Jilin Zou

High-sensitivity fiber Bragg grating pressure sensor using metal bellows

A novel structure of an optical fiber pressure sensor based on a fiber Bragg grating (FBG) and metal bellows is presented. Due to the novel structure, the sensitivity is improved to 48 pm/kPa. The relationship between Bragg wavelength and the applied pressure is derived. Experimental data indicates that there is a good linear relation between the Bragg wavelength shift and the applied pressure. This sensor can be utilized in low-pressure measurement.

Pressure Sensor Based on Fiber Bragg Grating and Carbon Fiber Ribbon-Wound Composite Cylindrical Shell

A novel pressure sensor structure comprising a carbon fiber ribbon-wound composite cylindrical shell is presented in this paper. Based on this mechanical structure combined with a Fiber Bragg Grating (FBG), an accurate low-pressure sensor is developed. Theoretical analysis and first-principle investigations are conducted. Further, experimental results indicate that the pressure sensitivity and measurement range can reach 0.452 nm/MPa and 8 MPa, respectively.

Liquid-level sensor using a fiber Bragg grating and carbon fiber composite diaphragm

ABSTRACT A novel liquid-level sensor based on fiber Bragg grating and carbon fiber composite diaphragm is proposed and demonstrated. The sensing principle and fi nite element analysis result are described. From the experimental result, this sensor shows high sensitivity and good repeatability. This sensor can find applications in the area of the liquid level sensing. Keywords : liquid-level sensor, fiber Bragg grating, carbon fiber composite diaphragm 1 INTRODUCTION Liquid-level measurement is important in modern industry such as water level monitor, fuel storage in a tank, and other applications. Various kinds of liquid-level sensing methods based on mechanical, electrical, and optical techniques have been proposed. Electrical liquid-level sensors are widely utilized. However, their applications are limited if the temperature of the monitored liquid is too high, conductive, potentially explosive or corrosive. Due to the inherent advantages of electrically passive operation, dielectric and im munity to the electromagnetic interference, high sensitivity and multiplexing capabilities, fiber Bragg grating sensors have attracted more interests. In the past few years, several optical fiber liquid-level sensors have been developed. These include sensors based on the photoelastic effect[1], multiple micro-bending sensor[2], liquid-level sensor based on the refractive index sensitivity of a long period grating [3], an intensity modulation approach using a pair of optical fibers to transmit the source light and receive the light partially reflected by the liquid surface through a glass prism[4], FBG sensors based on bending cantilever beam[5], FBG sensors consisting of diaphragm and Bourdon tube[6], liquid-level sensor based on etched Bragg grating[7]. For practical application, the above mentioned methods are limited due to the complicated sensor structure or the repeatability issue. In this paper, a novel method based on carbon fiber composite diaphragm and fiber Bragg grating and is proposed. It is well known that carbon fiber reinforced composite materials are an important class of engineering materials. They offer outstanding properties such as unique flexibility in design capabilities, ease of fabrication and also the advantages of light weight, corrosion resistance, impact resistance, excellent fatigue strength and good repeatability. In [8] we have previously reported an accurate high pressure sensor of 70Mpa which is based on FBG and carbon fiber laminate composite material. In this paper, to our knowledge, it is the first time that the carbon fiber composite diaphragm is proposed to be used as a sensing elemen t and experimental results are presented in detail.

High-sensitivity pressure sensor based on fiber Bragg grating and metal bellows

An optical fiber pressure sensor based on fiber Bragg grating (FBG) and metal bellows is presented in this paper. Due to the lower spring rate of metal bellows, the sensitivity is improved to 48pm/kPa. The relationship between Bragg wavelength and the applied pressure is derived. Experimental data indicates that there is good linear relation between the Bragg wavelength shift and the applied pressure. This sensor can be utilized in low pressure measurement.

Floating OE sensor array for offshore marine oil spill monitoring and pollution control

Based on our successful technology of conductance liquid level sensor, combined with the long-period fiber Bragg grating sensor technology, a floating optical-electrical (OE) sensor array system is designed aimed at the early monitoring of oil contamination of offshore marine oil spill and pollution control as well as the safety at sea.

A discrete liquid level sensor based on fiber Bragg grating

A discrete liquid level sensor based on fiber Bragg grating (FBG) that is suitable for liquid level monitoring is proposed. FBG (fiber Bragg grating) is embedded in a cantilever beam which is made of carbon fiber composite. And an iron sheet is bonded with the end of cantilever beam. For the float, a magnet is bonded with the float. When the liquid level rises or fall, the float will move up or down. The cantilever beam will bend downward or upward, it will induce strain on the FBG. Therefore, the Bragg wavelength of FBG will shift. An extra reference grating was utilized for temperature compensation.

Cognitive Fiber Bragg Grating Sensors System Based on Fiber Fabry-Pérot Tunable Filter Technology

The wavelength demodulation based on a Fiber Fabry-Pérot Tunable Filter (FFP-TF) is a common method for multiplexing Fiber Bragg Grating (FBG) sensors. But this method cannot be used to detect high frequency signals due to the limitation by the highest scanning rate that the FFP-TF can achieve. To overcome this disadvantage, in this paper we present a scheme of cognitive sensors network based on FFP-TF technology. By perceiving the sensing environment, system can automatically switch into monitoring signals in two modes to obtain better measurement results: multi measurement points, low frequency (<1 KHz) signal, and few measurement points but high frequency (~50 KHz) signals. This cognitive sensors network can be realized in current technology and satisfy current most industrial requirements.

Monitoring the hysteresis effects in the strain-stress curve of carbon fiber reinforced laminates by FBG technology

In this paper, we present a study of detecting the hysteresis effect in strain-stress curve of carbon fiber reinforced materials by Fiber Bragg Grating technology. By calculating the dissipative energy density contoured by hysteresis loops, this method can be further applied in detecting the cracks and fatigue of carbon fiber reinforced laminates. In contrast to the traditional sensors, such FBG sensors have numerous merits, such as small size, immunity to Electromagnetic Interference and easy installation into the carbon fiber reinforced laminates. This method can also be extended into monitoring other materials which also exhibit hysteresis effects in their strain-stress curves.

Pressure sensor using carbon fiber laminate tube and fiber Bragg grating

In this paper, a novel pressure sensor based on carbon fiber laminate tube (CFLT) and fiber Bragg grating is proposed. Theoretical analysis and investigation are conducted. Experiment results indicate that the pressure sensitivity is 138pm/MPa. Pressure sensitivity is improved due to the hollow tube structure compared with solid structure of pressure sensor that we proposed before.

The design of strain rosette on fiber Bragg grating and carbon fiber laminate composite

A temperature-compensated strain-sensing sensor based on fiber Bragg gratings (FBGs) that is suitable for strain mapping of rock in coal exploring application is demonstrated. FBGs were bonded to carbon fiber laminated composite (CFLC) and they were arranged in a FBG rosette configuration used to determine the direction and magnitude of the principal strain, information that is required for strain mapping. An extra reference grating was utilized for temperature compensation measurement.