FBG sensors for temperature and pressure measurement

FBG sensors for temperature and pressureNowadays fiber optic solutions play a crucial role in information technology. Fiber optic technology promotes the development of advanced fiber optic sensors. These fiber sensors offer numerous benefits that make them very attractive. The benefits include “durability, flexibility, biocompatibility, high sensitivity, and electromagnetic interference immunity.”

The applications of fiber optic sensors consist of numerous fields. They are widely used in medicine, environmental protection, industrial production, and structural health monitoring. Herewith, different types of fiber sensors allow for measuring various physical and chemical parameters. For instance, they sense temperature, acoustic, pressure, humidity, and others.

The production of distributed sensing systems requires different types of fibers. The following types are the most popular: photonic crystal, polarization-maintaining, double-core, sapphire optical fibers, etc. It should be noted that various fiber optic sensors use various measurement principles. Additionally, fiber Bragg gratings (FBGs) – the most popular measurement principle.

FBG sensors can also perform multi-parameter measurements to meet the practical demands of scientists. Thus, a team of researchers has demonstrated a cascaded multi-mode FBG sensor that performs the dual-parameter measurement. They apply optical fiber with several modes to create a distributed sensing system. Moreover, the FBG sensors measure the Brillouin frequency shift for temperature and strain sensing.

To be more precise, these FBG sensors have a hybrid structure (FBGs and FPI) with a nano-silica diaphragm on the tip. Besides, the total length of the fiber sensor is less than a human hair. These FBG sensors determine both environmental temperature and pressure. Therefore, such a fiber optic solution is highly promising in specific applications in severe environments.

Finally, the hybrid fiber optic sensor has been already produced and even tested. The distributed sensing system includes an FPI with a silica diaphragm. Also, fiber optic technology applies the femtosecond laser inscription technique and arc discharge methods. These FBG sensors demonstrate a high level of pressure and temperature sensitivity.

Additionally, the fiber optic sensor has an ultra-low level of cross sensitivities. “The temperature-induced error of the pressure measurement was –1.4286 kPa/ and ℃ pressure-induced error of the temperature measurement was ~0℃/MPa.” The mentioned-above benefits of FBG sensors make them perfect for numerous fields of applications.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating sensors, for example, fbg strain sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in structural health monitoring systems and want to learn more, please contact us at info@optromix.com

Fiber optic sensors for smart battery charge

FBG sensors for battery chargeRecently a team of scientists from an American research center has presented a fiber optic technology used to create a battery management system applying embedded fiber optic sensors and machine learning. The thing is that the combination of fiber sensors and machine learning allows for developing more efficient and low-cost designs of smart battery charge management systems.

The important fact is that scientists pay careful attention to lithium-ion battery packs applied in hybrid and electric devices. Therefore, these fiber optic sensors allow for monitoring cell degradation and health data and predicting remaining battery life. Moreover, the fiber sensors have been already tested and demonstrated high precision across different use-cases at both the cell and module levels.

The operating principle of such a fiber optic system is based on the wavelength-shift detection technology that “measures the signals from fiber sensors installed within the active chemistry of the battery.” The fiber optic system has a resolution of 30fm and the KHz speed leading to obtaining the data about the charge’s state and failure warning.

Additionally, a read-out device records these data. Then machine learning algorithms evaluate it to offer real-time performance management of battery charge. Recently, the tests of fiber optic sensors have been finished at the module level of electric car batteries after tests on individual lithium-ion cells. According to the test results, these fiber sensors enable to decrease in the form factor of hybrid and electric car batteries by more than 25% leading to low-cost manufacturing at the same energy density.

Nevertheless, the team plans to perform additional testing and research to learn how to scale the fiber optic technology for larger batteries. Thus, scientists want to use original equipment manufacturers to examine the fiber optic system installed in hybrid and electric vehicles and to open new applications of fiber optic sensors for various energy and structural systems.

The thing is that the developed fiber sensors are regarded as a part of the energy technology program that aims at developing clean and abundant energy for a wide range of applications. Finally, the team paid attention to chemical energy storage for hybrid and electric systems, consumer electronics, and the electrical grid; advanced energy conversion devices; wireless fiber sensors; and advanced analytics before the novel fiber optic technology to increase energy utilization.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating sensors, for example, fbg strain sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in structural health monitoring systems and want to learn more, please contact us at info@optromix.com

Novel FBG sensors and their promising applications

new FBG sensors A dramatic increase in the application of composite materials, involving aerospace technology, as well as other fields that need high reliability of structures, for instance, oil production, building industry, etc., makes the task of structural health monitoring very important. 

