Due to their high mechanical and corrosion resistance and their small dimensions, optical fibre sensors and more particularly fibre Bragg gratings have demonstrated their high potential in the composite material field for monitoring purpose when there are placed under constrain, vibration or temperature variation. In this paper, we evaluate the capability of an Optical Backscatter Reflectometer (OBR) to address two configurations of sensors. The first one is with FBGs of different wavelengths distributed along a unique optical fibre. The second one consists in a high number of identical Fibre Bragg Grating (FBG) sensors cascaded in a single optical fibre and embedded in fibre reinforced polymer composites. In this last case, the optical fibre was placed in such a way that the set of FBGs yields a mapping of the flexural strain applied on the composite sample. For this, the Bragg wavelength evolution of the different FBGs subject to flexion (three and four-points bending) is computed from the OBR trace. This equipment being used in these two special FBGs sensors distribution, we compare them and we present advantages and drawbacks of each others.
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.
The potential impact of optical fiber sensors embedded into medical textiles for the continuous monitoring of the patient
during Magnetic Resonance Imaging (MRI) is now proved. We report how two pure optical technologies can
successfully sense textile elongation between, 0% and 3%, while maintaining the stretching properties of the textile
substrates for a good comfort of the patient.
Investigating influence of different patients' morphology as well as textile integration issues to let free all vitals organs
for medical staff actions, the OFSETH harness allows a continuous measurement of respiration movements.
For example, anaesthesia for MRI examination uses the same drugs as for any surgical procedure. Even if spontaneous
respiration can be preserved most of the time, spontaneous respiration is constantly at risk of being impaired by
anaesthetic drugs or by upper airway obstruction. Monitoring of the breathing activity is needed to assess adequate
ventilation or to detect specific obstruction patterns.
Moreover artefacts due to physiological motions induce a blooming effect on the MRI result. The use of synchronisation
devices allows reducing these effects. Positioned at certain strategic places according to the investigated organ, the
presented sensors could constitute an efficient and adapted solution for respiratory synchronisation of the MRI
acquisition.
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