High Gas Pressure Sensitivity Research Articles

High sensitivity gas pressure and temperature optical sensors based on tapered no-core fiber coated with polydimethylsiloxane (PDMS)

This article introduces a novel high-sensitivity pressure and temperature sensor utilizing a tapered no-core fiber (NCF) structure created by splicing the NCF with a single-mode fiber (SMF) to form a “SMF-NCF-SMF” structure, tapering the NCF, and applying a polydimethylsiloxane (PDMS) film on the tapered NCF surface. The experimental results show that the device with a diameter of 10 μm has a pressure sensitivity of 86.63 nm/MPa within one to two atmospheres. Furthermore, the temperature sensitivity is −1.97 nm/°C from 30 °C to 60 °C. The sensor exhibits excellent stability and repeatability, and the PDMS film enhances the mechanical strength of the device, indicating promising potential for high-sensitivity pressure and temperature applications.

Flexible FPI sensor fabricated by fiber end photopolymerization and integration for high sensitivity gas pressure sensing

This work presents a new design framework for highly sensitive fiber gas pressure sensor. We construct a Flexible Fabry–Perot Interferometer (F-FPI), which consists of three polymer pillars and an end cap, on a fiber end face. A unique fiber-end photopolymerization and integration (FEPI) technique is adopted for fabricating the device. The varied gas pressure in the enclosed space not only changes the refractive index (RI) of the gas but also the length of the pillars. Therefore the difference in the optical path length of the FPI is more sensitive to pressure changes. Experimental results indicate that the F-FPI realizes a gas pressure sensitivity up to 79.0 pm/kPa in the range of 0–200 kPa. In addition, the Vernier effect is introduced to amplify the sensitivity to −409.7 pm/kPa. The temperature compensation is achieved by cascading a Fiber Bragg Grating (FBG) behind the F-FPI. Such a design framework provides a new idea for highly sensitivity gas pressure sensing.

Simultaneous measurement of temperature and pressure sensing technology based on double cavity matching in batteries

A compact sensor based on fiber Fabry-Pérot (FP) cavities dual-cavity matching technique cascaded with fiber Bragg grating (FBG) is proposed and demonstrated to measure pressure and temperature variations inside battery. The sensitivity amplification mechanism for two-parameter measurements is analyzed and a cased reference chamber scheme is designed. Low-cost, small-size, high-temperature and corrosion-resistant all-fiber-optic high sensitivity gas pressure sensors targeting the interior of energy storage batteries are fabricated and cascaded with FBGs to measure temperature parameters. The experimental results show that the sensor has a sensitivity of −26.8322 nm/MPa in a pressure range of 1.86 MPa, the gas pressure inside the battery and the temperature inside and outside the battery at different discharge rates of 1500mAH capacity monobloc batteries can be measured practically, directly and instantly. It has potential applications in detecting subtle pressure variations caused by gas precipitation inside the battery and in temperature measurement, and provides a new concept and a feasible technological path for the measurement of key parameters inside lithium-ion batteries.

Ultra-sensitive gas pressure and temperature sensor based on self-forming film technique and vernier effect

In this paper, an ultra-sensitive gas pressure and temperature sensor based on vernier effect is presented. It consists of a single mode fiber (SMF) and hollow cylindrical waveguides (HCW). Through the self-forming film technique, a gelatin film is manufactured at the air core of HCW, and the thickness of the gelatin film manufactured by this technique is only 3.16 μm. The vernier spectrum is formed by the superposition of the spectra of the air cavity (AC) and the mixing cavity. The mixing cavity is composed of AC and gelatin cavity (GC). The thin gelatin film makes the optical path difference between the AC and the mixing cavity smaller, which is beneficial to increase the vernier magnification factor. When the gas pressure changes, the gelatin film will deform abnormally. This abnormally deformation squeezes the film, causing the cavity length of the air cavity to become longer. The experimental results show that the sensor exhibits a high gas pressure sensitivity of 788.22 nm/MPa, and the temperature sensitivity is 0.39 nm/℃. The proposed sensor enables simultaneous measurement of gas pressure and temperature. It also processes the advantages of compact size, low cost, and strong mechanical strength, which makes it suitable for aerospace, Biomedical and Natural gas detection.

