RESUMEN
The present research exposes a novel methodology to manufacture fiber optic sensors following the etching process by Hydrofluoric Acid deposition through a real-time monitoring diameter measurement by computer vision. This is based on virtual instrumentation developed with the National Instruments® technology and a conventional digital microscope. Here, the system has been tested proving its feasibility by the SMS structure diameter reduction from its original diameter of 125 µ until approximately 42.5 µm. The results obtained have allowed us to demonstrate a stable state behavior of the developed system during the etching process through diameter measurement at three different structure sections. Therefore, this proposal will contribute to the etched fiber optic sensor development that requires reaching an enhanced sensitivity. Finally, to demonstrate the previously mentioned SMS without chemical corrosion, and the etched manufactured SMS, both have been applied as glucose concentration sensors.
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Tecnología de Fibra Óptica , Fibras Ópticas , Tecnología de Fibra Óptica/métodosRESUMEN
BACKGROUND: Fiber optic dosimetry (FOD) has emerged as a useful technique that can be used in those cases when intracavitary, real time, high spatial resolution dose assessment is required. Among the several factors characterizing a dosimeter, angular response of FOD probes has to be assessed in order to consider possible clinical application. PURPOSE: The objective of this study was to characterize the angular response of a FOD probe based on a cylindrical shaped YVO4 :Eu3+ scintillator under irradiation with a 6 MV photon beam generated by a linear accelerator (LINAC). METHODS: A FOD probe was irradiated inside a plastic phantom using a 6 MV LINAC photon beam at different azimuthal angles (0° to 360°, 15° steps). Scintillation output was measured with a photomultiplier tube. Similar measurements were performed with a second FOD probe having an optical filter interposed between the scintillator and the fiber. Monte Carlo simulations using PENELOPE were carried out in order to interpret the observed results. RESULTS: The FOD output was symmetrical with respect to the scintillator axis. For the unfiltered probe, the signal was maximum at rear incidence (0°) and steadily decreased down to its minimum value at frontal incidence (180°) having a signal ratio of 37%. The output of the filtered probe showed a plateau from 15° up to 115°. The signal was maximum at 60° and minimum at 180° having a signal ratio of 16%. Monte Carlo simulations predicted symmetry of the deposited dose about 0° and 90°, which contrasts with experimental findings. CONCLUSIONS: Photoluminescence (PL) of the scintillator induced by the Cherenkov light increases the angular dependence. Radiation attenuation inside the scintillator and partial light collection of the scintillation yield by the optical fiber (OF) are responsible for asymmetrical response. Results from this study should be considered in order to minimize angular dependence in FOD.
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Radiometría , Conteo por Cintilación , Conteo por Cintilación/métodos , Radiometría/métodos , Tecnología de Fibra Óptica , Fibras Ópticas , Aceleradores de PartículasRESUMEN
This paper presents the development and application of a multiplexed intensity variation-based sensor system for multiplane shape reconstruction. The sensor is based on a polymer optical fiber (POF) with sequential lateral sections coupled with a flexible light-emitting diode (LED) belt. The optical source modulation enables the development of 30 independent sensors using one photodetector, where the sensor system is embedded in polydimethylsiloxane (PDMS) resin in two configurations. Configuration 1 is a continuous PDMS layer applied in the interface between the flexible LED belt and the POF, whereas Configuration 2 comprises a 20 mm length PDMS layer only on each lateral section and LED region. The finite element method (FEM) is employed for the strain distribution evaluation in different conditions, including the strain distribution on the sensor system subjected to momentums in roll, pitch and yaw conditions. The experimental results of pressure application at 30 regions for each configuration indicated a higher sensitivity of Configuration 1 (83.58 a.u./kPa) when compared with Configuration 2 (40.06 a.u./kPa). However, Configuration 2 presented the smallest cross-sensitivity between sequential sensors (0.94 a.u./kPa against 45.5 a.u./kPa of Configuration 1). Then, the possibility of real-time loading condition monitoring and shape reconstruction is evaluated using Configuration 1 subjected to momentums in roll, pitch and yaw, as well as mechanical waves applied on the sensor structure. The strain distribution on the sensor presented the same pattern as the one obtained in the simulations, and the real-time response of each sensor was obtained for each case. In addition, the possibility of real-time loading condition estimation is analyzed using the k-means algorithm (an unsupervised machine learning approach) for the clusterization of data regarding the loading condition. The comparison between the predicted results and the real ones shows a 90.55% success rate. Thus, the proposed sensor device is a feasible alternative for integrated sensing in movement analysis, structural health monitoring submitted to dynamic loading and robotics for the assessment of the robot structure.
