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Background
With the growth of optoelectronics and fiber optic communications
industries over the past 20 years, two significant achievements
have been revealed. The first is the direct replacement of existing
sensors with fibre optic sensors, which offer tremendous performance,
reliability, safety and cost efficiency to the end user. The second
area is the development and deployment of fiber optic sensors in
new market areas.
With the falling of component prices and the enhancement of products’
quality, the ability of fiber optic sensors to replace the traditional
sensors is obvious especially in the areas of acceleration measurement,
chemical measurement, and electromagnetic field measurement. Though
its disadvantages of high cost and unfamiliarity to the end user,
the benefits easily outweigh its drawbacks.
Some of the advantages of fiber optic sensors as follows:
• Lightweight
• Small size
• Passive (low risk to end user)
• Resistant to electromagnetic interference
• High sensitivity
• Wide dynamic arrange
• Environmental ruggedness
Laser diodes that cost $3000 in 1979 with lifetimes measured in
hours, now selling at a few dollars in small quantities with extremely
great reliability of a few tenth thousands operation hours. It is
widely used in compact disc players, laser printers, laser pointers
and bar code readers. Single mode optical fiber that cost $20/m
in 1979 and now costs less than $0.10/m with immeasurably improved
in optical and mechanical properties. As the trends continue, opportunities
will increase for fiber optic sensor designers to produce more innovative
products.
Project Objectives
The main objective is to provide engineers with our self-customized
fibre gratings strain, temperature and gas sensor systems that allow
them to enhance structural safety, maintainability, and performance
due to the following advantages:
| • |
Multiplexing potential
- Many FBGs can now be written in the same optical fiber at
a predetermined location and each sensing element can monitor
the temperature and strain at each remote location |
| • |
A number of FBG sensors on a fiber
string can be addressed simultaneously |
| • |
Small-size, lightweight, robust |
| • |
Immune to EMI, durable under harsh
environment and resistant to corrosion
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| • |
Easy for embedding or surface mounting |
| • |
Increases sensor reliability and
ease of installation and maintenance with little training,
ideally fitting into the so-called “fit and forget”
systems
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| Features of the
technology |
| 1. Temperature-compensated
FBG strain sensor |
| • |
Sensing range: up to ±1% strain |
| • |
High Sensitivity: 0.5pm/me |
| • |
High Resolution:0.4me |
| • |
Operating temperature: -40°C~+120°C |
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| 2. Strain-insensitive
temperature sensor |
| • |
Excellent linearity |
| • |
Sensing range: -40°C ~ +80°C |
| • |
High sensitivity: 10pm/°C |
| • |
High resolution: 0.02 °C |
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| 3. Very-high-temperature
grating sensor |
| • |
Measurement range: up to 1100°C |
| • |
Sensitivity: 14pm/ °C |
| • |
Resolution: 0.7 °C |
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Benefits
Improvements in environmental ruggedness and safety are the major
plus points of fiber optic sensors. It is especially useful in areas
where electrical discharges could be hazardous or where conventional
electronic sensors cannot match up to fiber optic sensors’
relative immunity to electromagnetic interference, significant weight
savings and safety improvements. Another area where fiber optic
sensors are highly beneficial is the field of medicine, where they
are being used to measure blood gas parameters and dosage levels.
As these sensors are completely passive, they pose no electrical
shock threat to the patient and their inherent safety has inevitably
led to their rapid adoption in the medical field.
Applications of the technology
In order to support large structures such as buildings, bridges
and aircraft, it is necessary to have large numbers of sensors that
are rapidly re-configurable and redundant to monitor its health
and damage assessment systems. One approach to this problem is to
use fiber optic sensors that have the potential to be manufactured
inexpensively in very large quantities while offering superior performance
characteristics. Here, sensors are multiplexed along fiber strings
and an optical switch is used to support the many strings. The fiber
strings could potentially have tens or hundreds
of sensors and the optical switches could support a similar number
of strings.
Strain sensor
1. Buildings
2. Bridges and Tunnels
3. Roads and Rails
4. Slope/ground movement
5. Petroleum Refineries and containers
6. Long-distance conduit pipes
7. Aeronautics
8. Dams
Temperature sensor
1. Petroleum
2. Aircraft
3. Steel and iron industry
Gas Sensor
1. Petroleum
2. Aircraft
3. Medicine
For enquiries/explore collaboration, please contact:
Industry Development Department
Tel: 65 6874 8399
Fax: 65 6775 9923
Email: inddev@i2r.a-star.edu.sg
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