scholarly journals Fatigue Performance of Type I Fibre Bragg Grating Strain Sensors

Sensors ◽  
2019 ◽  
Vol 19 (16) ◽  
pp. 3524 ◽  
Author(s):  
Naizhong Zhang ◽  
Claire Davis ◽  
Wing K. Chiu ◽  
Tommy Boilard ◽  
Martin Bernier
Keyword(s):  
Microscopic Analysis ◽  
Fatigue Performance ◽  
Fibre Bragg Grating ◽  
Type I ◽  
Strain Sensing ◽  
Contributing Factors ◽  
Sensing Applications ◽  
Fibre Coating ◽  
Spectral Profiles ◽  
Fibre Bragg Gratings

Although fibre Bragg gratings (FBGs) offer obvious potential for use in high-density, high-strain sensing applications, the adoption of this technology in the historically conservative aerospace industry has been slow. There are several contributing factors, one of which is variability in the reported performance of these sensors in harsh and fatigue prone environments. This paper reports on a comparative evaluation of the fatigue performance of FBG sensors written according to the same specifications using three different grating manufacturing processes: sensors written in stripped and re-coated fibres, sensors written during the fibre draw process and sensors written through fibre coating. Fatigue cycling of the fibres is provided by a customized electro-dynamically actuated loading assembly designed to provide high frequency and amplitude loading. Pre- and post-fatigue microscopic analysis and high-resolution transmission and reflection spectra scanning are conducted to investigate the fatigue performance of FBGs, the failure regions of fibres as well as any fatigue-related effects on the spectral profiles. It was found that because of the unique fabrication method, the sensors written through the fibre coating, also known as trans-jacket FBGs, show better fatigue performance than stripped and re-coated FBGs with greater control possible to tailor the optical reflection properties compared to gratings written in the draw tower. This emerging method for inscription of Type I gratings opens up the potential for mass production of higher reflectivity, apodised sensors with dense or complex array architectures which can be adopted as sensors for harsh environments such as in defence and aerospace industries.

scholarly journals Trans-Jacket Fibre Bragg Gratings for In-Situ Health Monitoring of Defence Platforms in Harsh Environments

2021 ◽  
Keyword(s):  
Fatigue Life ◽  
Health Monitoring ◽  
Damage Threshold ◽  
Fatigue Loading ◽  
Bragg Gratings ◽  
Fatigue Performance ◽  
Type I ◽  
Type Ii ◽  
Fbg Sensors ◽  
Fibre Bragg Gratings

Abstract. Packaged optical fibre sensors offer excellent strength and resistance to environmental degradation, but the reported reliability and durability of fibres containing fibre Bragg gratings (FBGs) varies greatly. This is partly due to the fabrication methodologies used to create the sensors. The trans-jacket grating inscription technique uses an infrared laser to write gratings into the fibre core through the polymer coating. This method eliminates the need for harsh coating removal processes and exposure of the glass fibre core and thus dramatically reduces fibre damage during grating fabrication. In addition, the automated trans-jacket inscription process introduces greater flexibility to control the writing parameters, facilitating a consistent process for producing robust, fatigue resistant distributed FBG sensing arrays with reliable and repeatable performance that could revolutionise their application in structural health monitoring (SHM). This paper reports on the durability and reliability of Bragg gratings with different fibre geometries, dopants, and photo-sensitising approaches to compare the overall fatigue performance of trans-jacket FBG sensors. Both type I gratings which are inscribed using a laser power intensity below the damage threshold of the glass core, and type II gratings which are inscribed exceeding this threshold, are considered. The fatigue performance of these FBG sensors was assessed using a custom designed electro-dynamically actuated loading assembly. It is concluded that type I trans-jacket gratings have a significantly higher fatigue life compared to type II gratings for the same fatigue loading regime. Despite the lower fatigue life, type II trans-jacket gratings are found to perform significantly better than conventional electrical foil gauges. Therefore, trans-jacket gratings have significant potential for application as dense sensing arrays in harsh operational environments in defence and aerospace industries.

scholarly journals Strain Sensor via Wood Anomalies in 2D Dielectric Array

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1022
Author(s):  
Rashid G. Bikbaev ◽  
Ivan V. Timofeev ◽  
Vasiliy F. Shabanov
Keyword(s):  
Higher Plants ◽  
Numerical Study ◽  
Reciprocal Lattice ◽  
Strain Sensing ◽  
Photonic Materials ◽  
Sensing Applications ◽  
Wide Range ◽  
Sensor Structure ◽  
Optical Behavior ◽  
Chlorophyll Absorption

