Abstract
A new and easy-to-fabricate strain sensor has been developed, based on fiber Bragg grating (FBG) technology embedded into a thermoplastic polyurethane filament using a 3-dimensional (3D) printer. Taking advantage of the flexibility and elastic properties of the thermoplastic polyurethane material, the embedding of the FBG provides durable protection with enhanced flexibility and sensitivity, as compared to the use of a bare FBG. Results of an evaluation of its performance have shown that the FBG sensors embedded in this way can be applied effectively in the measurement of strain, with an average wavelength responsivity of 0.013 5 nm/cm of displacement for tensile strain and −0.014 2 nm/cm for compressive strain, both showing a linearity value of up to 99%. Furthermore, such an embedded FBG-based strain sensor has a sensitivity of ∼1.74 times greater than that of a bare FBG used for strain measurement and is well protected and suitable for in-the-field use. It is also observed that the thermoplastic polyurethane based (TPU-based) FBG strain sensor carries a sensitivity value of ∼2.05 times higher than that of the polylactic acid based (PLA-based) FBG strain sensor proving that TPU material can be made as the material of choice as a “sensing” pad for the FBG.
Highlights
The optical fiber sensing technology has been applied in a wide range of applications due to its adaptability in different types of harsh environments and possessing several other beneficial attributes.The emergence of optical fiber sensors has created an effective, and improved group of alternatives to existing technologies for many in-the-field measurement situations, as it is immune to electromagnetic interference (EMI) [1], has better resistance to corrosion [2], offers easy installation [3]Article type: RegularPhotonic Sensors and provides excellent geometric adaptability [4]
These different fiber Bragg grating (FBG)-based sensors have been applied across various fields due to their being small in size and lightweight [6], showing good mechanical flexibility [7], compatibility with quasi-distributed monitoring systems [8], and allowing a variety of multiplexing arrangements [9], as well as continuous monitoring [10], good chemical stability, and potentially reducing costs and time needed for the whole measurement process [11]
The embedded FBG-based strain sensor discussed in this work is shown in Fig. 1, which shows an FBG sensor embedded inside a 3D-printed thermoplastic polyurethane (TPU) material
Summary
The optical fiber sensing technology has been applied in a wide range of applications due to its adaptability in different types of harsh environments and possessing several other beneficial attributes. As fiber Bragg grating (FBG) is one of the most common types of fiber optic sensor technology, it possesses all of these advantages compared to other conventional sensors such as electrical and piezoelectric sensors [5] Over time, these different FBG-based sensors have been applied across various fields due to their being small in size and lightweight [6], showing good mechanical flexibility [7], compatibility with quasi-distributed monitoring systems [8], and allowing a variety of multiplexing arrangements [9], as well as continuous monitoring [10], good chemical stability, and potentially reducing costs and time needed for the whole measurement process [11]. A commercial adhesive material can be used to bond the FBG and the inner walls of the TPU material as it has good sensitivity coefficients and can function well over a wide range of temperatures [26]
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