Temperature-Insensitive Gas Pressure Sensor Based on Photonic Crystal Fiber Interferometer

A temperature-insensitive gas pressure sensor was proposed and experimentally investigated. This sensor was based on a photonic crystal fiber sandwiched between two single-mode fibers, where the impact of length on the performance of the sensor has been studied. Air holes of photonic crystal fiber were employed as gas or liquid inlet and outlet channel which provide the medium for direct interaction between the light transmitted in the fiber and the target gases. The experimental results show that the length of photonic crystal fiber has little effect on the sensitivity to gas pressure. The photonic crystal fiber interferometer has a high gas pressure sensitivity of 2.39 nm/MPa when gas pressure increases from 100 KPa to 900 KPa. The demonstrated gas pressure sensor has excellent stability and reversibility with negligible temperature cross-sensitivity. The proposed photonic crystal fiber interferometer can also be used for liquid sample detection with high refractive index (RI) sensitivity of 3026 nm/RIU when the length of photonic crystal fiber is 1 cm at a RI range of 1.334-1.34. Therefore, the proposed photonic crystal fiber interferometer holds a great potential in applications for chemical gas leakage detection and biochemical sensing.

Ultra-high-sensitivity gas pressure sensor based on a cascaded Fabry-Perot interferometer and the Vernier effect

Subject of study. An ultra-sensitive gas pressure sensor based on a cascaded Fabry-Perot interferometer is proposed. Purpose of the work. In the proposed sensor, we greatly improve the gas pressure sensitivity of the sensor by using the optical Vernier effect method. Method. During the fabrication of the sensor, one Fabry-Perot interferometer is used as the sensing interferometer, and the other Fabry-Perot interferometer is used as the reference interferometer. Both Fabry-Perot interferometers are fabricated by two sections of single-mode fiber spliced at both ends of a section of a quartz capillary. Then, a micro-hole is drilled in the capillary wall of the sensing Fabry-Perot interferometer by using femtosecond laser micro-processing technology for gas pressure measurement. When the free spectral ranges of two Fabry-Perot interferometers are similar, the optical Vernier effect will be generated by cascading them. By precisely controlling the cavity length difference between two Fabry-Perot interferometers, a very high sensitivity magnification factor can be obtained. Main results. The experimental results show that the sensitivity of the Vernier effect sensor is 133.2 nm/MPa in the pressure measurement range of 0–0.8 Mpa, which is 33.3 times higher than that of the single sensor Fabry-Perot interferometer. In addition, the temperature cross-sensitivity of the sensor is relatively small, only 0.93 kPa/°C. The sensor is flexible in design and easy to manufacture and operate. Practical significance. The proposed sensor has extremely high gas pressure sensitivity, and it can be used in the fields of chemical production, pharmaceuticals, oil and gas storage, and environmental protection for high-sensitivity gas pressure measurement.

High-sensitivity gas pressure sensor with low temperature cross-talk based on Vernier effect of cascaded Fabry-Perot interferometers

A gas pressure sensor composed of cascaded Fabry-Perot interferometers (FPIs) based on Vernier effect was demonstrated. Two hollow silica tubes (HSTs) with different inner diameters were used to construct the FP cavities, and spliced with single-mode fiber (SMF) to make a gas pressure sensor with a closed cavity FPI and an open cavity FPI in series. The experimental results show that the proposed sensor achieves a high gas pressure sensitivity of −44.31 nm/MPa in the range of 0–2.2 MPa due to the Vernier amplification effect and a very low temperature cross-sensitivity of −0.6 KPa/℃. This sensor has high sensitivity, wide measurement range, small temperature crosstalk, good robustness and low production cost in gas pressure measurement.

High sensitivity gas pressure sensor based ondifferent inner diameter quartz capillary cascading and Vernier effect.

In this paper, a highly sensitive optical fiber gas pressure sensor is proposed and experimentally verified. The sensor is composed of two Fabry-Pérot (F-P) cavities, and two F-P cavities are fabricated by a single-mode fiber and two quartz capillaries with different inner diameters splicing. Among them, the small inner diameter capillary is used as a gas channel connecting the large inner diameter capillary and the external environment. The manufacturing process of the sensor only involves capillary cleaver and splicing and does not involve other complex manufacturing technologies. By correctly adjusting the length of the two quartz capillaries, when the free spectral range of the two F-P cavities is very close, the optical Vernier effect will be observed and used as a sensitive probe for detecting gas pressure. The experimental results show that, in the pressure range of 0-0.8 MPa, the gas pressure sensitivity of the sensor reaches -81.73 nm/MPa with a linearity of 99.7%, and the temperature cross-sensitivity is only 1.82 kPa/°C. Due to its easy manufacture, high sensitivity, compact structure, and small volume, the sensor has become one of the preferred structures for large-scale use in the field of gas sensing.

