Tag: FBG pressure sensors

Fiber Optic Sensors for the Structural Health Monitoring

Structural health monitoring or SHM is a crucial technique thanks to the development of architectural design. Its main goal is ensuring safety for the civil infrastructure. Due to the fiber optic sensors‘ benefits, a great number of the distributed sensing systems have found application in civil engineering as SHM systems.

What is a Structural Health Monitoring System?

Structural health monitoring is a technique of evaluating and monitoring structural health. Thanks to its capability to respond to unfavorable changes, this method is widely used in many fields including aerospace, civil, and energy sectors, etc.

Why is SHM necessary?

All structures are vulnerable to various internal and external factors that can lead to wear or malfunction. There are various reasons that can cause it. For instance, deterioration, problems in construction process, an accident or environmental load, etc. That’s why it is important to implement a monitoring system.

Damage identification systems monitor all the changes in rates in real time 24/7. It gives an opportunity to detect deviations quickly and react properly in a short period of time before significant damage is caused. Therefore, timely maintenance and repair actions reduce the repair time and operating costs.

The structural health monitoring systems provide the following benefits:

Increased security;
Detecting of the damages at an early stage of difficulties;
Continuous tracking;
Saving of operating costs and time;
Development of rational management and maintenance strategies, etc.

Typical Fiber Optic Sensors

In accordance with the increase of the number of buildings’ and bridges’ under construction, the health monitoring of the concrete structures has become a topical issue.

1. Temperature Sensors

Most of all, the health of the concrete structure depends on the temperature influence. Its monitoring influences the general quality and thermal resistance of the entire structure.

At early stages, the temperature shifts affect structure’ cracks and thermal stresses that are usually caused by hydration. Besides, with the help of the two crucial parameters, the maximum temperature and the temperature trend, specialists predict the future structural health.

In addition to that, there is a special system called Distributed Temperature Sensing (DTS) that helps to monitor the cracks that may appear in the concrete structures. Its low cost and well-considered technology are believed to be important advantages in measurement. Other advantages of the FBG temperature sensors are their accurate measurements and fast response. Besides, temperature sensors are perfect for hard-to-reach places and massive sensing networks.

2. Strain Sensors

Another popular type of the fiber optic sensors is FBG strain sensors. To find out the deformation degree, the structure’s density information is used. In fact, the stability of the structure depends on its strength. It is safe when the structure strength is greater than the applied pressure.

After calibration, the unit acquires the features of a force transducer. The strain sensor transfers the component strain accurately. Characteristics such as light phase, frequency, amplitude, or polarization state, allow operators to monitor the health of the structure. All these features change under the influence of deformation.

Due to the common features of the strain sensors, like small size, they are universal sensors for force and load control. They are often used in large machines and steel constructions where there are high loads.

3. Displacement sensors

The other type of sensors are displacement sensors the main task of which is displacement measurement. It becomes possible by the constant measurement of the distance between the sensor and an object.

These FBG sensors are frequently used because they are greatly resistant to external impacts like corrosion and electromagnetic interference. Moreover, they are applied where long term reliability and safety are demanded.

If we compare them to the strain sensors and temperature sensors, FBG displacement sensors can’t measure quantity using only fiber optic sensors. They utilize FBG response to its equivalent Bragg wavelength.

Displacement sensors are perfect for monitoring of the civil engineering structures 24/7. They are suitable for monitoring aircraft, concrete structures and other industrial applications.

4. Pressure sensors

FBG pressure sensors use reflected wavelength analysis. This kind of sensors measure various parameters under severe conditions like high temperature or pressure rates.

The fiber pressure sensor’ operational principle is based on the fact that external factors affect the Bragg wavelengths by influencing the pressure sensor. In such a case, changes of the FBG’s physical or geometrical properties are implicitly measured.

FBG pressure sensors have the same characteristics as the other fiber optic sensors. They are small, portable and provide the highest accuracy and stability.

Usually, fiber pressure sensors measure the levels of liquids and gas in pipelines or tanks. They are used for the indirect flow control in tanks and pipes. FBG pressure sensors are crucially essential in various industrial fields like liquid level monitoring in oil storage tanks, gas turbine engines, etc.

