Fiber Optic Pressure Sensor Research Articles

Temperature desensitization of a fiber-optic pressure sensor by simultaneous measurement of pressure and temperature

A fiber-optic hydrostatic pressure sensor initially temperature compensated by optical means is further desensitized below the limits associated with second-order effects by the method proposed in this paper. We achieved this goal by using an integrated system of two coherence-multiplexed separate sensor components for simultaneous measurement of hydrostatic pressure and temperature and by on-line numerical processing of measurement data delivered simultaneously from both sensor parts. The system is based on highly birefringent fibers, employs electronic scanning, and can be used for quasi-static measurements.

A production process of silicon sensor elements for a fibre-optic pressure sensor

Silicon micromachining has been used for small-scale production of sensor elements for a fibre-optic pressure sensor. Each sensor is integrated with a guide wire for insertion of catheters during balloon dilatation of constricted arteries of the heart. The manufacturing process of the sensor elements is described in detail. It consists of four lithographic steps and five etch steps. The sensor elements have been manufactured using anisotropic etching of slowly dissolving {100} silicon planes in KOH. The sensor elements are supported by a carrier for use of a micromanipulator when assembling the sensor. The dimensions of the sensor elements are 55 μ × 76 μm × 1240 μm, and the resulting guide-wire pressure sensor has an outer diameter of 0.36 mm. Critical element dimensions determing the sensor performance have been identified, and resulting etch depth variations are presented. It is shown that the sensor elements could be produced with sufficient accuracy using time etching of {100} planes. The yield of the total manufacturing process is about 40%. The sensor is a commercial product and the production volume of sensor elements is 10 000 units/year.

Smart interpolator for a fiber-optic pressure sensor

A smart interpolator is proposed to improve the long-term stability of a fiber-optic pressure sensor. This method relies on decomposing the compensation model into signal and reference channel parameters. Analysis shows that this interpolator can be used for self-calibration and cancellation of the long-term drift. Experiments prove its effectiveness.

Design of high-sensitivity photoelastic optical fiber pressure sensor: a differential approach

A differential method is described for an optical fiber photoelastic pressure sensor to implement high sensitivity and low drift optically. The method relies on importing two orthogonal polarization light beams into the system alternately in time to produce two differential output signals that are derived from conventional compensation methods. The difference of the two output signals can reduce the long-term drift significantly. The measurement range of 0/spl sim/0.15 MPa has been demonstrated with an accuracy of 0.1% within the temperature range of -20/spl deg/C/spl sim/50/spl deg/C. The practical application proves its efficiency.

A Single Mode Optical Fiber Pressure Sensor for Gas Insulated Equipments.

A Single Mode Optical Fiber Pressure Sensor for Gas Insulated Equipments.

Fiber optic pressure sensor for biomedical applications.

In vivo measurement of blood pressure is critical in many settings, including patient care, medical research, and control of cardiovascular assist and replacement devices. This article describes a pressure sensor based on fiber optic, white light interferometry. An optical interference filter formed between the end face of an optical fiber and the sensing diaphragm selectively reflects a wavelength component. A low cost, thin film optical wedge interferometer placed at the output end detects the wavelength of the reflected signal, which represents a unique cavity length of the interference filter directly related to the diaphragm deflection and, therefore, pressure. Several key features of this sensing scheme include low drift, high accuracy, and insensitivity to light loss factors along the length of the optical fiber. This fiber optic pressure sensor promises significant advances as a medical monitoring tool, a research instrument, and a component of cardiovascular assist and replacement devices. A prototype pressure gauge has been built, and the feasibility of the optical approach verified. Experimental results of the prototype gauge for resolution, repeatability, and drift and a preliminary design for a high resolution, low drift, miniature fiber optic pressure probe are presented herein.

Fiber-optic pressure sensors detect cavitation and flow instabilities in centrifugal pumps

A vibration monitoring program is a common means of protecting mechanical equipment from catastrophic failures. For critical pumps handling highly flammable or toxic fluids, prudent operation also requires users to monitor pressure pulsations as a means of ensuring proper hydraulic operation and preventing flow related mechanical failures.

A fiber-optic silicon pressure sensor for ultra-thin catheters

We have developed a new type of fiber-optic pressure microsensor (sensing-element size: 350 μm × 350 μm × 350 μm) suitable for medical instruments such as catheters and endoscopes. The sensing element consists of a diaphragm structure, glass plate and alignment structure. For the transmitting source and signal light, a multimode optical fiber 50/125 μm (core/clad) in diameter has been used. The sensors have been fabricated using micromachining, for example, anisotropic etching and anodic bonding. Pressure measurement is based on modulation of the intensity of optical reflection by deflection of the diaphragm. Pressure measurements of the sensor with sufficient sensitivity (0.19 μW MPa −1 on the average) and accuracy have been obtained.

