This publication aims to describe the design, implementation, and verification of a fiber-optic wrist sensor based on the Bragg grating (FBG) for monitoring the heart rate (HR) of the human body. One of our primary goals was also to create a sensor suitable for measurements in harsh environments such as magnetic resonance imaging (MRI). For this reason, we used polylactic acid (PLA) material for the encapsulation of Bragg grating itself. This combination results in a sensor solution that is resistant to electromagnetic interference (EMI). Based on their previous agreement, the sensor has been properly and systematically tested based on a group of six volunteers of one sex. The acquired data were then processed and evaluated, using the absolute error (AE), relative error (RE), and its mean. The outcome of this study indicated an RE of 9.07 %, implying promising results and the first step of this study.
This article deals with the issue of fire safety monitoring of wooden buildings. Wooden buildings currently represent a quick and relatively inexpensive option for acquiring a family house. However, with regard to the building material and its flammability, the construction possibilities are strongly regulated by standards. The aim of this paper is to describe the possibilities of monitoring temperature changes during a simulated fire using optical fiber and a distributed temperature measurement system (DTS). The DTS system uses the principle of stimulated Raman scattering, which allows longitudinal temperature measurements with a spatial resolution of 1 m. The increase in spatial resolution was achieved by winding the optical fiber into 5 cm diameter rings, with a fiber length of 3 m in each ring. The measuring rings of optical fiber were attached to fabric arranged in a rectangular grid. This fabric with the rings was then placed at the surveyed locations in the construction panels. During the temperature loading of the test samples with the gas torch, temperature monitoring was carried out both on the reverse side of the samples and in the inner layers. The results showed that this system with conventional multimode optical fibers can measure temperatures ranging from 20 °C to approximately 500 °C. This method offers the possibility to accurately monitor the temperatures of wooden buildings, including the inner layers of the building panels. The proposed method can therefore be used to thoroughly verify the fire safety of wooden buildings and their components.
This paper discusses a proposed fiber-optic sensor that was based on the combination of the material called polyethylene terephthalate glycol (PETG) and a fiber Bragg grating (FBG). The practical experiments were conducted under laboratory conditions with a group of 6 volunteers. The data were compared with a conventional electrocardiogram (ECG) and processed using a Bland-Altman method. The results described in this paper show that the 3D printing technique can be used for encapsulating the FBG and for the purpose of biomedical engineering.
In this paper, a performance study of VLC communication channel impaired by rain, is presented. Our solution is based on software defined radio (SDR), LabVIEW and commercially available LED car taillights. This work focuses on performance testing of multistate QAM modulation formats throughout variable rain intensity and its influence on basic communication parameters (EVM, BER, transmit speed). This work will present our testing prototype, measured parameters and possible weak spots, which will be adjusted in future iterations.
In this paper, the impact of fog on performance of VLC communication is explored. Highly modular testing system is based on LabVIEW software, modified National Instruments software defined radios (SDR) and commercially available LED car taillights. This work focuses on performance testing of multistate QAM modulations formats impaired by fog. An optional reference laser is used to monitor fog density throughout the whole measurement. This paper will present our testing solution and measured parameters.
From the vibration analysis generated by biological and mechanical systems, it is possible to determine whether there has been a fundamental change in their time or frequency domain. This analysis can provide information about the internal state of the system and its dynamics without the need for invasive intervention. In addition, the measured data can be used together with advanced signal processing algorithms (neural networks or machine learning) to create a predictive maintenance and diagnostic system. According to the measured data diagnostics, it will be possible to identify a defective component (e.g. a damaged bearing, loose part or worn belt), replace it and prevent possible system failure. This work describes a modular measuring device based on closed acoustic tube. Acoustic tube parameters are measured and optimized for use in remote monitoring, which is part of a project dealing with measurement of vital signs in magnetic resonance.
Indirect monitoring of room's occupancy are two of the key requirements for technological systems that are used to secure independent housing for people in their home environment. For indirect monitoring of the Smart Home room's occupancy, we used Fiber Bragg grating sensor, temperature sensor T(°C), CO2(ppm) sensor, and humidity sensor rH (%). The first part of the paper describes the proposal of an implementation of Fiber Bragg grating for the detection of human presence in a room of SH. The second part of this paper dealing with the use of CO2 concentration measurement for detecting and monitoring room's occupancy with the implementation of Artificial Neural Network for the detection of human presence in the room of SH. Experimental results verified high method accuracy (<90%) within the short-term and long-term experiments. Utilization of Fiber Bragg grating in SH was proven on the experimental basis with the combination of measurement CO2 for room's occupancy monitoring in SH.
