Fiber Optic Detection Research Articles

Study on Polymer Matrix Composites Used as Greenhouse Coverings: Optical Properties

The greenhouse is widely used in agriculture, and its covering material is one of the most important factors that affect its performance. In summer, the inner temperature of the greenhouse is usually too high for people to cultivate plants. In this work, a polymer matrix composite (PMC) was developed to reduce the inner temperature of the greenhouse without affecting the photosynthesis for the growth of plants. The PMC developed in this study was made of LDPE with suitable additives such as pigments, metal oxide etc. The morphology of the covering layer made of the PMC was observed with the atomic force microscopy (AFM). The transmittance of visible light and NIR through the cladding layer was measured with an optical fiber detector and used as the primarily performance index. Finally a simulated greenhouse was used to verify the cooling effect of the cladding layer. Experimental results showed that the PMC developed in this study gave more temperature reduction than that of the commercial PE covering.

Analysing Human Nails Composition by Using Laser Induced Breakdown Spectroscopy

This study investigated the elemental composition of pathological and normal nails, according to different age groups and genders. The nail elemental composition was analyzed by using Laser Induced Breakdown Spectroscopy (LIBS) technique. A Q-switched Nd:YAG laser at 1064 nm with output energy of 100 mJ, pulse duration of 6 ns and repetition rate of 1 Hz was fired to the human nails sample. The laser pulse ablated the target sample surface and produced plasma plume with characteristic spectral line comprising sample's elemental composition. The plasma emission spectrum of nail samples were captured by fibre optic detection device and spectrometer equipped with ASEQ Spectra Software for elemental analysis. The elements detected in nails were Mg, Al, Ca, P, Ti, K and Na. Classification of nails into different age groups and genders demonstrate efficient results if compared with Dietary Reference Intakes (DRI). The results indicate that Ca, Al, Ti, P and K composition were higher among female. However, Mg and Na were higher among male. The results also show that Ca and K element decline as the age increase in both genders. The pathological nails' elemental compositions were also noticeably related to the nail disorder condition itself. It is proven that LIBS could be a possible method for analyzing the nails and identification of various nail disorders.

Ultra-high sensitive optical fiber hydrogen sensor using self-referenced demodulation method and WO3-Pd2Pt-Pt composite film.

A novel fiber optic hydrogen concentration detection platform with significantly enhanced performance is proposed and demonstrated in this paper. The hydrogen sensing probe was prepared by depositing WO3-Pd2Pt-Pt composite film on the fiber tip of two Bragg gratings paired with high-low reflectivity. At a room temperature of 25°C, the hydrogen sensor has a significant response towards 10 ppm hydrogen in nitrogen atmosphere, and may detect tens of ppb hydrogen changes when the hydrogen concentration is between 10~60 ppm. Besides, the proposed system shows quick response when the hydrogen concentration is above 40 ppm. Moreover, the hydrogen sensor shows good repeatability during the hydrogen response. This work proposes a new concept to develop hydrogen sensing technology with ultra-high sensitivity, which can significantly promote its potential application in various fields, especially for ultra-low hydrogen detection in oxygen-free environment.

Fluorescence fiber-optic turn-on detection of trace hydrazine vapor with dicyanovinyl-functionalized triazatruxene-based hyperbranched conjugated polymer nanoparticles

A solution-processed triazatruxene-based hyperbranched conjugated polymer nanoparticle was applied for fluorescence fiber-optic detection of hydrazine vapor with a limit of detection down to 1.1 mg m−3 in 5 minutes.

Bioanalytical system for detection of cancer cells with photoluminescent ZnO nanorods

Using photoluminescent ZnO nanorods and carbohydrate marker SSEA-4, a novel cancer cell recognition system was developed. Immobilization of SSEA-4 antibodies (αSSEA-4) on ZnO nanorods was performed in buffer solution (pH = 7.1) over 2 h. The cancer cell line probes were fixed on the glass slide. One hundred microliters of ZnO-αSSEA-4 conjugates were deposited on the cell probe and exposed for 30 min. After washing photoluminescence spectra were recorded. Based on the developed methodology, ZnO-αSSEA-4 probes were tested on patient-derived breast and colorectal carcinoma cells. Our data clearly show that the carbohydrate SSEA-4 molecule is expressed on cancer cell lines and patient-derived cancer cells. Moreover, SSEA-4 targeted ZnO nanorods bind to the patient-derived cancer cells with high selectivity and the photoluminescence signal increased tremendously compared to the signal from the control samples. Furthermore, the photoluminescence intensity increase correlated with the extent of malignancy in the target cell population. A novel portable bioanalytical system, based on optical ZnO nanorods and fiber optic detection system was developed. We propose that carbohydrate SSEA-4 specific ZnO nanorods could be used for the development of cancer diagnostic biosensors and for targeted therapy.

