Fiber Optic Pressure Sensor Research Articles

Research on the Fabrication and Parameters of a Flexible Fiber Optic Pressure Sensor with High Sensitivity

In recent years, flexible pressure sensors have garnered significant attention. However, the development of large-area, low-cost, and easily fabricated flexible pressure sensors remains challenging. We designed a flexible fiber optic pressure sensor for contact force detection based on the principle of backward Rayleigh scattering using a single-mode optical fiber as the sensing element and polymer PDMS as the encapsulation material. To enhance the sensor’s sensitivity and stability, we optimized its structural design, parameters, and fabrication process and measured the fiber strain using an optical frequency domain reflectometer (OFDR). The results showed that the sensor achieved a high sensitivity of 6.93247 με/kPa with a PDMS concentration ratio of 10:1, a curing time of 2 h, and a substrate thickness of 5 mm. The sensor demonstrated excellent linearity and repeatability in static performance tests and was successfully used to monitor the plantar pressure distribution in real time. This flexible fiber optic pressure sensor can be developed via a simple fabrication process, has a low cost, and has high sensitivity, highlighting its potential applications in smart wearables and medical diagnostics.

Dynamic Wave Measurement With a High Spatial Resolution Distributed Fiber Optic Pressure Sensor

Dynamic Wave Measurement With a High Spatial Resolution Distributed Fiber Optic Pressure Sensor

Epidural pressure measurement using a fiber-optic sensor (proof-of-principle invivo animal trial).

An increase in epidural pressure around the stenosis has been observed in patients with lumbar spinal stenosis (LSS) with positive signs of sedimentation or redundant nerve roots. Further analysis of the pressure conditions in the stenotic area would be of great interest. We hypothesized that it would be possible to determine the physiological parameters of the epidural pulse wave and its course in pathological stenosis as a basis for objective identification of LSS based on pressure using a new measuring method with continuous spatial and temporal resolution. We performed a single-case proof-of-principle invivo animal trial and used a newly developed hybrid pressure-measurement probe with a fiber-tip Fabry-Pérot interferometer and several fiber Bragg gratings (FBG). With reproducible precision, we determined the mean epidural pressure to be 7.5 mmHg and the peak-to-peak value to be 4-5 mmHg. When analyzing the pressure measured by an FBG array, both the heart and respiratory rates can be precisely determined. This study was the first to measure the pulse wave velocity of the cerebrospinal fluid pressure wave as 0.97 m/s using the newly developed pressure probe. A simulated LSS was detected in real time and located exactly. The developed fiber-optic pressure sensor probe enables a new objective measurement of epidural pressure. We confirmed our hypothesis that physiological parameters of the epidural pulse wave can be determined and that it is possible to identify an LSS.

Study by simulation and realization of a fiber optic pressure sensor based on a PDMS flexible µ-membrane

Study by simulation and realization of a fiber optic pressure sensor based on a PDMS flexible µ-membrane

Diaphragm-Structured Fiber-Optic Pressure Sensors for Oil Downhole Applications

Diaphragm-Structured Fiber-Optic Pressure Sensors for Oil Downhole Applications

Intrarenal pressure detection during flexible ureteroscopy with fiber optic pressure sensor system in porcine model

To validate the feasibility of a fiber-optic pressure sensor-based pressure measurement device for monitoring intrarenal pressure and to analyze the effects of ureteral acess sheath (UAS) type, surgical location, perfusion flow rate, and measurement location on intrarenal pressure (IRP). The measurement deviations and response times to transient pressure changes were compared between a fiber-optic pressure sensing device and a urodynamic device IRP in an in vitro porcine kidney and in a water tank. Finally, pressure measurements were performed in anesthetized female pigs using fiber-optic pressure sensing device with different UAS, different perfusion flow rates, and different surgical positions at different renal calyces and ureteropelvic junctions (UPJ). According to our operation, the result is fiber optic pressure sensing devices are highly accurate and sensitive. Under the same conditions, IRP varied among different renal calyces and UPJ (P < 0.05). IRP was lowest at 50 ml/min and highest at 150 ml/min (P < 0.05). Surgical position had a significant effect on IRP (P < 0.05). 12/14 Fr UAS had a lower IRP than 11/13 Fr UAS. Therefore fiber optic pressure sensing devices are more advantageous for IRP measurements. In ureteroscopy, the type of ureteral sheath, the surgical position, the perfusion flow rate, and the location of the measurement all affect the intrarenal pressure value.