Optical fiber Fabry-Perot silica-microprobe for a gas pressure sensor

An all-fiber Fabry-Perot microprobe gas pressure sensor based on the femtosecond (fs) laser micromachining technology is proposed and demonstrated. The protruding-shaped silica-microprobe is spliced on the tip of the single mode fiber (SMF), and the gas microcavity is fabricated by the fs laser to form the Fabry-Perot interferometer (FPI), and the machining accuracy of the gas microcavity is better than 2 μm. The length of silicon-microprobe is less than 150 μm and its diameter is less than 30 μm, and the length of gas microcavity in microprobe is about 52 μm. The third reflective surface is formed at the junction between the microprobe and the SMF, the vernier effect can be cleverly utilized to improve the sensitivity of gas pressure. The experiment results indicate that the microprobe FPI gas pressure sensor has a sensitivity of 16.3536 nm/MPa with the increase of gas pressure, and a sensitivity of temperature is only 0.0043 nm/°C from 30 °C to 100 °C. The gas pressure sensor has the advantages of small size, high gas pressure sensitivity and low cross-sensitivity of temperature, and is expected to be applied in the special field, such as detection of gas pressure in alveoli.

High-Sensitivity Gas Pressure Sensor with Low Temperature Cross-Crosstalk Based on Vernier Effect of Cascaded Fabry-Perot Interferometers

High-Sensitivity Gas Pressure Sensor with Low Temperature Cross-Crosstalk Based on Vernier Effect of Cascaded Fabry-Perot Interferometers

High sensitivity gas pressure sensor based on two parallel-connected Fabry–Perot interferometers and Vernier effect

In this study, a highly sensitive gas pressure sensor based on two Fabry–Perot interferometers (FPIs) in parallel with the Vernier effect is designed and demonstrated. In the sensor, FPI1 and FPI2 were used as the detection and reference units, respectively. FPI1 and FPI2 have similar structures, both comprising a single-mode fiber and capillary splicing. However, the microaperture is processed on the capillary of the FPI1 with a femtosecond laser, enabling the external gas to enter the FPI1 cavity through the microaperture channel to realize the gas pressure measurement. The Vernier effect is achieved by superimposing the reflective spectra of FPI1 and FPI2, which have a small cavity length. The gas pressure response, repeatability, and stability of the sensor structures were investigated. The sensitivity of the sensor was improved owing to the Vernier effect. Experimental results indicate that the sensor sensitivity is up to 47.76 nm MPa−1, which is 11.9 times that of a single FPI1 sensor without the Vernier effect. The measured temperature cross-sensitivity of the sensor is approximately 5.1 kPa/ °C. In addition, the sensor has the advantages of simple manufacturing, robust structure, and stable operation. Finally, the manufacturing method of FPI and the parallel connection mode of FPIs could also be used in other sensing fields, providing an alternative design scheme for high-sensitivity sensors.

Cascaded fiber MZIs for simultaneous measurement of pressure and temperature

A hybrid cascade structure composed of two Mach–Zehnder interferometers (MZI) is proposed and demonstrated to measure gas pressure and temperature, simultaneously. The key sensing components of the two MZIs are all based on a tapered single mode fiber (TSMF) spliced between two multimode optical fibers. The difference is that one of the TSMFs is covered with PDMS material, while the other one is exposed to air. Because of the large changes in the refractive index versus air pressure and the high thermo-optic coefficient of PDMS, the MZI covered with PDMS has a high sensitivity to gas pressure and temperature. While the MZI exposed to air has only high gas pressure sensitivity because the air is directly involved in the sensing as a signal of interferometer and the effective refractive index of air varies with the pressure. Experimental results show that the gas pressure and temperature sensitivities of the MZI filled with PDMS can be as high as 78.553 nm/MPa and 8.455 nm/°C, respectively, and another MZI can obtain −8.405 nm/MPa and 0.038 nm/°C, respectively. Therefore, the simultaneous measurement can be achieved by utilizing two MZIs with different gas pressure and temperature sensitivities.