Random Quadrature Demodulation for Direct Detection Single-Pulse Rayleigh C-OTDR

We present a demodulation method that partially compensates for the nonlinear and random transfer function of fiber-optic direct detection coherent Rayleigh optical time-domain reflectometry (C-OTDR). Specifically, the proposed method is shown to improve the detection of small amplitude, high-frequency dynamic optical fiber strain as it occurs in acoustic emission sensing. The method is applicable provided that the dynamic fiber strain to be sensed is known to affect a longer section of sensing fiber in a spatially homogeneous way. It is shown that this knowledge can be used to extract more quantitative information from the measured C-OTDR signal by averaging signal components from the affected fiber section in a suitable and efficient way. The theoretical basis of the method is developed and supporting experimental results are presented.

Design of optical fiber communication network monitoring and detection system based on address resolution protocol cheats

Optical fiber communication network security is getting more and more prominent, while the optical fiber communication network monitoring is another challenges of the optical fiber communication network security. In order to Address Resolution Protocol key technology was used. In addition, design of optical fiber communication network detection system was also designed.

Development of Ultrasensitive Terahertz ESR Spectroscopy for Metalloprotein Using a Microcantilever

In this article, we report a novel method for ultrasensitive high-frequency electron spin resonance (HFESR) using a microcantilever. With this method, a field-gradient force exerting on a sample-holding cantilever is detected as cantilever displacement. A unique feature of this method is that a very tiny sample (~1 µg) is sufficient for HFESR measurement in the terahertz region. Thus, the application of this method to metalloprotein is expected to be of particular interest in the future. In this study, we developed two types of HFESR techniques: one for fiber-optic detection and the other for piezoresistive detection. We applied these techniques to multi-frequency HFESR measurements of metal-containing porphyrin compounds as a model metalloprotein substance and evaluated the sensitivity and feasibility of each technique.

Early clinical experience utilizing scintillator with optical fiber (SOF) detector in clinical boron neutron capture therapy: its issues and solutions.

BackgroundReal-time measurement of thermal neutrons in the tumor region is essential for proper evaluation of the absorbed dose in boron neutron capture therapy (BNCT) treatment. The gold wire activation method has been routinely used to measure the neutron flux distribution in BNCT irradiation, but a real-time measurement using gold wire is not possible. To overcome this issue, the scintillator with optical fiber (SOF) detector has been developed. The purpose of this study is to demonstrate the feasibility of the SOF detector as a real-time thermal neutron monitor in clinical BNCT treatment and also to report issues in the use of SOF detectors in clinical practice and their solutions.Material and methodsClinical measurements using the SOF detector were carried out in 16 BNCT clinical trial patients from December 2002 until end of 2006 at the Japanese Atomic Energy Agency (JAEA) and Kyoto University Research Reactor Institute (KURRI).ResultsThe SOF detector worked effectively as a real-time thermal neutron monitor. The neutron fluence obtained by the gold wire activation method was found to differ from that obtained by the SOF detector. The neutron fluence obtained by the SOF detector was in better agreement with the expected fluence than with gold wire activation. The estimation error for the SOF detector was small in comparison to the gold wire measurement. In addition, real-time monitoring suggested that the neutron flux distribution and intensity at the region of interest (ROI) may vary due to the reactor condition, patient motion and dislocation of the SOF detector.ConclusionClinical measurements using the SOF detector to measure thermal neutron flux during BNCT confirmed that SOF detectors are effective as a real-time thermal neutron monitor. To minimize the estimation error due to the displacement of the SOF probe during treatment, a loop-type SOF probe was developed.

A compact fiber-optic probe-based singlet oxygen luminescence detection system.

This paper presents a novel compact fiberoptic based singlet oxygen near‐infrared luminescence probe coupled to an InGaAs/InP single photon avalanche diode (SPAD) detector. Patterned time gating of the single‐photon detector is used to limit unwanted dark counts and eliminate the strong photosensitizer luminescence background. Singlet oxygen luminescence detection at 1270 nm is confirmed through spectral filtering and lifetime fitting for Rose Bengal in water, and Photofrin in methanol as model photosensitizers. The overall performance, measured by the signal‐to‐noise ratio, improves by a factor of 50 over a previous system that used a fiberoptic‐coupled superconducting nanowire single‐photon detector. The effect of adding light scattering to the photosensitizer is also examined as a first step towards applications in tissue in vivo. figureWiley-VCH Verlag & Co.KGaA

