Optical sensors based on plastic fibers Bilro, Lúcia; Alberto, Nélia; Pinto, João L ...
Sensors,
09/2012, Letnik:
12, Številka:
9
Journal Article, Book Review
Recenzirano
Odprti dostop
The recent advances of polymer technology allowed the introduction of plastic optical fiber in sensor design. The advantages of optical metrology with plastic optical fiber have attracted the ...attention of the scientific community, as they allow the development of low-cost or cost competitive systems compared with conventional technologies. In this paper, the current state of the art of plastic optical fiber technology will be reviewed, namely its main characteristics and sensing advantages. Several measurement techniques will be described, with a strong focus on interrogation approaches based on intensity variation in transmission and reflection. The potential applications involving structural health monitoring, medicine, environment and the biological and chemical area are also presented.
In this work, a network of fiber sensors has been developed for real time, in situ, and in operando multipoint monitoring the surface temperature distribution on a smartphone Li-ion battery (LiB). ...Different temperature and relative humidity conditions are considered, in order to mimic the LiB response in the dry, temperate, and cold climates. In total, the temperature variations that occur in five different locations of the LiB are monitored, during constant current charge and different discharge rates, under normal and abusive operating conditions, performing a thermal spatial mapping of the battery surface. In general, the sensors detect temperature variations according to the voltage signal change and faster variations of voltage usually translate in higher temperature rise at the LiB surface. For instance, under abusive discharge, where the voltage drop is fast, the temperature increases at least twice when compared to the normal operating conditions. Absolute temperature values as high as (65.0 ± 0.1) °C are detected by the optical sensor located near the electrodes, under the higher discharge rate (5.77 C) and dry climate. A thermal gradient is identified from the top to the bottom on the LiB surface during the experimental tests. A lower battery performance is observed when it operates under the cold climate, with maximum temperature variations of (30.0 ± 0.1) °C for the higher discharge rate. These results can be helpful to design of next generation of LiBs, improving a faster cooling in critical areas, in order to reduce accumulated heat and preventing consequences such as thermal runaway and failure.
Three different types of strain and temperature sensors based on negative curvature hollow core fiber (NCHCF) are proposed. Each sensor is produced by splicing a small section of the NCHCF between ...two sections of single mode fiber. Different types of interferometers are obtained simply by changing the splicing conditions. The first sensor consists on a single Fabry-Perot interferometer (FPI). The remaining two configurations are attained with the same sensing structure, depending on its position in relation to the interrogation setup. Thus, a double FPI or a hybrid sensor, the latter being composed by an FPI and a Michelson interferometer, are formed. The inline sensors are of submillimeter size, thus enabling nearly punctual measurements.
This paper focuses on three main issues regarding Material Extrusion (MEX) Additive Manufacturing (AM) of thermoplastic composites reinforced by pre-functionalized continuous Nickel-Titanium (NiTi) ...wires: (i) Evaluation of the effect of the MEX process on the properties of the pre-functionalized NiTi, (ii) evaluation of the mechanical and thermal behavior of the composite material during usage, (iii) the inspection of the parts by Non-Destructive Testing (NDT). For this purpose, an optical fiber sensing network, based on fiber Bragg grating and a cascaded optical fiber sensor, was successfully embedded during the 3D printing of a polylactic acid (PLA) matrix reinforced by NiTi wires. Thermal and mechanical perturbations were successfully registered as a consequence of thermal and mechanical stimuli. During a heating/cooling cycle, a maximum contraction of ≈100 µm was detected by the cascaded sensor in the PLA material at the end of the heating step (induced by Joule effect) of NiTi wires and a thermal perturbation associated with the structural transformation of austenite to R-phase was observed during the natural cooling step, near 33.0 °C. Regarding tensile cycling tests, higher increases in temperature arose when the applied force ranged between 0.7 and 1.1 kN, reaching a maximum temperature variation of 9.5 ± 0.1 °C. During the unload step, a slope change in the temperature behavior was detected, which is associated with the material transformation of the NiTi wire (martensite to austenite). The embedded optical sensing methodology presented here proved to be an effective and precise tool to identify structural transformations regarding the specific application as a Non-Destructive Testing for AM.
