FBG Pressure Sensor Research Articles

FBG pressure sensor in pressure distribution monitoring of ship.

In order to realize the multi-point load measurement of ship hull during wave experiments, an FBG pressure sensor was developed to monitor ship bottom liquid level. The principle is to measure the responses of optical fiber sensing units caused by hydraulic pressure. By utilizing a designed steel diamond structure and reasonable selected material, the sensor realized the temperature self-compensation function of a single FBG. The theoretical models and experimental methods are analyzed in detail. Lots of sensing tests showed that, the sensor had a sensitivity of 58.94 pm/kPa and a precision of 1.7 Pa. The temperature sensitivity was only 2.7 pm/°C, which basically achieved the effect of temperature self-compensated. Finally, 15 sensors were installed at the bottom of the hull and a series of wave load experiments were carried out, which further showed that the pressure sensor had good measuring ability and wide application prospect.

Enhanced Sensitivity of Bare Fbg Pressure Sensor Based on the Oval-Shaped 3d Printed Structure

Enhanced Sensitivity of Bare Fbg Pressure Sensor Based on the Oval-Shaped 3d Printed Structure

Dynamic Effects of Temperature on FBG Pressure Sensors Used in Combustion Engines

In this work, we described a study of the influence of dynamical temperatures on pressure measurements in two different packaging types used in FBG pressure sensors. We developed these sensors to measure internal combustion pressure in closed-loop control of thermoelectric engines. The packaging techniques development considered the available monitoring points in the thermoelectric engine and the harsh environment of the monitoring points. In a monitoring point, the temperature can exceed 300 °C and the pressure can reach 250 bar. We detailed the use of single-ended and double-ended FBG fixation methods as packaging techniques. The FBG pressure sensors using these techniques were tested in the laboratory and a thermoelectric engine. The results demonstrated that the dynamical behavior of the high-temperature gas originated from the combustion chamber affects the dynamical pressure measurements performed by the single-ended FBG pressure sensors when they were exposed to the hot gas. This effect can be suppressed by using a double-ended FBG pressure sensor mainly due to its packaging method. Its signal shape is comparable to a reference sensor used in the same condition became this FBG packaging solution the most suitable to use in the closed-loop control of thermoelectric engines.

Pipeline Leakage Test Based on FBG Pressure Sensor

Because of the problem of oil and gas pipeline leakage, a pipeline leakage detection platform based on FBG pressure sensor has been build, which experiments on measurement of negative pressure wave and localization of pipeline leak. And this platform analysis the detection model, as well as denoised and singularly solved to the pressure signal which have been measured through wavelet transform motion. The test results show that the average error of leakage location is 14.17%. This proves that FBG pressure sensor can be fully used in the field of pipeline leak detection.

A practical FBG pressure sensor based on diaphragm-cantilever

A practical FBG pressure sensor on the basis of diaphragm-cantilever was proposed and experimentally demonstrated. The measurement principle and the simulation verification were introduced. The proposed sensor is composed of a diaphragm, a cantilever, a rod and a cover. The rod transfer the deformation of the diaphragm to the cantilever. A pair of FBGs were stuck on the two sides of the cantilever respectively. Theoretical relationship between the wavelength shift and pressure had been established by theoretical analysis. The experiment showed the sensitivity was 258.28 pm/MPa in the range of 0–2 MPa, and its linearity can reach 0.999. The pressure sensor has potential to be applied to pipeline pressure measurement.

A fiber bragg grating pressure sensor with temperature compensation based on diaphragm-cantilever structure

Pressure sensors are essential devices for pressure measurement and safety evaluation in modern industrial production and engineering application. According to the FBG sensing technology, this paper presents and studies a FBG pressure sensor that uses a diaphragm and a cantilever as a sensing unit. Two FBGs of this sensor are bonded on the top and bottom surfaces of the cantilever, respectively, and the center wavelength shift difference between the two FBGs is used as a measuring signal, thus improving the pressure measuring sensitivity and avoiding any effect of temperature cross-sensitivity. The measuring principle of this sensor is introduced, and the diaphragm structure of the sensor is analyzed through theoretical calculation and finite element analysis. Experimental results indicate that this sensor has a sensitivity of 339.956pm/MPa and a linear fitting coefficient of 99.997% in the pressure range from 0 to 10MPa, and the maximum pressure measuring error caused in the temperature range from 5 to 70°C is 0.93%, so the temperature compensation effects are remarkable. Such a FBG pressure sensor can be extensively used for quasi-distributed long-term online monitoring of the static or dynamic pressure of liquid or gas in industrial production.

Numerical Analysis of the E-Type Diaphragm Based on ANSYS

With finite element method, the numerical model of the E-type diaphragm was built in this paper. Based on the model, we got the shear strain law of the E-type diaphragm surface under uniform pressure. Taking it as elastic element and the FBG as sensing element, we made a FBG pressure sensor and obtained the experiment result. The result fit well with finite element simulation value. It shows that the finite element model in the paper is reasonable and effective. The model can be used to design and optimize the sensor.