A rapid method for measuring fat content in milk based on W-type optical fibre sensor system

A measurement system based on a W-type optical fibre sensor for determining the fat content in milk is investigated in this paper. The system consists of a light source, W-type optical fibre sensor, detector, amplifier, A/D converter, microprocessor and thermoelectric cooler (TEC). According to Mie-scattering theory, the standard models of the system at different temperatures (25°, 30°, 35°, 40° and 45 °C) are obtained. Evaluations of all the models at different temperatures are made, which illustrate that 40 °C is the optimal temperature for fat content in milk. At 40 °C, the linear relationship between the absorbance and the fat content is significant. Furthermore, a prediction experiment has been performed to confirm the validity of the standard model. As a result, the measurement system based on a W-type optical fibre sensor is capable of measuring the fat content in milk effectively and in real time.

Characterization of wave physics in acoustic metamaterials using a fiber optic point detector

Due to limitations of conventional acoustic probes, full spatial field mapping (both internal and external wave amplitude and phase measurements) in acoustic metamaterials with deep subwavelength structures has not yet been demonstrated. Therefore, many fundamental wave propagation phenomena in acoustic metamaterials remain experimentally unexplored. In this work, we realized a miniature fiber optic acoustic point detector that is capable of omnidirectional detection of complex spatial acoustic fields in various metamaterial structures over a broadband spectrum. By using this probe, we experimentally characterized the wave-structure interactions in an anisotropic metamaterial waveguide. We further demonstrated that the spatial mapping of both internal and external acoustic fields of metamaterial structures can help obtain important wave propagation properties associated with material dispersion and field confinement, and develop an in-depth understanding of the waveguiding physics in metamaterials. The insights and inspirations gained from our experimental studies are valuable not only for the advancement of fundamental metamaterial wave physics but also for the development of functional metamaterial devices such as acoustic lenses, waveguides, and sensors.

A MEMS torsion magnetic sensor with reflective blazed grating integration

A novel magnetic sensor based on a permanent magnet and blazed grating is presented in this paper. The magnetic field is detected by measuring the diffracted wavelength of the blazed grating which is changed by the torsion motion of a torsion sensitive micro-electromechanical system (MEMS) structure with a permanent magnet attached. A V-shape grating structure is obtained by wet etching on a (1 0 0) SOI substrate. When the magnet is magnetized in different directions, the in-plane or out-of-plane magnetic field is detected by a sensor. The MEMS magnetic sensor with a permanent magnet is fabricated after analytical design and bulk micromachining processes. The magnetic-sensing capability of the sensor is tested by fiber-optic detection system. The result shows the sensitivities of the in-plane and out-of-plane magnetic fields are 3.6 pm μT−1 and 5.7 pm μT−1, respectively. Due to utilization of the permanent magnet and fiber-optic detection, the sensor shows excellent capability of covering the high-resolution detection of low-frequency signals. In addition, the sensitive direction of the magnetic sensor can be easily switched by varying the magnetized direction of the permanent magnet, which offers a simple way to achieve tri-axis magnetic sensor application.

Optical fiber detector for monitoring volatile hydrocarbons during electrokinetic treatment of polluted soil

Optical fiber detector for monitoring volatile hydrocarbons during electrokinetic treatment of polluted soil

Preparation and evaluation of novel galantamine hydrobromide sustained-release capsule

In present study, a novel galantamine hydrobromide sustained-release capsule was prepared with the extrusion-spheronization method and the optimized preparative formulation. The release studies were performed using marketed capsules (Razadyne ER) as a reference and data were analyzed in terms of cumulative release amounts as a function of time. Furthermore, fiber-optic real time detection was adopted to monitor the release process. Results demonstrated that our developed formulation had superior properties, worked better as sustained-release carriers and lasted longer time to release compared with the marketed product. The in vitro release characteristics of different batches of preparations were quite similar with each other, the total release proportions of galantamine hydrobromide from sustained-release capsules reached higher than 90% within 12 hours. Similar factors f2 of two preparations were all higher than 50, the release profile of drugs from capsules fitted to Higuchi model with the equation of Q% = 0.2681t1/2 + 0.0684 (r = 0.9966). Pharmacokinetics profile and parameters in beagle dogs after oral administration also revealed the superior release performances of new capsules being consistent with the in vitro study. The developed sustained-release formulation may be a promising alternative dosage form for treatment of related diseases.

High resolution monitoring of strain fields in concrete during hydraulic fracturing processes.

