Bent optical fiber multi-parameter sensor based on bionic lateral line

Abstract

One end of an input optical fiber is connected with a light source emitting end, and the other end of the input optical fiber sequentially penetrates through a sensor base and an artificial cilia cantilever beam to be fixedly connected with an exposed optical fiber; the other end of the exposed fiber is fixedly connected with the output fiber; and the other end of the output optical fiber penetrates through the artificial cilium cantilever beam and is in communication connection with the light source receiving end. The sensor provided by the invention can monitor various parameters such as the flow velocity, the flow velocity direction, the salinity and the like at the same time, and can meet the multi-dimensional monitoring requirements in a complex marine environment. Meanwhile, by simulating the structure of lateral hair cells of fishes and adopting a bendable artificial cilia cantilever beam as a core sensing element, the speed and direction of water flow can be accurately detected. In addition, the sensor is in direct contact with the fluid through the exposed optical fiber part, and the salinity of the fluid is detected by utilizing the difference of refractive indexes of different fluids.

Description

Technical Field

[0001] The invention relates to the technical field of optical fiber sensors, and in particular to a bent optical fiber multi-parameter sensor based on a bionic lateral line. Background Art

[0002] With the acceleration of marine resource development, marine environmental monitoring has become an important research field worldwide, especially in the real-time monitoring of parameters such as water flow velocity and fluid salinity, and the demand for sensor technology is increasing. Traditional marine sensors mainly rely on micro-electromechanical systems (MEMS) technology. Such sensors are expensive and have high sensitivity and accuracy to a certain extent, but they face many challenges in complex marine environments.

[0003] Secondly, existing sensors can often only monitor a single parameter. However, with the diversification and refinement of marine monitoring needs, single parameter detection can no longer meet the multi-dimensional monitoring needs in complex marine environments. Existing technologies have limited capabilities in multi-parameter synchronous detection and cannot achieve simultaneous monitoring of multiple parameters such as flow velocity, flow direction, and salinity.

[0004] Finally, existing sensors are deficient in directional sensing capabilities. Traditional directional sensors rely on fixed structures or single sensing elements, which make it difficult to flexibly sense subtle changes in the direction of fluid flow. This limits the accuracy of the sensor in detecting changes in the direction of water flow, especially in complex flow field environments, where it is difficult to accurately sense changes in the direction of the flow field.

[0005] Traditional water flow sensors, such as hot wire sensors, Doppler laser velocimeters, and acoustic velocimeters, are mostly bulky, expensive, susceptible to electromagnetic interference, and have poor scalability. They can only complete a single task and have a complex structure. These limitations make it difficult for traditional sensors to meet the needs of building an increasingly digital, intelligent, and array-based marine monitoring network. At the same time, they are also difficult to integrate due to structural design limitations. Summary of the invention

[0006] The invention discloses a bent optical fiber multi-parameter sensor based on a bionic lateral line, so as to overcome the technical problems of existing sensors such as insufficient directional sensing capability, poor electromagnetic interference resistance and corrosion resistance, and difficulty in realizing multi-parameter detection.

[0007] In order to achieve the above object, the technical solution of the present invention is:

[0008] A bent optical fiber multi-parameter sensor based on a bionic lateral line, comprising: an artificial ciliary cantilever beam, a sensor base, an input optical fiber, an output optical fiber, a bare optical fiber, and a plurality of light source receiving ends;

[0009] The artificial cilia cantilever beam is provided with a first through hole and a second through hole, and the axes of the first through hole and the second through hole are both parallel to the axis of the artificial cilia cantilever beam;

[0010] One end of the input optical fiber is connected to the light source emission end, and the other end sequentially passes through the sensor base and the artificial cilia cantilever beam via the first through hole, and is fixedly connected to the exposed optical fiber;

[0011] The other end of the exposed optical fiber is fixedly connected to one end of the output optical fiber;

[0012] The other end of the output optical fiber passes through the artificial ciliary cantilever beam via the second through hole and is communicatively connected with the light source receiving end, so as to obtain the flow field direction, flow field velocity and salinity of the flow field according to the voltage signal received by the light source receiving end;

[0013] The artificial cilia cantilever beam is fixedly connected to the sensor base.

