CN-121994753-A - High-sensitivity double-Fabry-Perot interference hydrogen sensor resistant to temperature and humidity interference

Abstract

The invention discloses a high-sensitivity dual-Fabry-Perot interference hydrogen sensor resistant to temperature and humidity interference, and belongs to the technical field of optical fiber sensing. The invention adopts a modularized integrated design, and the core comprises a dual Fabry-Perot interferometer connected in series, wherein the dual Fabry-Perot interferometer is respectively a temperature compensation unit FPI-1 and a hydrogen sensing unit FPI-2, and is matched with a software controllable vernier processing module, the FPI-1 realizes temperature real-time compensation by filling PDMS into an open microcavity, the FPI-2 adopts a PDMS/Pd-WO 3 composite material as a hydrogen sensitive layer, and has the anti-interference capability in a wide humidity range through structural optimization, and weak hydrogen signals are amplified through Fourier transform filtering, sine function fitting, twin interference spectrum construction and vernier effect. The invention realizes accurate detection of ultra-trace hydrogen in complex temperature and humidity environment, and has strong temperature and humidity interference resistance.

Inventors

• YAN YINUO
• ZHAO YONG
• LI CHAOFAN
• WEN CHAOYAN
• LIU YINXI
• ZHOU LIMING
• YANG JINGHAN
• FAN YIXUAN
• ZHAO YUTING
• LIU YINGXUAN

Assignees

• 东北大学秦皇岛分校

Dates

Publication Date

20260508

Application Date

20260318

Claims (6)

1. 1. The high-sensitivity dual-Fabry-Perot interference hydrogen sensor resistant to temperature and humidity interference is characterized by comprising a dual-Fabry-Perot interferometer FPI and a software controllable vernier processing module which are integrated in series, wherein the dual-Fabry-Perot interferometer is constructed based on a single-mode fiber and comprises a temperature compensation unit FPI-1 and a hydrogen sensing unit FPI-2; The temperature compensation unit FPI-1 is of an open microcavity structure prepared by femtosecond laser etching, and PDMS material is filled in the cavity and used for monitoring the ambient temperature in real time and outputting a compensation signal to offset the interference of the temperature on the hydrogen sensing unit FPI-2; The inner wall of an interference cavity of the hydrogen sensing unit FPI-2 is coated with a PDMS/Pd-WO 3 composite sensitive layer, and after hydrogen is adsorbed by Pd-WO 3 , lattice expansion occurs to cause the optical path difference change and spectral displacement of the interference cavity, and the compensation signal of the temperature compensation unit FPI-1 and the signal amplification mechanism of the software controllable vernier processing module are matched; The temperature compensation unit FPI-1 comprises a single-mode fiber 1, a reflection surface 2, a single-mode fiber 2, a reflection surface 3, and a PDMS/Pd-WO 3 composite sensitive layer, wherein the single-mode fiber 1 is arranged on the left side of the temperature compensation unit FPI-1, the reflection surface 1 is arranged on the right end surface of the single-mode fiber 1, the reflection surface 2 is arranged on the right side of the temperature compensation unit FPI-1, the reflection surface 4 is arranged on the right end surface of the single-mode fiber 2; The software controllable vernier processing module carries out Fourier transform filtering, sine function fitting, twin interference spectrum construction and vernier superposition on the double-path interference signals, amplifies weak hydrogen signals and combines temperature compensation data to realize accurate quantitative detection of hydrogen concentration.
2. 2. The high-sensitivity dual-fabry-perot interference hydrogen sensor for resisting temperature and humidity interference according to claim 1, wherein the temperature compensation unit FPI-1 and the hydrogen sensing unit FPI-2 are prepared by adopting quartz hollow optical fibers HCF, the specification of the optical fibers is 125 μm in outer diameter and 50 μm in inner diameter, and the deviation of the coaxiality of optical axes of the temperature compensation unit FPI-1 and the hydrogen sensing unit FPI-2 is less than or equal to 0.1 μm.
3. 3. The high-sensitivity dual-fabry-perot interference hydrogen sensor with temperature and humidity interference resistance according to claim 1, wherein the PDMS/Pd-WO 3 composite sensitive layer is formed by mixing Pd-WO 3 composite sensitive powder with a PDMS system, wherein the PDMS system is formed by mixing a methyl vinyl siloxane PDMS matrix with a curing agent according to a volume ratio of 10:1, and the Pd-WO 3 composite sensitive powder is mixed with the PDMS system to form the composite sensitive material.
4. 4. The high-sensitivity dual fabry-perot interference hydrogen sensor resistant to temperature and humidity interference according to claim 1, wherein the open microcavity of the temperature compensation unit FPI-1 is of a C-type structure, and is prepared by femtosecond laser etching, wherein the size deviation length range is less than or equal to + -2 μm, and the size deviation width and depth range are less than or equal to + -1 μm.
5. 5. The high-sensitivity dual-Fabry-Perot interference hydrogen sensor for resisting temperature and humidity interference according to claim 3 is characterized in that the preparation process of the PDMS/Pd-WO 3 composite sensitive layer comprises the steps of reacting tungsten powder with 30% of H 2 O 2 solution by mass fraction to generate tungstic acid sol, centrifuging, replacing a solvent, doping PdCl 2 , solidifying and grinding to obtain Pd-WO 3 composite sensitive powder, mixing a PDMS matrix and a curing agent according to a volume ratio of 10:1, adding the composite sensitive powder after defoaming, dispersing for 30 minutes at an ultrasonic frequency of 20kHz, coating on the inner wall of an air core optical fiber by a dip-coating method, and curing at a constant temperature of 80 ℃ for 2 hours to form an integrated structure.
6. 6. The high-sensitivity dual fabry-perot interference hydrogen sensor of claim 1, wherein the software controllable vernier processing module is arranged in a computer, and the signal processing steps are as follows: S1, spectrum preprocessing, namely performing Fourier transform filtering on an original interference spectrum acquired by a hydrogen sensing unit FPI-2, eliminating noise interference and extracting clear interference signals; s2, performing sine function fitting, namely performing sine function accurate fitting on the filtered spectrum to obtain a spectrum mathematical expression; S3, constructing a twin interference spectrum and performing vernier effect, namely carrying out twin superposition on the basis of a fitting expression and an original interference spectrum to generate the twin interference spectrum, and superposing the original interference spectrum and the twin interference spectrum to form a vernier spectrum; S4, tracking the cursor spectrum envelope peak drift amount, and combining the compensation data of the temperature compensation unit FPI-1 to finish the quantitative detection of the hydrogen concentration.