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Fibras Ópticas , Robótica , Elastómeros , Polímeros , Dimetilpolisiloxanos/químicaRESUMEN
This paper presents the development of an optical fiber sensor system for multiparametric assessment of temperature and turbidity in liquid samples. The sensors are based on the combination between fiber Bragg gratings (FBGs), intensity variation and surface plasmon resonance (SPR) sensors. In this case, the intensity variation sensors are capable of detecting turbidity with a resolution of about 0.5 NTU in a limited range between 0.02 NTU and 100 NTU. As the turbidity increases, a saturation trend in the sensor is observed. In contrast, the SPR-based sensor is capable of detecting refractive index (RI) variation. However, RI measurements in the turbidity calibrated samples indicate a significant variation on the RI only when the turbidity is higher than 100 NTU. Thus, the SPR-based sensor is used as a complementary approach for the dynamic range increase of the turbidity assessment, where a linearity and sensitivity of 98.6% and 313.5 nm/RIU, respectively, are obtained. Finally, the FBG sensor is used in the temperature assessment, an assessment which is not only used for water quality assessment, but also in temperature cross-sensitivity mitigation of the SPR sensor. Furthermore, this approach also leads to the possibility of indirect assessment of turbidity through the differences in the heat transfer rates due to the turbidity increase.
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Fibras Ópticas , Resonancia por Plasmón de Superficie , Temperatura , RefractometríaRESUMEN
An in-line digital optical sensor was proposed. It was built from a tapered depressed-cladding single-mode fiber and modeled as a coaxial Mach-Zehnder interferometer. The principle of operation of the optical digital sensor is based on the computation of the number of optical power transfer turning points (PTTP) from the transmission data of the component. Biconic tapers with high values of PTTP, high spectral resolution, high extinction ratio, and low insertion loss were modeled, fabricated, and characterized. As a proof of concept, an in-line digital strain sensor was fabricated and characterized. It presents a free spectral range of 1.3 nm, and produced 96 PTTP, at λ0 = 1.55 µm, under stretch of ΔL = 707 µm, therefore producing a digital resolution of 7.4 µm/PTTP. The sensor also produced a quasi-symmetric response to stretch and compression.
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Interferometría , Fibras ÓpticasRESUMEN
An optical strain gauge based on a balloon-like interferometer structure formed by a bent standard single-mode fiber combined with a 3D printer piece has been presented and demonstrated, which can be used to measure displacement. The interferometer has a simple and compact size, easy fabrication, low cost, and is repeatable. The sensor is based on the interference between the core and cladding modes. This is caused by the fiber's curvature because when light propagates through the curved balloon-shaped interferometer region, a portion of it will be released from the core limitation and coupled to the cladding. The balloon has an axial displacement as a result of how the artwork was constructed. The sensor head is sandwiched between two cantilevers such that when there is a displacement, the dimension associated with the micro bend is altered. The sensor response as a function of displacement can be determined using wavelength shift or intensity change interrogation techniques. Therefore, this optical strain gauge is a good option for applications where structure displacement needs to be examined. The sensor presents a sensitivity of 55.014 nm for displacement measurements ranging from 0 to 10 mm and a strain sensitivity of 500.13 pm/µÏµ.
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Tecnología de Fibra Óptica , Interferometría , Diseño de Equipo , Interferometría/métodos , Fibras Ópticas , Refractometría/métodosRESUMEN
As corrosion has slow development, its detection at an early age could be an alternative for reducing costs of structural rehabilitation. Therefore, the employment of structural health monitoring (SHM) systems, sensing configurations collecting data over time allowing for observing changes in the properties of the materials and damage emergence, for monitoring corrosion can be a good strategy to measure the damage and to decide the better moment for intervention. Nonetheless, the current corrosion sensor technology and the high costs of the sensing system implementation are limiting this application in the field. In this work, an optical fiber Bragg grating (FBG)-based sensing system is proposed for monitoring the thickness loss of a 1020 carbon steel metal plate subjected to controlled corrosion. The natural frequency of the plate was collected as a function of the corrosion time over 3744 h. To validate the experimental results, ultrasound measures and electrochemical tests were also carried out under similar conditions. The experimental results show adequate reliability, indicating the suitable functionality of the proposed system for monitoring the thickness loss caused by corrosion in metallic structures, in comparison with traditional methods, as ultrasonic and electrochemical measures.