[0014] Further, the sensor base is provided with a groove along its axial direction, and the interior of the groove is provided with a third through hole, a fourth through hole, a fifth through hole, a sixth through hole and a seventh through hole coaxial with the groove;

[0015] The input optical fiber passes through the sensor base via the third through hole; the light source receiving end is fixedly arranged in the fourth through hole, the fifth through hole, the sixth through hole and the seventh through hole;

[0016] The fourth through hole, the fifth through hole, the sixth through hole and the seventh through hole are evenly arranged with the axis of the output optical fiber as the center.

[0017] Furthermore, the artificial cilia cantilever beam comprises a first artificial cilia cantilever beam segment and a second artificial cilia cantilever beam segment; the first artificial cilia cantilever beam segment and the second artificial cilia cantilever beam segment are coaxially fixed;

[0018] One end of the input optical fiber passes through the first artificial cilia cantilever beam section and the second artificial cilia cantilever beam section in sequence through the first through hole;

[0019] The outer wall surface of the first artificial cilia cantilever beam section is fixedly connected to the inner wall surface of the groove, and a space for optical signal transmission is formed between the bottom surface of the first artificial cilia cantilever beam section and the bottom surface of the groove.

[0020] Furthermore, the artificial cilia cantilever beam is made of flexible thermoplastic polyurethane material.

[0021] Furthermore, the artificial cilia cantilever beam is a cylindrical structure.

[0022] Furthermore, the formula used to obtain the flow velocity of the flow field is as follows:

[0023] max{|y4-y2|,|y3-y1|}=Ax 3 +Bx 2 +Cx+D where: y1, y2, y3, and y4 are the voltage signal received by the first light source receiving end, the voltage signal received by the second light source receiving end, the voltage signal received by the third light source receiving end, and the voltage signal received by the fourth light source receiving end, respectively, wherein the first light source receiving end, the second light source receiving end, the third light source receiving end, and the fourth light source receiving end are arranged in sequence in a clockwise direction; x represents the flow field velocity; A, B, C, and D represent the cubic coefficient, square coefficient, linear coefficient, and constant term, respectively.

[0024] Furthermore, the formula used to obtain the salinity of the flow field is as follows:

[0025] y1=an f +b

[0026] Among them, y1 is the voltage signal received by the first light source receiving end, n f is the refractive index of the liquid, a is the coefficient of voltage decreasing with the refractive index, and b is the initial voltage signal received by the first light source.

[0027] n f =n0+k·S

[0028] Among them, n f is the refractive index of the liquid, n0 is the refractive index of pure water, S is the salinity, and k is the refractive index variation coefficient of salinity.

[0029] Beneficial effects: The invention relates to a curved optical fiber multi-parameter sensor based on a bionic lateral line, wherein one end of the input optical fiber is connected to the light source transmitting end, and the other end passes through the sensor base and the artificial ciliary cantilever beam in sequence and is fixedly connected to the bare optical fiber; the other end of the bare optical fiber is fixedly connected to the output optical fiber; the other end of the output optical fiber passes through the artificial ciliary cantilever beam and is connected to the light source receiving end in communication, so as to obtain the flow field direction, the flow velocity of the flow field and the salinity of the flow field according to the voltage signal received by the light source receiving end. The sensor of the invention can monitor multiple parameters such as the magnitude of the flow velocity, the direction of the flow velocity, and the salinity at the same time, and can meet the multi-dimensional monitoring requirements in complex marine environments. At the same time, by imitating the structure of the hair cells of the lateral line of fish and using a bendable artificial ciliary cantilever beam as the core sensing element, the magnitude and direction of the water flow velocity can be accurately detected. In addition, the sensor is in direct contact with the fluid through the exposed optical fiber part, and the difference in the refractive index of different fluids is used to detect the salinity of the fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0031] Figure 1 It is a schematic diagram of the overall structure of the bent optical fiber multi-parameter sensor based on the bionic lateral line of the present invention;

[0032] Figure 2 It is a schematic diagram of the connection between the artificial ciliary cantilever beam of the present invention and the input optical fiber, the output optical fiber and the exposed optical fiber;