This paper deals with mechanical properties of polydimethylsiloxane (PDMS) as material for preparation of deformation sensors. PDMS is widely used especially in medical area. Some application of PDMS as material for preparation of deformation sensors with fiber optics has been prepared. Due to its hyper-elastic and viscoelastic of this material is complicate to use it with long time and large deformation mechanics. In this paper authors compare the numerical models of prepared sensor using hyper-elastic models and mechanical experiment at large deformation.
This article describes the combination of the polymer material polydimethylsiloxane (PDMS) and fiber-optic sensors for monitoring the heart rate (HR) of the human body. We proposed, created, and encapsulated into PDMS two type of fiberoptic sensors based on the interferometric and Bragg grating principle. Both above-mentioned fiber-optic sensors we compared with the conventional ECG monitoring system. Measurement was performed in the laboratory conditions with the group of 6 volunteers with their written contest. Acquired data were compared by the Bland-Altman method. The result presented in this short article confirms that fiber-optic sensors can be used as an alternative to conventional ECG.
This article focuses on the analysis of the selected optical coupler parameter which have been thermal stressed for 30 weeks at temperature 95 °C ± 5 °C. Optical couplers with 10:90, 1:99 and 50:50 dividing ratio were tested. A total of 6 optical couplers were tested. Measurements were made for two wavelengths 1310 nm and 1550 nm. The observed parameter was the insertion loss. The insertion loss is very important parameter because the fiber-optic passive components (such as optical couplers) disrupt signal transmissions as the continuous core of the optical fiber carrying the signal mates with the component in a manner that causes some amount of scattering and reflection of light waves. The degree to which the signal has been depleted is described as insertion loss, which is the undesired attenuation of the signal measured in decibels (dB).
This paper presents the comparison of fibre-optic Bragg Grating Sensor with the commercially available probes for heart sounds measurement based on microphones. The analysis of the sensitivity and specificity was carried out to assess the efficacy of the individual measuring probes. Since fibre-optic sensing uses light in optical fibre rather than electricity, it solves the limitations of electrical sensors such as transmission loss and susceptibility to electromagnetic interference (EMI). Experimental results have shown that Fibre-Optic Bragg Grating Sensor significantly outperforms the devices using the microphones. Moreover, the sensor embedded in polydimethylsiloxane polymer and is fixed on the thorax by means of elastic belt. The material is biocompatible and immune to electromagnetic interference, which is major advantage for the healthcare environment. The probe dimensions are small; therefore, it would be convenient for the patient and easily implemented into clinical practice. Nevertheless, the signal processing methods must be applied to separate the desired signal from the environmental noise.
KEYWORDS: Fetus, Independent component analysis, Principal component analysis, Signal to noise ratio, Signal processing, Heart, Sensors, Electrodes, Abdomen, Ultrasonography
Fetal Phonocardiography (fPCG) is still secondary tool but provides very important information about fetal well-being that cannot be given by another fetal monitoring method. Independent Component Analysis (ICA) and Principal Component Analysis (PCA) were chosen for testing on synthetic data that are able to extract fPCG from abdominal signals. Results show that ICA and PCA could be used in clinical practice for fetal Heart Rate (fHR) monitoring, because after extraction of components it is easy to determine fHR. Signal to Noise Ratio (SNR) proved that after the extraction there was a significant improvement in estimated signal to compare with input abdominal signals. We found that ICA method works better than PCA method on this data, even though it changes the amplitude of the output components.
Fiber optic Bragg gratings are among the most widely used fiber optic sensors. It uses in dangerous explosive environments thanks to the electrical passivity of the sensor itself, but also in applications with high electromagnetic disturbance. Maintaining immunity of the sensor to electromagnetic interference requires non-electrical encapsulation material. This paper describes the encapsulation of the FBG sensor on a plastic plate fixed by gluing to the monitored structure. The proposed FBG sensor is suitable for measuring deformations or vibrations of iron and concrete structures. Due to the material used, the FBG sensor keeps resistance to electromagnetic interference, humidity, and corrosion. The results show the almost equal sensitivity of FBG strain sensors mounted on a metal carrier when measuring very small deformations and vibrations. The proposed FBG sensor concept reduces the cost of its manufacturing by using a 3D printer to produce the plastic carrier.
