This article describes the fiber-optic Bragg grating sensor which is encapsulated by using 3D print and polylactic acid material. This FBG sensor is designed for heart rate monitoring of the human body. In this article, we describe the complete process consisting of creating, encapsulating, and experimental verification of the sensor. This sensor we compared with the conventional ECG monitoring system. Measurement was performed with a group of 5 volunteers in the laboratory conditions. The measured data were compared by the Bland-Altman method.
This paper describes the proposal, manufacture, and overall testing of a portable measuring sensor based on the fiber-optic Bragg grating (FBG). The sensor is made of two-component silicone rubber (ZA 50 LT) and can be used to monitor the density of car traffic in cities at a maximum speed of 60 kph in one lane. The construction of the sensor, which is over 2 m long and 1.8 cm wide, contains optical fiber with FBG encapsulated in a carbon tube and allows the detection of individual vehicle axles. Functional verification of the sensor was performed in real traffic on overall 761 vehicles (various types) with a high detection success rate of 97.19 %.
This article describes the research work in search of an optimized solution for the measurement of compressive force using the detection of the intensity of the optical power coupled into the optical fiber. In the experimental part of the research a product realized by 3D printing was used the outer case of which was made of FLEXFILL 98A material and the inner part was formed by a three-part PETG layer while the middle sensory part was changeable. This model was used to test different shapes of deformation elements in the variable part to find suitable configurations of the deformation plate. A standard 50/125 μm multimode graded index optical fiber was placed in the sensory part. It can be assumed that the results of this research can be used for the design of sensors based on the detection of changes in optical power intensity
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.
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.
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.
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.
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.
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.
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.
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.
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.
Polydimethylsiloxane (PDMS) can be used for its optical properties, and its composition offers the possibility of use in the diverse environments (industry, photonics, medicine applications, security devices and etc.). Therefore authors of this article focused on more detailed working with this material. This material could be use for the sensory applications such as the sensor of pressure or weight, which may find use also in the field of security and defense. The article describes the process of making the prototype of the sensor and its verification based on laboratory results. Measurement methodology is based on the determination of the change of optical power at the output of the sensor prototype depending on the change in pressure or weight. We estimate the maximum load of the sensor on the basis of the laboratory results in the units of tons. Using a calibration measurement can determine the amount of pressure and weight with an accuracy of ± 2 %.
Polydimethylsiloxane (PDMS) can be used for its optical properties and its composition offers the possibility of use in the dangerous environments. Therefore authors of this article focused on more detailed working with this material. The article describes the methodology of preparing the end faces of the cylindrical waveguide of polymer polydimethylsiloxane (PDMS) to minimize losses during joining. The first method of preparing the end faces of the cylindrical waveguide of polydimethylsiloxane is based on the polishing surface of the sandpaper of different sizes of grains (3 species). The second method using so-called heat smoothing and the third method using aligning end faces by a new layer of polydimethylsiloxane. The outcome of the study is to evaluate the quality of the end faces of the cylindrical waveguide of polymer polydimethylsiloxane based on evaluating the attenuation. For this experiment, it was created a total of 140 samples. The attenuation was determined from both sides of the created samples for three different wavelengths of the visible spectrum.
Polydimethylsiloxane (PDMS) can be used for its optical properties and its composition offers the possibility of use in the dangerous environments. Therefore authors of this article focused on more detailed working with this material. The authors describe the use of PDMS polymer for the light transmission over short distances (up to tens of centimeters). PDMS offers good prerequisites (mechanical properties) for the creating cylindrical lighting waveguide e.g. for the purpose of the automotive industry. The objective is to determine the maximum bending radius of the cylindrical waveguide of polydimethylsiloxane for different wavelengths of the visible spectrum and thus extend the knowledge for subsequent use in lighting. The created cylindrical waveguide consist of a core and a cladding. Cladding was formed by a PDMS having a lower refractive index in order to respect the condition of total reflection.
Polydimethylsiloxane (PDMS) has good optical properties, and its composition offers the possibility of use in many applications (industry, security device, medicine applications and etc.). We focused on the alternative option of temperature measurement in this article. Our approach is based on measuring changes of chromaticity correlated temperature corresponding to changes in temperature. Described device uses an optical fiber with a defined layer of PDMS and luminophore and we assume that it can find use also in the field of security. The article describes the process of making the prototype of the device and its verification based on laboratory results. The measured temperature depends mainly on the type of optical fiber and the measured temperature range is determined by the thermal resistance of used optical fiber. Using a calibration measurement can determine the value of temperature with an accuracy of ± 2,5 %.
The article describes a method for fabrication of polymer optical micro-lenses using polydimethylsiloxane (PDMS) at the end of optical fibers. PDMS is an optically clear substance having a refractive index very similar to the optical fibers. Therefore it is an interesting material for optical purposes. PDMS is characterized by resistance to electromagnetic interference (EMI), enabling the use in electromagnetically noisy environments. These lenses could be used for example for the security applications. For the manufacture of the micro-lenses is used Sylgard silicone elastomer 184. When applied to the end of conventional optical fiber is cured by treatment at 100 °C ± 5 °C. Authors performed a series of experimental measurements. The optical characteristics of the treated fibers compared with conventional fibers without micro-lenses. The fibers provided with optical lenses made of PDMS may be used for security applications, in the visible light communication (VLC) or as a microprobe.