[0033] Figure 3 It is a schematic diagram of the artificial cilia cantilever beam of the present invention;

[0034] Figure 4 is a schematic diagram of a sensor base in an embodiment of the present invention;

[0035] Figure 5 Schematic diagram of the relationship between voltage, refractive index and salinity in an embodiment of the present invention;

[0036] Figure 6 Schematic diagram of voltage differences in opposite directions at different speeds in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] This embodiment provides a bent optical fiber multi-parameter sensor based on a bionic lateral line, such as Figure 1-4 As shown, it includes: an artificial cilia cantilever beam 1, a sensor base 5, an input optical fiber 2, an output optical fiber 3, a bare optical fiber 4, and a plurality of light source receiving ends 6;

[0039] The artificial cilia cantilever beam 1 is provided with a first through hole 11 and a second through hole 12, and the axes of the first through hole 11 and the second through hole 12 are parallel to the axis of the artificial cilia cantilever beam 1;

[0040] One end of the input optical fiber 2 is connected to the light source emission end, and the other end passes through the sensor base 5 and the artificial ciliary cantilever beam 1 via the first through hole 11 in sequence, and is fixedly connected to the bare optical fiber 4;

[0041] The other end of the exposed optical fiber 4 is fixedly connected to one end of the output optical fiber 3;

[0042] The other end of the output optical fiber 3 passes through the artificial ciliary cantilever beam 1 via the second through hole 12, and is in communication connection with the light source receiving end 6; so as to obtain the flow field direction, flow field velocity and salinity of the flow field according to the voltage signal received by the light source receiving end;

[0043] The artificial cilia cantilever beam 1 is fixedly connected to the sensor base 5 .

[0044] Preferably, the sensor base 5 is provided with a groove 56 along its axial direction, and the interior of the groove 56 is provided with a third through hole 51, a fourth through hole 52, a fifth through hole 53, a sixth through hole 54 and a seventh through hole 55 coaxial with the groove 56;

[0045] The input optical fiber 2 passes through the sensor base 5 via the third through hole 51; the light source receiving end is fixedly disposed in the fourth through hole 52, the fifth through hole 53, the sixth through hole 54 and the seventh through hole 55;

[0046] The fourth through hole 52 , the fifth through hole 53 , the sixth through hole 54 and the seventh through hole 55 are evenly arranged with the axis of the output optical fiber 3 as the center.

[0047] Preferably, the artificial cilia cantilever beam 1 comprises a first artificial cilia cantilever beam segment 13 and a second artificial cilia cantilever beam segment 14; the first artificial cilia cantilever beam segment 13 and the second artificial cilia cantilever beam segment 14 are coaxially fixed;

[0048] One end of the input optical fiber 2 passes through the first through hole 11 and sequentially passes through the first artificial cilia cantilever beam section 13 and the second artificial cilia cantilever beam section 14;

[0049] The outer wall surface of the first artificial cilia cantilever beam section 13 is fixedly connected to the inner wall surface of the groove 56 , and a space for optical signal transmission is formed between the bottom surface of the first artificial cilia cantilever beam section 13 and the bottom surface of the groove 56 .

[0050] Specifically, the sensor base 5 is a structure with a blind hole in the form of a groove at the center, the inner diameter of the blind hole matches the outer diameter of the first artificial cilia cantilever beam section 13, and the depth of the blind hole is half the thickness of the sensor base 5. In addition, four through holes on the upper, lower, left and right sides form a symmetrical distribution centered on the center point, and the distances between them are equal, so as to fix the light source receiving end 6.

[0051] The sensor base 5 is used to fix the artificial ciliary cantilever beam 1 and the optical fiber sensing module, and is provided with five through holes, wherein the third through hole 51 is used to fix the input optical fiber 2, and the inner diameter of the third through hole 51 matches the outer diameter of the input optical fiber 2, and the other four through holes are used to fix the light source receiving end 6, which are evenly distributed inside the blind hole of the sensor base with the axis of the output optical fiber as the center. Among them, the inner diameters of the fourth through hole 52, the fifth through hole 53, the sixth through hole 54 and the seventh through hole 55 match the fiber head of the fixed light source receiving end, and are used to fix the optical fiber and receive the light beam signal output by the output optical fiber 3.