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Tecnología de Fibra Óptica , Fibras Ópticas , Corrosión , Tecnología de Fibra Óptica/métodos , Reproducibilidad de los ResultadosRESUMEN
Sensing technologies using optical fibers have been studied and applied since the 1970s in oil and gas, industrial, medical, aerospace, and civil areas. Detecting ultrasound acoustic waves through fiber-optic hydrophone (FOH) sensors can be one solution for continuous measurement of volumes inside production tanks used by these industries. This work presents an FOH system composed of two optical fiber coils made with commercial single mode fiber (SMF) working in the sensor head of a Michelson's interferometer (MI) supported by an active stabilization mechanism that drives another optical coil wound around a piezoelectric actuator (PZT) in the reference arm to mitigate external mechanical and thermal noise from the environment. A 1000 mL glass graduated cylinder filled with water is used as a test tank, inside which the sensor head and an ultrasound source are placed. For detection, amplitudes and phases are measured, and machine learning algorithms predict their respective liquid volumes. The acoustic waves create patterns electronically detected with resolution of 1 mL and sensitivity of 340 mrad/mL and 70 mvolts/mL. The nonlinear behavior of both measurands requires classification, distance metrics, and regression algorithms to define an adequate model. The results show the system can determine liquid volumes with an accuracy of 99.4% using a k-nearest neighbors (k-NN) classification with one neighbor and Manhattan's distance. Moreover, Gaussian process regression using rational quadratic metrics presented a root mean squared error (RMSE) of 0.211 mL.
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Tecnología de Fibra Óptica , Fibras Ópticas , AlgoritmosRESUMEN
In many areas, the analysis of a cylindrical structure is necessary, and a form to analyze it is by evaluating the diameter changes. Some areas can be cited: pipelines for oil or gas distribution and radial growth of trees whose diameter changes are directly related to irrigation and the radial expansion since it depends on the water soil deficit. For some species, these radial variations can change in around 5 mm. This paper proposes and experimentally investigates a sensor based on a core diameter mismatch technique for diameter changes measurement. The sensor structure is a combination of a cylindrical piece developed using a 3D printer and a Mach-Zehnder interferometer. The pieces were developed to assist in monitoring the diameter variation. It is formed by splicing an uncoated short section of MMF (Multimode Fiber) between two standard SMFs (Singlemode Fibers) called SMF-MMF-SMF (SMS), where the MMF length is 15 mm. The work is divided into two main parts. Firstly, the sensor was fixed at two points on the first developed piece, and the diameter reduction caused dips or peaks shift of the transmittance spectrum due to curvature and strain influence. The fixation point (FP) distances used are: 5 mm, 10 mm, and 15 mm. Finally, the setup with the best sensitivity was chosen, from first results, to develop another test with an optimization. This optimization is performed in the printed piece where two supports are created so that only the strain influences the sensor. The results showed good sensitivity, reasonable dynamic range, and easy setup reproduction. Therefore, the sensor could be used for diameter variation measurement for proposed applications.
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Tecnología de Fibra Óptica , Interferometría , Diseño de Equipo , Interferometría/métodos , Fibras Ópticas , AguaRESUMEN
A data-driven-based methodology for SHM in reinforced concrete structures using embedded fiber optic sensors and pattern recognition techniques is presented. A prototype of a reinforced concrete structure was built and instrumented in a novel fashion with FBGs bonded directly to the reinforcing steel bars, which, in turn, were embedded into the concrete structure. The structure was dynamically loaded using a shaker. Superficial positive damages were induced using bonded thin steel plates. Data for pristine and damaged states were acquired. Classifiers based on Mahalanobis' distance of the covariance data matrix were developed for both supervised and unsupervised pattern recognition with an accuracy of up to 98%. It was demonstrated that the proposed sensing scheme in conjunction with the developed supervised and unsupervised pattern recognition techniques allows the detection of slight stiffness changes promoted by damages, even when strains are very small and the changes of these associated with the damage occurrence may seem negligible.
