CN-122015976-A - Distributed optical fiber temperature and humidity sensor and preparation method thereof

CN122015976ACN 122015976 ACN122015976 ACN 122015976ACN-122015976-A

Abstract

The application relates to the technical field of optical fiber sensors, and provides a distributed optical fiber temperature and humidity sensor and a preparation method thereof, wherein the distributed optical fiber temperature and humidity sensor comprises a sensing unit and a supporting structure, the sensing unit is formed by connecting a plurality of optical fiber gratings in series through optical fibers, coating a humidity sensitive material on the surface to form a sensing string, and sensing the temperature and the humidity through the wavelength change of the gratings; the supporting structure comprises an optical cable unit and a knotting structure, the optical cable unit is formed by compounding an armored spiral sleeve, a steel wire and a PE (polyethylene) sheath, the sensing unit is implanted into the armored spiral sleeve, the steel wire is compounded on the outer side, the PE sheath is coated with polyethylene materials, the knotting structure is arranged at the end of the steel wire and is spliced with an external steel drill rod, and the sensor is fixed inside a grain pile through implantation force of the external steel drill rod. The sensor accurately senses the temperature and humidity of the grain pile through an optical fiber sensing principle, the sensing protection unit filters dust, the sensing protection unit is adapted to the complex environment of the grain bin, the automation level of monitoring the temperature and humidity of grain storage is improved, and storage loss is reduced.

Inventors

ZHAO LIN
LI JIAMENG
YANG HUINING
WANG JIQIANG

Assignees

山东省科学院激光研究所
山东翼派普光学科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260409

Claims (10)

1. A distributed optical fiber temperature and humidity sensor, comprising: The sensing unit (1) is formed by connecting a plurality of fiber bragg gratings (11) in series through optical fibers (12), the fiber bragg gratings (11) are arranged at intervals along the direction of the optical fibers (12), the surface of each fiber bragg grating (11) is coated with a humidity-sensitive material, and a distributed temperature and humidity sensing string is formed after thermal curing and is used for sensing temperature and humidity through grating wavelength change; -a support structure (2), the support structure (2) comprising an optical cable unit (21) and a knotting structure (23); The optical cable unit (21) is formed by compounding an armored spiral sleeve (211), a steel wire (212) and a PE sheath (213); The sensing unit (1) is implanted into the armored spiral sleeve (211), the steel wire (212) is compounded on the outer side of the armored spiral sleeve (211), the PE sheath (213) is coated on the outer side of the steel wire (212), and the PE sheath (213) is made of polyethylene materials; the knotting structure (23) is arranged at the end part of the steel wire (212), and the knotting structure (23) is configured to be spliced with an external steel drill so as to fix the sensor in the grain pile through implantation force of the external steel drill.
2. A distributed optical fibre temperature and humidity sensor according to claim 1, characterized by further comprising a coating device (3); The coating device (3) is a cuboid substrate (31) made of a hydrophobic material, and a plurality of grating grooves (32) are etched in parallel in the middle area of the top of the cuboid substrate (31); Each grating groove (32) is used for accommodating a single fiber grating (11), fiber grooves (33) are engraved on two sides of each grating groove (32), and the optical fibers (12) are laid in the fiber grooves (33) and fixed through adhesive tapes; the humidity-sensitive material is filled on the surface of the fiber grating (11) in the grating groove (32), and the sensing unit (1) is formed after heat curing.
3. The distributed optical fiber temperature and humidity sensor according to claim 2, wherein the armored spiral sleeve (211) is matched with the outer diameter of the optical fiber (12), and the steel wire (212) is compounded with the armored spiral sleeve (211) and the PE sheath (213) through an integral molding process; The PE sheath (213) is provided with a stripping area according to a preset distance, and the stripping area is used for exposing the armor spiral sleeve (211) and the steel wire (212); the stripping area is provided with a sensing protection unit (22), and the sensing protection unit (22) is used for accommodating the fiber bragg grating (11).
4. A distributed optical fiber temperature and humidity sensor according to claim 3, characterized in that the sensing protection unit (22) comprises a stainless steel sleeve (221), a dust filter screen (222) and a waterproof joint (223); The stainless steel sleeve (221) is of a cylindrical structure, an air exchange hole (224) is formed in the outer wall of the stainless steel sleeve, and the dust filter screen (222) is attached to the inner wall of the stainless steel sleeve (221); the waterproof connectors (223) are arranged at two ends of the stainless steel sleeve (221) and are used for connecting the optical cable unit (21) and the stainless steel sleeve (221); the fiber bragg grating (11) of the sensing unit (1) is positioned inside the stainless steel sleeve (221) and is fixed through the armored spiral sleeve (211).
5. A distributed optical fiber temperature and humidity sensor according to claim 4 characterized in that the knotting structure (23) is a wire rope lock configured to be inserted with the U-shaped structure of the outer drill rod front end for implanting the sensor into a grain pile through the outer drill rod.
6. The distributed optical fiber temperature and humidity sensor according to claim 4, wherein the stainless steel sleeve (221) has an outer diameter of 12mm, an inner diameter of 10mm and a length of 80mm, the air exchange hole (224) has a diameter of 1.5mm, and the dust filter (222) has a pore diameter of 100 mesh.
7. A method for preparing a distributed optical fiber temperature and humidity sensor, which is used for preparing the distributed optical fiber temperature and humidity sensor as claimed in any one of claims 1 to 6, and is characterized by comprising the following steps: preparing a plurality of fiber gratings which are arranged at intervals along the length direction of the fiber to form a grating string; A plurality of grating grooves are formed in a substrate, fiber gratings in the grating strings are correspondingly placed in the grating grooves, moisture sensitive materials are coated on the surfaces of the fiber gratings in the grating grooves, and distributed sensing units are formed after the fiber gratings are solidified; Implanting the sensing unit into an optical cable unit formed by compounding an armored spiral sleeve, a steel wire and a PE sheath, wherein the sensing unit penetrates into the armored spiral sleeve of the optical cable unit, the steel wire is compounded on the outer side of the armored spiral sleeve, and the PE sheath is coated on the outer side of the armored spiral sleeve; the optical cable unit is provided with a sensing protection unit which is sleeved outside the optical cable unit and accommodates the fiber bragg grating of the sensing unit; and packaging the optical cable units and the sensing protection units, and connecting a plurality of optical cable units in series to obtain the distributed optical fiber temperature and humidity sensor.
8. The method for manufacturing a distributed optical fiber temperature and humidity sensor according to claim 7, wherein the step of providing a plurality of grating grooves on the substrate comprises: and etching a plurality of grating grooves side by side at the top of a cuboid substrate, and etching optical fiber grooves at two sides of each grating groove, wherein the cuboid substrate is made of a hydrophobic material.
9. The method for manufacturing a distributed optical fiber temperature and humidity sensor according to claim 8, wherein the step of correspondingly placing the optical fiber gratings in the grating string in the grating grooves comprises: And placing the fiber gratings in the grating strings into the grating grooves one by one, and laying and fixing the fiber parts connected with the adjacent fiber gratings in the corresponding fiber grooves.
10. The method of manufacturing a distributed optical fiber temperature and humidity sensor according to claim 9, wherein the step of installing a sensing protection unit on the optical cable unit comprises: arranging stripping areas on PE sheaths of the optical cable units at intervals of preset distance to expose the inner armor spiral sleeves and steel wires; The sensing protection unit is installed in the stripping area and comprises a stainless steel sleeve, a dust filter screen attached to the inner wall of the stainless steel sleeve and waterproof connectors arranged at two ends of the stainless steel sleeve, and the waterproof connectors are used for connecting a plurality of optical cable units in series.