This article is focused on the advanced signal processing methods for third-generation sensors requirements. These sensors are based on the influence of a non-electric quantities on a light beam. This generation of sensors, also known as fiber optic sensors, is based on the principles of optoelectronics and integrated optics. These sensors are used in a variety of real-world applications such as biomedical engineering, industry 4.0, transportation, etc. In real-world applications, the signals sensed by these sensors are distorted by a variety of interference due to its sensitivity. We often encounter the problem that the useful information and the interference overlap in the spectral domain, therefore we cannot use conventional frequency selective filters. This article focuses on the implementation of adaptive filtering, Principle Component Analysis and Independent Component Analysis to reduce the interference in various application areas. The methods were tested on real data. This paper offers the comparison of the tested methods in different application areas.
The article describes the use of fiber-optic interferometer in the rail transport. We proposed a measuring sensor system based on the Mach-Zehnder interferometer. The basic tracked parameter of vehicles are detection (count of vehicles). The proposed system was tested in the real tram traffic. Altogether, 435 vehicles were detected with 100 % success. The basic advantages of the solution include immunity to electromagnetic interference (EMI) and the ability to remotely evaluate information about the traffic.
Distributed fiber optic systems based on Brillouin Time Domain Reflectrometry BOTDR offer an exclusive solution for monitoring the load of large building structures such as buildings, bridges, tunnels, etc. Deformation measurements use special optical cables with added reinforcement element and a closer bond between cable jacket and fiber optic to achieve high sensitivity to mechanical deformation. Alternatively, cheaper standard optical fiber cables with single-fiber optic fibers are used. Alternatively, there is possible to use cheaper standard optical cables with single mode optical fibers. The paper deals with the analysis of the suitability of standard optical cables for the deformations measurement using a distributed BOTDR system. Several standard types of telecommunication optical cables were implemented into concrete beams and bent in a hydraulic press. The main result of this paper is the deformation sensitivities determination of optical cables for load measurement and the suitability analysis for embedding into the concrete beam with regard to long life.
Nowadays optical fibers are used in many industries. In addition to the data transmission, many sensor applications with using some special optical fibers are expanding. Faraday's phenomenon is often used for detection of the magnetic field. The size of the deviation of the polarization plane of optical radiation passing through the optical fiber is evaluated in Faraday's phenomenon that occurs due to the influence of the external magnetic field. This paper describes our new approach to addressing this issue using standard telecommunication fibers, PDMS-based optical connections, specialty products and some magnetic field sensitive materials. Our detector of the magnetic field can find a use for simplified measurement of weak magnetic fields up to 0.3 T.
This article focuses on determining the attenuation properties and homogeneity of cylindrical waveguides made of specific polymer materials. Cylindrical waveguides were made from clear silicone rubbers based on polydimethylsiloxane (PDMS) - Sylgard 184 and RTV615. The mixture of PDMS and the curing agent was homogenized by means of an ultrasonic bath for two different frequencies (20 and 40 kHz) and for different time points (5, 10, and 20 minutes). Curing of the waveguides took place in a heat box at a constant temperature of 70 ° C ± 3 ° C. This procedure was applied to a total of 180 cylindrical waveguides with the same dimensions and diameter of the core. Attenuation dependencies were tested for two different light emitting diodes (LEDs) with central wavelengths of 470 and 625 nm. The analysis was conducted with respect to the use of PDMS in fiber-optic applications for its good mechanical and optical properties.
Optical fibers can be used in many ways. In addition to telecommunication applications, they are increasingly used in sensory applications as well. The temperature measurement is one of many areas of using of optical fibers. The most commonly used are DTS (Distributed Temperature Sensor) also known as Raman optical time-domain reflectometry (OTDR). The using of fiber Bragg gratings (FBGs) is one of the other options. This paper describes our approach to temperature measurement using optical fibers, heat-sensitive materials and specialty products based on polydimethylsiloxane (PDMS) and other materials. The temperature sensor created by us can also be used in an unfavorable environment (chemical influences, etc.) in the temperature range up to approx. 400 K.
The authors focused on the problem of production and measurement parameters of optical couplers created from polymer polydimethylsiloxane (PDMS) for fiber-optic sensors. For the production of optical couplers, clear two-component elastomers Sylgard 184 and RTV 615 (manufacturer Dow Corning) was used. These elastomers offer a suitable combination of mechanical and optical properties. For the experiments, a total of 50 optical couplers were created. The effect of thermal aging on their transfer properties was analyzed. The thermal load was performed in a temperature box at 100 and 200 ° C under constant conditions for 48 hours. Measurements were made for a wavelength of 1550 nm and 1310 nm.
