Tag: FBGs

FBG sensors: a comprehensive review

A fiber Bragg grating is an optical interferometer embedded in an optical fiber. At the same time, fiber optics combined with certain substances (usually germanium) can change its refractive factor when the fiber is exposed to ultraviolet light. If such a fiber is illuminated with ultraviolet light with a specific spatial periodic structure, the optical fiber becomes a kind of diffraction grating. In other words, this optical fiber will almost completely reflect the light of a certain, predetermined range of wavelengths, and transmit light of all other wavelengths.

Application of FBG sensors

The FGB application includes the following fields:

Point sensors (that is able to measure deformation, temperature, pressure, tilt, displacement), embedded in composite materials and others;
Laser systems and amplifiers (filters, mirrors);
Telecommunications (dispersion compensation modules, WDM technology);
Research and development.

Difference between electrical and fiber sensors

For decades, electrical sensors (tensor-resistive, string, potentiometric, etc.) have been the main method of measuring physical and mechanical phenomena. Despite their widespread use, electrical sensors have several disadvantages, such as loss during signal transmission, sensibility to electromagnetic interference, the need to organize a spark-resistant electrical circuit (if there is a danger of explosion). These mentioned above limitations make electrical sensors unsuitable or difficult to use for a number of applications.

The use of fiber optic sensors is an excellent solution to these problems. In fiber optic sensors, the signal is light in the optical fiber instead of electricity in the copper wire at traditional electrical sensors.

Over the past twenty years, a huge number of innovations in optoelectronics and in the field of fiber optic telecommunications has led to a significant reduction in prices for optical components and to a significant improvement in their quality. This factor allows fiber optic sensors to move from the category of experimental laboratory tools to the category of widely used devices in various areas.

Operating principle of Bragg gratings

A fiber Bragg grating or FBG acts as a sensitive element of point fiber optic sensors, which is capable to reflect certain wavelengths of light and transmit all others. This effect is achieved by periodically changing the refractive index in the core of the fiber optics.

When the laser light passes through an optical fiber, a part of it is reflected from the fiber grating at a certain wavelength. This peak of reflected light is registered by measuring equipment. As a result of the numerous parameters influence, the interval between the FBG bundles and the refractive index of the fiber optics change.

Consequently, the wavelength of the light reflected from the fiber Bragg grating changes. In addition, it is possible to determine the exact characteristics of the changes by changing the wavelength. In fiber optic sensors based on Bragg gratings, the measured value is converted to a Bragg wavelength offset. The recording system converts the wavelength offset into an electrical signal.

The sensing element of such FBG sensor does not contain electronic components and therefore it is completely passive, which means it can be used in the area of increased explosiveness, aggressiveness, strong electromagnetic interference. Numerous fiber Bragg gratings can be installed on a single fiber, each of which gives a response at its own wavelength. In this case, instead of a point sensor, we get a distributed sensing system with multiplexing along the wavelength.

The use of the light wavelength as an information parameter makes the FBG sensor insensitive to the long-term changes of the parameters of the source and radiation detector, as well as random attenuation of power in the optical fiber.

Common types of FBG sensors

The following types of fiber optic sensors based on FBG technology are used for automated monitoring:

FBG strain sensors;
FBG displacement sensors;
FBG temperature sensors;
FBG pressure sensors;
Fiber optic tilt sensors;
Fiber optic acceleration and vibration sensors;
Data recorders for fiber optic sensors;
Additional equipment for data recorders.

The principle of FGB sensor operation is based on the modulation of one or several properties of a propagating light wave (intensity, phase, polarization, frequency), which change occurs with a change in the measured physical quantity.

The basis of fiber-optic sensing technology is an optical fiber – a thin glass thread that transmits light through its core. The optical fiber consists of three main components: core, shell, and coating. The shell reflects the scattered light back into the core, allowing light to pass through the core with minimal loss.