High-sensitivity gas pressure sensor based on a multimode interferometer using hollow-core tube lattice fiber.

A non-diaphragm fiber gas pressure sensor based on a multimode interferometer (MI) using a hollow-core tube lattice fiber (HC-TLF) as a gas cell is proposed and experimentally demonstrated. The sensor is fabricated by fusion splicing a sandwich structure of a graded-index multimode fiber, HC-TLF, and lead-in/out single mode fiber. Several side-holes are drilled by using a femtosecond laser on the side wall of the HC-TLF to allow gas in and out of the fiber. The positions of side-hole in HC-TLF have been investigated during the experiments, which indicate that the highest gas pressure sensitivity existed as the side-hole located in the gap between adjacent cladding holes of the HC-TLF. The proposed structure exhibits a high sensitivity of 8.1 nm/MPa with the average gas fill time of 2.2 s. This sensor also has low temperature sensitivity and low temperature cross sensitivity of 12.3 pm/°C and 1.5 kPa/°C as the temperature rises to 400°C. In addition, the advantages of the gas pressure sensor, such as small size, rapid response, low temperature cross sensitivity, and simple fabrication process, make it suitable for high-pressure measurement in harsh conditions, e.g., downhole and ocean bottom.

Phase-shifted fiber Bragg grating modulated by a hollow cavity for measuring gas pressure

A gas pressure sensor, based on a phase-shifted fiber Bragg grating (PS-FBG) modulated by a hollow cavity, is proposed and demonstrated in this Letter. The device was fabricated by fusing a hollow-core fiber (HCF) between two single-mode fibers (SMFs) exhibiting FBGs that were inscribed using line-by-line femtosecond (fs) laser etching. A pair of micro-channels were drilled orthogonally into the HCF using an fs laser to allow the argon gas to get in and out freely. Such a sensor exposes a high spectrum finesse, e.g., a Q -factor of ∼ 7302 , which can be improved by increasing the grating pitch quantity. Furthermore, a high gas pressure sensitivity of 1.22 nm/Mpa is obtained, corresponding the improved sensor with a grating pitch quantity of 300 and a hollow cavity length of 88.3 µm. In addition, the device exhibited a low temperature sensitivity of 8.92 pm/°C.

Gas Pressure Sensor Based on BDK-Doped Polymer Optical Fiber

This paper presents a high sensitivity gas pressure sensor with benzyl-dimethylketal (BDK)-doped polymer optical fiber Bragg grating (POFBG), whose sensitivity is up to 8.12 pm/kPa and 12.12 pm/kPa in positive and negative pressure atmosphere, respectively. The high sensitivity can be explained by its porous chemical structure. The stability and response behavior under air pressure atmosphere has also been investigated. The new understanding of the air pressure response principle and sensitivity difference for the presented sensor can be a worthy reference.

Temperature insensitive air-cavity Fabry-Perot gas pressure sensor based on core-offset fusion of hollow-core fibers

A temperature insensitive air-cavity Fabry-Perot Interferometer (FPI) based on core-offset fusion (FPI-CFH) of hollow-core fibers with different inner diameters was developed. This sensing structure consists of input single mode fiber (SMF), two short sections of hollow-core fibers (HCF1 and HCF2), and a gold film. The HCF1 with an inner diameter of 70 μm is used to construct air-cavity FPI, and the HCF2 with an inner diameter of 10 μm is offset spliced with HCF1 to provide a flat reflective surface of air-cavity FPI, which can increase the reflection to enhance the fringe contrast, and meanwhile the microfluidic channel of HCF2 is used for the gas inlet. The left end-face of HCF2 is coated with gold film (the thickness of ∼50 nm) to improve the light reflectivity, so that, increasing the fringe contrast of air-cavity FPI spectrum. The experimental results show that the proposed FPI-CFH sensor has a high gas pressure sensitivity of 4.314 nm/MPa with a good linear response (the value of R-Square is 0.9987) when the gas pressure increases from 400 to 1000 kPa, and what's more, the proposed sensor has a negligible temperature cross-sensitivity (0.0051nm/°C) in the range of 20–80 °C due to the structure of all-fiber and the essential characteristics of air-cavity FPI. The maximal relative error of the proposed sensor in the measurement process of gas pressure decrease is less than 1%, which illustrates the sensor has good precision and repeatability. Moreover, the proposed sensor has good stability in a long-term gas pressure testing. Therefore, the proposed FPI-CFH sensor can achieve high precision gas pressure sensing but is insensitive to the variation of temperature.