This paper deals with methods for processing signals from an optical interferometer to monitor vital signs (Respiration Rate and Heart Rate). Optical interferometer signals are contaminated by variety of technical and biological artifacts (motion artifacts, hospital/patient-generated noise, etc.). Tested optical sensors are very sensitive, it therefore crucial to reduce such unwanted signals. In this article, a complex application for processing the signals from optical interferometer based on virtual instrumentation was developed. The experiments were conducted on data sensed by optical interferometer using a National Instruments card NI USB-6216 BNC and application in the LabVIEW environment. Frequency selective filters were tested in the experiments. The results obtained by using optical interferometer were statistically compared with the ECG and PCG reference. According to the results, optical interferometers are able to measure both the Respiration and Heart Rate under the given conditions. Unfortunately, the measurement is very difficult to replicate in the hospital environment, which is the primary reason why these methods are not used in clinical practice.
This article deals with the implementation of fiber-optic Bragg Grating Sensors signal processing methods for the detection of respiration rate, pulse rate, and body temperature. The sensed signals are influenced by a variety of interferences (motion artifact, environmental noise, etc.). Clinically relevant information is only available at certain frequencies, while the utilized optical sensor is able to cover relatively broad spectrum range. For real-world medical applications, the desired signal needs to be separated from the noise, which can often be other clinical information. This article introduces a virtual instrument for the extraction of clinically relevant information, such as respiration and heart rate, and body temperature. Frequency-selective filters were implemented in the proposed application. The functionality of the application was tested on real data using the FBGUARD and LabVIEW evaluation unit. The results were verified with commercially available devices and also statistically processed. Experimental results have shown that Fiber-Optic Bragg Grating Sensor signal processing is a key aspect of a successful incorporation of these sensors into clinical practice.
The publication describes the use of fiber-optic Bragg sensors in biomedical applications. Fiber-optic sensors are characterized by the immunity to electromagnetic interference (EMI) and by the electrical passivity. Currently, these types of sensors are increasingly being used in biomedical applications, for example, for measuring the temperature or the heart and respiratory rate of the human body. It is very important to encapsulate these types of sensors because encapsulation itself has a major effect on the sensor functionality. This publication describes a comparison of two materials - polymer polydimethylsiloxane (PDMS) and fiberglass (fiberglass is a composite material made up of glass fiber (fabric) and cured synthetic resin). The comparison was conducted by a series of laboratory experiments with ten volunteers with their written consent. Acquired data were compared by the Bland-Altman method.
Optical fibers have many uses and in addition to communications applications for example in fiber-optic sensor applications. The area of pressure and vibration measurement is one of the many fields of applicability of optical fibers too. Very often, the fiber Bragg gratings (FBGs) is also used for medical applications. This paper describes our alternative approach to addressing this issue, based on standard optical fibers, special optical connections, PDMS-based products, and other materials. It is known that the vibrations of some machines can negatively affect the human body. The vibration detector created by us can find a use for indicative measurement of these negative vibrations of machines, especially in the frequency range up to about 100 Hz.
Authors of this article have focused on the use of fiber-optic technology in the car traffic. The article describes the use of fiber-optic interferometer for the purpose of the dynamic calculation of traffic density and inclusion the vehicle into the traffic lane. The objective is to increase safety and traffic flow. Presented solution is characterized by the non-destructive character to the road - sensor no need built into the roadway. The sensor works with standard telecommunications fibers of the G.652 standard. Other hallmarks are immunity to electromagnetic interference (EMI) and passivity of concerning the power supply. The massive expansion of optical cables within telecommunication needs along roads offers the possibility of connecting to the existing telecommunications fiber-optic network without a converter. Information can be transmitted at distances of several km up to tens km by this fiber-optic network. Set of experimental measurements in real traffic flow verified the functionality of presented solution.
In this article, we describe an innovative non-invasive method of Fetal Phonocardiography (fPCG) using fiber-optic sensors and adaptive algorithm for the measurement of fetal heart rate (fHR). Conventional PCG is based on a noninvasive scanning of acoustic signals by means of a microphone placed on the thorax. As for fPCG, the microphone is placed on the maternal abdomen. Our solution is based on patent pending non-invasive scanning of acoustic signals by means of a fiber-optic interferometer. Fiber-optic sensors are resistant to technical artifacts such as electromagnetic interferences (EMI), thus they can be used in situations where it is impossible to use conventional EFM methods, e.g. during Magnetic Resonance Imaging (MRI) examination or in case of delivery in water. The adaptive evaluation system is based on Recursive least squares (RLS) algorithm. Based on real measurements provided on five volunteers with their written consent, we created a simplified dynamic signal model of a distribution of heartbeat sounds (HS) through the human body. Our created model allows us to verification of the proposed adaptive system RLS algorithm. The functionality of the proposed non-invasive adaptive system was verified by objective parameters such as Sensitivity (S+) and Signal to Noise Ratio (SNR).