It can be achieved by a higher refractive index in the core relative to the shell, resulting in a complete internal reflection of light. The outer coating protects the fiber optics from external influences and physical damage. It can consist of several layers depending on the required protection.

Benefits of fiber sensors based on Bragg gratings

The advantages of FBG sensors include:

Wide sensing range;
Possibility to integrate the FBG sensing system into the object structure;
Full fire and explosion safety;
Long-distance signal transmission;
Integration of several fiber optic sensors in one channel;
Insensitiveness to electromagnetic and radio frequency influences;
No need for recalibration (stable over time under constant external conditions).

At the moment, most of the sensors used in the world are electrical sensors. As it was mentioned above, in optical sensors based on fiber Bragg gratings, the signal is light passing through an optical fiber (instead of an electric current passing through a copper wire). This fundamental difference allows FBG sensors to overcome many problems typical for electrical sensors.

Features of fiber optic sensors

Optical fibers and sensors are non-conductive, electrically passive, and immune to electromagnetic interference. Monitoring with a tunable high-power laser system allows sensing over long distances with virtually no signal loss. In addition, each optical channel is able to monitor a variety of FBG sensors unlike the electrical channel, which significantly reduces the size and complexity of such a sensing system.

Optical sensing systems are ideal for use in conditions where conventional electrical sensors (strain gauge, string, thermistor, etc.) can be difficult to use (long distances, EM fields, explosion safety, etc.). It is easy to switch to fiber optic solutions since the installation and operation of optical sensors are similar to traditional electrical sensors.

Understanding the principles of FBG operation and the benefits of Bragg grating sensor applications can greatly facilitate the solution of various problems in the field of sensing measurement (for example, monitoring of structures).

Nowadays FBG sensors are applied in various fields that require precise and fast measurements. Fiber Bragg sensing systems can be used in aeronautic, automotive, civil engineering structure monitoring, undersea oil exploration, in the mining industry, geotechnical engineering, structural engineering, tunnel construction engineering, etc.

Bragg sensors in medicine

The most promising application of FBG sensors is medicine. Now FBG technology is highly used for fiber-based biomedical sensing including biosensing, safety or security, and structural health monitoring. FBG sensors offer a new and effective way of real-time measurements. They can be applied in laser systems, medical tiny intra-aortic probes, and body sensors for biochemical analysis making.

For example, today fiber Bragg gratings apply optical-fiber sensing probes that are able to dissolve due to such ability as controlled solubility in a physiological environment. Thus, FBG technology enables safer diagnostic of sensitive human organs and there is no need for a surgical extraction. The development of FBG continues, and it is possible that very soon new FBG sensors with improved characteristics appear.

How to choose the right fiber optic product?

If you want to obtain a highly efficient sensing system, you should choose the Optromix company. Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for monitoring worldwide. Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, distributed acoustic sensing (DAS) systems, distributed temperature sensing (DTS) systems. If you are interested in FBG sensors and want to learn more, please contact us at info@optromix.com

Fiber Bragg grating sensors provide groundwater flow sensing

Groundwater flow sensing is highly important when it comes to the extraction of drinking water because it allows for avoiding well clogging and pollution. Nevertheless, fiber Bragg grating sensors with optical fibers are considered to be a promising new technique for monitoring of groundwater flow.

The fact is that FBG sensors enable us to identify even tiny changes in temperature, pressure, and fiber shape taking into account the sensitivities influenced by the packaging. Thus, fiber Bragg grating sensors are able to create a multiplexed sensor for the groundwater flow direction and magnitude.

It should be mentioned that the fiber-optic technology of FBG sensors has numerous application range, for example, in aerospace (load monitoring and shape sensing), in civil engineering (structural health monitoring), and in the oil and gas industry (temperature and pressure monitoring).

Today the technology of fiber Bragg grating sensing is also used for groundwater flow monitoring. FBG sensors allow measuring various physical properties, strain, or temperature variations such as pressure, vibrations, and curvature of the optical fiber, herewith, fiber sensors make instant and precise measurements.