[0052] Preferably, the artificial ciliary cantilever beam 1 is made of flexible thermoplastic polyurethane material.

[0053] Specifically, the fiber optic sensing module described in this embodiment includes an input optical fiber 2, an output optical fiber 3, an exposed optical fiber 4, and a light source receiving end 6; wherein the input optical fiber 2 and the output optical fiber 3 are fixed in the artificial ciliary cantilever beam 1, and as the artificial ciliary cantilever beam 1 is deformed, the output optical fiber 3 will change the direction of the output light, thereby affecting the light intensity received by the light source receiving end 6 arranged in the sensor base 5. The artificial ciliary cantilever beam 1 can imitate the lateral line hair cell structure of fish that senses environmental changes. One end is fixed to the sensor base 5 and the other end is exposed to the fluid. The artificial ciliary cantilever beam 1 is made of flexible thermoplastic polyurethane (TPU) material and can be deformed under the action of water flow. The first through hole 11 and the second through hole 12 arranged thereon are used to fix the input optical fiber 2 and the output optical fiber 3, respectively; the light source receiving end 6 is provided with four independent optical fiber ports, which are fixed by the fourth through hole 52, the fifth through hole 53, the sixth through hole 54 and the seventh through hole 55, respectively. The size of each optical fiber port is the same, and the same optical fiber is used to receive the light beam emitted by the output optical fiber 3 to obtain light intensity in different directions.

[0054] Preferably, the artificial cilia cantilever beam 1 is a cylindrical structure.

[0055] Specifically, the artificial cilia cantilever beam 1 of this embodiment is a cylindrical structure with two through holes, and its length is 30 mm. The inner diameters of the two through holes match the outer diameters of the input optical fiber and the output optical fiber used, respectively.

[0056] Specifically, the artificial ciliary cantilever beam 1 of this embodiment, together with the input optical fiber 2, the output optical fiber 3, and the bare optical fiber 4, constitute a complete ciliary structure. Among them, the input optical fiber 2, the bare optical fiber 4, and the output optical fiber 3 are different regions of the same optical fiber divided by the artificial ciliary cantilever beam 1. The two ends of the bare optical fiber are respectively connected to the input optical fiber and the output optical fiber arranged in parallel to form a U-shaped structure; the input optical fiber 2 passes through the first through hole of the sensor base 5 to transmit light to the ciliary structure, and its range is from the light source used to the end of the U-shaped structure connected to the bare optical fiber 4. The bare optical fiber 4 is the optical fiber core except for the optical fiber epidermis, which is a U-shaped curved structure, exposed outside the artificial ciliary cantilever beam 1, and used to detect changes in the external environment. Most of the output optical fiber 3 is wrapped in the artificial ciliary cantilever beam 1, and a small section protrudes at the end to constrain the change in the beam angle caused by the deformation of the artificial ciliary cantilever beam 1.

[0057] Specifically, the output optical fiber 3 is suspended on the light source receiving end 6 , and the center points of the two are ensured to coincide, that is, the output light beam of the output optical fiber 3 can be vertically irradiated on the center point of the light source receiving end 6 .

[0058] The four optical fiber heads fixed on the light source receiving end 6 are used to transmit the received optical signals, which are connected to the back-end acquisition circuit. Specifically, a photodiode is used to convert the optical signal into a voltage signal, and a collector is used to record the voltage signal. The four voltage signals represent four directions for direction judgment.

[0059] The material of the artificial ciliary cantilever beam 1 is a flexible thermoplastic polyurethane TPU material; the material of the sensor base 5 is PLA polylactic acid; the sensor base 5 and the artificial ciliary cantilever beam 1 are fixed with a solid adhesive, the main component of which is ethylene-vinyl acetate copolymer; it can solve the problem that the existing MEMS sensors have poor performance in anti-electromagnetic interference and corrosion resistance, and the electromagnetic interference and high-salinity water bodies in the marine environment are easy to affect the sensor, resulting in inaccurate measurement data or equipment damage. In addition, the flexible thermoplastic polyurethane TPU material of the artificial ciliary cantilever beam 1 of this embodiment can effectively reduce the corrosion of the chemical components and biological attachment in seawater to the sensor, and extend the service life of the sensor. Therefore, in long-term monitoring, the sensor of this embodiment has an incomparable advantage in solving the lack of durability and stability of existing sensors.

