Adilson R. Prado

Corrosion Resistant FBG-Based Quasi-Distributed Sensor for Crude Oil Tank Dynamic Temperature Profile Monitoring

This article presents a corrosion resistant, maneuverable, and intrinsically safe fiber Bragg grating (FBG)-based temperature optical sensor. Temperature monitoring is a critical activity for the oil and gas industry. It typically involves acquiring the desired parameters in a hazardous and corrosive environment. The use of polytetrafluoroethylene (PTFE) was proposed as a means of simultaneously isolating the optical fiber from the corrosive environment and avoiding undesirable mechanical tensions on the FBGs. The presented sensor head is based on multiple FBGs inscribed in a lengthy single mode fiber. The sensor presents an average thermal sensitivity of 8.82 ± 0.09 pm/°C, resulting in a typical temperature resolution of ~0.1 °C and an average time constant value of 6.25 ± 0.08 s. Corrosion and degradation resistance were verified by infrared spectroscopy and scanning electron microscopy during 90 days exposure to high salinity crude oil samples. The developed sensor was tested in a field pilot test, mimicking the operation of an inland crude tank, demonstrating its abilities to dynamically monitor temperature profile.

Polymethyl methacrylate (PMMA) recycling for the production of optical fiber sensor systems

This paper proposes the recycling of poly (methyl methacrylate) plates, formerly used in LCD monitors to produce polymer optical fibers without cladding for sensor systems and a discussion about the fabrication process of the fiber cladding is briefly presented. After disassembling LCD monitors the acrylic plate is cleaned and submitted to an extrusion process. Extrusion temperatures of 220°C, 230°C and 240°C were applied, and the produced polymer fibers were characterized by infrared and visible spectrometry, as well as evaluated for thermal analysis through differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Furthermore, a refractive index sensor was developed with the recycled fibers. Results show that the recycled fiber refractive index sensor is linear (R2 = 0.99) and presents a sensitivity of more than 4 times higher when compared to a sensor using a commercial POF.

Surface-Enhanced Raman Plasmon in Self-Assembled Sulfide-Coated Gold Nanoparticle Arrays

This paper investigates the surface-enhanced Raman plasmon in self-assembled gold nanoparticle arrays. The self-assembly process reported in this paper is triggered by the addition of sulfide in a sample of citrate-stabilized gold nanoparticles (AuNPs). The characterization of gold nanoparticle arrays was carried out by UV-visible absorption spectrum, transmission electron microscopy (TEM), and Raman map. Results demonstrate an aggregation of AuNPs with a peculiar physical docking resembling nanowires. Moreover, these nanostructures exhibited intense Raman scattering signal when compared with regular AuNPs. This simple technique is a candidate for future applications such as sensors for detecting sulfide compounds and nanosystem fabrication.

Comparison between the synthesis of gold nanoparticles with sodium citrate and sodium tetraboreto

Background With gold nanoparticles (AuNPs) is possible to develop nanoscale devices that can interact with chemical and biological systems. The phenomenon explored in these nanosystems is called Localized Surface Plasmon Resonance (LSPR), which promotes electromagnetic wave oscillation electronics on these small metallic structures. It is interesting to note that this resonance is directly linked to the size of the nanoparticles, the nature of the dielectric material and support environment where the device is being studied [1,2]. This work makes a comparison between results obtained in the synthesis of AuNP’s reduction method using a Sodium Citrate (Na3C6H5O7) and Sodium Borohydride (NaBH4). Was expected to demonstrate the viability of these two reducing agents and highlight the potential differences obtained in each of the mechanisms. Since knowledge is the ability of stabilizing citrate ions and the strong reducing action of NaBH4 [3]. The dominance of this knowledge will provide the development of systems with particle size specific for various applications in biosensors.

Ultrasensitive nanosensor based on silver nanoparticles to detect hydrogen peroxide

Studies to determine the concentration of hydrogen peroxide (H2O2) are important in biological system due to cellular damages provoked by reative oxygen species that include H2O2. An alternative to detect H2O2 is through an optical nanosensors based on silver nanoparticles, which have great potential for chemical and biological sensing applications. Here we demonstrate that attenuated total reflectance (ATR) from interaction of silver nanoparticles and hydrogen peroxide were able to detect very low levels of H2O2 around 0,001mM.