One more technique that can be used for monitoring is distributed temperature sensing, and the intended application influences directly the choice of technology – fiber Bragg grating or DTS sensing. DTS uses conventional single-mode or multimode fibers that find various applications in the telecom industry, that is why DTS fibers are available in large lengths.

Moreover, the FBG sensors are possible to be written in traditional and specialty fiber optics, and consequently, their price increases per sensor number. However, the cost of fiber interrogators that are required for the DTS sensing data collection is five times more expensive than FBG units.

Traditional fiber Bragg grating sensors already possess a sufficient temperature resolution for the measurement of groundwater temperature changes without additional packaging. In addition, this FBG system has been recently tested to demonstrate its benefits for groundwater flow monitoring.

Thus, the experiment has shown that the use of FBG sensors enables to measure the relative temperature with a precision of 0.85 ℃ for the differential measurements. Also, the used fiber Bragg grating system is able to make a multiple-sensor interrogation with the possibility of an expansion into a larger distributed sensing network.

Finally, the data results presented that fiber Bragg grating sensors can be employed as a temperature sensing system in the subsurface environment, but in this case, they did not demonstrate any benefits over the existing fiber sensing technologies. Nevertheless, multiplexed fiber Bragg grating pressure or strain sensors would possibly find their application in groundwater flow monitoring.

DTS FBGs fiber optic sensors

Quasi-distributed fiber optic sensor based on fiber Bragg gratings

At the present time distributed optical fiber sensors based on Raman, Brillouin, and Rayleigh scattering play a crucial role in the area of monitoring due to their ability to measure strain or temperature distributions. Nevertheless, weak signals within optical fibers cause numerous challenges, such as limited spatial resolution, low measurement speed, high system complexity, or high cost of the system. That is why new technology that replaces the previous one and is called a quasi-distributed fiber optic sensing based on fiber Bragg gratings is developed now.

The fact is that over the last decades, fiber optic sensors have become one of the fastest-growing and promising areas of modern sensing technologies. Thus, distributed fiber optic sensing has been successfully employed in numerous strain- or temperature-sensing applications because of the multiple benefits of many sensing points and a long sensing range. Nevertheless, weak signals create new difficulties in the monitoring process.

The use of fiber Bragg grating (FBG) sensors is the only solution to the problem because FBG sensors have stronger reflection signals within an optical fiber. As a result, it is possible to use the technology for obtaining numerous physical and chemical parameters from discretized local points of a few millimeters along with a single optical fiber. Moreover, these fiber optic sensors based on fiber Bragg grating can be easily multiplexed for assurance of high measurement speeds.

Unfortunately, at the moment fiber Bragg grating sensors have several drawbacks. The first is the limit of fiber optic sensors for FBG interrogation systems based on multiplexing. Thus, the maximum available number of sensors is considered to be a few tens or less. The second drawback of FBG sensors is the relatively high cost of the writing of periodic grating that is needful for the assurance of high reflectivity at different Bragg wavelengths. This is the reason why fiber optic sensors based on fiber Bragg grating are not suitable for mass production.

Herewith, a novel real-time quasi-distributed fiber optic sensor with weak fiber Bragg gratings allows increasing the number of FBG sensors up to 31 for the successful and efficient process of interrogation. Such a system does not require special maintenance, has a long lifetime because its most components are optical fibers and semiconductor tools that can be easily found in the optical industry.

Finally, this FBG system offers the following advantages that can find numerous applications in the near future:

high linearity;
high speed;
high stability against harsh environmental factors such as vibration, temperature, and humidity.

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

FBGs fiber Bragg gratings fiber optic sensors

Fiber optic solutions for security monitoring system

Recently a new simple low-cost technology has been developed for security monitoring of the borders. Initially, the technology that includes fiber-optic cables has been tested at the US-Mexico border. It allows the determination of a wide range of invasions such as animals, people, vehicles and it is even possible to detect their precise location.