One of the most promising techniques is considered to be fiber optic sensors as an integral part of the monitoring system. Fiber optic sensors have several essential benefits over conventional ones. Compared to standard sensing systems, fiber sensors offer:

– a small mass;

– a high level of sensitivity;

– an electromagnetic compatibility;

– the ability to be combined in a network, as well as multiplexing;

– the compatibility with other systems for structural health monitoring;

– the ability to measure a variety of quantities.

A great benefit provided by fiber sensors also includes the ability to measure a variety of parameters such as deformation, pressure and force, electric and magnetic fields, sound and vibration, pH and viscosity, the presence of molecules, bacteria, and so on.

The sensitive element of a point fiber sensor is a fiber Bragg grating (FBG). The fiber Bragg grating reflects emission with a certain wavelength and it is transparent to other wavelengths. This selective reflection is achieved by writing a periodic structure in the optical fiber core. The reflected signal is registered by the receiving device.

FBG sensors do not have electronic components, i.e. they are passive. Thus, this property of FBG sensors opens up a wide range of possibilities for the application of such sensors in hazardous areas and areas with strong electromagnetic interference.

Herewith, multiple fiber Bragg gratings can be created on a single optical fiber. Each of the FBGs will reflect laser beam emission at its wavelength. This allows for producing a distributed monitoring system with wavelength multiplexing. The use of fiber optic sensors for structural health monitoring is regarded as very promising. 

The widespread use of composite materials in the aviation industry, as well as the creation and application in the future of “smart” materials and structures even with adaptive properties, will require continuous improvement of the structural health monitoring systems. Promising integrated sensing systems installed in optical fibers will significantly transform the way FBG sensors are employed in aviation materials and structures.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating sensors, for example, fbg strain sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in structural health monitoring systems and want to learn more, please contact us at info@optromix.com

New FBG sensors with copper and aluminum coatings

copper FBG sensorsResearchers-manufacturers of fiber optic solutions from the U.S have presented new fiber Bragg grating sensors (FBG sensors) with copper and aluminum coating. Herewith, this fiber optic system has a compact size, it is hermetically sealed, and can maintain high temperatures leading to new opportunities for metal-coated fiber optic sensors.

To be more precise, FBG sensors and gold-coated sensors allow for developing new “inherently humidity-proof strain, temperature, displacement, acceleration, pressure, load, tilt, bio, and other useful fiber sensors and systems.” The researchers claim that FBG technology is considered to be very useful for numerous sensing applications in harsh environmental conditions because of its benefits provided.

The benefits of FBG sensors include the ability of absolute temperature measurement, rapid response, numerous sensing points on a single optical fiber strand with minimal mechanical burden and intrusion, as well as EMI immunity, spark-free, and chemical inertness.

Nonetheless, such conditions as a high level of humidity or temperatures, corrosive chemicals, or strong mechanical stress often presented in real environmental conditions create obstacles for fiber optic sensors with glass coating. New FBG sensors with copper, aluminum, and gold coatings enable researchers to enlarge current applications and develop new ones.

It should be noted that such processes as stripping and recoating are necessary for all laser writing methods included metals. The researchers demonstrate a robust technique to produce fiber sensors with acrylate, polyimide, aluminum, copper, and gold coatings installed into conventional high-temperature fiber Bragg gratings, which then are recoated with acrylate, polyimide, or gold coatings. 

Thus, such FBG technology makes it possible to change lengths of window stripping and recoating as well as control material thickness and length. Different types of inscription and coating allow for employing FBG sensors in different conditions from the cryogenic temperature of -200℃ to the high temperatures of +1000℃. 

These FBG sensors have a metal coating, and they are created by excimer and/or femtosecond laser writing methods. Additionally, the fiber optic system has been already tested, and the results show specific benefits in offering multipoint and multifunction sensing abilities in a constantly expanding range of applications not previously addressable by standard FBGs. The thing is that the coating of properly designed fiber optic sensors plays a crucial role in the integrity, survivability, functionality, and durability of FBG sensors.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating sensors, for example, fbg strain sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in structural health monitoring systems and want to learn more, please contact us at info@optromix.com

Seismic application of FBG sensors

FBG sensors in seismologyA team of researchers presents a fiber optic technology based on fiber Bragg gratings (FBGs) for sensing to monitor the activity of an active volcano. The monitoring of volcanic activity plays a crucial role in better understanding and even prediction of important and potentially disruptive volcanic events, therefore, the fiber optic sensing system has to maintain harsh environmental conditions.