Description

Distributed optical fiber temperature and humidity sensor and preparation method thereof Technical Field The application relates to the technical field of optical fiber sensors, and provides a distributed optical fiber temperature and humidity sensor and a preparation method thereof. Background During the storage process of the granary, maintaining proper storage conditions is important to prevent the quality of the grain food from deteriorating. Because of large storage scale and long period, if the storage condition is controlled improperly or the post-production supervision technology is behind, obvious loss is easy to generate in the storage and circulation links. In the aspect of temperature and humidity monitoring, the existing system mostly adopts digital sensors, such as thermistors, humidity-sensitive capacitors and the like, and transmits signals to a monitoring terminal through cables. However, the operations of humidity, dust and fumigation in the warehouse environment easily lead to corrosion of cable joints and increase of line resistance, which causes signal attenuation or communication faults and affects the reliability of the system. Meanwhile, the sensors are usually distributed in a dot shape, the system needs to collect data point by point, and the real-time performance of data collection and processing can be reduced along with the increase of monitoring points. Therefore, the existing sensor for monitoring the mildew of the grains has the problems of low reliability and limited monitoring coverage density in a complex storage environment. Disclosure of Invention The application provides a distributed optical fiber temperature and humidity sensor, which solves the problems of low reliability and limited monitoring coverage density of the existing sensor for monitoring grain mildew in a complex storage environment, and comprises the following components: the sensing unit is formed by connecting a plurality of fiber gratings in series through fibers, the fiber gratings are arranged at intervals along the fiber direction, the surface of each fiber grating is coated with a moisture-sensitive material, and a distributed temperature and humidity sensing string is formed after thermal curing and is used for sensing temperature and humidity through the wavelength change of the fiber gratings; A support structure comprising an optical cable unit and a knotting structure; the optical cable unit is formed by compounding an armored spiral sleeve, a steel wire and a PE sheath; The sensing unit is implanted into the armored spiral sleeve, the steel wire is compounded on the outer side of the armored spiral sleeve, the PE sheath covers the outer portion of the steel wire, and the PE sheath is made of polyethylene material; The knotting structure is arranged at the end part of the steel wire and is configured to be spliced with an external steel drill rod so as to fix the sensor in the grain pile through implantation force of the external steel drill rod. In one possible implementation, the device further comprises a coating device; The coating device is a cuboid substrate made of hydrophobic materials, and a plurality of grating grooves are etched in the middle area of the top of the cuboid substrate side by side; Each grating groove is used for accommodating a single fiber grating, fiber grooves are engraved on two sides of each grating groove, and the fibers are laid in the fiber grooves and fixed through adhesive tapes; the fiber bragg grating surface in the grating groove is filled with the moisture-sensitive material, and the sensing unit is formed after the fiber bragg grating surface is thermally cured. In one possible implementation, the armored spiral sleeve is matched with the outer diameter of the optical fiber, and the steel wire, the armored spiral sleeve and the PE sheath are compounded through an integral molding process; The PE sheath is provided with a stripping area according to a preset distance, and the stripping area is used for exposing the armored spiral sleeve and the steel wire; The stripping area is provided with a sensing protection unit, and the sensing protection unit is used for accommodating the fiber bragg grating. In one possible implementation, the sensing and protecting unit comprises a stainless steel sleeve, a dust filter screen and a waterproof joint; The stainless steel sleeve is of a cylindrical structure, the outer wall of the stainless steel sleeve is provided with air exchange holes, and the dust filter screen is attached to the inner wall of the stainless steel sleeve; the waterproof connectors are arranged at two ends of the stainless steel sleeve and are used for connecting the optical cable unit and the stainless steel sleeve; the fiber bragg grating of the sensing unit is positioned inside the stainless steel sleeve and is fixed through the armored spiral sleeve. In one possible implementation, the knotting structure is a wire rope shackle configured to