In conclusion, we should say that any of these fiber optic sensors can perform measurements as a structural health monitoring. According to the existing situation and characteristics, the specialists choose the suitable variant, thus ensuring safety for any kind of civil construction.

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

FBG pressure sensors detect the smallest changes

A group of scientists from China has designed a very sensitive tiny fiber optic sensor for the measurement of the slightest pressure changes. Such FBG pressure sensors are suitable for medical applications. Herewith, they do not have numerous disadvantages of silica-based optical fibers.

According to scientists, such a fiber sensor is extremely sensitive, and it allows for measuring lung pressure even while breathing. The thing is that pressure changes in the lungs are very small and difficult to be detected. The operating principle of FBG pressure sensors is based on a fiber Bragg grating (FBG) inscribed into an optical fiber.

It should be noted that the optical fiber used is made of a new polymer. The pressure sensor detects the slightest pressure changes of 2 kilopascals. The biocompatibility of these fiber optic sensors makes them suitable for medical applications. Additionally, the fiber sensors are chemically inert, herewith they are not sensitive to moisture.

The scientists plan to use FBG pressure sensors to control different parameters that contain pressure, temperature, and strain. Moreover, numerous modern fiber sensors use FBG technology, “ tiny periodic microstructures that can be inscribed onto a fiber.”

FBG sensors made of conventional silica-based fibers have several disadvantages for medicine. They are not convenient for long-term use in the body because these optical fibers are relatively hard and very frangible. Moreover, most FBG sensors made of silica perform limited sensitivity to the slightest pressure changes.

Compared to silica sensors, there are polymer fiber optic sensors. However, they absorb water. This is the main reason why scientists create advanced polymer optical fiber to solve the current problems. Novel FBG pressure sensors can be applied in aqueous environments.

Also, such material offers a higher light shift in response to a pressure change. The production of these FBG sensors becomes easier because it doesn’t require the use of dopants. Thus, scientists produce optical fibers with good reproducibility.

The FBG pressure sensors have been already tested by comparing their performance with the standard polymer counterpart. Herewith, novel fiber sensors provide a linear, repeatable response. They can be employed for low-pressure measurement up to 50 kilopascals above or below atmospheric pressure with a resolution of 2.0 kilopascals.

Finally, these FBG sensors demonstrate higher sensitivity (80% higher than standard polymer-based sensors). Their promising applications include the operation not only in medical and high-altitude environments but also in gaseous containers.

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Fiber optic sensors in healthcare applications

Fiber optic sensors of different physical quantities based on fiber Bragg gratings (FBGs) find its popularity and they are actively used in various fields of industry to solve a variety of engineering problems. The general operating principle of such fiber sensors is based on a change in the FBG wavelength under the action of external impacts.
It should be noted that nowadays the population presents specific requirements to the application of assistive technology and, in particular, towards novel healthcare tools and fiber optic sensors. For instance, novel fiber sensors offer such benefits he electromagnetic field immunity, high flexibility, high sensitivity for mechanical parameters higher elastic limits, and impact resistance.

To be more precise, such benefits of fiber optic technology comply ideally with the instrumentation requirements of numerous healthcare tools and in movement analysis. Additionally, fiber optic sensors are considered to be lightweight, compact, stable to chemical substances, and they have also multiplexing capabilities. Therefore, fiber sensors are regarded as safe technology suitable for industrial, medical, and structural health monitoring applications.

The thing is that fiber optic sensors allow measuring various parameters, for example, angle, refractive index, temperature, humidity, acceleration, pressure, breathing rate, oxygen saturation, etc. It is even possible to install optical fibers in textiles for sensing applications, as well as incorporate them in composite metals, concrete and etc.

The development of fiber sensors based on fiber optic technology leads to high demands for healthcare systems, especially because of the population aging. The appearance of new medical systems results in higher demands on the fiber sensors’ performance because reliable control strategies require a robust fiber optic sensing system.

The modern fiber optic sensor should be tiny, herewith, saving its flexibility and compactness as possible. Herewith, intrusive sensing systems have higher requirements – they also need for biocompatibility, this is the reason why fiber optic technology continues developing to overcome the current challenges and provide high performance of novel healthcare systems and tools.

