Marcus Schukar

Optical Fiber Sensors Embedded Into Medical Textiles for Healthcare Monitoring

The potential impact of optical fiber sensors embedded into medical textiles for the monitoring of respiratory movements in a magnetic resonance imaging environment is presented. We report on three different designs, all textile based: a macrobending sensor, a Bragg grating sensor, and a time reflectometry sensor. In all three cases, the sensing principle is based on the measure of the elongation of the abdominal circumference during breathing movements. We demonstrate that the three sensors can successfully sense textile elongations between 0% and 3%, while maintaining the stretching properties of the textile substrates for a good comfort of the patients.

Smart technical textiles with integrated POF sensors

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.

Medizinische Textilien mit integrierten polymeroptischen Fasern zur AtmungssensorikMedicinal Textiles with Integrated Polymer-Optical Fibers for Respiration Monitoring

Zusammenfassung In diesem Beitrag werden medizinische Textilien mit integrierten polymeroptischen Fasern (POF) zur Messung der Atembewegung vorgestellt. Die Sensorentwicklung dient primär der Überwachung von anästhesierten oder bewusstlosen Patienten bei der Magnetresonanztomographie. Es werden zwei unterschiedliche Sensoren präsentiert. Der eine Sensor basiert auf der optischen Zeit-Bereichs-Reflektometrie und ermöglicht eine ortsaufgelöste Messung der Atembewegung, der andere verwendet eine mikrostrukturierte POF, in die ein langperiodisches Gitter eingeschrieben ist.

Optical fibre sensors embedded into medical textiles for monitoring of respiratory movements in MRI environment

The potential impact of optical fibre sensors embedded into medical textiles for the monitoring of respiratory movements in MRI environment is presented. Preliminary investigations of the feasibility of sensing respiration movements with a POF OTDR are reported. In addition, a macro-bending sensor based on a periodic design is demonstrated and successfully implemented using a narrow fabric production process. It allows monitoring human abdominal breathing movements with a very simple monitoring set-up.

Investigation of sensing properties of microstructured polymer optical fibres

We investigated sensing properties of single mode poly methyl methacrylate (PMMA) microstructured polymer optical fibres (MPOF) with mechanically imprinted long period gratings (LPG). After preparation of the MPOF end-faces the samples were elongated with silica fibres. These samples were used to measure the influence of strain to the LPG wavelength which showed the viscoelastic nature of PMMA. We also measured the influence of temperature and humidity. The results show that MPOF LPGs are well suited for strain sensing. One MPOF LPG was stitched to a textile. Using this textile we measured a simulated respiratory motion.

Strain sensing with femtosecond inscribed FBGs in perfluorinated polymer optical fibers

In this work, the potential of fiber Bragg gratings (FBGs) in low-loss perfluorinated polymer optical fibers (PF-POFs) is explored. The FBG is femtosecond-inscribed in a commercial multi-mode (MM) PF-POF based on Cytop polymer. Femtosecond inscription leads to creation of a highly saturated grating with a number of higher order reflection peaks visible throughout the visible and near-infrared spectral region. For 2 mm long FBG having a pitch of 2.2895 μm, a total of nine higher-order MM reflection bands are visible spanning from 1548 nm (4th order) to 520 nm (12th order). Strain sensitivity was measured for 6 peak bands in 500-900 nm region, where relatively low cost CCD based spectrometers and broadband LEDs are available. Strain sensitivity increases almost linearly with increasing initial peak wavelength, growing from 4.82 ± 0.02 nm/% measured for 12th order peak at 517 nm to 8.12 ± 0.04 nm/% measured for 7th order peak at 883 nm. These values correspond to roughly 20 % higher sensitivity than silica FBGs exhibit in this spectral range. The gratings in PF-POFs combine the higher strain sensitivity and low-loss operation while maintaining the mechanical advantages of polymer optical fibers. Therefore, they hold a high potential for considerable broadening of polymer optical fiber Bragg gratings application range.

Integration of Cu-coated single-mode optical fiber into carbon/PEEK composite for distributed structural healthmonitoring based on Rayleigh backscatter reflectometry

In this paper a technique for integrating copper coated silica optical fibers into AS-4/PEEK composite for Structural Health Monitoring (SHM) is presented. The integration steps are described in detail. X-ray and microscopic images indicate a successfully integrated optical fiber which does not seem to affect the fiber/matrix distribution around it. Optical backscatter reflectometry shows losses of approximately 2dBm-1 along the integrated parts of the optical fiber due to temperature induced shrinkage of the composite.

Evaluating distributed fibre optic sensors integrated into thermoplastic composites for structural health monitoring

Strain sensors used for structural health monitoring (SHM) must provide reliable measurement data during their entire service lifetime. To achieve this for fibre optic sensors integrated into composites, the integration of the sensor has to be adapted according to the process conditions. This paper describes the fabrication of thermoplastic composite samples with integrated distributed fibre optic sensors (DFOS) based on copper-nickel and polyimide coated silica optical fibres. The performance of these DFOS as SHM sensors is evaluated in terms of reliability by measurements derived from comparative measurements with resistance strain gauges and from fatigue tests with 10 million load cycles.

Investigation of sensing properties of long period gratings based on microstructured polymer optical fibres

We investigated the sensing properties of a single mode Poly Methyl Methacrylate (PMMA) Microstructured Polymer Optical Fibre (MPOF) with mechanically imprinted Long Period Grating (LPG). We measured the influence of strain to the LPG wavelength which showed the viscoelastic nature of PMMA. We also measured the influence of temperature and humidity to the LPG wavelength.

Strahlungsüberwachung mit Faser-Bragg-Gitter-Sensoren am Elektronenspeicherring BESSY II (Radiation Monitoring of the Electron Storage Ring BESSY II by Fiber Bragg Grating Sensors)

Die Eignung von Faser-Bragg-Gitter-(FBG)-Sensoren zur Messung ionisierender Strahlung wurde an einem Undulator des Elektronenspeicherrings BESSY II untersucht. Über einen Zeitraum von 20 Wochen wurde eine durch Strahlung verursachte Bragg-Wellenlängenänderung der FBG-Sensoren von 25pm gemessen, was einer Strahlendosis von 720 Gy entspricht. The suitability of using fiber Bragg grating (FBG) sensors for the measurement of ionizing radiation on the electron storage ring BESSY II by measuring the Bragg wavelength shift caused by radiation was investigated. During a time period of 20 weeks a Bragg wavelength shift of 25pm caused by the ionizing radiation was measured by FBG sensors at the storage ring. This Bragg wavelength shift corresponds to a radiation dose value of 720 Gy.