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Tecnología de Fibra Óptica , Fibras Ópticas , Tecnología de Fibra Óptica/métodos , AceroRESUMEN
In this work a plasmonic sensor with a D-Shaped microstructured optical fiber (MOF) is proposed to detect a wide range of analyte refractive index (RI ;na) by doping the pure silica (SiO2) core with distinct concentrations of Germanium Dioxide (GeO2), causing the presentation of high spectral sensitivity. In this case, the fiber is shaped by polishing a coating of SiO2, on the region that will be doped with GeO2, in the polished area, a thin gold (Au) layer, which constitutes the plasmonic material, is introduced, followed by the analyte, in a way which the gold layer is deposited between the SiO2. and the analyte. The numerical results obtained in the study shows that the sensor can determine efficiently a range of 0.13 refractive index units (RIU), with a limit operation where na varies from 1.32 to 1.45. Within this application, the sensor has reached an average wavelength sensitivity (WS) of up to 11,650.63 nm/RIU. With this level of sensitivity, the D-Shaped format and wide range of na detection, the proposed fiber has great potential for sensing applications in several areas.
Asunto(s)
Germanio , Fibras Ópticas , Resonancia por Plasmón de Superficie , Oro , Dióxido de Silicio , Resonancia por Plasmón de Superficie/instrumentaciónRESUMEN
Shape reconstruction is growing as an important real-time monitoring strategy for applications that require rigorous control. Polymer optical fiber sensors (POF) have mechanical properties that allow the measurement of large curvatures, making them appropriate for shape sensing. They are also lightweight, compact and chemically stable, meaning they are easy to install and safer in risky environments. This paper presents a sensor system to detect angles in multiple planes using a POF-intensity-variation-based sensor and a procedure to detect the angular position in different planes. Simulations are performed to demonstrate the correlation between the sensor's mechanical bending response and their optical response. Cyclic flexion experiments are performed at three test frequencies to obtain the sensitivities and the calibration curves of the sensor at different angular positions of the lateral section. A Fast Fourier Transform (FFT) analysis is tested as a method to estimate angular velocities using POF sensors. The experimental results show that the prototype had high repeatability since its sensitivity was similar using different test frequencies at the same lateral section position. The proposed approach proved itself feasible considering that all linear calibration curves presented a coefficient of determination (R2) higher than 0.9.
Asunto(s)
Fibras Ópticas , Polímeros , CalibraciónRESUMEN
In recent years, the chemical modification of optical fibers (OFs) has facilitated the manufacture of sensors because OFs can identify several analytes present in aqueous solutions or gas phases. Nevertheless, it is imperative better to understand the chemical interactions in this molecular system to generate low-cost and efficient sensors. This work presents a theoretical and experimental study of organic polymeric functionalized OF structures and proposes a cost-effective alternative to monitor breathing and humidity. The device is based on silicon optical fibers functionalized with (3-Aminopropyl) triethoxysilane (APTES) and alginate. The theoretical analysis is carried out to validate the activation of the silicon dioxide fiber surface; moreover, the APTES-alginate layer is discussed. The computational simulation suggests that water can be absorbed by alginate, specifically by the calcium atom linked to the carboxylic acid group of the alginate. The analysis also demonstrates a higher electrostatic interaction between the water and the OF-APTES-alginate system; this interaction alters the optical fiber activated surface's refractive index, resulting in transmission power variation. The humidity analysis shows a sensitivity of 3.1288 mV/RH, a time response close to 25 s, and a recovery time around 8 s. These results were achieved in the range of 50 to 95% RH. Moreover, the recovery and response time allow the human breath to be studied. The proposed mechanism or device is competitive with prior works, and the components involved made this sensor a cost-effective alternative for medical applications.
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Pruebas Respiratorias , Tecnología de Fibra Óptica , Fibras Ópticas , Diseño de Equipo , Humanos , Humedad , Polímeros , Refractometría , Dióxido de Silicio , AguaRESUMEN
Diabetes mellitus is a chronic metabolic disorder, being globally one of the most deadly diseases. This disease requires continually monitoring of the body's glucose levels. There are different types of sensors for measuring glucose, most of them invasive to the patient. Fiber optic sensors have been proven to have advantages compared to conventional sensors and they have great potential for various applications, especially in the biomedical area. Compared to other sensors, they are smaller, easy to handle, mostly non-invasive, thus leading to a lower risk of infection, high precision, well correlated and inexpensive. The objective of this review article is to compare different types of fiber optic sensors made with different experimental techniques applied to biomedicine, especially for glucose sensing. Observations are made on the way of elaboration, as well as the advantages and disadvantages that each one could have in real applications.