In spite of the fact that this fiber-optic application is not new and has been around for years, the government of the USA has been slow to use it. The fiber-optic cable technology is able to detect exactly what is moving above it, and it does not matter whether it is a huge man, a group of people, a passing car, or a wandering dog.

Today, the US government continues to build a border wall that critics name a “medieval” solution to provide security, even despite the fact that the use of the fiber-optic system is cheaper than the building of a real wall. Other advantages of fiber optic cables include:

precise determination of border invasion location;
accurate detection of border invaders;
possibility to send quickly the information to border patrol agents in real-time.

It should be mentioned that only 1% of human communications is accounted for by satellites, and 99% is accounted for by fiber-optic cables spreading across the seafloor, buried under cities. Herewith, comparing to satellites, the fiber-optic technology is able not only to transmit data but also to determine movement that makes it more advantageous.

Moreover, the fiber-optic technology is already developed enough to be implemented in the security monitoring system of the US-Mexico border, and it is nearly ten times cheaper than a wall and can be put into operation instantly. Nevertheless, the main obstacle is the support of the US government.

The fiber-optic system is quite simple, that is why it is not necessary to put any sensors on the fiber because the fiber itself is a sensor that is able to determine motion as well as events anywhere along the fiber-optic cable length. Some companies made some improvements and enlarge the field of fiber-optic applications that now includes telecommunication, security monitoring, and even broadband internet access.

The principle of work is based on converting sound waves into acoustic information. Although the fiber-optic technology on its own will not completely get rid of the activity such as illegal border-crossing and drug-smuggling, its combination with border patrol agents will significantly improve the situation.

FBGs fiber optic cable fiber optic solutions

FBG biosensor is able to detect thrombin in human blood

Thrombin plays a very important role in normal and pathological blood coagulation because its high level is an indication of tumor cell presence. Also, the level of thrombin is growing while atherosclerosis, thromboembolic disease, cancer, and inflammatory disease. Thus, its clinical importance provokes the development of devices for fast and precise thrombin detection and most of them are based on aptamers.

One of the ways to solve the problem is the use of optical-fiber grating-based sensors that have a great range of advantages:

high level of sensitivity;
multiplexing ability;
compact size;
lightweight;
possibility of multi-modal sensing;
tolerance to electromagnetic interference;
low manufacturing cost.

All FBG sensors are based on different operation principles. There are LPG, etched fiber Bragg gratings, tilted FBG, microstructured Bragg gratings, photonic crystal fibers, or PCF. Nowadays the development of these types of sensors, especially, those which can detect thrombin, is the primary objective.

Etched fiber Bragg grating (EFBG) is one of them, its manufacturing is highly simple and fast because it has chemical etching liquids (for example, hydrofluoric acid) that are able to take away the cladding very quick at a controlled rate. Also, EFBG differs from core-exposed micromachined gratings by the absence of a laser micromachining station that makes the process of fabrication harder.

In spite of the fact that etched fiber Bragg gratings sensors have less sensitivity than in other types, there are numerous advantages over these sensing devices. For example, EFBG systems obtain simple adjustability of their sensitivity. Moreover, there is no need for a polarization control because etched Bragg gratings measure reflection.

This optical-fiber grating-based sensing system operates with a wavelength of 1550 nm, uses hydrofluoric acid as etching fluid for approximately 27 minutes. It is able to detect thrombin in concentrations ranging from 10 nM to 80 nM and the use of EFBG has a promising future as the manufacture of FBG biosensors needs only chemical etching, also it is simple and less expensive than other types of sensing systems. Moreover, etching fiber Bragg grating sensors are easy for multiplexing and, consequently, can be used in vivo. Finally, all the advantages expand the opportunities for thrombin detection.

