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Novel liquid sensor for crude oil detection

Chen, Hao (2015). Novel liquid sensor for crude oil detection. Master of Engineering Thesis, Charles Darwin University.

Document type: Thesis
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Author Chen, Hao
Title Novel liquid sensor for crude oil detection
Institution Charles Darwin University
Publication Date 2015
Thesis Type Master of Engineering
Abstract Crude oil plays a significant role in human’s life. How can we detect it underground and distinguish it from other liquids is an important issue. The common methods used in industry are chemical methods and optical methods such as near-infrared absorption and refractometry technique. However, they are high cost and difficult to use underground. Surface plasmon resonance (SPR) and refractive index (RI) sensing are two other optical techniques used to distinguish different liquids in the laboratory. SPR sensors are difficult to build and need expensive special instruments. On the other hand, RI sensors have many advantages such as small size and high sensitivity. Furthermore, they have remote accessing ability, which makes them to have great potential applications. In order to tackle current limitations in crude oil detection, a new crude oil sensor should be developed. This thesis aims to develop a new crude oil sensor based on refractive index and microwave photonics techniques. It can distinguish crude oil from other liquids underground directly. In addition, it has high sensitivity and is low cost. This new sensing structure consists of a fibre laser and a microwave photonics notch filter. The sensor head, which is formed by removing part of cladding in a fibre Bragg grating, is the key component. In this case, the grating characteristic becomes sensitive with surrounding liquids. In addition, the fibre laser can generate a light with very narrow bandwidth. As a result, it is easy to detect a small change in the liquid composition by measuring wavelength shift. The sensor consists of a microwave photonics notch filter, which is used to improve the sensing resolution. Light with different wavelength can be reflected at different position of the chirped fibre Bragg grating in the notch filter, which results in different time delays. As a result, notch frequency shifts can be obtained. Consequently, a small wavelength shift can be detected by measuring the shift in the notch frequency on a network analyser. The performance of the sensor is analysed and simulated using MATLAB and VPITransmissionMaker photonic simulation software. In addition, experiments have been conducted to verify the idea.
Keyword optical sensor
refractive index sensor
fibre Bragg grating
microwave photonics
crude oil detection
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Created: Tue, 08 Dec 2015, 14:59:21 CST by Jessie Ng