Nonetheless, the recording process of seismic activity now faces several difficulties concerning both discriminating between various sources of seismic wave, and the design of fiber optic sensing systems that can operate in active volcanic settings without any damages.

The team of researchers from France demonstrates the results obtained from the first high-resolution seismometer based on FBG sensors installed on an active volcano. It should be noted that the lifetime of modern fiber optic systems is quite short during their operation at high temperatures and the billowing, sulfurous, acidic gases near a fumarole.

Additionally,  standard FBG sensors can fail in emergency deployment, or repair, even in pre‐eruptive phases. The operating principle of novel fiber optic sensing systems is based on interferometry forms that apply more sensitive fiber optic elements such as fiber Bragg grating resonators that enable to detect the acceleration of the ground as a change in the signal from the FBG sensor.

These fiber optic systems can be used for networking across long distances and monitoring these distance via optical fibers. The FBG sensor is considered to be “a purely optomechanical geophone that is interrogated through a 1.5-kilometer fiber optic cable by a remote, and thus it is a much safer fiber optic system down the volcano’s flank.”

Moreover, the fiber optic sensing system has been already tested and recorded tiny seismic events within the volcano for nine months. The development of new FBG sensors lasts almost a decade, the researchers use previous researches of a high-resolution optical seismometer prototype that includes a 3-kilometer fiber optic cable. 

Finally, FBG sensors are regarded as highly reliable, fiber optic technology allows installing the sensors in locations that were not previously practical, providing more data about microseismic events under a volcano’s dome. The researchers claim that such fiber optic sensing systems offer more detailed information about “the fumarole signature, which helps to constrain the geometry and activity of the plumbing system of the dome”.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating sensors, for example, fbg strain sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in structural health monitoring systems and want to learn more, please contact us at info@optromix.com

Various fiber optic coatings for fbg strain sensors

FBG strain sensors' coatingsDistributed fiber optic strain gauges are known for their crucial advantages compared with traditional measurement techniques, for instance, inductive displacement transducers, etc. To be more precise, fbg strain sensors are corrosion resistant, dielectric, and insensible to electromagnetic radiation. 

It should be noted that any part of optical fibers is applied as the sensing element for the fiber optic strain sensors, herewith, the measurement is not limited by a specific section. Moreover, fbg strain sensors provide one more benefit that includes the opportunity of installing the optical fiber into the building material matrix.

Such a fiber optic sensing system allows detecting strain within concrete elements, which can include data about the curing and load behavior. The thing is that distributed fiber optic strain gauges play an important role in massive concrete structures, for example, foundations or concrete roads, therefore, these fbg strain sensors demonstrate the structural and loading conditions.

Herewith, such a fiber optic technology enables to combine the quality management of posttreatment and health monitoring. The operating principle of fbg strain sensors is based on the use of optical fibers, the core of which detects the strain. Also, it is necessary to pay careful attention to two techniques that influence the deformations of the fiber optic sensors: “slippage can occur between the fiber cladding (the so-called coating) and surrounding substrate; depending on the coating material, the cladding cannot wholly transfer the strain from the substrate to the fiber cladding and the core.”

Finally, optical fiber coatings are also important, therefore, different teams of scientists have analyzed their effect on strain transfer during matrix measurements. For instance, such a technique as Brillouin scattering shows that fiber optic cables have lower strain values in the matrix than the reference technique. Herewith, there are the strain transfer rates of embedded FBG sensors in mortar prisms.

The fiber optic technology has been already tested. The team installed the optical fiber into a reinforcing bar, which was later installed in the concrete. Herewith, a brass frame and optical fiber with a single-layer polyimide coating allow researchers to install the fiber in small concrete specimens and obtain similar values to the reference sensing measurements.

Additionally, distributed fiber optic sensors demonstrate higher values than the standard strain gauge measurements on the surface.  The researchers claim that the concrete is required to be quite cured to provide the strain transfer in the fiber optic sensors. However, the acrylate coating has higher strain losses.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating sensors, for example, fbg strain sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in structural health monitoring systems and want to learn more, please contact us at info@optromix.com

Fiber Bragg grating sensors perform structural health monitoring

FBG sensors for sctructural health monitoringNowadays fiber Bragg gratings are actively applied in the aerospace industry. The thing is that fiber optic multiplexing abilities of sensors based on FBG technology allow performing structural health monitoring of airborne vehicles resulting in an increase of their lifetime. Thus, fiber Bragg grating sensors play a crucial role in the spacecraft industry where mistakes and damage can lead to death.