[0060] Specifically, Figure 1-4As shown, the artificial cilia cantilever beam 1 is a long cylindrical flexible structure, the upper part of which is exposed to the flow field together with the bare optical fiber 4, and deforms under the shear stress of the flow field. At the same time, the input optical fiber 2 and the output optical fiber 3 fixed in the artificial cilia cantilever beam 1 will also deform under the deformation of the upper part, thereby causing the light beam output by the output optical fiber 3 to be offset, so that the light intensity received by the four optical fibers at the light source receiving end 6 changes, and then the flow velocity and direction can be judged. The artificial cilia cantilever beam 1 is provided with two through holes, and after fixing the input optical fiber 2 and the output optical fiber 3, a solid adhesive will be applied to the through holes for waterproofing. The five through holes of the light source receiving end 6 are also treated in the same way. The lower part of the artificial cilia cantilever beam 1 is buried in the blind hole of the sensor base, and its burying distance is controlled so that the sensor is in the most sensitive state, and it is ensured that when the artificial cilia cantilever beam 1 is not deformed, the light beam output by the output optical fiber 3 is just vertically irradiated on the center point of the four optical fibers at the light source receiving end 6, and finally fixed with a solid adhesive.

[0061] Specifically, the bare optical fiber 4 is the optical fiber core except for the optical fiber skin, which is a U-shaped bending structure with a bending diameter of 3 mm. The bare optical fiber 4 is obtained by removing the buffer layer and the cladding from an ordinary optical fiber, wherein the buffer layer is mainly removed by cutting, and the cladding is removed by soaking and wiping with a polyethylene solution.

[0062] In this embodiment, the material of the sensor base 5 is PLA polylactic acid, which is a biodegradable polymer material formed by polycondensation of lactic acid monomers, has good seawater corrosion resistance, does not pollute the environment, and has a simple manufacturing method and can be manufactured by 3D printing, thereby improving production efficiency and design flexibility; the material of the artificial ciliary cantilever beam 1 is flexible thermoplastic polyurethane (TPU) material, which is a high-performance polymer with excellent elasticity and flexibility, can be deformed within a large range without losing its original shape, and has good wear resistance and oil resistance, thereby ensuring that the sensor can maintain stable performance during long-term use;

[0063] Preferably, the flow velocity of the flow field can be obtained according to the light signal received by the light source receiving end, and the formula used is as follows:

[0064] max{|y4-y2|,|y3-y1|}=Ax 3 +Bx 2 +Cx+D

[0065] Wherein: y1, y2, y3, y4 are the voltage signals received by the first light source receiving end, the voltage signals received by the second light source receiving end, the voltage signals received by the third light source receiving end, and the voltage signals received by the fourth light source receiving end, respectively, wherein the first light source receiving end, the second light source receiving end, the third light source receiving end, and the fourth light source receiving end are sequentially arranged in a clockwise direction; x represents the flow velocity of the flow field. A, B, C, and D represent the cubic coefficient, square coefficient, linear coefficient, and constant term, respectively.

[0066] In a specific embodiment of the present invention,

[0067] max{|y4-y2|,|y3-y1|}=0.608x 3 +0.0092x 2 +0.0536x+0.0022

[0068] Specifically, the optical fiber of this embodiment integrates the input and output of light into a single artificial ciliary cantilever beam 1 through a curved structure, which simplifies the sensor structure. When the flow field causes the artificial ciliary cantilever beam 1 to deform, the direction of the output light will change, that is, the cantilever arm bends in the direction of the flow field, and the output light moves in the opposite direction of the flow field, and then the light intensity received by the light source receiving end 6 in the direction of the flow field will increase, and the light intensity received by the light source receiving end 6 in the opposite direction of the flow field will decrease, and the flow field direction can be distinguished according to the change of the light intensity signal.

[0069] Specifically, the voltage signals received by the four light source receiving ends of this embodiment are as follows: Figure 6 shown.