Optromix is a fiber Bragg grating (FBG) products manufacturer that offers FBG sensors, FBG interrogators and multiplexers, DAS systems, DTS systems. Optromix creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you have questions or would like to buy FBG products, please contact us at info@optromix.com

FBGs fiber Bragg gratings fiber optic sensors

Bioresorbable Fiber Bragg Grating sensor advances medicine

Today environmental change provokes the appearance of new diseases and, finally, human health care requirements continue increasing for several decades. Moreover, it is necessary to have new advanced tools for the disease diagnosis at early stages, for monitoring and treatment of patients. Then unconventional biomedical instrumentation and sensors, including optical-fiber sensors come for help to modern medicine. And devices with bioresorbable fiber sensors increase the efficiency of monitoring and treatment.

Fiber Bragg Grating (FBG) is one of the most productive ways suggested for fiber-based biomedical sensing. Fiber Bragg grating sensing technology provides a new and effective way of real-time measurements. The fields of FBGs application contain biosensing, safety or security, and structural-health monitoring. Also, FBG sensors are highly suitable for laser systems, medical tiny intra-aortic probes, and body sensors for biochemical analysis making.

Modern Fiber Bragg Gratings use bioresorbable optical-fiber sensing probes that have such ability as controlled solubility in a physiological environment. A bioresorbable material is the main component of FBG sensors and the human body easily and safely assimilates it at a special time interval. The technology allows safer diagnostic of sensitive human organs and there is no need for a surgical extraction. Fiber Bragg Gratings sensors are easy to install and use, their sensing points have quite high density. It is an ideal, cost-effective, and accurate technology for extreme environmental conditions.

The advantages of optical fiber include:

good mechanical durability;
high optical transmission;
stoichiometrically tunable dissolution rate.

It should be mentioned that tilted Bragg gratings with a 1-degree tilt angle that are immersed in phosphate-buffered saline solution with temperature and pH conditions similar to those of the human body allow fiber dissolution studying. Finally, selective chemical-etching effects were found out thanks to scanning electron microscope images and micro-Raman spectroscopy.

Thus, bioresorbable fiber Bragg grating sensors are considered to be effective for the development of soluble, compact photonic sensing probes that can be used for in vivo monitoring of vital mechanical or chemical factors with a specific time limit, and also in controlled in-body drug delivery.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. Optromix creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. The range of services includes research programs, interpretation reports, layout design, system software modeling, commissioning, user training, real-time data transition, equipment supply, ground part installation, engineering, and technical support. If you have questions or would like to buy FBG products, please contact us at info@optromix.com

FBGs fiber Bragg grating sensors fiber optic sensors

Fiber Bragg Grating Based Chemical Sensors

Fiber Bragg grating (FBG) can be used as miniature, inexpensive, and lightweight strain, temperature, and pressure sensors for applications such as real-time health monitoring of aircraft, space vehicles, and smart materials and structures. Nowadays only a few applications of FBGs in chemical sensing have been reported.

The key to a chemical sensor using an FBG lies in the transfer of stress from a swelling material, such as a polymer, to the FBG, resulting in a measurable strain via the shift in resonant Bragg wavelength.

The main principle of FBG sensors for applications in chemical sensing is based on the axial strain of the fiber. The chemicals that surround the fiber cause it to shift and, deform. The strain caused by the presence of a particular chemical causes the spectral pattern of reflected light to change; the shift in reflected wavelength is observed. To monitor the shift in wavelength FBG interrogators are used. The data gathered by the interrogator can then be converted to environmental concentrations.

The key component of fiber Bragg grating sensors for chemical sensing is a highly sensitive coating. The coating should be stiff and adhere easily and firmly to the glass fiber. Most often the coating is based on polymers. However, the coating needs to have a high modulus of elasticity that remains high at high temperatures and during analytes absorption. Most polymers are restricted by temperature due to softening and material relaxation.

Some ways of FBG sensors polymer coating include:

improved coating processing;

The improvement of the coating process, like improved adhesion, may aid in the reduction of material relaxation and shifting. The glass fiber may be treated before the application of polymer coating for improved adhesion.

improved data processing;

The use of two different coatings that respond in equal, but the opposite manner to environmental changes. The combination of the two responses limits the temperature drift.

improved material properties.