Ultra-sensitive pressure sensor with low-temperature crosstalk based on the Vernier effect and helical structure

What we believe to be a novel high-sensitivity fiber-optic pressure sensor based on the vernier effect and helical structure is proposed and experimentally verified. The sensor utilizes the superposition of higher-order mode Mach-Zehnder interference and Sagnac fundamental mode polarization interference in a single fiber ring to achieve the vernier effect. In addition, a non-invasive encapsulation structure was fabricated to convert the rise and fall of the pressure value into the change in the twist angle of the optical fiber. This approach reduces the interference of the detecting medium on the sensor signal while simultaneously increasing the sensitivity of the pressure sensor. According to experimental data, the detection sensitivity of the sensor can reach −67277 nm/MPa, which is 65 times higher than the sensitivity of the conventional vernier effect pressure sensor. It also solves the issue of temperature interference with the Vernier-effect structured fiber optic sensor. The sensor has a measured temperature cross-sensitivity of 0.000065 kPa/°C, which is significantly lower than that of comparable sensors. This makes the sensor highly sensitive and ideal for low crosstalk pressure measurement.

Highly sensitive optical fiber pressure sensor based on the FPI and Vernier effect via femtosecond laser plane-by-plane writing technology.

In this paper, a highly sensitive pressure sensor based on fiber-optic Fabry-Perot interferometers (FPIs) and the Vernier effect (VE) is proposed and experimentally demonstrated. We employ a closed capillary-based F P I s for the sensing cavity, and an F P I r created through femtosecond laser refractive index modulation for the reference cavity, which remains impervious to pressure changes. Connecting these two FPIs in series produces a VE-based cascaded sensor with a clear spectral envelope. The femtosecond laser micromachining technique provides precise control over the length of F P I r and facilitates adjustments to the VE's amplification degree. Experimental results reveal significant pressure sensitivities of -795.96p m/M P a and -3219.91p m/M P a, respectively, representing a 20-fold and 80-fold improvement compared to F P I s (-39.80p m/M P a). This type of sensor has good sensitivity amplification and, due to its all-fiber structure, can be a promising candidate for high-temperature and high-pressure sensing, especially in harsh environments.

Hourglass-Shaped Fiber-Optic Mach-Zehnder interferometer for pressure sensing

A fiber-optic pressure sensor based on an hourglass-shaped structure (HSS) is proposed and demonstrated. A Mach-Zehnder interferometer (MZI) is constructed in the inside cavity of the HSS. The HSS consists of a silica frame and two photoresist diaphragms covered on side holes of the frame. Pressure response of the MZI is analyzed by theoretical calculation, the mechanical deformation of the HSS is simulated by using the finite element method, and the spectral characteristics of the sensor are simulated by using the finite-difference beam propagation method. Experimental results indicate that the pressure sensitivity of the sensor with a size of 0.2 × 0.2 × 0.5 mm3 reaches –1.27 nm/kPa with a linear response range of 0–35 kPa. In addition, repeatability, time stability, the cross-responses to ambient refractive index (RI) and temperature, and response time of the sensor are evaluated experimentally. With advantages of high sensitivity, compact size, and insensitivity to ambient RI, the proposed sensor shows promising potential in optofluidic and biomedical sensing fields.

Seawater Dual Parametric Fiber Optic Temperature and Pressure Sensors Demodulated by Machine Learning Method

By employing polydimethylsiloxane (PDMS) characterized by elevated thermo-optical and elastic-optical coefficients for encapsulating an optical microfiber coupler integrated with a sagnac loop (OMCSL) structure, which exhibits large abrupt field characteristics, a fiber optic sensor capable of simultaneously measuring seawater temperature and pressure can be created. Nevertheless, the utilization of the traditional sensitivity matrix method (SMM) for demodulating the sensor led to unstable and considerably erroneous demodulation results. To enhance the accuracy of the demodulation process, this paper investigates and employs a machine learning method (MLM) for sensor demodulation. This paper centers on the investigation and application of MLM for sensor demodulation. The experimental results exhibit a significant decrease in demodulation error attained via MLM when contrasted with the traditional SMM.