[0070] Specifically, the sensor is installed in the flow field to be measured, and the input optical fiber 2 is connected to the light source. The flow velocity in the flow field to be measured acts on the artificial cilia cantilever beam 1, causing its deformation, and the acquisition circuit records the voltage changes in four directions;

[0071] For example, the water flow coming from direction 1 acts on the artificial ciliary cantilever beam 1, causing it to bend in the opposite direction, causing the output optical fiber 3 to shift in direction 1, so that the voltage collected in direction 1 increases, and the voltage in the opposite direction decreases. The direction is determined by the change in the signal, and the speed is determined by the amplitude of the change.

[0072] Preferably, the salinity of the flow field can be obtained according to the light signal received by the light source receiving end, and the formula used is as follows:

[0073] y1=an f +b

[0074] Among them, y1 is the voltage signal received by the first light source receiving end, n fis the refractive index of the liquid, a is the coefficient of voltage decreasing with the refractive index, and b is the initial voltage signal received by the first light source.

[0075] In a specific embodiment of the present invention, the expression relationship between the voltage signal received by the light source receiving end and the refractive index of the liquid is as follows: Figure 5 As shown:

[0076] Among them, this sensor detects salinity through light intensity attenuation based on the difference in refractive index inside and outside the optical fiber. When the light beam is reflected in the exposed core, part of the light is refracted into the water at the interface, resulting in light intensity attenuation. The degree of light intensity attenuation is closely related to the refractive index of the liquid. Increased salinity will increase the refractive index of the water body, thereby exacerbating light loss. By monitoring the change in light intensity, the refractive index can be inferred, and the salinity can be further calculated using the approximate linear relationship between the refractive index of the liquid and the salinity. In the salinity range of 0‰ to 40‰, the approximate relationship between the refractive index and salinity is:

[0077] n f =n0+k·S

[0078] Among them, n f is the refractive index of the liquid, n0 is the refractive index of pure water, S is the salinity, and k is the refractive index variation coefficient of salinity. By combining the relationship between light intensity and refractive index, a quantitative correlation between light intensity and salinity can be indirectly established.

[0079] Specifically, when the artificial ciliary cantilever beam 1 is deformed, the input optical fiber 2 and the output optical fiber 3 therein can be deformed. The deformation of the output optical fiber 3 will change the direction of the output light, thereby affecting the light intensity received by the four receiving ends of the light source receiving end 6 in the sensor base 5, wherein the four receiving ends each receive the light intensity in the corresponding direction. When the light beam passes through the exposed optical fiber 4 with the optical fiber skin removed, consumption will occur. The consumption of different liquid salinities is different, which is reflected in the general decrease in the light intensity received by the light source receiving end 6. In the process and use of judging the salinity of this embodiment, one of the voltages is used as the basis for judgment. Since the changes in the four directions are consistent when the voltages in the four directions decrease at the same time, the voltage signal of any one of the light source receiving ends is selected and brought into its light intensity refractive index formula to calculate the refractive index, and then the salinity is calculated. Among them, the salinity measurement method of the bent optical fiber multi-parameter sensor of this embodiment includes the following steps:

[0080] The sensor is installed in fluids with different salinities, and the input optical fiber 2 is connected to the light source, and the voltage output of the current acquisition circuit is recorded;

[0081] Light propagates in the optical fiber by total internal reflection, which can maintain signal transmission. However, since the optical fiber core of the exposed optical fiber 4 is in direct contact with the fluid, it will be affected by the refractive index of the fluid and produce consumption. The degree of light consumption of fluids with different salinities is different, and the salinity information of the fluid can be obtained by comparing the voltage output of the acquisition circuit.

[0082] Specifically, the sensor of this embodiment can also obtain the direction information of the flow field. The method of obtaining the direction information of the flow field based on the four electrical signals converted from the signals received by the light source receiving end is a common method in the field and is described in detail here.

[0083] A specific application scenario of this embodiment is as follows:

[0084] A single sensor is suitable for scenarios with clear flow direction and simple local environment, such as monitoring the direction of fluid in a pipeline and optimizing the cooling system.