Strain and temperature are critical parameters to monitor in Li-ion batteries (LIBs) to improve their safety and long-term cycling stability. High local current densities can result in a massive heat ...release, decomposition of the electrolyte, gas evolution and even explosion of the battery cell, known as thermal runaway. However, the corrosive chemical environment in the batteries is a challenge to monitor strain and temperature. Optical fiber sensors, due to their high chemical stability and small diameter, can be embedded within the LIBs, thus becoming an interesting solution for operando and in situ measurements. In this work, a hybrid sensing network constituted by fiber Bragg gratings and Fabry-Perot cavities is proposed for the discrimination of strain and temperature. The proof-of-concept was performed by attaching the sensing network to the surface of a smartphone battery. Afterwards, it was embedded in a Li-ion pouch cell to monitor and simultaneously discriminate internal strain and temperature variations in three different locations. Higher thermal and strain variations are observed in the middle position. The methodology presented proves to be a feasible and non-invasive solution for internal, real-time, multipoint and operando temperature and strain monitoring of LIBs, which is crucial for their safety.
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•Optical fiber sensors embedded in LIBs for operando and in situ measurements.•Hybrid sensing network for internal discrimination of temperature and strain.•Thermal comparison between internal and external sensors.•Real-time and multipoint cell strain and temperature quantification.•Non-invasive, effective, and precise solution to promote LIB safety improvement.
•Cortisol detection based on surface plasmon resonance (SPR) using an unclad plastic optical fiber (POF).•High sensitivity and low limit of detection (LOD).•Selectivity of the proposed sensor for ...stress hormone was performed showing high specificity.•Optical sensor solution with relatively low-cost interrogation method, straightforward signal processing.•Interesting working range (0.005−10 ng/mL) for different biological samples from human or marine life.
This paper presents the development and feasibility tests of a cortisol immunosensor. The sensor is based on surface plasmon resonance (SPR) using an unclad plastic optical fiber (POF) in which the SPR is used as sensitivity enhancer, promoted by a gold/palladium (AuPd) alloy coating. The AuPd coated fibers were functionalized with an anti-cortisol antibody and passivated with bovine serum albumin (BSA) to be tested in the presence of cortisol as target analyte. The antibody-antigen binding reaction caused a variation of the refractive index on the surface of the AuPd coating, which leads to a shift of the SPR signature wavelength. The sensor was tested for different cortisol concentrations, ranging from 0.005 to 10 ng/mL. The reported biosensor presented a total wavelength shift of 15 nm for the testing range, putting in evidence a high sensitivity. Control tests for selectivity assessment were also performed. Concentrations as high as 10 ng/mL of cortisol, in a sensor functionalized with anti-hCG antibodies, only resulted in 1 nm variation of the resonance wavelength, 15 times lower than the one functionalized with the anti-cortisol antibodies, which indicates a high selectivity for the proposed approach. For this sensing approach the limit of detection (LOD) was determined to be 1 pg/mL. The proposed SPR based POF sensor has a low-cost interrogation method, high sensitivity and low LOD, straightforward signal processing and find important applications in different biological fields.
We experimentally demonstrate the first polymer optical fiber Bragg gratings inscribed with only one Nd:YAG laser (266 nm) pulse. The gratings have been inscribed in a single-mode poly (methyl ...methacrylate) optical fiber, with a core doped with benzyl dimethyl ketal for photosensitivity enhancement. One laser pulse with a duration of 8 ns and energy of 72 µJ is adequate to introduce a refractive index change of 0.5 × 10
in the fiber core. The stability of the gratings has been confirmed and the strain and temperature sensitivity measurements demonstrate their tunable properties.