This article deals with the description of the monitoring system of hydraulic lifting device based on the fiber-optic sensors. For minimize the financial costs of the proposed monitoring system, the power evaluation of measured signal has been chosen. The solution is based on an evaluation of the signal obtained using the single point optic fiber sensors with overlapping reflective spectra. For encapsulation of the sensors was used polydimethylsiloxane (PDMS) polymer. To obtain a information of loading is uses the action of deformation of the lifting device on the pair single point optic fiber sensors mounted on the lifting device of the tested car. According to the proposed algorithm is determined information of pressure with an accuracy of +/- 5 %. Verification of the proposed system was realized on the various types of the tested car with different loading. The original contribution of the paper is to verify the new low-cost system for monitoring the hydraulic lifting device based on the fiber-optic sensors.
Authors of this article focused on the analysis of the use of distributed fiber-optic technology for security monitoring of structural loads of road and motorway tunnels. Authors focused on measurements of deformation utilizing Brillouin Time Domain Reflectometry (BOTDR). The principle is based on the measurement of the stimulated Brillouin scattering. The article describes the load of tunnel based on the real measurements made during the construction of the motorway tunnel in the Slovakia Republic in a time horizon of several months. Experiments were carried out with standard optical telecommunication cable with water-absorbing aramid yarns and jacketing of diameter 4.2 mm. The outcome of this article is an introductory analysis the use of fiber-optic technology for security monitoring of structural loads for road and motorway tunnels.
This article describes an analysis of the use of fiber-optic technology in biomedical applications, specifically for the monitoring heart rate of the pregnant (mHR) and fetal (fHR). Authors focused on the use of Fiber Bragg Grating (FBG) and Fiber-Optic Interferometers (FOI). Thanks to the utilization of conventional method so-called cardiotocography (CTG), the mortality of newborn babies during delivery has decreased. Generally, among disadvantages of this method, there is a high sensitivity to noises caused by the movement of a mother, and it is connected with the frequent transfer of ultrasonic converters. This method is not suitable for a long-term continuous monitoring due to a possible influence of ultrasonic radiation on the fetus. Use of fiber-optic technology offers many advantages, for example, use measuring probes based FBG or FOI does not represent any additional radiation burden for the pregnant woman or fetus, fiber-optic measurement probes are resistant to technical artifacts such as electromagnetic interferences (EMI), thus they can be used in situations where it is impossible to use classic methods, e.g. examination by magnetic resonance (MR) or in case of delivery in water. The article describes the first experimental knowledge of based on real measurements.
Authors of this article focused on the utilization of fiber optic sensors based on interferometric measurements for securing entrance areas of buildings such as windows and doors. We described the implementation of the fiber-optic interferometer (type Mach-Zehnder) into the window frame or door, sensor sensitivity, analysis of the background noise and methods of signal evaluation. The advantage of presented solution is the use of standard telecommunication fiber standard G.652.D, high sensitivity, immunity of sensor to electromagnetic interference (EMI) and passivity of the sensor regarding power supply. Authors implemented the Graphical User Interface (GUI) which offers the possibility of remote monitoring presented sensing solution.
This article focuses on the analysis and verification of a non-invasive fiber Bragg grating (FBG) sensor used for the monitoring of a patient`s heart rate (HR) and respiratory rate (RR) in a magnetic resonance environment (MRI). Measuring heart and respiratory rate were carried out on a group of five volunteers with their written consent during MRI examinations. The type of the scanner used in the experiment was GE Signa HDxt 1.5T. The benefit of this article lies in the design of a sensor in the form of a sensor pad. The sensor is placed beneath a patient`s body lying supine. The purpose is to increase and improve the patient`s safety as well as to help doctors to predict panic and hyperventilation attacks of patients during MRI examinations. Provided Bland-Altman statistical analysis demonstrates the heart and respiratory rate detection with a satisfactory accuracy for all five volunteers.
This article discusses the topic of the monitoring of the operating condition of the pressing machines. In the process of pressing there are a large acting of the forces of the press machine on the machined material. It is accompanied by an expression of deformation of parts of the pressing machines. Knowledge about the resulting loading is important for the final product quality and durability of these machines. In the case of multi-columned presses is important even load distribution among the individual columns. For this reason, it is necessary to monitor the load of the hydraulic pistons. Conventional approaches of load monitoring utilize piezoelectric sensors and strain gauges, which are sensitive to electromagnetic interference, require electrical power, subject to corrosion and action of moisture. A suitable alternative is the fiber Bragg gratings (FBGs) sensors, that those failures have. Their use for load monitoring production presses have been verified by the real measurement on a four-post hydraulic press ALPHA 4 from the company FORM + TEST Seidner. For measurements were used the FBG sensors and classic foil strain gauges (reference). Real measurement was performed during a load of press in the range from 0 to 2000 kN with a step of 500 kN.