We present a distributed fiber optic sensing scheme to image 3D strain fields inside concrete blocks during laboratory-scale hydraulic fracturing. Strain fields were measured by optical fibers embedded during casting of the concrete blocks. The axial strain profile along the optical fiber was interrogated by the in-fiber Rayleigh backscattering with 1-cm spatial resolution using optical frequency domain reflectometry (OFDR). The 3D strain fields inside the cubes under various driving pressures and pumping schedules were measured and used to characterize the location, shape, and growth rate of the hydraulic fractures. The fiber optic sensor detection method presented in this paper provides scientists and engineers an unique laboratory tool to understand the hydraulic fracturing processes via internal, 3D strain measurements with the potential to ascertain mechanisms related to crack growth and its associated damage of the surrounding material as well as poromechanically-coupled mechanisms driven by fluid diffusion from the crack into the permeable matrix of concrete specimens.

Probabilistic Performance Assessment of Fiber Optic Leak Detection Systems

Leak detection systems (LDSs) play a major role in enhancing reliability and operability of oil and gas pipelines. They have the functional capabilities to detect, locate, and quantify leaks before they can cause devastating effects to the environment and operation. The performance of LDSs is typically influenced by three different types of failures that may have severe consequences: delayed detection, missed detection, and false detection of a leak. The consequences of these failures lead to extensive financial losses. For example, missed detection leads to oil spills and exposes operating companies to financial risk and destroyed image while false detection results in unnecessary deployment of personnel and equipment. To maintain safety of personnel and the environment and ensure operation continuity, LDSs should be assessed regularly. To fulfill this need, a probabilistic performance assessment scheme based on limit state approach for fiber optic LDS has been developed. The inherent uncertainties associated with leak detection and reporting capabilities are modeled to determine the LDS detection failure probability that combines two failure events: missed detection and delayed detection. Moreover, the probability of false detection is derived in terms of the lowest detectable change, the threshold. These three parameters establish the basis for an overall assessment scheme that can be used to predict the performance of the LDS. The proposed assessment scheme has been applied to a case study to demonstrate its usefulness and feasibility.

A Torsion MEMS Magnetic Sensor with Permanent Magnet and Fiber-optic Detection

A novel microelectromechanical system (MEMS) magnetic sensor based on fiber-optic detection is presented in this paper. The magnetic field is detected by measuring the tilting motion of a mechanical suspension with permanent magnet attached. When the magnet is magnetized in different directions, the magnetic sensor can detect the in-plane or out-of-plane magnetic field. The MEMS structure was designed analytically, fabricated by using a bulk micromachining process, and assembled with the permanent magnet manually. Finally, the magnetic-sensing capability of an as-prepared sensor was tested by assembling it into the fiber-optic detection system. The testing result shows a sensitivity of 2.86 mV/ $\mu \text{T}$ for the in-plane magnetic field and 6.57 mV/ $\mu \text{T}$ for the out-of-plane. According to the mechanical–thermal noise theory, estimated resolutions are, respectively, close to 142 and 62 nT for the in-plane and out-of-plane magnetic field, which suggest the adequacy for measurement in earth magnetic field range. The reported magnetic sensor shows the capability to fulfill the high-resolution detection of low-frequency signals, benefitted from the utilization of permanent magnet and fiber-optic detection. Moreover, the sensitive direction of reported magnetic sensor can be easily switched by varying its magnetized direction, which, therefore, paves the way to the integrated tri-axis magnetic sensor.

Development of Experimental Set for Determination of Refractive Index of Liquid Using Optical Fiber

The construction of an experimental set for measurement of refractive index of liquids using fiber optics has been described in this work. The experimental set is aimed for demonstration in physics high school class. A prototype fabricated in laboratory composes of plastic-clad-plastic (PCP) optical fiber with the length of 50 cm, fiber optic transmitter diode, fiber optic phototransistor detector, and liquid container. The diameter and refractive index of the core of PCP optical fiber were 1 mm and 1.492, respectively. The thickness and refractive index of fiber cladding were 1.2 mm and 1.417, respectively. The fiber cladding surface at the central region was removed approximately 5 cm long to form a sensor area. This sensor area was inserted into a cylindrical glass which acted as the container. One end of the fiber was connected to the transmitter diode with a wavelength of 660 nm, and the other end was connected to the detector. A digital multimeter was used to measure an output voltage from the detector. In this work, the effect of water temperature on its refractive index was determined. The results showed that the water refractive index decreased with increasing water temperature and result in the increase of measured output voltage. Furthermore, it was found that the output voltage measured at different temperatures of water depends linearly on water refractive index.

Study of azo-coupling derivatization by sequential injection coupled with spectrophotometric optical fibre detection for propofol analysis

A new method for rapid automated propofol determination that can avoid interference, improve detection and consume small amounts of samples and reagents.