Description

High-sensitivity double-Fabry-Perot interference hydrogen sensor resistant to temperature and humidity interference Technical Field The invention relates to the technical field of optical fiber sensing, in particular to a high-sensitivity dual-Fabry-Perot interference hydrogen sensor resistant to temperature and humidity interference. Background The optical fiber sensing technology has become a core technical direction of hydrogen detection because of the advantages of intrinsic safety, electromagnetic interference resistance, quick response, remote networking and the like, wherein a Fabry-Perot interferometer (FPI) sensor has paid attention to by virtue of the characteristics of compact structure, convenience in demodulation and the like. However, the existing optical fiber hydrogen sensor still has the following problems that 1) the traditional FPI hydrogen sensor is not provided with a special temperature-humidity compensation mechanism, the temperature fluctuation can cause the optical path difference drift of an interference cavity, the humidity change can easily cause the performance attenuation of sensitive materials, and the two are coupled with hydrogen concentration signals to cause measurement deviation, 2) the detection sensitivity is insufficient, the signal change is weak only by directly demodulating the FPI interference spectrum, the detection requirement of ultra-trace hydrogen (ppm level) is difficult to meet, the early warning capability is limited, 3) the anti-interference and the sensitivity are difficult to be combined, the anti-interference capability is improved by adding a compensation structure in part of schemes, the structure is complex, the detection sensitivity is not optimized, and the part of high-sensitivity schemes lack effective temperature-humidity interference suppression design and cannot adapt to complex working conditions. At present, patent CN121049208A proposes an optical fiber hydrogen sensor based on a silver film-nanowire hole array structure and a preparation method thereof, but lacks a temperature-humidity compensation unit, has weaker temperature-humidity interference resistance, and patent CN120992703A proposes a hydrogen sensor with ultra-fast hydrogen response speed and a preparation method thereof, but has lower hydrogen measurement sensitivity. Disclosure of Invention The invention aims to provide a high-sensitivity dual-Fabry-Perot interference hydrogen sensor resistant to temperature and humidity interference, solves the problems that the existing optical fiber hydrogen sensor is serious in temperature and humidity interference, insufficient in detection sensitivity, stiff in vernier regulation and control and incapable of realizing accurate early warning of ultra-trace hydrogen under complex working conditions, breaks through the technical limitation of traditional single function optimization, builds a cooperative technology system of hardware temperature and humidity independent compensation, software twin controllable vernier amplification and integrated structure, isolates the temperature and humidity interference through a hardware layer, flexibly amplifies weak signals through a software layer, ensures stable adaptation of a structure layer, realizes real-time, online and accurate detection of ultra-trace hydrogen (ppm level) under complex environments, and meets the severe requirements of the fields of new energy storage, aerospace, chemical synthesis and the like on hydrogen safety monitoring. In order to achieve the aim, the invention provides a high-sensitivity dual-Fabry-Perot interference hydrogen sensor resistant to temperature and humidity interference, which comprises a dual-Fabry-Perot interferometer FPI and a software controllable cursor processing module which are integrated in series, wherein the dual-Fabry-Perot interferometer is constructed based on a single-mode fiber and comprises a temperature compensation unit FPI-1 and a hydrogen sensing unit FPI-2; The temperature compensation unit FPI-1 is of an open microcavity structure prepared by femtosecond laser etching, and PDMS material is filled in the cavity and used for monitoring the ambient temperature in real time and outputting a compensation signal to offset the interference of the temperature on the hydrogen sensing unit FPI-2; The inner wall of an interference cavity of the hydrogen sensing unit FPI-2 is coated with a PDMS/Pd-WO 3 composite sensitive layer, and after hydrogen is adsorbed by Pd-WO 3, lattice expansion occurs to cause the optical path difference change and spectral displacement of the interference cavity, and the compensation signal of the temperature compensation unit FPI-1 and the signal amplification mechanism of the software controllable vernier processing module are matched; The temperature compensation unit FPI-1 comprises a single-mode fiber 1, a reflection surface 2, a single-mode fiber 2, a reflection surface 3, and a PDMS/Pd-WO 3 composite sensitive