The increasing demands on fiber optic sensors and the fast development of the technology result in the appearance of numerous sensing systems for healthcare and medical tools. The fiber sensors enable to examine bones decalcification and strain distribution, evaluation of intervertebral disks, dental splints, cardiac monitoring, and pathologies detection.

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Embedded fbg strain sensors for robotic applications

Fiber optic technology continues to find new applications in various fields including medicine, biomechanics, space, oil industry, geophysics, etc. According to researchers from the U.S., fiber optic sensors are regarded as uniquely suited for utilizing in robotic hands. To be more precise, the researchers have developed a three-fingered soft robotic hand with multiple embedded fbg strain sensors resulting in emerging of a new type of stretchable fiber sensor.

The application of fiber optics allows installing 14 fbg strain sensors into each of the fingers in the robotic hand, therefore, it can “determine where its fingertips are in contact and to detect forces of less than a tenth of a newton”. Moreover, the researchers confirm that the new stretchable optical sensing material could find highly promising application in a soft robotic skin to offer even more feedback in the future.

Modern robotic hands include more strain sensors than is typical today, thus, they can operate autonomously and react safely to unexpected forces in everyday environments. It should be noted that human skin consists of thousands of tactile sensory units only at the fingertip, while a spider has about hundreds of mechanoreceptors on each leg, however, nowadays conventional humanoid includes only 42 fiber sensors in its hand and wrist.

Herewith, it is difficult to add traditional force or pressure sensors because of complex wiring, it is prone to breaking and susceptible to interference from different electromagnetic tools. Nevertheless, it is possible to embed several fbg strain sensors in a single optical fiber. The operating principle of such a robotic hand is based on several fiber sensors in each of the fingers that are connected with 4 optical fibers, through a single fiber can be used for this purpose.

Additionally, the embedded fbg strain sensors offer such an advantage as the immunity to electromagnetic interference. Other benefits of FBG sensors include:

Fiber sensors are passive and can be used in explosive environments.
Non-conductivity of fibers.
Opportunity to install more than 80 fiber sensors per optical fiber.
The fast response of FBG sensing systems.
Fbg strain sensors do not corrode and have a small diameter.

Robots used in the industry provide extremely accurate manipulation with only limited fiber sensors, herein, they operate in controlled environmental conditions where people do not risk to do it. Nevertheless, the development of soft robots, which will interact routinely and safely with people, require careful attention to tactile and force sensing. That is why fbg strain sensors are considered to be a perfect fiber optic solution.

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

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FBG pressure sensors for pipeline leakage detection

The technology of fiber Bragg grating or FBG is widely used in numerous sensing technology fields of application. For example, today FBG pressure sensors are installed to detect the leakage process of prestressed concrete cylinder pipe. This type of pressure sensor is based on the use of a Bourdon tube with two fiber Bragg gratings attached on its outside and inside surfaces.

Such a wider sensing application is caused by an increasingly large number of attractive characteristics of FBG sensors that include intrinsic safety, immunity to electromagnetic fields, remote sensing, and large multiplexing capabilities. Therefore, the pressure parameter remains the most important physical factor in the process industry.

Nevertheless, conventional pressure sensors based on electrical train gauge, vibration wire, mechanics have several disadvantages that include the absence of the ability to withstand harsh environmental conditions with critical electromagnetic interference, adventurous chemicals, or explosion matters. Moreover, such sensing systems do not allow making pressure’s multipoint measurement and online monitoring at a long distance.

It should be noted that the intrinsic pressure sensitivity of an FBG sensor is considered to be about 3.04 pm/MPa, which is quite a low index for the practical pressure measurement. Despite numerous ways proposed to increase the sensitivity factor of FBG pressure sensors, such as the installation of FBG in polymer, soldering metal-coated FBGs on a free elastic cylinder, and embedding the FBG fiber to a diaphragm, all these techniques propose relatively complex structures which are difficult to produce.

The thing is that the prestressed concrete cylinder pipe is widely used for water transportation in different areas, for example, municipal, industrial, and plant piping systems. Thus, the role of FBG pressure sensors for security monitoring and reliability management of huge cylinder pipes remains very important because now the sensing technology still faces numerous challenges.