Millisecond pulses of laser light delivered to gold nanoparticles residing in close proximity to the surface membrane of neurons can induce membrane depolarization and initiate an action potential. ...An optocapacitance mechanism proposed as the basis of this effect posits that the membrane-interfaced particle photothermally induces a cell-depolarizing capacitive current, and predicts that delivering a given laser pulse energy within a shorter period should increase the pulse’s action-potential-generating effectiveness by increasing the magnitude of this capacitive current. Experiments on dorsal root ganglion cells show that, for each of a group of interfaced gold nanoparticles and microscale carbon particles, reducing pulse duration from milliseconds to microseconds markedly decreases the minimal pulse energy required for AP generation, providing strong support for the optocapacitance mechanism hypothesis.
Abstract Background Puncture of the renal collecting system represents a challenging step in percutaneous nephrolithotomy (PCNL). Limitations related to the use of standard fluoroscopic-based and ...ultrasound-based maneuvers have been recognized. Objectives To describe the technique and early clinical outcomes of a novel navigation system for percutaneous kidney access. Design, setting, and participants This was a proof-of-concept study (IDEAL phase 1) conducted at a single academic center. Ten PCNL procedures were performed for patients with kidney stones. Surgical procedure Flexible ureterorenoscopy was performed to determine the optimal renal calyx for access. An electromagnetic sensor was inserted through the working channel. Then the selected calyx was punctured with a needle with a sensor on the tip guided by real-time three-dimensional images observed on the monitor. Outcome measurements and statistical analysis The primary endpoints were the accuracy and clinical applicability of the system in clinical use. Secondary endpoints were the time to successful puncture, the number of attempts for successful puncture, and complications. Results and limitations Ten patients were enrolled in the study. The median age was 47.1 yr (30–63), median body mass index was 22.85 kg/m2 (19–28.3), and median stone size was 2.13 cm (1.5–2.5 cm). All stones were in the renal pelvis. The Guy's stone score was 1 in nine cases and 2 in one case. All 10 punctures of the collecting system were successfully completed at the first attempt without X-ray exposure. The median time to successful puncture starting from insertion of the needle was 20 s (range 15–35). No complications occurred. Conclusions We describe the first clinical application of a novel navigation system using real-time electromagnetic sensors for percutaneous kidney access. This new technology overcomes the intrinsic limitations of traditional methods of kidney access, allowing safe, precise, fast, and effective puncture of the renal collecting system. Patient summary We describe a new technology allowing safe and easy puncture of the kidney without radiation exposure. This could significantly facilitate one of the most challenging steps in percutaneous removal of kidney stones.
PtOEP–PDMS-Based Optical Oxygen Sensor Penso, Camila M.; Rocha, João L.; Martins, Marcos S. ...
Sensors,
08/2021, Letnik:
21, Številka:
16
Journal Article
Recenzirano
Odprti dostop
The advanced and widespread use of microfluidic devices, which are usually fabricated in polydimethylsiloxane (PDMS), requires the integration of many sensors, always compatible with microfluidic ...fabrication processes. Moreover, current limitations of the existing optical and electrochemical oxygen sensors regarding long-term stability due to sensor degradation, biofouling, fabrication processes and cost have led to the development of new approaches. Thus, this manuscript reports the development, fabrication and characterization of a low-cost and highly sensitive dissolved oxygen optical sensor based on a membrane of PDMS doped with platinum octaethylporphyrin (PtOEP) film, fabricated using standard microfluidic materials and processes. The excellent mechanical and chemical properties (high permeability to oxygen, anti-biofouling characteristics) of PDMS result in membranes with superior sensitivity compared with other matrix materials. The wide use of PtOEP in sensing applications, due to its advantage of being easily synthesized using microtechnologies, its strong phosphorescence at room temperature with a quantum yield close to 50%, its excellent Strokes Shift as well as its relatively long lifetime (75 µs), provide the suitable conditions for the development of a miniaturized luminescence optical oxygen sensor allowing long-term applications. The influence of the PDMS film thickness (0.1–2.5 mm) and the PtOEP concentration (363, 545, 727 ppm) in luminescent properties are presented. This enables to achieve low detection levels in a gas media range from 0.5% up to 20%, and in liquid media from 0.5 mg/L up to 3.3 mg/L at 1 atm, 25 °C. As a result, we propose a simple and cost-effective system based on a LED membrane photodiode system to detect low oxygen concentrations for in situ applications.
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