Demodulation and Vibration Signal Systems for Photonic Fiber Optic Pressure Sensor

The article describes the optical elements of signal demodulation and polling systems from photonic pressure sensors on inclined fiber Bragg gratings, which are often used to measure the refractive index (RI). A new design of a photonic fiber-optic Bragg pressure sensor with an inclined lattice has been developed, which is connected to standard multimode fibers with an inclined Bragg lattice connected to a metal diaphragm, which is a deformed inclined cantilever. The light source is polarized using the first polarizer and directed to the photonic crystal fiber in such a way as to excite multimode fibers. In this work, a method was developed for determining the optical elements of the spectral contour length system, which consists of setting the cut-off wavelength and then determining the accompanying refractive index. An experimental study determined the curve of the chain length change in the set. To process random signals, the spatial correlation method is used in combination with an approach to digital images based on the number of lanes and the direction of movement. The experimental results differ from the theoretical ones by about 4%. The developed correlation method reflects frequency as well as randomness, it is used in the photographic process together with the image correction given in this document.

Recent Progress in MEMS Fiber-Optic Fabry-Perot Pressure Sensors.

Pressure sensing plays an important role in many industrial fields; conventional electronic pressure sensors struggle to survive in the harsh environment. Recently microelectromechanical systems (MEMS) fiber-optic Fabry-Perot (FP) pressure sensors have attracted great interest. Here we review the basic principles of MEMS fiber-optic FP pressure sensors and then discuss the sensors based on different materials and their industrial applications. We also introduce recent progress, such as two-photon polymerization-based 3D printing technology, and the state-of-the-art in this field, e.g., sapphire-based sensors that work up to 1200 °C. Finally, we discuss the limitations and opportunities for future development.

Ultra-sensitive air pressure sensor based on gelatin diaphragm-based Fabry-Peroy interferometers and Vernier effect

We proposed and experimentally demonstrated a gelatin diaphragm-based Fabry-Perot interferometer (FPI) structure ultra-sensitive fiber optic air pressure sensor. The Fabry-Perot (F–P) cavity of the sensing probe FPI1 is made of gelatin diaphragm, with a thickness of approximately 0.8 μm and the probe length of approximately 136 μm. The air pressure sensitivity of the probe obtained in the experiment is as high as 334 nm/MPa. In order to further improve the sensitivity of the probe, we fabricated an FPI2 with an air F–P cavity that is approximately the length of the FPI1 cavity, and then paralleled FPI2 with FPI1 to generate a Vernier effect. The average sensitivity of the Vernier probe obtained in the experiment reached −2650 nm/MPa, which magnified the sensitivity of a single FPI1 by about 7.9 times. The temperature cross-sensitivity is only 3.6 kPa/°C. This proposed air pressure sensor has the advantages of ultra-high sensitivity, simple manufacturing, low cost, good repeatability and stability, and has broad application prospects in high sensitivity pressure and acoustic detection.

High performance of SPR-based optical fiber pressure sensor: role of silicone rubber diaphragm

High performance of SPR-based optical fiber pressure sensor: role of silicone rubber diaphragm

MEMS silicon-glass fiber-optic FP pressure sensor for high-pressure measurements

MEMS silicon-glass fiber-optic FP pressure sensor for high-pressure measurements

A ground-breaking Distributed fiber-optic Pressure Sensor for geohydraulic applications

Distributed fiber optic (DFO) technology has provided significant insight into various engineering problems by enabling high spatial resolution and accurate temperature and strain measurements. Recently, a novel distributed fiber-optic pressure sensor (DPS) has been developed at the University of Applied Sciences of Eastern Switzerland (OST), which may change the paradigm of monitoring geohydraulic structure monitoring. The key innovation of the sensor is its ability to measure hydrostatic pressure with high spatial resolution and over long distances.This study provides a comprehensive characterization of this novel sensor for two different applications. In the first application the DPS was tested in a water column to measure the vertical hydraulic pressure. In the second application the sensor is tested in a laboratory-scale dike (1:4). The DPS was embedded directly into the earth structures, providing real-time monitoring of pore pressure variations during saturation. For both applications, the DPS measurements were compared with conventional pressure and piezometer sensors, demonstrating good agreement.The results of these two applications illustrate the potential of the DPS to revolutionize geohydraulic monitoring and improve our understanding of dynamic processes in water-related structures. The implementation of this technology promises to improve the safety, predictability, and performance of critical infrastructure.