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.
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 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.
The authors of this article focused on the issue of measurement of the chromaticity temperature of proposed bulbs made from polydimethylsiloxane, depending on the temperature of proposed bulbs. The advantage of this solution is the immunity to electromagnetic interference (EMI) and the ability to use, for example in dangerous environments (such as mines, factories, etc.). For the realization of incandescent bulbs was used transparent two-component elastomer Sylgard 184. A mixture of polydimethylsiloxane (PDMS) and a curing agent in a defined ratio (10:1) and admixture with garnet phosphor YAG: Ce was cured in the temperature box at temperature 90°C ± 3°C in the shape of the bulbs. All experiments were realized with eight different weight ratios of phosphor and Sylgard 184. Optical power (5 W) from a laser with a wavelength of 455 nm was fed to the proposed bulbs using the cylindrical waveguide of polydimethylsiloxane with a diameter of 5 mm. Chromaticity temperature was measured by two temperature sensors for 12h. The outcome of this study is the evaluation of the chromaticity temperature of output light depending on temperature variations of proposed bulbs due to the conversion of optical power into heat.
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).
Protection of persons and assets is the key challenge of Smart City safeguards technologies. Conventional security technologies are often outdated and easy to breach. Therefore, new technologies that could complement existing systems or replace them are developed. The use of optical fibers and their subsequent application in sensing is a trend of recent years. This article discusses the use of fiber-optic sensors in perimeter protection. The sensor consists of optical fibers and couplers only and being constructed without wires and metal parts bring many advantages. These include an absence of interference with electromagnetic waves, system presence can be difficult to detect as well as affect its operation. Testing installation of perimeter system was carried out under reinforced concrete structure. Subjects walked over the bridge at different speeds and over the different routes. The task for the system was an absolute detection of all subjects. The proposed system should find application mainly in areas with the presence of volatile substances, strong electromagnetic fields, or in explosive areas.
The authors focused on the problems of measurement of attenuation and homogeneity of special fibers of polydimethylsiloxane (PDMS) depending on three different procedures for mixing PDMS and curing agent. We used a two-component elastomer Sylgard 184. For mixing was used a defined ratio of 10:1 for PDMS, which was determined based on the datasheet. Curing of samples took place in a heat box at a constant temperature of 80 °C ± 3 °C. Three procedures were defined for mixing PDMS and curing agent: manual, using a laboratory shaker and ultrasonic baths. For each method of mixing was carried out a total of 25 samples. The test samples have a defined shape in the form of a cylindrical waveguide with a diameter of 5 mm and a length of 50 mm. The whole process of production of cylindrical waveguides applied in the protective vacuum box. To verify the homogeneity of the samples were divided into 5 mm sections, measured was the attenuation constant in both directions. As a source of radiation was used LED (Light Emitting Diode) with a wavelength of 470 nm. The outcome of this study is the evaluation of the quality waveguides by the size of the total attenuation and the attenuation constant for analysis of spreading out in homogeneities depending on the procedure of mixing PDMS and curing agent. The analysis performed with regarding the use of PDMS for its optical properties.
White light is produced by a suitable combination of spectral components RGB (colors) or through exposure excitation of blue light (the blue component of light). This blue part of the light is partly and suitably transformed by luminophore so that the resulting emitted spectrum corresponded to the spectral characteristics of white light with a given correlated color temperature (CCT). This paper deals with the measurement of optical properties of a mixture polydimethylsiloxane (PDMS) and luminophore, which is irradiated by the blue LED (Light-Emitting Diode) to obtain the white color of light. The subject of the investigation is the dependence of CCT on the concentration of the luminophore in a mixture of PDMS and different geometrical parameters of the samples. There are many kinds of PDMS and luminophore. We used PDMS Sylgard 184 and luminophore-labeled U2. More accurately Yttrium Aluminium Oxide: Cerium Y3Al5O12: Ce. From the analyzed data, we determined, which mutual combinations of concentration of the mixture of luminophore and PDMS together with the geometric parameters of the samples of the special optical fibers are suitable for illumination, while we get the desired CCT.
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.
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.
Polydimethylsiloxane belongs among polymeric organosilicon compounds which find utilization in many industries. Within telecommunication technologies, the primary use is in the field of encapsulation of electronic units, circuit boards, optical splice or optical cables. This article focuses on the use of polydimethylsiloxane (below PDMS) for its optical properties. We created test samples with a defined ratio of PDMS polymer and luminophore which can to radiate part of the absorbed energy in the form of light. LED (Light-Emitting Diode) with the wavelength range of 440 nm to 470 nm, which corresponds to a blue color in the visible spectrum, was used as the source of excitation energy. Used luminophore is Yttrium Aluminium Oxide: Cerium (Y3Al5O12:Ce). The output of the selected combination generates white light. The value of the chromaticity temperature determines the color of light. The output of article is a definition of the suitable ratio of PDMS and luminophore whose the emitted light has the range of chromaticity temperatures matching white light, for example, for lighting. A USB-650 Red Tide spectrometer and SpectraSuite software, which has chromaticity temperature and spectral characteristic as output, were used to finding the chromaticity temperature.
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.
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