A reliable and cost effective fibre optic oxygen sensor for monitoring of human breathing has been developed using a
normal 200μm silica core/silica cladding optical fibre and a polymer sensing matrix. The fibre optic oxygen sensor is
based on the fluorescence quenching of a fluorophore by oxygen. The sensing matrix, containing immobilized Pt(II)
complexes, was coated at the end of the silica core/silica cladding optical fibre. The sensitivity and time response of the
sensor were evaluated using the method of luminescence lifetime measurement. The polymer substrate influence on the
time response of the sensor was improved by using a fibre taper design, and the response time of the optimized sensor
was less than 200ms. This silica fibre based optic oxygen sensor is suitable for monitoring of patient breathing in
intensive care unit in terms of safety and low cost.
A reliable, robust and low cost fibre optic oxygen sensor for measuring rapid changes in oxygen partial pressure has been
developed using a polymer optical fibre and a polymer sensing matrix which is biocompatible with human tissue. These
materials have been used in many medical and biomedical applications. The polymer fibre optic oxygen sensor is based
on the fluorescence quenching of a fluorophore by oxygen. The sensing matrix, containing immobilized Pt(II) complexes,
was coated at the end of the polymer optical fibre. The sensitivity and time response of the sensor were evaluated using
the method of luminescence intensity measurement. The polymer substrate influence on the sensor time response was
reduced by using a fibre taper design, and the response time of the optimized sensor was less than 200ms. This all
polymer fibre optic oxygen sensor is more suitable for clinical use in terms of safety, robustness, flexibility, and low
cost.
The development of a cylindrical-core fiber optic oxygen sensor for fast measurement of oxygen partial pressure (pO2)
is described. The fibre sensing element is based on a cylindrical-core waveguide structure formed by a polymer sensing
film that contains immobilized Pt (II) complexes. The performance of the fibre optic oxygen sensor was evaluated using
luminescence intensity measurement. To determine accurately the response time of the oxygen sensor, a test chamber
was used to provide rapid changes in the partial pressure of oxygen. The result showed that the time response of this
cylindrical-core fibre based optic oxygen sensor can be less than 0.2 second. The details of the sensor chemistry,
experimental system and the results are reported.
The development of a rapid response time, plastic optical fiber (POF) based oxygen sensor for the measurement of
oxygen partial pressure (pO2) is described. The POF oxygen sensor is based on the luminescence quenching of a
luminophore by oxygen and consists of PMMA plastic optical fibre and a polymer matrix medium that contains
immobilized Pt (II) complexes. The performance of the POF oxygen sensors was evaluated using luminescence intensity
measurement. In order to accurately determine the response time of the POF oxygen sensors, a test chamber was used
to provide rapid step changes in the partial pressure of oxygen. The details of the sensor chemistry, experimental system
and the results are presented.
At the previous SPIE conference in San Diego (2008), the authors presented and compared a range of low-cost optical fibre sensors for monitoring the cross-linking process of a thermosetting resin. The same sensor was used subsequently
to monitor and quantify the diffusion of water in the cross-linked polymer.
The current paper presents recent data on the deployment of an array of low-cost fibre-optic sensors to monitor the water
diffusion front. The data obtained from the sensors are compared with conventional gravimetric measurements and
theoretical predictions for the diffusion profile for water ingress in a cross-linked epoxy/amine resin system.
This paper presents the design, theory, characterisation and application of a novel fibre optic acoustic emission (AE)
sensor. The sensor consists of a pair of optical fibres that are heated, fused and drawn to create a fused-tapered region
that is sensitive to acoustic perturbations. The sensor is housed in a silica V-groove. The modelling of this fibre optic AE
sensor is presented with a finite element analysis on the strain field based on the effect of the geometry within the
sensing region. The characterisation of the sensor was carried out using a glass block with 160mm thickness as an
acoustic medium. The applications of this sensor were demonstrated in three experiments. Firstly, the sensor was
surface-mounted in carbon fibre reinforced composite samples and tested to failure under tensile loading. In the second
experiment, the sensor was surface-mounted on double-cantilever Mode-I test specimens. The AE response from the
sensor was correlated to the inferred modes of failure during the Mode-I test. In the third experiment, the sensor was
surface-mounted onto the composite "blow-off" test samples. The feasibility of using the sensor to detect damage
development in real-time was demonstrated.
It is generally appreciated that the ingress of moisture in composites can have adverse effects on matrix-dominated
properties such as the glass transition temperature and compressive mechanical properties. Moisture ingress in
composites can also lead to swelling and blistering. A number of excellent studies have been reported on the detection,
modelling and effects of moisture ingress on the properties of thermosetting resins (matrix) and composites. However, it
is generally taken for granted that the quality of the resin and the processing conditions used to cross-link the resin are
identical. Given the recent advances in the design and deployment of optical-fibre sensors in composites, it is now
possible to use the same sensor to facilitate in-situ cure monitoring and structural health monitoring (after processing).
This paper will present recent developments in the design of
low-cost fibre-optic sensor systems for in-situ chemical
process monitoring and the detection of moisture ingress after curing. The cure kinetics derived from three fibre optic
sensor designs is presented as well as those obtained from evanescent-wave spectroscopy using E-glass fibres.
After conducting the in-situ cure monitoring experiments, one of the fibre-optic sensor designs was selected and the
samples (with the embedded sensors) were dried to constant mass at 50°C then transferred to water baths maintained at
70, 50, and 30 °C. The diffusion kinetics for the samples was determined using samples without and with embedded
optical-fibre sensors. The effect of moisture ingress in the resin was also assessed using dynamic mechanical thermal
analysis (DMTA), transmission infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). Preliminary
results are also presented to demonstrate that the reinforcing fibres in E-glass composites can be used to track the cross-linking
kinetics of a commercial epoxy/amine resin is presented.
Cure monitoring is a term that is used to describe the cross-linking reactions in a thermosetting resin system. Advanced
fiber reinforced composites are being used increasingly in a number of industrial sectors including aerospace, marine,
sport, automotive and civil engineering. There is a general realization that the processing conditions that are used to
manufacture the composites can have a major influence on its hot-wet mechanical properties. This paper is concerned
with the design and demonstration of a number of sensor designs for in-situ cure monitoring of a model thermosetting
resin system. Simple fixtures were constructed to enable a pair of cleaved optical fibers with a defined gap between the
end-faces to be held in position. The resin system was introduced into this gap and the cure kinetics were followed by
transmission infrared spectroscopy. A semi-empirical model was used to describe the cure process using the data
obtained at different cure temperatures. The same sensor system was used to detect the ingress of moisture in the cured
resin system.
A fiber acousto-optic device is analyzed experimentally, which based on a single mode fiber coupler. The cutoff wavelength and splitting ratio in 630 nm are about 600 nm and 3 dB. When a strain wave acts on the packaged fiber coupler, the splitting ratio of the coupler will be changed which cause the modulation of output in the fiber coupler. At some frequency of strain wave, the modulation will get at Maximum.
We report here a novel way to fabricate fiber LPG using moire pattern amplitude mask (MPAM). Theoretical analysis of diffraction effect on MPAM has revealed that geometric optics rules are followed when area concerned is so close to diffractive grating that even Fresnel approximation can not be used. Experimental result of grating written in As2S3 fiber support the theoretic conclusion. And the temperature dependence is reported also.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.