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Técnicas Biosensibles , Glucosa/análisis , Tecnología de Fibra Óptica , Humanos , Fibras ÓpticasRESUMEN
Vital signs not only reflect essential functions of the human body but also symptoms of a more serious problem within the anatomy; they are well used for physical monitoring, caloric expenditure, and performance before a possible symptom of a massive failure-a great variety of possibilities that together form a first line of basic diagnosis and follow-up on the health and general condition of a person. This review includes a brief theory about fiber optic sensors' operation and summarizes many research works carried out with them in which their operation and effectiveness are promoted to register some vital sign(s) as a possibility for their use in the medical, health care, and life support fields. The review presents methods and techniques to improve sensitivity in monitoring vital signs, such as the use of doping agents or coatings for optical fiber (OF) that provide stability and resistance to the external factors from which they must be protected in in vivo situations. It has been observed that most of these sensors work with single-mode optical fibers (SMF) in a spectral range of 1550 nm, while only some work in the visible spectrum (Vis); the vast majority, operate through fiber Bragg gratings (FBG), long-period fiber gratings (LPFG), and interferometers. These sensors have brought great advances to the measurement of vital signs, especially with regard to respiratory rate; however, many express the possibility of monitoring other vital signs through mathematical calculations, algorithms, or auxiliary devices. Their advantages due to miniaturization, immunity to electromagnetic interference, and the absence of a power source makes them truly desirable for everyday use at all times.
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Tecnología de Fibra Óptica , Monitoreo Fisiológico/métodos , Algoritmos , Frecuencia Cardíaca , Humanos , Interferometría , Fibras Ópticas , Signos VitalesRESUMEN
In this study, plastic optical fibre (POF) was considered as a light-transmitting medium and substrate for use in a photocatalytic environmental purification system, using Ag2MoO4 and ß-Ag2MoO4/Ag3PO4 as photocatalysts. Pure Ag2MoO4 and a ß-Ag2MoO4/Ag3PO4 composite were synthesized using a facile precipitation method. The composition, structures and optical properties of as-prepared catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emission scanning electron microscopy (FESEM), UV/Vis diffuse reflectance spectroscopy (UV/Vis DRS), BET surface area and TGA/DTG. The catalysts were immobilized on POF and on the glass reactor surface and their efficiency in the phenol degradation was evaluated in a batch reactor under visible light. The use of POF offers advantages such as ease of handling and good adherence characteristics to support Ag2MoO4. The photoactivity follows the order ß-Ag2MoO4/Ag3PO4 â Ag2MoO4 > TiO2 P25, for photocatalysts immobilized on the glass reactor surface or in aqueous suspension. The immobilization of Ag2MoO4 on POF revealed that thinner Ag2MoO4 coatings achieved faster pollutant removal rates from solution, and the optimal catalyst deposition is 0.64â mg/cm2, causing maximum the light penetration and electron-hole generation close to the solid-liquid interface.
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Fenol , Plata , Catálisis , Luz , Fibras Ópticas , Plásticos , Compuestos de PlataRESUMEN
Os fotopolimerizadores vêm sendo utilizados como dispositivos fundamentais na Odontologia para confecção de restaurações. No entanto, a etapa de fotopolimerização da resina composta inadequada pode afetar a união entre o material restaurador e o substrato. No caso dos agentes cimentantes resinosos a dificuldade está na limitação do local de incidência da luz. Em cimentações de retentores intrarradiculares pré-fabricados, normalmente são utilizados os cimentos de ativação química ou dupla ativação, devido a limitações anatômicas. Portanto, o objetivo deste trabalho foi avaliar o efeito da emissão de luz com fibra óptica, na cimentação de retentor intrarradicular experimental capaz de fotoativar em toda a extensão do conduto radicular. No estudo foi confeccionado um protótipo de ponta acessória em fibra óptica para fonte transmissora de luz que acoplado a um aparelho fotoativador (Bluephase, Ivoclar, Brasil) transmite a luz pelo interior do conduto radicular. Desta forma foram confeccionados em parceria com a empresa Angelus, retentores experimentais vazados ao longo dos seus eixos em fibra de vidro parcialmente opacos. Para simulação do conduto radicular foram utilizadas 80 amostras de resina G10 seccionadas no tamanho de 10 mm de largura por 14 mm de altura (n=80). Cada amostra foi