Design and Performance of an Adaptive Filter in Fiber Optical Pressure Sensors

In this paper, a compensation model based on the signal channel and the reference one is established. Then an electronic adaptive filter is performed using one-step residual error for the optical fiber pressure sensor. In our realization we employ only one parameter to be tracked by adaptive filter. Thus a real-time processing is obtained.

A micromachined pressure sensor with fiber-optic interferometric readout

Abstract A high sensitivity, batch fabricated, fiber-optic pressure sensor has been fabricated using silicon micromachining technology. The transducer consists of a fiber positioning v-groove, a 45° stationary mirror and a silicon membrane, micromachined in silicon by anisotropic etching in KOH solution, and a single mode optical fiber. The membrane and optical fiber end form a Fabry-Perot cavity whose length varies with pressure. The generated optical interference fringes are used to detect and measure the change in membrane deflection. Pressure range of operation is dictated by the thickness, size and material of the membrane. The sensor described here was designed for low pressure range (0–25 mm Hg) applications. Temperature sensitivity and stability problems which are commonly encountered with currently available piezoresistive and capacitive pressure sensors are significantly reduced by the inherent differential nature of interferometric measurement and the use of all silicon construction. The fabrication, packaging and testing of the sensor are described in this paper. The performance of the sensor was evaluated and found to compare favorably with theoretical predictions.

O-ring fiber optic pressure sensor

Two optical fiber pressure sensor techniques are applied to the measurement of the distributed pressure of an O-ring. These sensors are polarimetrically and interferometrically based. Experimental results are presented for measuring the pressure exerted on an O-ring placed in a vacuum chamber and are compared with analytical results. Resolution and dynamic range of the fiber sensors are discussed.

Fiber optic microbend sensor for detection of dynamic fluid pressure at gear interfaces

An intensity-based microbend fiber optic pressure sensor has been developed and tested that is capable of detecting the dynamic fluid pressure between spinning gears. The microbend response of various fibers was measured in order to select the best fiber for the application and to determine the optimum deformer periodicity. The sensing fiber was embedded into the root of a modified gear, using a deformer method based on the compression of silicone rubber under pressure. Embedded gear sensors were calibrated under static pressure to 100 psi, yielding consistent results with different sensors. Gearbox tests demonstrated successful detection of dynamic fluid pressures at gear interfaces, and the ability to perform in a highly rugged environment.

Fiber-optic pressure sensors for internal combustion engines

Two designs incorporating embedded fiber Fabry-Perot interferometers as strain gauges were used for monitoring gas pressure in internal combustion engines. Measurements on a Diesel engine, a gasoline-fueled engine, and a natural-gas engine are reported.

Development of prototype fiber-optic-based Fizeau pressure sensors with temperature compensation and signal recovery by coherence reading

A range of prototype fiber-optic-based Fizeau interferometric pressure sensors with temperature compensation and signal recovery by dual-wavelength coherence reading have been developed. A separate fiber-optic-based Fizeau temperature sensor with similar cavity length was incorporated into the pressure sensor to allow the pressure measurement to be corrected for the temperature dependence of the pressure probe. The pressure and temperature probes were multiplexed spatially. For the low-pressure sensor, the obtained range to resolution ratio and the accuracy were /spl sim/6.7/spl times/10/sup 3/:1 and better than /spl plusmn/1 percent over a pressure range of 0-0.48 bar, respectively. For the medium pressure sensor, the achieved range to resolution ratio and the overall accuracy were 3.6/spl times/10/sup 4/:1 and /spl plusmn/0.15 percent over a full-pressure range of /spl sim/10 bar. For the high pressure sensor, a range to resolute ratio of /spl sim/1.67/spl times/10/sup 4/:1 and an overall measurement accuracy of /spl plusmn/0.69 percent over a pressure range of /spl sim/1000 bar have been achieved. Due to the universality of the signal-processing scheme based on the dual-wavelength coherence-reading technique, the signal-processing box can be compatible with a range of sensors illuminated by the sources with similar central wavelengths. This study would be readily used to develop a range of commercial fiber-optic pressure sensors with similar optical path differences, interrogated by a universal signal-processing box, for different applications. >

Multiplexed fiber optic pressure and vibration sensors for hydroelectric dam monitoring

The use of fiber optic sensors in the civil structures arena is increasing, particularly in the instrumentation of high-performance structures. However, the physical configurations of many such sensor platforms necessitates the use of fiber optic sensor multiplexing. Typically fiber optic sensor multiplexing has involved the grouping of similar or identical sensors along single transmit/receive fiber optic leads coupled with some form of time-, phase-, frequency- or polarization-based multiplexing. Based on work on embedding sensors into multiple large civil structures, the authors feel that multi-media sensors (i.e. fiber optic sensor configurations in which multiple parameters of interest can be measured simultaneously with a single fiber) represent a potentially better method of sensor multiplexing. Results based on sensor multiplexing and interrogation of pressure sensors and vibration sensors used in the health monitoring of a modest-sized hydroelectric dam are described.