Authors of this article present the fiber-optic system based on fiber Bragg gratings (FBGs) which are used to secure the entrance areas such as buildings, halls, warehouses, etc. The system uses the specially encapsulated sensory array of fiber Bragg gratings which are implemented into the floor or on the floor and allows for monitoring the area of 1 m2 up to 100 m2 depending on the number of FBG sensors. The sensory array is characterized by immunity to electromagnetic interference (EMI), passivity regarding electrical power supply, the possibility of remote evaluation (up to units of km) and high sensitivity. Proposed sensor system has detection capability greater than 99 % and furthermore, provides information about the weight load to an accuracy of ± 5 kg. The concept has been tested in a real environment within the test polygon for several weeks. As the reference devices, we used the CCTV (Closed Circuit Television).
The team of authors focused on analyzing of using fiber-optic sensor based on Fiber Bragg Grating (FBG) for the monitoring of heart rate (HR) of long-term ill patients with a minimum of physical movement load. During all experiments, test subjects were asked to simulate their natural behavior in the most accurate way (for instance, the focus was on the use of fine motor skills - not only movements of hands and arms, legs, and feet, coughing, changes in body positions, but also walking). All these external aspects are taken into account in the bellow-described results of the probe efficiency and show that it is very necessary to know the impact of these artifacts for the determine the heart rate of the human body. Final results were discussed with the senior doctor of the long-term care department.
Authors of this article focused on the analysis of the influence location of the fiber-optic sensor on the measurement and determination the heart rate of the human body. The sensor uses a Fiber Bragg Grating (FBG) and is encapsulated in the polymer polydimethylsiloxane (PDMS). The combination of fiber-optic technology and its encapsulation in a polymer PDMS allows the use of the sensor e.g. in magnetic resonance environments (MRI). Among currently solved doctors requirements belongs field focusing on the study of hyperventilation and panic attacks of patients during MRI examination due to their very frequent occurrence. Proposed FBG sensor can help doctors to predict (based on heart rate) hyperventilation and panic attacks of patients during MRI examinations. For the most accurate determination of the heart rate, it is necessary to know the influence location of the sensor on the human body. The sensor functionality and analysis of the sensor placement on the heart rate has been verified by a series of real experimental measurements of test subjects in laboratory environment.
Authors of this article focused on the use of fiber-optic technology for monitoring heart and respiratory rate of the human body. The article describes an innovative method of encapsulating fiber Bragg grating (FBG) into polymer polydimethylsiloxane (PDMS) and comparison of this measuring probe with an FBG sensor glued on the plexiglass pad. The team of authors offers a solution which is basically focused on the monitoring of long-term ill patients with a minimum of physical movement load. Real data were acquired from a group of 10 volunteers with their written consent in the laboratory environment. Acquired data was compared by the Bland-Altman method.
Authors of the article focused on the possible encapsulation method of fiber Bragg gratings (FBGs) for the needs of dynamic weighing. For monitoring the parameters, we used broad-spectrum light source LED (Light-Emitting Diode) with a central wavelength of 1550 nm and optical spectrum analyzer with sampling rate 300 Hz. For encapsulation of used FBGs was chosen a specific material polymer polydimethylsiloxane (PDMS). A characteristic feature of this material is very high mechanical resistance, chemical resistance and temperature stability in the range of values -60 °C to + 200 °C. The combination of characteristic advantages of optical fibers (electromagnetic immunity) with stated properties of PDMS gives us the innovative type of encapsulated sensor which could be used for example for the needs of dynamic weighing in worsened or potentially hazardous conditions. This type of monitoring weighing is fully dielectric. Experimental measurements were carried out in laboratory conditions in the weight range of 35 up to 180 kg.
Article deal of the problematic of impact fixing optical fiber for measuring the deformation with the distributed system known as Brillouin Optical Time Domain Reflectometry (BOTDR). The measurement principle of BOTDR system based on scanning of Brillouin frequency. Authors focused on monitoring changes Brillouin frequency for various bends and size of the substrate layer in combination with different types of fixing materials. We used distributed system DiTEST STA-R Omnisense. For the analysis was used a standard telecommunication optical fiber G.652.D. Deformation of the optical fiber was carried out by bending at a special tool. This article aims to find the most suitable method of implementing a fiber-optics for practical applications. It showed that it is necessary to pay attention to the size of the substrate layer and the fixing material to optimize the sensitivity in the measurement of mechanical deformations and the forces.