Automatic irrigation system with a fiber-optic pressure sensor regulating intrapelvic pressure for flexible ureteroscopy

Increased intrapelvic pressure (IPP) due to irrigation during flexible ureteroscopy (f-URS) can pose a risk of postoperative severe urinary tract infection associated with pyelovenous backflow. An automatic regulation system for maintaining safe IPP levels could enable surgeons to perform f-URS safely without postoperative complications. This study aimed to assess the measurement accuracy of an ultra-miniature fiber-optic pressure sensor incorporated into a small-caliper ureteroscope for assessing IPP and to develop an automatic irrigation system linked to this sensor. A porcine kidney was used for the ex vivo experiment. The nephrostomy catheter, connected to the conventional pressure transducer, was placed on the renal pelvis to evaluate the actual IPP (a-IPP). For measuring IPP using the fiber-optic pressure sensor (fo-IPP) built into the f-URS, a diaphragm pressure sensor of Φ250 μm was used. To establish an irrigation system, the optimal proportional–integral–derivative (PID) controller was explored to accurately adjust the irrigation pump flow rate. A high correlation between a-IPP and fo-IPP was confirmed across irrigation pressure values of 60–180 mbar (all, r ≥ 0.7, p < 0.001). When performing bolus irrigation, although fo-IPP showed relatively a higher peak value than a-IPP, the response time of fo-IPP was equivalent to that of a-IPP. After PID parameter optimization, our automatic irrigation system based on fo-IPP smoothly and accurately regulated the intended IPP set in the 5–20 mmHg range without overshooting. We successfully developed and demonstrated an automatic irrigation system regulating IPP based on the PID controller for f-URS, utilizing a fiber-optic pressure sensor. Further research, including in vivo studies, will be needed to assess clinical feasibility.

A Novel Distributed Fiber-Optic Hydrostatic Pressure Sensor for Dike Safety Monitoring

A Novel Distributed Fiber-Optic Hydrostatic Pressure Sensor for Dike Safety Monitoring

All-sapphire-based optical fiber pressure sensor with an ultra-wide pressure range based on femtosecond laser micromachining and direct bonding

An all-sapphire extrinsic Fabry-Perot interferometer (EFPI) optical fiber pressure sensor with ultra-wide pressure range and high temperature resistance is proposed and experimentally demonstrated. The sensor is fabricated by direct bonding three sapphire wafers, including the sapphire substrate, the sapphire wafer with a through hole, and the sapphire pressure-sensitive diaphragm. A femtosecond (fs) laser is used to inscribe a through hole in the center of the sapphire wafer and roughen the outer surface of the sapphire pressure-sensitive diaphragm. By using original polished surfaces of sapphire wafers with low surface roughness as reflective surfaces of the Fabry-Perot (FP) cavity, the high-quality interference signal can be obtained, thereby improving the measurement accuracy of the sensor. The optical cavity length (OCL) of the proposed sensor changes linearly with the applied pressure in the wide range of 0 - 50 MPa at room temperature, and the pressure sensitivity is 0.0921 µm/MPa. The pressure measurement accuracy reaches 0.31%FS (full scale). High temperature experiments show that the sensor can work stably at 1000 ℃.

Highly sensitive gas pressure sensor utilizing the harmonic vernier effect in parallel FPIs with femtosecond laser processing

This work proposes and prepares a high-sensitive fiber optic gas pressure sensor based on the first harmonic vernier effect (FHVE). It has two parallel Fabry-Perot interferometers (FPI), each made of a single-mode fiber and a small segment of capillary tube fused as a sensing cavity and a reference cavity, and the end face of the sensing cavity is cut into a thin slice with a femtosecond laser pulse to make it sensitive to gas pressure. When the sensing cavity's (FPI1) and reference cavity's (FPI2) free spectral ranges are close to each other, a traditional vernier effect occurs, and the gas pressure sensitivity approaches 58.49 nm/MPa, which is approximately 14.64 times that of the single sensing cavity (FPI1). When the free spectral range of the sensing cavity (FPI1) is roughly twice that of the reference cavity (FPI3), the first harmonic vernier effect is observed. This leads to a significant increase in gas pressure sensitivity, up to 141.80 nm/MPa, which is about 35.45 times higher than what a single sensing cavity (FPI1) would achieve. Furthermore, testing results reveal that the sensor is temperature insensitive, with a low cross-sensitivity of 3.1 × 10−5 MPa/°C for gas pressure to temperature. This device is made of pure quartz glass, has high mechanical strength, a sealed construction, is easy to fabricate, has a high sensitivity of gas pressure, and may be used to monitor pressure in extreme conditions such as offshore oil or underwater operations.