Miniaturized pressure‐guide‐wire: evaluation in vitro and in isolated hearts

The present study focused on the accuracy and reproducability of measurements performed with a miniaturized pressure guidewire system (PGWS) under standardized in vitro conditions and in an isolated pig heart model. We used a pressure guide wire system provided by Pressure Guide, Radi Medical Systems, Uppsala, Sweden. Pressures were recorded by a fiber optic pressure sensor located laterally and 3 cm from the distal end. The basic principle is that the element modulates an optical reflection by pressure induced elastic movements. The light source is an emitting diode in the control unit. The PGWS replaces a standard 0.018 in. guidewire. The PGWS was introduced through a Y-adapter in a recirculating perfusion model, consisting of tubing with internal diameters from 1.00 to 4.00 mm. Different perfusion pressures (range 20-140 mm Hg) were generated by a pressure controlled roller pump. Different lumen sizes from 1 to 4 mm had no influence on the measurements. a) In a range from 20 to 140 mm Hg no significant differences were found between the perfusion pressure and the pressures obtained by the PGWS, resulting in an r-value of 0.99 and an equation of y = 1.04x + 1.9. b) In pressure measurements proximal and distal of an artificial stenoses resulting in gradients from 0 to 100 mm Hg, the PGWS correctly identified the pressure difference with an equally high accuracy, 1, 2, and 3 cm behind the stenoses.(ABSTRACT TRUNCATED AT 250 WORDS)

High-fidelity translesional pressure gradients during percutaneous transluminal coronary angioplasty: Correlation with quantitative coronary angiography

A fiberoptic pressure sensor mounted on an 0.018-inch guidewire (Pressure Guide) was used to measure the transstenotic pressure gradient in 30 patients undergoing percutaneous transluminal coronary angioplasty (PTCA) with lesions considered suitable for quantitative coronary angiographic (QCA) assessment. The aim of the study was to correlate pressure gradients with parameters obtained with QCA. After intracoronary injection of 125 micrograms of nitroglycerin, multiple angiographic views were taken of the lesion. The Pressure Guide fiberoptic sensor was then positioned distal to the stenosis and the pressure gradients were recorded before and after PTCA. There was a significant correlation between mean pressure gradients (delta P) and percent diameter stenosis (r = 0.73; p < 0.001) and absolute stenosis diameter (r = -0.67; p < 0.001) and with percent area stenosis (r = 0.69; p < 0.001) and absolute stenosis area (r = -0.63; p < 0.001). The closest relationship, though, was found with stenotic flow reserve (SFR), which is an integrated parameter calculated from QCA. This relationship can be described by the equation: delta P = 65.2 - 12.6.SFR (r = -0.79; p < 0.001). With a measured gradient of > 15 mm Hg, the sensitivity was 94% and the specificity 96% to predict an SFR < 3.5. In conclusion, a statistically significant relationship could be found between stenosis pressure gradients and angiographic parameters in this study with lesions without complicated morphology. The independent information obtained by pressure gradient measurement may be of particular value in intermediately severe lesions or in stenoses where the angiographic assessment otherwise is difficult.

Automatic compensation fiber-optic differential pressure sensor

A novel multimode fiber-optic differential pressure sensor based on a rotating reflector is described. This sensing technique can automatically compensate the influence of source fluctuation, the losses in the input fiber, and the changes in reflectivity of the reflecting surface. Furthermore, if all the fibers are in one cable and subject to the same bending, much of the noise associated with fiber-bend losses will also be cancelled out. By the symmetric compensation principle, a pair of pressure-transfer devices was used in the fiber-optic differential pressure transducer, which can automatically compensate the effect of temperature on the sensor. To test this transducer, a prototype sensor has been constructed and the test results are given here.

A polarimetric interferometry-based optical fibre pressure sensor with potential application to flow measurement

The force/pressure induced birefringence in an ordinary single mode optical fibre has been investigated as a possible element for a differential pressure flow sensor. The relative sensitivities of coated and uncoated fibres at various temperatures have been measured using polarimetric interferometry. The sensitivity of an uncoated sensing fibre was found to be increased by 18% over that of the coated fibre. Results are presented showing good linearity and acceptable stability in measurements over the temperature range 20°C to 95°C, and application to flow sensing are discussed.

Analysis of a shift interferometer as a component of a fiberoptic acoustic pressure sensor

Analysis of a shift interferometer as a component of a fiberoptic acoustic pressure sensor