Alternative coatings, like ones based on ceramic materials, may expand the temperature application range.

Chemical sensing is a developing field of fiber Bragg grating sensors. It is involved in the control of chemical processes, oil recovery, environment quality improvement. There are several factors that play a role in the implementation of chemical sensors – suitability for remote sensing, sensitivity, low costs, selectivity, ability to work consistently in harsh environments. The oil and gas applications require sensors that can withstand high temperatures and pressures, and environmental sensors must have a wide coverage area and limited signal fluctuations.

Fiber Bragg grating sensors have been used in numerous applications, including aircraft monitoring, structural health monitoring, strain, and temperature measurements. In the last decade, FBG sensors have been implemented as chemical sensors due to their ability to withstand high temperatures, immunity to electromagnetic interference, and the absence of electronics.

Optromix, Inc. is a U.S. manufacturer of innovative fiber optic products for the global market, based in Cambridge, MA. Our team always strives to provide the most technologically advanced fiber optic solutions for our clients. Our main goal is to deliver the best quality fiber optic products to our clients. We produce a wide range of fiber optic devices, including our cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Optromix, Inc. 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

FBGs fiber optic sensors fiber optic solutions

Optical Pressure Detector for Improving Robot Skin, Wearable Devices, and Touch Screens

A new type of fbg pressure sensor based on light could allow the creation of sensitive artificial skins to give robots a better sense of touch. The silicone sheet can be placed on display panels to enable touch screens or can be wrapped on robot surfaces as an artificial skin layer for tactile interactions. In addition to this, such a new sensor could allow the creation of optically transparent touch screens and devices and wearable blood-pressure monitors for humans.

Researchers from the Electronics and Telecommunications Research Institute (Daejeon, South Korea) and Hanyang University (Seoul, South Korea) developed a flexible, transparent fiber optic device that detects pressure by analyzing changes in the amount of light traveling through tiny tunnels embedded in polydimethylsiloxane (PDMS), a common type of silicon. This device is sensitive to even gentle pressure and is less prone to failure compared to previous types of fbg pressure sensors. It also should be feasible to incorporate the embedded optical sensors across a large surface area.

The fiber optic device works by measuring the flow of light through a precisely arranged pair of optical waveguides called a photonic tunnel-junction array. The waveguides run parallel to each other and are embedded in PDMS. PDMS is a very well-known biocompatible, non-toxic material, so the sensor sheet may even be applied on or inside the human body, for example, to monitor blood pressure.

Several steps are needed to move the sensor from a laboratory demonstration to a practical device. In developing the prototype, the research team used precision alignment tools, which would be too expensive and time-consuming to use in most commercial applications. An alternative approach, pigtail fibers, which telecommunications companies use to couple fibers in their systems, should make the process easier.

If you have any questions, please contact us at info@optromix.com

FBG pressure sensors FBGs fiber optic sensors

Fiber Bragg Grating Strain Sensors for Creating Modern Sophisticated Equipment

Strain measurement is imperative during prototype design and testing. Strain measurements ensure that materials perform as they should and that the equipment is safe and durable. Measuring strain is crucial for testing complex structures, like aircraft, turbines, etc. There multiple ways in which stress can be measured. However, it is widely accepted that FBG sensors are the most efficient way of strain measurement. FBG sensors provide multiple advantages over other methods:

1) high sensitivity;

2) small size;

3) ability to be mounted on any surface;

4) immunity to electromagnetic interference;

5) reliability even in harsh environments;

6) low sensitivity to vibration and heat.

FBG strain sensors are used in wing load testing to determine the structure’s performance and possible limitations under the lifting forces during flight. There are several benefits that FBG strain sensors offer to the aerospace field for this type of application. For instance, FBG technology provides strain measurement using a big number of continuous sensors which ensures maximum coverage from a single optical fiber. The immunity to electromagnetic interference, radio frequency interference and other electrical influences makes FBG strain sensors ideal for use in hazardous environments, such as flight. Also, FBG sensors are less cumbersome to install. In addition, the FBG strain sensor prices are expected to decrease by 20% which will open up new opportunities for various markets.