[0085] For example: in the environmental monitoring scenario of aquaculture farms, it is used to detect the flow rate, flow direction and salinity of water in real time. The sensor can be deployed at multiple key locations in the farm (such as water inlets, outlets, and breeding areas) to achieve multi-point monitoring functions through low-cost arrangements. The sensor monitors the flow rate and flow direction to ensure that fresh water flows into the breeding area in the expected direction, avoiding hypoxia caused by too low flow rate, and preventing water pollution caused by wastewater backflow. The salinity monitoring function can sense slight changes in the salinity of the water in real time. Once an abnormality is found, the sensor can quickly warn and assist in adjusting the water conditions.

[0086] The optical fiber sensor of this embodiment also has the characteristics of anti-electromagnetic interference and low cost, and can maintain stable performance even in offshore or high-density industrial farms. The sensor is small and flexible, suitable for large-scale deployment in farms, and a complete environmental monitoring network is formed through multi-point arrangement. Once the flow rate or salinity in a certain area is abnormal, the problem area can be quickly located, providing accurate control basis, significantly reducing the operation and maintenance costs of the farm, while improving production efficiency and the stability of the breeding environment.

[0087] The sensor imitates the lateral line sensing system of fish. Through the curved bionic cantilever beam structure and multi-directional fiber optic detection, it can sense the directionality and intensity of water flow. This structural design effectively improves the directional sensing capability of the sensor, which is a relatively weak part of the existing technology.

[0088] The "multi-parameter" of the present invention is reflected in that the sensor can not only detect the flow velocity of the water flow (including the magnitude and direction of the flow velocity), but also detect the salinity of the fluid through the contact between the exposed optical fiber part and the water body.

[0089] Flow velocity detection: The sensor senses the change of water flow velocity through the bionic cantilever beam structure. Under the action of water flow, the cantilever beam deforms, which in turn affects the change of light intensity signals in the optical fiber in all directions. By analyzing these light intensity signals, the magnitude and direction of the flow velocity can be determined, thereby achieving comprehensive detection of water flow velocity.

[0090] Salinity detection: When the exposed optical fiber part contacts the fluid, the different salinities of the fluid will cause the loss of light intensity. By comparing the light intensity signals received in different directions, the salinity of the fluid can be detected.

[0091] The bent optical fiber multi-parameter sensor based on the bionic lateral line of this embodiment has the following beneficial effects:

[0092] 1. Directional sensing capability: This sensor imitates the structure of the lateral line hair cells of fish and uses a vertical bendable artificial cilia cantilever as the core sensing element. The cantilever deforms under the shear stress of the flow field, thereby changing the direction of the light beam emitted by the output optical fiber, causing the light intensity signals received by the light source receiving end in four different directions to change, which can effectively distinguish the direction of the flow field and realize the precise sensing of water flow shear stress to optical signals.

[0093] 2. Anti-interference and anti-corrosion capabilities: The sensor of the present invention is made of quartz material, has good corrosion resistance and anti-electromagnetic interference capabilities, can work stably in complex and harsh marine environments, extend the service life of the sensor, and overcome the shortcomings of the prior art micro-electromechanical system sensors that are easily damaged when used in seawater.

[0094] 3. Multi-parameter detection capability: The present invention can not only detect the shear stress of water flow, but also detect the salinity of fluid by using the difference in the refractive index of fluid through the direct contact between the exposed optical fiber part and the fluid. By comparing the light intensity signal received by the light source receiving end, the degree of light intensity consumption can be accurately calculated, thereby obtaining the salinity information of the fluid, realizing the multi-parameter detection function.