Optical sensing is one of many promising applications for all-dielectric photonic materials. Herein, we present an analytical and numerical study on the strain-responsive spectral properties of a bioinspired sensor. The sensor structure contains a two-dimensional periodic array of dielectric nanodisks to mimic the optical behavior of grana lamellae inside chloroplasts. To accumulate a noticeable response, we exploit the collective optical mode in grana ensemble. In higher plants, such a mode appears as Wood’s anomaly near the chlorophyll absorption line to control the photosynthesis rate. The resonance is shown persistent against moderate biological disorder and deformation. Under the stretching or compression of a symmetric structure, the mode splits into a couple of polarized modes. The frequency difference is accurately detected. It depends on the stretch coefficient almost linearly providing easy calibration of the strain-sensing device. The sensitivity of the considered structure remains at 5 nm/% in a wide range of strain. The influence of the stretching coefficient on the length of the reciprocal lattice vectors, as well as on the angle between them, is taken into account. This adaptive phenomenon is suggested for sensing applications in biomimetic optical nanomaterials.

scholarly journals A Review: Carbon Nanotube-Based Piezoresistive Strain Sensors

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Waris Obitayo ◽  
Tao Liu
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Composite Films ◽  
Strain Sensors ◽  
Voltage Response ◽  
Strain Sensing ◽  
Multiwalled Carbon ◽  
Sensing Applications ◽  
Mechanical Deformations ◽  
Electrical Resistivities

The use of carbon nanotubes for piezoresistive strain sensors has acquired significant attention due to its unique electromechanical properties. In this comprehensive review paper, we discussed some important aspects of carbon nanotubes for strain sensing at both the nanoscale and macroscale. Carbon nanotubes undergo changes in their band structures when subjected to mechanical deformations. This phenomenon makes them applicable for strain sensing applications. This paper signifies the type of carbon nanotubes best suitable for piezoresistive strain sensors. The electrical resistivities of carbon nanotube thin film increase linearly with strain, making it an ideal material for a piezoresistive strain sensor. Carbon nanotube composite films, which are usually fabricated by mixing small amounts of single-walled or multiwalled carbon nanotubes with selected polymers, have shown promising characteristics of piezoresistive strain sensors. Studies also show that carbon nanotubes display a stable and predictable voltage response as a function of temperature.

Intrinsic mechanical properties of the extracellular matrix affect the behavior of pre-osteoblastic MC3T3-E1 cells

2006 ◽  
Vol 290 (6) ◽  
pp. C1640-C1650 ◽  
Author(s):  
Chirag B. Khatiwala ◽  
Shelly R. Peyton ◽  
Andrew J. Putnam
Keyword(s):  
Mechanical Properties ◽  
Type I Collagen ◽  
Focal Adhesions ◽  
Microscopic Analysis ◽  
Maximal Activity ◽  
Type I ◽  
Cell Functions ◽  
Collagen Density ◽  
Cells Cultured ◽  
In Cells

Mechanical cues present in the ECM have been hypothesized to provide instructive signals that dictate cell behavior. We probed this hypothesis in osteoblastic cells by culturing MC3T3-E1 cells on the surface of type I collagen-modified hydrogels with tunable mechanical properties and assessed their proliferation, migration, and differentiation. On gels functionalized with a low type I collagen density, MC3T3-E1 cells cultured on polystyrene proliferated twice as fast as those cultured on the softest substrate. Quantitative time-lapse video microscopic analysis revealed random motility speeds were significantly retarded on the softest substrate (0.25 ± 0.01 μm/min), in contrast to maximum speeds on polystyrene substrates (0.42 ± 0.04 μm/min). On gels functionalized with a high type I collagen density, migration speed exhibited a biphasic dependence on ECM compliance, with maximum speeds (0.34 ± 0.02 μm/min) observed on gels of intermediate stiffness, whereas minimum speeds (0.24 ± 0.03 μm/min) occurred on both the softest and most rigid (i.e., polystyrene) substrates. Immature focal contacts and a poorly organized actin cytoskeleton were observed in cells cultured on the softest substrates, whereas those on more rigid substrates assembled mature focal adhesions and robust actin stress fibers. In parallel, focal adhesion kinase (FAK) activity (assessed by detecting pY397-FAK) was influenced by compliance, with maximal activity occurring in cells cultured on polystyrene. Finally, mineral deposition by the MC3T3-E1 cells was also affected by ECM compliance, leading to the conclusion that altering ECM mechanical properties may influence a variety of MC3T3-E1 cell functions, and perhaps ultimately, their differentiated phenotype.

scholarly journals Etched Polymer Fibre Bragg Gratings and Their Biomedical Sensing Applications

Sensors ◽  
2017 ◽  
Vol 17 (10) ◽  
pp. 2336 ◽  
Author(s):  
Ginu Rajan ◽  
Kishore Bhowmik ◽  
Jiangtao Xi ◽  
Gang-Ding Peng
Keyword(s):  
Bragg Gratings ◽  
Polymer Fibre ◽  
Biomedical Sensing ◽  
Sensing Applications ◽  
Fibre Bragg Gratings
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