perfurada ao centro nas seguintes dimensões: diâmetro de 3,0 mm e 10 mm de altura. Para cimentação dos retentores intrarradiculares foram utilizados cimento resinoso fotoativado ou dual. A fotoativação foi realizada diretamente com a ponta do aparelho fotoativador ou utilizando o dispositivo experimental transmissor de luz. As amostras foram analisadas imediatamente ou após o envelhecimento térmico de 10.000 ciclos. Para análiseda resistência de união as amostras foram seccionadas em 3 partes, com 2 mm cada (coronal, média e apical) e submetidas aos testes de resistência de união por push out, seguido da análise estereomicroscópica e análise espectroscópica no infravermelho transformada por Fourier (FT-IR). O dispositivo experimental transmissor de luz foi avaliado quanto a sua irradiância, e esta obteve 50% da energia quando comparada com obtida diretamente da ponteira do fotoativador. Após testes mecânicos, os resultados encontrados foram submetidos aos testes estatísticos, Anova com 3 fatores (cimento x fotoativação x profundidade) e Anova 2 fatores (envelhecimento x cimento), seguida de teste Tukey com nível de significância de 5%. Nos resultados de resistência houve diferença estatística entre os tipos de cimentos, profundidade, fotoativação e interação entre oscimentos e a profundidade, sendo que os grupos cimentados com os cimentos fotoativados e com o dispositivo houve uma maior resistência de união na porção média e apical. Com relação ao grau de conversão houve uma maior conversão e a análise estereomicroscópica apresentou maior falha adesiva na porção apical, independente da realização do envelhecimento. Portanto, a utilização do dispositivo obteve resultados promissores e o retentor intrarradicular experimental contribuiu para aumentar a adesão entre o cimento e o substrato em sua porção mais apical.
Photopolymerizers have been used as a fundamental device in dentistry for making restorations. Nonetheless, the stage for the photopolymerization of the composite resin is critical and can affect the adhesion between the restorative material and the substrate. In the case of resin cementing agents, the difficulty lies in limiting the location of the incidence of light. In cementations of prefabricated intraradicular retainers, chemical activation or double activation cements are normally used, due to anatomical limitations. Therefore, the objective of this work was to evaluate the effect of light emission with optical fiber in the cementation of experimental intraradicular retainer capable of photoactivating in the entire length of the root canal. In the study, a prototype of fiber optic accessory tip for light transmitting source was made, which coupled to a photoactivator device (Bluephase, Ivoclar, Brazil) transmits the light inside the root canal. Thus, they were made in partnership with the company Angelus, experimental retainers cast along their axes in partially opaque fiberglass. For simulation of the root canal were used 80 samples of resin G10 sectioned in size 10mm wide by 14mm high (n=80). Each sample was drilled in the center in the following dimensions: diameter 3.0 mm and height 10 mm. For the cementation of the intraradicular seals, light-cured or dual resin cement was used. The photoactivation was performed directly with the tip of the photoactivator device or using the light transmitting experimental device. The samples were analyzed immediately or after thermal aging of 10,000 cycles. For bond strength analysis, the samples were sectioned into 3 parts, with 2 mm each (coronal, mean and apical) and submitted to the bond strength tests by push out, followed by the stereomicroscopic analysis and infrared spectroscopic analysis by Fourier (FTIR). The Light Transmitting Experimental Device was evaluated for its irradiance and obtained 50% of the energy when compared to that obtained directly from the tip of the photoactivator. After mechanical tests, the results found were submitted to the statistical tests Anova with 3 factors (cement x photoactivation x depth) and Anova 2 factors (aging x cement), followed by Tukey's test with a significance level of 5%. In resistance results, there was a statistical difference between the types of cements, depth, photoactivation and interaction between the cements and depth, and the groups cemented with the photoactivated cements and the device had a greater bond strength in middle and apical portion. Regarding the degree of conversion, there was a greater conversion and the stereomicroscopic analysis, it showed greater adhesive failure in the apical portion, regardless of the performance of aging. Therefore, the use of the device obtained promising results and the experimental intraradicular retainer contributed to increase the adhesion between the cement and the substrate in its most apical portion.