Fiber-optic sensors (FOS), today among the most widespread measuring sensors and during various types of measuring, are irreplaceable. Among the distinctive features include immunity to electromagnetic interference, passivity regarding power supply and high sensitivity. One of the representatives FOS is the interferometric sensors working on the principle of interference of light. Authors of this article focused on the analysis of the detection material as resonant pads for attaching the measuring arm of the interferometer when sensing mechanical vibrations (low frequencies). A typical example is the use of interferometer sensors in automobile traffic while sensing a vibration response from the roadway while passing the cars. For analysis was used sensor with Mach-Zehnder interferometer. Defined were different detection materials about different size and thickness. We analyzed the influence on the sensitivity (amplitude response) of the interferometer. Based on the results we have defined the best material for sensing mechanical vibrations. The signal was processed by applications created in LabView development environment. The results were verified by repeated testing in laboratory conditions.
Authors of this article analyzed the influence of the cover layer in combination with the fixation material to measure
deformation with the distributed system Brillouin Optical Time Domain Reflectometry (BOTDR). This system is based
on the principle of measuring stimulated Brillouin scattering, which is frequency dependent on the measured temperature
and the mechanical stress of the optical fiber. Standard telecommunication optical fiber G.652.D was used for
experiments to verify whether this widely used type of fibers initially intended for telecommunication transmissions is
suitable for measuring the deformation with the distributed system BOTDR. Knowing the impact of encapsulation type
optical fiber is important in the use and implementation in practical applications. The results clearly show that it is
important to pay attention to the implementation type of optical fiber. Based on post-analysis, it was determined the most
appropriate implementation of optical fiber for optimal sensitivity in practical applications.
Fiber-optic sensors are one of the dynamically developing areas of photonics, which is today one of the key technologies.
Here include even fiber optic interferometers, allowing very sensitive sensing, they are immune to electromagnetic
interference and are entirely passive regarding electric power supply. This type of sensor is dependent on the phase shift,
the principle of the function based on interference of light. Fiber optic interferometers are used especially in areas that
require high sensitivity and measurement accuracy. The fundamental problem of fiber optic interferometry is a proposal
storing and fixing the measuring arm of the interferometer and its influence on the frequency range and sensitivity of the
interferometer. The authors focused on this issue and analyzed different types of fixing materials. We used a total of 8
different fixation elements with the different composition. We defined the standardized method of fixation and compared
it with a reference measurement without fixation. For the analysis of the frequency characteristic of the prototype was
used generator harmonic signal with fixed amplitude signal. Sensitivity verified using the size of the amplitude response.
The signal processed by the application written in LabView development environment. The results clearly showed that it
is necessary to pay attention to fixation materials in the design of the measuring arm of the interferometer for use in
practical applications. In the frequency range, thanks to the fixing material increased the value of bandwidth about value
2430Hz against the reference measurements. The sensitivity of the interferometer has increased threefold. The results
verified by retesting assembled prototype.
Technology fiber Bragg grating (FBG) belongs to the most widespread fiber optic sensors. It used for measuring a large number of chemical and physical quantities. Immunity to el ectromagnetic interference, small size, high sensitivity and principle information encoding about the measured value to the spectral characteristics cause usability of FBG sensors in medicine for monitoring vital signs such as heart rate, blood pressure, temperature or respiration. An important factor in this area is the use of an inert material for the Bragg gr atings encapsulation. An interesting choice is the elastomer polydimethylsiloxane (PDMS). PDMS is optically clear, general inert, non-toxic and non-flammable. The material commonly used for biomedical and medical applications. Experimental results presented in this paper describe the creation of prototype FBG sensor for the heart rate monitoring of a human body. The sensor is realized by Bragg grating encapsulated into polydimethylsiloxane. The FBG sensor is part of the elastic contact strap which encircles the chest of the patient. This chest expansion leads to a spectral shift of the reflected light from the FB G. The research based on the monitoring of eight different test persons. Heart rate meas urements were compared with a reference signal ECG and analyzed objectively by th e Bland-Altman statistic.
Fiber Bragg grating (FBG) is formed by the periodic structure in the core of the optical fiber and is one of the widelyused
types of fiber optic sensors. FBGs are primarily sensitive to strain and temperature. For sensory application is an
important encapsulation of FBG to achieve maximum sensitivity to the desired measurand and ensure of protection
against damage. Interesting way to encapsulate FBG is the use of elastomer polydimethylsiloxane (PDMS). Authors of
this paper followed on previous research regarding encapsulation of FBG and analyzed the influence of different
encapsulation types and shapes of PDMS on the temperature sensitivity and change of the reflected Bragg wavelength of
the FBG. Realization of encapsulation is composed of three parts: FBG insertion to a regular form with the liquid PDMS,
curing in a temperature box with a constant temperature 100 °C ± 5 % and 24 hours relaxation. Analysis of temperature
sensitivity and reflected Bragg wavelength was carried out after curing including relaxation time and it using the
broadband source of light LED (Light-Emitting Diode) with central wavelength 1550 nm and the optical spectrum
analyzer OSA 203.