It should be noted that fiber Bragg gratings are considered to be a thin optical fiber device that includes a physical “grating” area at its core. Herewith, the FBG core is not homogeneous, and the fiber optic sensor has a periodic variation in the refractive index of the material. Also, there is a dependency between the wavelength of light (reflected vs transmitted) and the periodic spacing of the grating.

FBG sensors can block specific wavelengths and transmit others like in laser cavities during the mode choice. Additionally, such factors as pressure and strain also influence the qualities of FBGs and the wavelengths resulting in stretching or compressing the grating period while temperature leads to thermo-optic effects. These and some other effects (for instance, vibration and displacement)  promote the application of fiber Bragg grating sensors to monitor various physical effects.

FBG sensors enable to determine ultrasonic and acoustic wave signals that are important in structural health monitoring of aerospace vehicles. For instance, acoustic-ultrasonic determination provided FBG technology helps to find out damage when the spacecraft is not mobile.

The detection offered by fiber optic sensors is regarded as highly accurate and quantitative because it is possible to monitor both the form function of the waves and the repetition of measurements. Nevertheless, the resolution and the bandwidth limitation of conventional tools employed with fiber Bragg gratings (for example, optical spectrum analyzers) do not enable accuracy in high-frequency determination.

The fact is that accurate determination of ultrasonic waves requires a demodulation method to interpret the detected signals. Four demodulation methods are distinguished in FBG technology both in practice and in laboratory testing: “a broadband light source (power detection), laser light source (edge-filter detection), Erbium-Doped Fiber Laser (EDFL), and modulated lasers.” Moreover, it is necessary to pay careful attention to the installation technique of the FBGs.

Finally, specialists apply several various techniques to employ fiber Bragg grating sensors into a vehicle or craft. The fiber optic sensors have been already tested at their installation into composite materials (inside of a fiber honeycomb sandwiches.) However, the technique can cause signal distortion, that is why an ideal way for spacecraft is gluing fiber Bragg gratings on with some adhesive.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in structural health monitoring systems and want to learn more, please contact us at info@optromix.com

Fiber Bragg grating sensors measure physical factors

FBG sensors for physical factorsFiber Bragg grating (FBG) has quickly become popular in fiber optics, and now it is impossible to imagine the absence of fiber optic sensing systems based on FBG technology. Researchers prefer to use fiber Bragg grating (FBG)-based sensing because of its benefits, for instance, compact size, fast response, distributed sensing, and immunity to the electromagnetic field. 

To be more precise, FBG technology finds its wide application in measurements of different physical factors (pressure, temperature, and strain for civil engineering, industrial engineering, military, maritime, and aerospace applications). Herewith, structural health monitoring of engineering and civil structures plays a crucial role now that can be easily carried out with fiber Bragg grating sensors.

It should be noted that the grating types of FBG include uniform, long, chirped, tilted, or phase-shifted (that has periodic perturbation of refractive index inside the core of the optical fiber). The development of fiber optic systems has greatly changed almost all areas of communication technology. Nowadays fiber optic sensors are widely used in the measurement of strain, refractive index, the vibration of structures and machines, electric current, voltage, impedance, temperature, pressure, humidity, etc.

Despite the crucial advancement in fiber optics,  integration of optical mirrors, partial reflector, and wavelength filters provide numerous difficulties because of the complexity and high cost of fiber optic systems. Nonetheless, FBG technology allows overcoming all these challenges because fiber Bragg grating can offer the function of reflection, dispersion, and filtering required for sensing applications.

Ever since its development, fiber Bragg grating sensors have obtained much attention because they offer numerous benefits, for example, pretty low cost, compact size, real-time response, high precision, high sensitivity, and independence to electromagnetic interference. Moreover, FBG sensors are considered to be very promising in measuring physical parameters.

Modern applications of fiber Bragg grating sensors include such areas as “high-temperature sensors, health and biomedical devices, structural engineering, industries, biochemical applications, radioactive environment, aerospace, maritime and civil engineering, and many other fields.” Additionally, FBG sensors rapidly moved from research laboratories to actual installation in fiber optic systems.