Asunto(s)
Cementación , Equipo Dental , Pins Dentales , Curación por Luz de Adhesivos Dentales , Fibras Ópticas , Materiales Biocompatibles , Ensayo de Materiales , Análisis de Varianza , Cementos DentalesRESUMEN
Advances in robotic systems for rehabilitation purposes have led to the development of specialized robot-assisted rehabilitation clinics. In addition, advantageous features of polymer optical fiber (POF) sensors such as light weight, multiplexing capabilities, electromagnetic field immunity and flexibility have resulted in the widespread use of POF sensors in many areas. Considering this background, this paper presents an integrated POF intensity variation-based sensor system for the instrumentation of different devices. We consider different scenarios for physical rehabilitation, resembling a clinic for robot-assisted rehabilitation. Thus, a multiplexing technique for POF intensity variation-based sensors was applied in which an orthosis for flexion/extension movement, a modular exoskeleton for gait assistance and a treadmill were instrumented with POF angle and force sensors, where all the sensors were integrated in the same POF system. In addition, wearable sensors for gait analysis and physiological parameter monitoring were also proposed and applied in gait exercises. The results show the feasibility of the sensors and methods proposed, where, after the characterization of each sensor, the system was implemented with three volunteers: one for the orthosis on the flexion/extension movements, one for the exoskeleton for gait assistance and the other for the free gait analysis using the proposed wearable POF sensors. To the authors' best knowledge, this is the first time that optical fiber sensors have been used as a multiplexed and integrated solution for the simultaneous assessment of different robotic devices and rehabilitation protocols, where such an approach results in a compact, fully integrated and low-cost system, which can be readily employed in any clinical environment.
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Dispositivo Exoesqueleto , Fibras Ópticas , Rehabilitación/instrumentación , Robótica , Marcha , Humanos , PolímerosRESUMEN
Abstract Introduction: In the management of the anticipated difficult airway (DA), awake intubation is the strategy of choice. In this context, flexible fibroscopy is the tool most widely used as the first choice. However, there is always the rare case where it may fail. Important findings: Six successful rescue cases using videolaryngoscopy following failed fibroscopy in patients with anticipated DA, and 1 case of rescued extubation of an airway previously secured with fiberoptic bronchoscopy. Conclusion: Videolaringoscopy may be an adequate tool to use as a backup plan for the management of an anticipated DA.
Resumen Introducción: En el manejo de vía aérea difícil anticipada la estrategia de elección es la intubación con el paciente despierto. En este contexto, la fibroscopia flexible es la herramienta más utilizada como plan A; sin embargo, en raras ocasiones puede fallar. Hallazgos importantes: Se presentan seis casos de rescates exitosos con videolaringoscopia luego de fibroscopia fallida en pacientes con vía aérea difícil anticipada, y un caso de rescate de extubación de vía aérea asegurada previamente con fibrobroncoscopio. Conclusión: La videolaringoscopia puede ser una adecuada herramienta como plan B para el manejo de la vía aérea difícil anticipada.
Asunto(s)
Humanos , Masculino , Femenino , Adulto , Persona de Mediana Edad , Manejo de la Vía Aérea , Fracaso de Rescate en Atención a la Salud , Intubación Intratraqueal , Laringoscopía , Técnicas de Diagnóstico del Sistema Respiratorio , Fibras ÓpticasRESUMEN
There is a general lack of published studies on the risk of mortality due to alterations in the safety of swallowing detected during the fiberoptic endoscopic evaluation of swallowing (FEES). We aimed at assessing the risk of mortality of the detection of aspiration, penetration, and pharyngeal residues by FEES. A cohort of consecutively evaluated patients suspected of experiencing oropharyngeal dysphagia undergoing FEES at a tertiary care university hospital were prospectively followed up on to assess mortality. The FEES findings, comorbidities, and potential confounders were studied as predictors of death using a Cox multivariate regression analysis. A total of 148 patients were included, 85 of whom were male (57.4%). The mean age (± standard deviation) was 52.7 years (± 22.1). The median of the follow-up time was 4.5 years. The most frequent conditions were stroke in 50 patients (33.8%), brain and spine traumas in 27 (18.2%), and neurodegenerative diseases in 19 (12.8%). Variables associated with mortality in bivariate analyses were age > 65 years (p < 0.001), pneumonia (p = 0.046), aspiration of any consistency (p < 0.001), and pharyngeal residues (p = 0.017). Variables independently associated with mortality in the Cox multivariate model were age (> 65 years) [adjusted hazard ratio (HR) 5.76; 95% CI 2.72 to 17.19; p = 0.001] and aspiration (adjusted HR: 3.96; 95% CI 1.82 to 14.64; p = 0.003). Aspiration detected by FEES and an age > 65 years are independent predictors of mortality in patients with oropharyngeal dysphagia.