Nevertheless, the use of a Bourdon tube in FBG pressure sensors as the spring element allows detecting spring elements. Herewith, the measurement sensitivity increases and becomes 1.414 pm/kPa in a range from 0 to 1 MPa while the correlative coefficient is 99.949%. That is the reason why the development of a totally new pressure sensor is planned, which probably finds new FBG sensing applications of pressure quasi-distributed measurement or online monitoring in industry and manufacture fields.

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

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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.

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

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Pressure measurement with fiber Bragg grating sensors

The pressure is one of the most physical parameters in a process industry, but traditional pressure sensors, mostly based on electrical strain gauge, vibration wire, mechanics, and suchlike are unable to adapt to the harsh environment and online monitoring at a long distance. Due to fiber Bragg grating sensors have become an important researching direction. An increasing interest in global industries towards the application of optical fiber sensor has brought to the rapid development in the monitoring of temperature and strain. Fiber Bragg grating products have a number of advantages such as relatively small size and long lifespan. Also, fbgs are inexpensive to manufacture, multiplexing ability, self-referencing with a liman response, ease of installation, durability, lightweight, and immune to electromagnetic interference. Sensing processes in extremely harsh environments such as explosive gas exposure setting, high-temperature combustion chamber, and environment which contains high electromagnetic interference are feasible by using fiber Bragg grating sensors due to their passive nature. Naked fiber Bragg grating sensors are fragile, but an approach to encapsulate them could solve the problem by adding carbon fiber for reinforcement and solidified by epoxy resin with encapsulation technique. Such encapsulation technology protects the fiber from the severe environment in mounting processing without influencing the transmission of the strain applied to the fbg.

The fbg pressure sensor presents a key optical fiber sensor technology for the safe operation of different technical products, systems, and technologies. These fbg pressure sensors are widely used in medicine as well as in different experimental, developmental, and diagnostic processes. Designing an intelligent fbg pressure sensor has been a burgeoning trend. Special fbg pressure sensors exist for explosive environments, which present very strict requirements for pressure sensor capsules, electronic systems, and communication interfaces.

The fbg pressure sensor is mainly based on a Bourdon tube with two fbgs bonded on its outside and inside surfaces. The wavelength shift difference of the two fbg is utilized as a pressure sensing signal: the sensitivity is enhanced, and the temperature cross-sensitivity is compensated. The experimental results demonstrate that the fiber Bragg grating pressure sensor possesses good linearity and repeatability with the measurement sensitivity of 1,414 pm/kPa, which is 465 times higher than a bare FBG. Compared to other pressure optical fiber sensor technology, the cost of the fiber Bragg grating sensors is still too high, even though it reduced significantly over the past decade. Such technology performs well, on a lost-per-measurement basis, only when several measurements are multiplexed on the same fiber.

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

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Fiber Bragg grating sensors for bolt force status monitoring

Over the past decades, bolts support has become a widely used method of roadway roof failure control due to the easy construction and its efficient reinforcement. Moreover, bolts support improve surrounding rock structure stability. Underground coal mining has been extending to deeper levels where high-stress conditions are present; high stress causes roof subsidence and floor heaving in coal mine roadways. This can have a negative effect on the safety of the miners and construction integrity. Therefore, real-time monitoring of bolts in coal mine roadways is vital for the long-term safety and stability of the surrounding rock structures.

The systems that are used currently for real-time status monitoring of the bolts support structures are easily affected by the harsh environments and high levels of stress. Fiber Bragg grating sensing technology provides a new and effective way of real-time measurements. FBG sensors have become one of the most promising optical fiber passive device applications. Fiber Bragg grating sensors have a variety of applications and are widely used for temperature sensing (FBG temperature sensors), pressure sensing (FBG pressure sensors), acceleration sensing (FBG accelerometers), deformation sensing (FBG displacement sensors), etc.

FBG sensors have multiple advantages over traditionally used measurement equipment: FBG sensors are immune to electromagnetic interference, have a strong multiplexing ability, high reliability, and sensitivity. Fiber Bragg grating sensing technology is already used in a variety of applications, like geotechnical engineering, structural engineering, civil engineering, tunnel construction engineering.

The use of FBG sensors in engineering applications shows that fiber optic sensors can automatically acquire, and monitoring results are of great significance in roadway anchorage engineering safety and bolt support quality evaluation.

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

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