Finally, it is very difficult to think of fiber optic sensors without employing fiber Bragg gratings due to its attractive parameters, which make them a highly advanced technology in the sensing field. The combination of FBG technology with other systems, in turn, will lead to the overall enhancement of sensor design in terms of sensitivity, performance, cost, and size.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in structural health monitoring systems and want to learn more, please contact us at info@optromix.com

Dynamic gratings produce new fiber optic sensors

FBG sensors with dynamic gratingsResearchers have presented dynamic gratings used instead of depending on fixed-position fiber Bragg gratings, and now core-launched laser beam light can unite to the cladding modes of conventional optical fiber resulting in distributed fiber sensing of the external environment.

The thing is that fiber optic sensors allow distinguishing between chemicals and liquids external to the optical fiber, herewith, they are usually based on refractive-index changes in the cladding modes of the fiber. Moreover, fixed-position fiber Bragg gratings (FBGs) are applied to excite these cladding modes and unite laser beam light from the core mode.

Nevertheless, FBG sensors need specific equipment to create the gratings at the optical fiber, also they only work as point sensors at specific, predetermined locations. A team of researchers from Israel tries to overcome these challenges by developing dynamic gratings at reconfigurable short sections along with the optical fiber.

Thus, the new gratings are independent of any permanent change in the fiber structure. It is possible to switch them on and off at will, and fiber optic sensors based on dynamic gratings allow scanning along with the optical fiber. According to researchers, after the installation of a grating, its effect is not restricted only to light in the core mode.

Similar to conventional FBGs, the dynamic gratings also unite laser beam light between core and cladding modes. Herewith, in analogy to fiber Bragg gratings, such connection will occur for the light at very specific frequencies. “An optical probe wave of tunable frequency is launched at the dynamic grating, and the exact frequency in which coupling takes place is carefully noted.”

Compared to FBGs, dynamic gratings enable the researchers to carry out tests in any chosen position. It should be noted that the developed fiber optic sensors have been already tested over 2 m of traditional optical fiber. To be more precise, fiber sensors consisted of  8 cm length dynamic gratings perform scanning along with the optical fiber resulting in the combination of spectra between core and cladding modes in each position.

Measurements accurately detect the parts of optical fiber that were immersed in ethanol and water, herewith, the fiber sensors can distinguish between the two with an 8 cm resolution. At the same time, the refractive index outside the fiber is possible to estimate precisely with fourth-decimal-point accuracy (0.0004).

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in structural health monitoring systems and want to learn more, please contact us at info@optromix.com

FBG sensors that dissolve inside the body have been developed

FBG sensors inside bodyResearchers have been firstly created a fiber optic sensing system, known as a fiber Bragg grating (FBG), inside bio-soluble optical fibers. According to Science Daily, fiber optic technology can be used to monitor the condition of fractures and safely study sensitive organs, such as the brain.

Fiber Bragg gratings that reflect the light of a particular wave are often applied in optical fibers used as distributed sensors. For example, such fibers are employed to monitor bridges in real-time or to track the integrity of aircraft wings. However, they have not yet been used in medicine. The new fiber technology will overcome these limitations by using optical fibers that break down in the body.

Firstly, researchers from Greece and Italy have created biodegradable glass for FBGs. They used phosphorus oxide in combination with oxides of calcium, magnesium, sodium, and silicon to perform this. The resulting optical glass combines excellent optical properties with water solubility and compatibility with living organisms, and its properties can be changed by adjusting the chemical composition.

Then the fiber Bragg gratings made from biodegradable glass were placed in conditions that are similar to the human body. As the experiment demonstrated, the created structures dissolve without a trace in such an environment, which opens the way for their medical application. Such FBG sensors are considered to be safe for the body and will not need to be removed after their use.

Possible examples of using optical fiber with FBGs include creating fiber optic sensors to assess joint pressure and monitor the heart and other sensitive organs. This optical fiber can also improve laser techniques for removing tumors by simultaneously conducting a laser beam and measuring temperature, necessary for the laser ablation process. Nevertheless, its safety and effectiveness will be tested on laboratory animals before developing medical applications of FBG technology.

Thus, a group of engineers from the University of Connecticut has created a biocompatible pressure sensor that will help doctors monitor chronic lung diseases, brain tumors, and other medical conditions, and then dissolve into the human body without a trace. Such a FBG sensor should replace existing implanted pressure sensors that are made up of potentially toxic substances and require removal after use.

Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for the clients. Optromix produces a wide range of fiber optic devices, including cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Moreover, Optromix is a top choice among the manufacturers of fiber Bragg grating monitoring systems. If you have any questions, please contact us at info@optromix.com