Application Research of Fiber Bragg Grating for Sensing Finger Pressure Detection on High Voltage Isolate Switch

The sensing finger pressure does not meet the requirements can cause isolation switch overheating, even lead to accident in the operation of high voltage isolate switch. According to the structure of isolating switch, FBG pressure sensor and FBG displacement sensor are installed on isolate switch, which constitute the sensing finger pressure detection system. The sensing finger pressure detection experiments indicate that, when the moving contact’s closing position of isolate switch changes from 0.267mm to 29.040mm, the sensing finger pressure ranges from 30.378N to 32.970N.However, when spring pressure changes from 42.776N to163.827N, the sensing finger pressure ranges from 29.033N to 111.193N.The sensing finger pressure measuring system can realize real-time and online monitoring of the sensing finger pressure.

Two dimensional polymer-embedded quasi-distributed FBG pressure sensor for biomedical applications

We report on the development of a flexible 2D optical fiber-based pressure sensing surface suitable for biomedical applications. The sensor comprises of highly-sensitive Fiber Bragg Grating elements embedded in a thin polymer sheet to form a 2x2 cm(2) sensing pad with a minimal thickness of 2.5mm, while it is easily expandable in order to be used as a building block for larger surface sensors. The fabricated pad sensor was combined with a low physical dimension commercially available interrogation unit to enhance the portability features of the complete sensing system. Sensor mechanical properties allow for matching human skin behavior, while its operational performance exhibited a maximum fractional pressure sensitivity of 12 MPa(-1) with a spatial resolution of 1x1cm(2) and demonstrated no hysteresis and real time operation. These attractive operational and mechanical properties meet the requirements of various biomedical applications with respect to human skin pressure measurements, including amputee sockets, shoe sensors, wearable sensors, wheelchair seating-system sensors, hospital-bed monitoring sensors.

Validation of a Novel Minimally Invasive Intervertebral Disc Pressure Sensor Utilizing In-Fiber Bragg Gratings in a Porcine Model

Nucleus pressure was measured within porcine intervertebral discs (IVDs) with a novel in-fiber Bragg grating (FBG) sensor (0.4 mm diameter) and a strain gauge (SG) sensor (2.45 mm). To validate the accuracy of a new FBG pressure sensor designed for minimally invasive measurements of nucleus pressure. Although its clinical utility is controversial, it is possible that the predictive accuracy of discography can be improved with IVD pressure measurements. These measurements are typically obtained using needle-mounted SG sensors inserted into the nucleus. However, by virtue of their size, SG sensors alter disc mechanics, injure anulus fibers, and can potentially initiate or accelerate degenerative changes thereby limiting their utility particularly clinically. Six functional spinal units were loaded in compression from 0 N to 500 N and back to 0 N; nucleus pressure was measured using the FBG and SG sensors at various locations along anterior and anterolateral axes. On average maximum IVD pressures measured using the FBG and SG sensors were within 9.39% of each other. However, differences between maximum measured pressures from the FBG and SG sensors were larger (22.2%) when the SG sensor interfered with vertebral endplates (P < 0.05). The insertion of the FBG sensor did not result in visible damage to the anulus, whereas insertion of the SG sensor resulted in large perforations in the anulus through which nucleus material was visible. The new FBG sensor is smaller and less invasive than any previously reported disc pressure sensor and gave results consistent with previous disc pressure studies and the SG sensor. There is significant potential to use this sensor during discography while avoiding the controversy associated with disc injury as a result of sensor insertion.

Development of a chirped/differential optical fiber Bragg grating pressure sensor

With its unique capabilities, the optical fiber Bragg grating has been used as a key component in the development of many sensors. Incorporating the theory of thin plates, the authors have developed an FBG-based pressure sensor by strategically attaching FBGs on the surface of a thin circular plate. The flexural strain in the circular plate induced by pressure applied to the circular plate is sensed by either a single FBG placed radially crossing a neutral point, or two FBGs placed respectively in zones where the strains are of opposite signs. When one FBG is used (i.e., the chirped FBG design), the applied pressure relates to the change in the chirped bandwidth of the FBG reflected waveform. When two FBGs are used (i.e., the differential FBG design), the pressure experienced by the circular plate is correlated to the difference in central wavelength from the two FBGs. In either case the sensing mechanism is immune to temperature fluctuation. The same configuration can potentially be applied for other purposes such as a load cell or displacement transducer. This paper describes the design principles of the FBG pressure sensor and demonstrates its capabilities through laboratory calibrations over a wide range of temperatures.

Ultrathin FBG Pressure Sensor With Enhanced Responsivity

An ultrathin fiber Bragg grating pressure sensor with enhanced sensitivity is demonstrated. A novel piston-like diaphragm with a hard core in the center is used as the sensing element to enhance the responsivity. Both the theoretical analysis and the experimental results show that the Young's modulus of the diaphragm and the radius of the hard core have significant effect on the pressure responsivity. By optimizing these two parameters, a pressure responsivity of 7 nm/MPa has been achieved.

Influence of stress birefringence on the performance of a FBG pressure sensor

The effects of using overall affix and two-spot affix between the FBG and underlay on the characteristics of the pressure sensors are compared both experimentally and theoretically. It is found that overall affix can produce large nonlinear effect on the characteristics of output of the sensors. The nonlinear effect caused by the expanded speciral width mainly due to the stress birefringence and the stress grads etc. The experimental result shows that the spectral width caused by using overall affix is 0.28 nm and the linearity can have up to 1.89% of increasing by using two-spot affix. The method of two-spot affix can improve response characteristics of the sensor which is benefit to achieve wavelength demodulation and to improve measurement precision.