Quantification of Inter-particle Spacing Caused by Thiol Self-Assembled Monolayers Using Transmission Electron Microscopy

AbstractNano-surface modification techniques have been increasingly reported in a multitude of applications. However, the metal-ligand interface can be difficult to characterize, mainly due to the inadequacy of analytical methodologies. Here, we analyze this interface using transmission electron microscopy, which can determine the thickness of the linkers. This work presents a comprehensive physical characterization of gold nanoparticles with modified surfaces using conventional transmission electron microscopy. We have successfully demonstrated a simple and reliable protocol for the quantification of inter-particle spacing caused by SAM thiol ligands bound onto AuNPs. This approach is based on the linear correlation of the distance between the gold nanoparticles and the length of 3-mercaptopropionic acid (MPA), 11-mercaptoundecanoic acid (MUA), and 16-mercaptohexadecanoic acid (MHA). Graphical Abstract

Probing the Sulfur-Modified Capping Layer of Gold Nanoparticles Using Surface Enhanced Raman Spectroscopy (SERS) Effects

Gold nanoparticles (AuNP) exhibit particular plasmonic properties when stimulated by visible light, which makes them a promising tool to many applications in sensor technology and biomedical applications, especially when associated to sulfur-based compounds. Sulfur species form a great variety of self-assembled structures that cap AuNP and this interaction rules the optical and plasmonic properties of the system. Here, we report the behavior of citrate-stabilized gold nanospheres in two distinct sulfur colloidal solutions, namely, thiocyanate and sulfide ionic solutions. Citrate-capped gold nanospheres were characterized using ultraviolet–visible (UV-Vis) absorption, transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM). In the presence of sulfur species, we have observed the formation of NP clusters and chain-like structures, giving rise to surface-enhanced effects. Surface-enhanced Raman spectroscopy (SERS) pointed to a modification in citrate vibrational modes, which suggests substitution of citrate by either thiocyanate or sulfide ions with distinct dynamics, as showed by in situ fluorescence. Moreover, we report the emergence of surface-enhanced infrared absorption (SEIRA) effect, which corroborates SERS conclusions. Further, SEIRA shows a great potential as a tool for specification of sulfur compounds in colloidal solutions, which is particularly useful when dealing with sensor technology.

Ultrasensitive nanosensor based on gold nanoparticles to detect vascular endothelial growth factor (VEGF)

We report on the use of new biosensor that enable a surface Plasmon resonance (SPR) sensor to detec VEGF in tissue extracts and cell lysates. This sensor consist of gold nanoparticles functionalized with antibodies anti-VEGF. To analyze the optical properties and their sensing ability was held optical absorption experiments in band plasmon resonance. We demonstrate that this approach makes it possible for the SPR biosensor to detect VEGF in tissues at low concentrations.

Erratum to: Surface-Enhanced Raman Plasmon in Self-Assembled Sulfide-Coated Gold Nanoparticle Arrays

Fig 5 should be replaced by the caption of Fig. 7. It means: Caption Fig 5/correct form: Raman maps from Raman spectroscopy. 3D for gold nanoparticles a without sulfide and b with sulfide, both excited by 532 nm laser Fig 6 should be replaced by the caption of Fig. 5. It means: Caption Fig 6/correct form: Raman spectra of AuNP’s excited by lasers emitting in 532 and 633 nm. Raman spectra peaks are labeled on the graph Fig 7 should be replaced by the caption of Fig. 6. It means: Caption Fig 7/correct form: Raman spectra of gold nanoparticles with citrate and sulfide excited by lasers emitting in 532 nm. Raman spectra peaks are labeled on the graph, excited by 532 nm

Polarização plasmônica de superfície em nanopartículas de ouro

Atualmente a Ressonância de Plasmon de Superficie (SPR) vem proporcionando resultados significativos nas areas de sensores e efeito fotonico. Um caso particular de SPR e a Ressonância de Plasmon de Superficie Localizada, porem ao inves de ocorrer sobre um filme metalico fino manifesta-se em NPAu, gerando assim um efeito localizado que e entendido como uma oscilacao concorrente entre os eletrons livres no metal. Desse modo, a comunicacao e transmissao de energia de uma nanoparticula para outra ocorre de forma mais eficiente quando maior for a interacao de dipolo desses sistemas. Portanto, a adicao de um componente que promova o aumento da interacao das nanoparticulas por dipolo gera elevacao na absorbância desse sistema. Nesse trabalho foi explorado a interacao que ocorrer entre NPAu e ions de sulfeto. Devido a alta capacidade de interacao entre o enxofre e o ouro, as NPAu tornam-se mais coesas melhorando assim suas interacoes no sistema e, por consequencia, aumentando a interacao energetica entre as nanoparticulas. Tal comportamento apresenta caracteristicas interessantes com relacao a aplicacao em sensores e dispositivos tecnologicos.