about Fiber Bragg Gratings (FBG), FBG Sensors and Monitoring Systems

Various fiber optic coatings for fbg strain sensors

on August 11, 2020

ricardo-gomez-angel-geBHIpvA6us-unsplashDistributed 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

editorVarious fiber optic coatings for fbg strain sensors

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