Interferometric sensors can be categorized as highly sensitive and precise devices with series inconsiderable benefits from the possibility of using standard telecommunication fibers. They can be measured even small changes in the deformation of shapes in time, changes in temperature, pressure, voltage, vibration, electric field, etc. The basic idea, which is described in this article is the usage of the interferometer as a security and monitoring component, which offers a solution for securing of closed spaces, especially before unwanted entries. Its primary task is to detect intrusions - disrupting the integrity of the transparent window area due to vibration response. The base of the solution is a Mach-Zehnder interferometer, which consists of two arms in the power distribution ratio of 1:1, consisting of the SM optical fiber excited by a DFB laser. The interferometer is working on the wavelength of 1550 nm. The resulting signal is registered as a result of interference of optical beams from the reference and sensor arm. Realized measuring scheme was terminated optical receiver comprising PbSe detector. Below described experimental measurements have shown that implemented interferometer has a sufficient value of the signal to noise ratio (SNR) and is able to detect very weak signals in a wide frequency range from tens of Hz to kHz units. The signal was processed by applications developed for the amplitude-frequency spectrum. Evaluated was the maximum amplitude of the signal and compared to the noise. The results were verified by retesting the assembled prototype.
Fiber Bragg gratings (FBGs) belongs to the single-point optical sensors used in many fields and applications where they often replace a standard sensors. They are easy to multiplex and the wavelength division multiplex is the most widely used method. FBGs in sensory branch are designed for a different Bragg wavelength which gives different measure and sensitivity coefficients. Existing algorithm is based on the determination of left and right boundaries of the measuring channel and the central Bragg wavelength. In this paper is presented the new mathematical model for calculation of Bragg wavelength, sensitivity coefficient and channel width of any FBG in the single step. The model takes into account the following input parameters: wavelength of the optical source, source bandwidth, the type of measured quantity, measuring ranges, width of the FBG reflected spectrum and the guard band between adjacent channels. The mathematical model is verified by using a simulation in software OptiSystem.
Fiber optic interferometers belong to a group of highly sensitive and precise devices enabling to measure small changes in the deformation shapes, changes in pressure, temperature, vibration and so on. The basis of their activity is to evaluate the number of fringes over time, not changes in the intensity of the optical signal. The methodology described in the article is based on using the interferometer to monitor traffic density. The base of the solution is a Mach-Zehnder interferometer operating with single-mode G.652 optical fiber at the wavelength of 1550 nm excited by a DFB laser. The power distribution of the laser light into the individual arms of the interferometer is in the ratio 1:1. Realized measuring scheme was terminated by an optical receiver including InGaAs PIN photodiode. Registered signal from the photodetector was through 8 Hz high pass filter fed to the measuring card that captures the analog input voltage using an application written in LabView development environment. The interferometer was stored in a waterproof box and placed at the side of the road. Here panned individual transit of cars in his environs. Vertically across the road was placed in contact removable belt simulating a retarder, which was used when passing cars to create sufficient vibration response detecting interferometer. The results demonstrated that the individual vehicles passing around boxing showed characteristic amplitude spectra, which was unique for each object, and had sufficient value signal to noise ratio (SNR). The signal was processed by applications developed for the amplitude-frequency spectrum. Evaluated was the maximum amplitude of the signal and compared to the noise. The results were verified by repeated transit of the different types of cars.
The new dynamic direction of wireless networks development is based on the idea of networks utilizing the optical radiation in the visible spectrum VLC (Visible Light Communications). The impulse of this development direction was improvement in the semiconductor lighting technologies, namely the white power LEDs (Light Emitting Diode). These types of wireless networks are denoted as the optical wireless networks for indoor spaces utilizing optical radiation in the visible spectrum. The paper deals with the issue of deployment of multi-state modulations into the indoor visible light communications in LOS (Line of Sight) configuration. The first part of the paper focuses on design of modulation element (SMD LED matrix 3 × 3) and problems connected to deployment of multi-state modulation M-QAM (subcarrier intensity modulation) through this modulation element into the indoor visible light communications (MER). The second part deals with the irradiation distribution in dark room in comparison with real room during used multi-state modulation scheme in both simulation and real measurement.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.