâmetros que impedem a proliferação do fitoplâncton mesmo em condições ótimas de nutrientes. Os bioensaios são utilizados para identificar a limitação de nutrientes ao crescimento fitoplanctônico, enquanto o índice de estado trófico é utilizado para avaliar o estado de enriquecimento nutricional de um ecossistema aquático. Este trabalho destaca a importância do estudo de diagnóstico da eutrofização nas águas naturais submetidas aos impactos decorrentes da ação humana e sugere ações para melhoria de suas condições, como a proteção de matas ciliares, terraceamento de áreas agrícolas, a utilização da quantidade necessária de fertilizantes e o tratamento dos efluentes oriundos dos esgotos para reduzir as cargas de N e P para os ambientes lóticos.