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Technical textiles with embedded fibre optic sensors habe been developed for the purposes of the structural health monitoring in geotechnical and civil engineering as well as for healthcare monitoring in the medical sector. The paper shows selected examples of using such sensor-based smart textiles for different applications.
Structural Health Monitoring of composite materials gains in importance with the increasing use of Composite structures for safety-related applications, e.g. in aerospace. Because of the material properties of composites, defects often occur inside the structures and raise the demand for integrated sensors. The advantages of optical fibres predestine them not only for the surface-application on composite structures but also for the Integration into composite structures. Even without quasi-distributed sensors such as FBGs or LPGs, the optical fibre itself can be used to measure the structure and occurring events over the entire fibre length by distributed sensing techniques. This paper presents the surface-application of polyimide coated silica optical fibres onto PEEK specimens and the integration of copper and polyimide coated silica optical fibres into an AS-4/PEEK Composite to be used as distributed fibre optic sensors for SHM. Results from distributed measurements by optical backscatter reflectometry based on Rayleigh backscattering are shown.
Fiber optic sensors based on polymer optical fibers (POF) take advantage of the high elasticity and high break-down strain of POF. Because of their outstanding elastic properties, POF are well suited for integration into technical textiles like geotextiles and medical textiles. Smart textiles with incorporated POF sensors, able to sense various mechanical and physical quantities, can be realized. The integration of POF as a sensor into geotextiles for monitoring of displacement of soil is very attractive since POF can be used for distributed strain measurement of strain values of more than 40 %. An online monitoring of critical mechanical deformations of geotechnical structures like dikes, dams, slopes, embankments as well as of masonry structures can be ensured. Medical textiles that incorporate POF sensors can control vital physiological parameters like respiratory movement and can be used for wearable health monitoring of patients requiring a continuous medical assistance and treatment. The biocompatibility of POF is an important criterion for selecting POF as a medical sensor. The paper shows selected examples of using POF sensors for the mentioned monitoring purposes.
We report on three respiration sensors based on pure optical technologies developed during the FP6 EU project
OFSETH. The developed smart medical textiles can sense elongation up to 3%, while maintaining the stretching
properties of the textile substrates for a good comfort of the patient. The sensors, based on silica and polymer fibre, are
developed for monitoring of patients during MRI examination. The OFSETH harness allows a continuous measurement
of respiration movements while all vitals organs are free for medical staff actions. The sensors were tested in MRI
environment and on healthy adults.
We investigate two real-time strain sensing principles based on the optical time-domain reflectometry
(OTDR) in polymer optical fibres (POF). The first sensing principle uses the increase of the level of backscattered light
in a stretched POF. The second sensing principle uses the effect of losses due to bending.
We investigated to our knowledge for the first time the capabilities of long period gratings (LPG) in single-mode microstructured polymer optical fibre (mPOF) as real-time gamma dosimeter. The fibre is made from polymethyl methacrylate (PMMA) with a polycarbonate jacket. We measured the radiation-induced wavelength shift of the mPOF LPG loss feature wavelength and the radiation-induced attenuation of a mPOF for
different wavelength between 600 nm and 800 nm for gamma radiation with an energy distribution between 6 keV and 18 keV.
A distributed acoustic sensor (DAS) based on wavelength-scanning coherent optical time domain reflectometer (WS-COTDR) is tested in an underground gas storage based on a multimode fiber for the first time to the best of our knowledge. The WS-COTDR acquires the reflection spectrum by scanning the wavelength of the laser and uses the spectra to calibrate strain. It overcomes the fading problem which is common for all DAS systems, and possesses the advantage of simple configuration and low-cost. The working principle of the system is well explained and the measurement results are presented. Various artificial and natural acoustic events have been successfully detected by the WS-COTDR. Such a sensor demonstrates several advantages over the traditional DAS systems, so it is supposed to be widely used in the oil and gas industry.
A distributed acoustic sensor (DAS) based on wavelength-scanning coherent optical time domain reflectometer (WS-COTDR) is tested in an underground gas storage based on a multimode fiber for the first time to the best of our knowledge. The WS-COTDR acquires the reflection spectrum by scanning the wavelength of the laser and uses the spectra to calibrate strain. It overcomes the fading problem which is common for all DAS systems, and possesses the advantage of simple configuration and low-cost. The working principle of the system is well explained and the measurement results are presented. Various artificial and natural acoustic events have been successfully detected by the WS-COTDR. Such a sensor demonstrates several advantages over the traditional DAS systems, so it is supposed to be widely used in the oil and gas industry.