Compact Mach–Zehnder interferometer based on processed hollow-core fiber for gas pressure sensing

A Mach–Zehnder interferometer based on processed hollow-core fiber (HCF) is proposed and experimentally demonstrated for gas pressure sensing. The fiber sensor is fabricated by splicing a segment of HCF between the two coreless fibers. One end of the HCF is processed into an open cavity, which allows gas pressure of the air-core to be equivalent to that of the external environment. Gas pressure change induces refractive index change of the air-core, thus the measurement of gas pressure can be achieved by monitoring wavelength shift of the interference pattern. The proposed fiber sensor exhibits a high gas pressure sensitivity of 9.35 nm / MPa in the range from 0.1 to 0.04 MPa and a temperature sensitivity of 30 pm / ° C in the range from 30°C to 90°C. Furthermore, the fiber sensor processes the advantages of compactness, low cost, and all-fiber configuration, which makes it suitable for gas pressure measurement.

High-Sensitivity Gas Pressure Fabry–Perot Fiber Probe With Micro-Channel Based on Vernier Effect

In this paper, we propose and demonstrate a gas pressure fiber probe with high sensitivity magnified by Vernier effect. The probe is composed of two cascaded Fabry–Perot interferometers based on a SMF–SOHST–OFC structure (SMF: single-mode fiber; SOHST: side-opened hollow silica tube; OFC: optical fiber column). The high-frequency CO2 laser drilling method for hollow silica tube can effectively maintain the transient balance of the air pressure inside and outside the cavity without destroying the reflective ends of the optical fibers. Experimental results show that the prepared fiber probe with the SOHST length of 375.2 μ m and column length of 247.3 μ m has high gas pressure sensitivity of 80.3 pm/kPa by demodulating Vernier envelope, and it has relatively low temperature cross-sensitivity of –1.33 kPa/°C. This sensor is highly sensitive and of compact size, which not only can be applied in gas pressure sensing but also has the potential for application in microfluidic detection.

Cascaded Fiber Mach–Zehnder Interferometers for Sensitivity-Enhanced Gas Pressure Measurement

A simple structured ultra-highly sensitive fiber optic gas pressure sensor with low temperature cross sensitivity is proposed and demonstrated. The sensor is composed of two cascaded Mach–Zehnder interferometers (MZIs), which consist of single mode-multimode-single mode fiber structure with a micro-machined air cavity in each multimode fiber. The micro air cavities are drilled by a femtosecond laser and act as a gas pressure sensing element. Interference happens between the beams transmitting along the air cavity and the remaining silica core of the multimode fiber. The difference between the fringe intervals of the two MZIs are small enough for generating Vernier effect in gas pressure measurement. The same configuration employed in the two MZIs is to obtain the same temperature response, so that preventing the Vernier effect from appearing in temperature changes. Therefore, the proposed sensor can achieve a high gas pressure sensitivity but is insensitive to temperature variation. Experimental results show that the sensitivity for gas pressure measurement is −82.131 nm/MPa.

A high sensitivity gas pressure sensor based on femtosecond laser micro/nano processing

A compact and novel Mach-Zehnder interferometer used for gas pressure sensing is proposed and demonstrated experimentally. The sensor is constructed by fusion splicing a short piece of dual side-hole fiber (DSHF) in between two sections of multimode fibers (MMF). Interference occurs as the optical path length difference (OPLD) between light beams along air holes and silica of the DSHF. With the opening drilled on one air hole by femtosecond laser micro/nano processing, the filled gas directly affects light beam along this air hole, which results in the interference spectrum shift. Experimental results show that the sensor exhibits a high sensitivity of −8.58 nm/MPa with the increasing gas pressure. The sensor has potential application in gas pressure sensing for its advantages of high sensitivity, low temperature crosstalk and easy fabrication.