[0095] The bent optical fiber multi-parameter sensor based on the bionic lateral line of this embodiment has strong directional sensing capability, excellent anti-interference and anti-corrosion capabilities, and rich multi-parameter detection functions. It can meet the needs of modern marine monitoring networks for high-precision, low-cost, anti-interference, and long-life sensor devices, and is an ideal marine monitoring equipment.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bent optical fiber multi-parameter sensor based on bionic lateral line, characterized in that: include: An artificial ciliary cantilever beam (1), a sensor base (5), an input optical fiber (2), an output optical fiber (3), an exposed optical fiber (4), and a plurality of light source receiving ends (6); The artificial ciliary cantilever beam (1) is provided with a first through hole (11) and a second through hole (12), and the axes of the first through hole (11) and the second through hole (12) are both parallel to the axis of the artificial ciliary cantilever beam (1); One end of the input optical fiber (2) is connected to the light source emission end, and the other end sequentially passes through the sensor base (5) and the artificial ciliary cantilever beam (1) via the first through hole (11), and is fixedly connected to the bare optical fiber (4); The other end of the bare optical fiber (4) is fixedly connected to one end of the output optical fiber (3); The other end of the output optical fiber (3) passes through the artificial ciliary cantilever beam (1) via the second through hole (12), and is communicatively connected with the light source receiving end (6) so as to obtain the flow field direction, flow field velocity and salinity of the flow field according to the voltage signal received by the light source receiving end; The artificial cilia cantilever beam (1) is fixedly connected to the sensor base (5).

2. The bent optical fiber multi-parameter sensor based on bionic lateral line according to claim 1, characterized in that: The sensor base (5) is provided with a groove (56) along its axial direction, and the interior of the groove (56) is provided with a third through hole (51), a fourth through hole (52), a fifth through hole (53), a sixth through hole (54) and a seventh through hole (55) coaxial with the groove (56); The input optical fiber (2) passes through the sensor base (5) via the third through hole (51); light source receiving ends are fixedly arranged in the fourth through hole (52), the fifth through hole (53), the sixth through hole (54) and the seventh through hole (55); The fourth through hole (52), the fifth through hole (53), the sixth through hole (54) and the seventh through hole (55) are evenly arranged with the axis of the output optical fiber (3) as the center.

3. The bent optical fiber multi-parameter sensor based on bionic lateral line according to claim 1, characterized in that: The artificial cilia cantilever beam (1) comprises a first artificial cilia cantilever beam segment (13) and a second artificial cilia cantilever beam segment (14); the first artificial cilia cantilever beam segment (13) and the second artificial cilia cantilever beam segment (14) are coaxially fixed; One end of the input optical fiber (2) passes through the first through hole (11) and sequentially passes through the first artificial ciliary cantilever beam section (13) and the second artificial ciliary cantilever beam section (14); The outer wall surface of the first artificial cilia cantilever beam section (13) is fixedly connected to the inner wall surface of the groove (56), and a space for optical signal transmission is formed between the bottom surface of the first artificial cilia cantilever beam section (13) and the bottom surface of the groove (56).

4. The bent optical fiber multi-parameter sensor based on bionic lateral line according to claim 1, characterized in that: The artificial cilia cantilever beam (1) is made of flexible thermoplastic polyurethane material.

5. The bent optical fiber multi-parameter sensor based on bionic lateral line according to claim 1, characterized in that: The artificial cilia cantilever beam (1) is a cylindrical structure.

6. The bent optical fiber multi-parameter sensor based on bionic lateral line according to claim 1, characterized in that: The formula used to obtain the flow velocity of the flow field is as follows: max{|y4-y2|,|y3-y1|}=Ax 3 +Bx 2 +Cx+D where: y1, y2, y3, and y4 are the voltage signal received by the first light source receiving end, the voltage signal received by the second light source receiving end, the voltage signal received by the third light source receiving end, and the voltage signal received by the fourth light source receiving end, respectively, wherein the first light source receiving end, the second light source receiving end, the third light source receiving end, and the fourth light source receiving end are arranged in sequence in a clockwise direction; x represents the flow field velocity; A, B, C, and D represent the cubic coefficient, square coefficient, linear coefficient, and constant term, respectively.

7. The bent optical fiber multi-parameter sensor based on bionic lateral line according to claim 1, characterized in that: The formula used to obtain the salinity of the flow field is as follows: y1=an f +b Among them, y1 is the voltage signal received by the first light source receiving end, n f is the refractive index of the liquid, a is the coefficient of voltage decreasing with the refractive index, and b is the initial voltage signal received by the first light source; n f =n0+k·S Among them, n f is the refractive index of the liquid, n0 is the refractive index of pure water, S is the salinity, and k is the refractive index variation coefficient of salinity.

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