The repeated loading and unloading of a material causes fatigue. It is estimated that around 90% of structural failures are a result of fatigue. To determine the breaking point of a structure, fatigue tests are performed. The tests indicate the number of loading cycles until failure. FBG sensors are able to provide real-time data on strain fields and load distributions. The immunity to both low and high temperatures enables the sensors to be monitored during the high-temperature cure phase of composite fabrication. The fatigue life of an FBG strain sensor far surpasses that of other methods of strain measurement.

The tendency to build longer wind turbines with longer blades complicates the maintenance. The design of stronger, lighter materials is necessary, however small imperfections during the manufacturing process can cause failures. FBG strain sensors may provide real-time knowledge of load distributions and turbine blade shape. This data will provide valuable information on the needed adjustments to the blades manufacturing.

If you have any questions, please contact us at info@optromix.com

FBG strain sensors FBGs fiber optic sensors

Development of Fiber Bragg Grating Sensors for Aircraft Structural Health Monitoring

The use of composite materials in modern aircraft has been growing because of the numerous advantages that they provide. Generally, composite materials are less sensitive to corrosion, have enhanced fatigue behavior, and higher specific mechanical properties when compared to traditional materials used in aerospace applications. By contrast, composite materials have problems with damage detection which is an important procedure in the air transport industry. The main issue that occurs during the process of use is the separation of laminae from each other which happens on the inside of the material and is hidden from the outside. Nondestructive methods of aircraft testing are not effective enough for material monitoring.

Structural health monitoring consists of placing measuring and sensing devices on a structure to record, localize, analyze, and eventually predict damage. Most structural health monitoring techniques strive to measure the needed data in a non-destructive way. Fiber Bragg grating sensors are optimal for measuring different variables as they are more cost-efficient, easy to implement on most surfaces, including composite materials.

Aircraft structures require regular, scheduled inspections and monitoring of all possible hazards due to their special conditions and the principles of their design. Therefore, structural health monitoring is conducted through fiber optic devices and has great potential to reduce the costs related to these operations. Fiber Bragg grating sensors have proved to constitute the most promising technology in this field. In order to prolong the operation period of all kinds of complex engineering systems and avoid catastrophic failures, so it is necessary to achieve the highest levels of damage detection. The automation of the inspection process is a point of major importance to reduce inspection efforts. The structural health monitoring system on the basis of fiber optic products can be defined as a set of devices that provide information that allows us to locate, evaluate, and predict the loading and damage conditions of a structure. The structural health monitoring of aircraft structures can conduct real-time checks, reducing costs, and improving the reliability and performance of the structures. A wide range of potential structural health monitoring technologies is being developed to meet these needs, and the most promising options are:

electrical strain gauges and crack wires
acoustic emissions methods
optical-based technologies
comparative vacuum monitoring
microelectromechanical systems (MEMS)

Fiber optic products and fiber optic devices, in general, are very appropriate to perform structural health monitoring due to the fact that they have their intrinsic capabilities, such as sensitivity to electromagnetic radiation, low weight, compact size, great sensitivity and resolution, and their suitability to be embedded into structures. Fiber optic devices for monitoring the strain in aircraft structures can be classified into the following categories: intensity-based, interferometric, distributed, and grating-based fiber optic devices.

Among grating-based sensors, FBGs and probably the most mature and widely employed optical sensors for structural health monitoring of engineering structures due to their fast development achieved in recent years.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line: fiber Bragg grating sensors, FBG interrogators and multiplexers, distributed temperature sensing (DTS) systems. We create and supply a broad variety of top-notch fiber optic solutions for the monitoring of various facilities all over the world.

If you are interested in Optromix FBG sensors, please contact us at info@optromix.com

FBGs Fiber Bragg Grating Sensor fiber optic sensors