In this paper, a highly sensitive airway pressure sensor based on Fabry-Perot interference principle is proposed. The sensor is fabricated by metallic silver film, zirconia ceramic casing, zirconia ceramic ferrule, single mode fiber, and copper nickel-plated tailstock, which meet the chemical stability requirements of medical device. The overall model design and local finite element simulation analysis of the sensor are performed. First, the solid mechanics module of COMSOL is used to emulate the distortion of the film at different pressure to obtain the respective sensor cavity length. Second, the reflectance spectra corresponding to different sensor cavity lengths are obtained using the fluctuating optical module of COMSOL. Thus, the correlation between pressure and spectral offset can be derived. The average spectral sensitivity of the sensor under pressure is obtained to be -1.68 nm/KPa. On this basis, the demodulation method of F-P sensor is explored. The spectral peak tracking principle is applied to the wavelength demodulation of reflection spectrum. The cavity length sensitivity of the sensor is calculated -570.197 nm/KPa. By comparison, the spectral sensitivity after demodulation is obviously improved. The sensor exhibits potential applications in the areas of airway pressure measurement and environmental surveillance.
The development of robots has played an important role in industrial production. Because of the complexity of application objects, traditional rigid robots have some shortcomings in security and flexibility. Due to the high flexibility of the material of the robot body, the robot soft hand provides a new idea and direction for solving the complex adaptability and flexibility of the robot in complex environment. However, the non-linearity and complex geometric characteristics of soft materials make modeling and control a problem. For this reason, this paper takes advantage of the advantages of high sensitivity, light weight and good flexibility of optical fibers. Fiber grating is embedded in the soft material to detect bending force and contact force without affecting the motion of the soft hand, so as to realize the sensing function. On the basis of pointing out the shortcomings of existing flexible sensors, an embedded soft material detection method based on optical fiber is proposed. Firstly, the structure of pneumatic soft finger is simulated and optimized, and the optimal size of soft finger is determined. Soft fingers were prepared by wax loss process. Fiber Bragg Grating (FBG) is embedded and a tactile sensing system is established. The results of FBG-based flexible finger bending and contact force detection are verified. The validity and rationality of the sensor are proved. This is of great significance to the research of soft robots. Finally, this paper summarizes the full text.
Currently, an acceleration sensor based on fiber Bragg grating (FBG) has been widely used. A cantilever FBG accelerometer is designed. The simulation of this structure was implemented by finite element software (ANSYS) to analyze its sensing performance parameters. And then the optimized structure was produced and calibration experiments were conducted. On the basis of simulation, optical fiber is embedded in the inner tank of the vibrating mass, and Bragg grating is suspended above the cantilever structure, which can effectively avoid the phenomenon of center wavelength chirp or broadening, and greatly improve the sensitivity of the sensor. The experimental results show that the FBG accelerometer exhibits a sensitivity of 75 pm/(m/s2) (100 Hz) and dynamic range of 60 dB. Its linearity error is <2.31% and repeatability error is <2.76%. And the resonant frequency is ∼125 Hz. The simulation results match the experimental results to demonstrate the good performance of FBG accelerometer, which is expected to be used in the actual project.
In this paper, a novel one-degree-of-freedom micro-seismic sensor based on Fiber vibrating wire is put forward. The oscillator is penetrated by the optical fiber and mounted near the grating to make a micro-seismic detecting structure. This design contributes to fiber Bragg grating’s response to tiny vibration directly. Some advantages such as small volume, high sensitive, easy for multiplexing, immunity of electromagnetic interference, low cost will be obtained. The new sensor with convenient zero adjust structure is fabricated as well. An experimental system based on high speed FBG interrogation analyzer is set up to demodulate vibration signal and analyze testing data. The micro-seismic simulation experimental results indicate that the sensor owns good performance with low frequency and high sensitivity. This study will be meaningful and helpful in Engineering seismic detection and Earthquake prediction application.
A novel flow sensor based on fiber Bragg grating is put forward in this paper. Chock parts and elastomers are employed as conversion elements. Two FBGs with the same parameter are installed on elastomers separately. An effective solution Double-grating structure has been taken. The temperature natural compensation and its measuring sensitivity are improved. The sensor can be used to measure the flow of gas and fluid. Its structure and the fluid field around it are simulated and analyzed by ANSYS software within the velocity of 1-20m / s . The sensitivity of the sensor is simulated and calculated. The performances of the sensor packaging before and after are tested and the reflection spectrum signal characteristic values of the fiber grating are extracted with good linearity, high response sensitivity of 1.71 nm / kg and 0.103 nm / kg , respectively. The experiment results show that the flow sensor owns simple structure, good linearity and high sensitivity.
A three-axis fiber Bragg grating for the measurement of acceleration is reported. Results obtained using intensity modulation-direct detection (IM-DD)method demonstrate a demodulated signal output range of 1.87Hz~80Hz.Modal analysis and harmonic analysis are performed utilizing finite element analysis method. The strain change is proportional to the acceleration. The sensitivity is 55.3με/g. Low cross-axis sensitivity is obtained. Arrays of such devices can be utilized in a variety of applications such as structural monitoring.
A novel hydraulic pressure sensor based on fiber Bragg grating and elastic metal film is proposed in this paper. Pressure sensing experiments are conducted after the finite element analysis of the sensor probe's structure. The experiments demonstrate that this kind of pressure sensor possesses good linearity and repeatability in its large measurement range with the sensitivity about 23.8 pm/MPa.
To increase the multiplying density of FBG sensors, a novel FBG sensing network using CDM + SDM by coding
measuring points directly is proposed, which increases the multiplying density greatly and is easy to implement in
engineering for its simple structure. Simulation of an example using (25,3,1)-OOC code indicates that although the
system's multiplying density increased greatly, its measuring precision decreased.
In order to increase the multiplying density of Fiber Bragg Grating (FBG) sensors, a novel FBG sensing network based
on measuring point CDMA encoding technology has been developed. Furthermore, the necessary condition of measuring
point CDMA code has been discussed and the measuring performances of this system have been analyzed. Simulation
experiment indicates that in a spectral range of 25.5nm, this type of sensing network can arrange 41 FBG sensors and the
measuring range of every sensor reaches 10 nm.
The temperature and solution concentration sensing characteristics of tilted fiber Bragg grating (TFBG) are investigated
by means of theoretical analysis and experiments in this paper. It shows that the core and cladding modes exhibit nearly
but not exactly the same thermal sensitivity with good linearity throughout the inquired temperature range. The dualsensitivity
problem of TFBG to temperature and solution concentration is solved by calibrating every cladding mode
wavelength with the core mode wavelength which is not sensitive to the solution concentration respectively to
compensate the temperature effect, and this method makes thermal independent solution concentration measurement
possible. It indicates that the cladding modes wavelengths linearly shift to the long wavelength direction with the
increasing sucrose aqueous solution concentration, the demonstrated sensitivity is up to 5.6 pm/(g/40mL).
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