Capacitance tomography sensor based on magneto-rheological fluid electrode and detection method

Abstract

The invention discloses an electrical capacitance tomography sensor based on a magnetic variation fluid electrode and a detection method, and relates to the technical field of electrical capacitance tomography, and the sensor comprises a strip-shaped main body which is used for forming a sensor capable of being stored and extended in the circumferential direction; the strip-shaped main body is made of a flexible thin film material, the strip-shaped main body is of a double-layer non-closed-loop structure, and the double-layer non-closed-loop structure comprises an inflation layer and an electrode layer; the isolating strip group is used for setting the position and the width of a preset electrode area in the electrode layer, and the isolating strip group comprises a plurality of used isolating strips and unused isolating strips; the magnetorheological fluid electrodes are used as electrodes with magnetic field response characteristics, and the magnetorheological fluid electrodes are manufactured by injecting magnetorheological fluid into preset electrode areas between the adjacent used isolating bars. The magnetorheological fluid with the liquid property is innovatively introduced to replace a traditional metal electrode, and universality measurement can be carried out on planes and quasi-cylinders of different sizes.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical capacitance tomography, and more specifically, to an electrical capacitance tomography sensor based on a magneto-variable fluid electrode and a detection method thereof. Background Art

[0002] Electrical Capacitance Tomography (ECT) is a non-invasive and non-contact process imaging technology. Since its inception in the 1980s, due to its unique sensing mechanism and broad application potential, it has attracted extensive attention in the fields of industrial process monitoring, multiphase flow analysis, etc. This technology measures the capacitance changes between the outer electrodes of the imaging area, combines the sensitive field model and the inversion algorithm, and reconstructs the spatial distribution of the dielectric constant within the area, providing an efficient and low-cost solution for visualizing the internal structure of complex media. In industrial process monitoring, traditional contact sensors are difficult to meet the real-time imaging requirements of high-temperature, high-pressure, corrosive fluids or multiphase flow mixing processes, while the non-contact characteristic of ECT technology makes it an ideal choice.

[0003] Magnetorheological fluid (MRF) is an intelligent material formed by dispersing micron- or nano-scale magnetic particles in a non-magnetic carrier liquid to form a suspension system. Its properties can be real-time regulated by an external magnetic field, achieving a reversible transformation from a liquid state to a quasi-solid state within milliseconds. In recent years, it has begun to show application potential in the electrical field. The core principle of ECT is based on Maxwell's electromagnetic field theory. When an excitation signal is applied to the electrode array, the electric field distribution formed between the electrodes will be distorted due to differences in the dielectric constant of the medium. By measuring the capacitance values of all independent electrode pairs, a sensitive field matrix related to the dielectric constant distribution can be constructed. Mathematically, the imaging problem can be formulated as a non-linear inverse problem. ECT sensors exhibit extremely high application value in the fields of energy and chemical engineering, food and pharmaceuticals, environmental engineering, etc., such as multiphase flow metering in shale gas extraction, coolant monitoring in nuclear reactors, uniformity detection of mixtures in pipelines, monitoring of the capsule filling process, visualization of soil pollutant migration, etc.

[0004] At present, there are already various ECT sensor designs on the market: for example, the patent document with the application number 201810528683.6 discloses a capacitance tomography sensor directly contacting the inside of a heat exchanger tube at high temperature and a real-time dynamic monitoring system. Its invention structure is fixed and cannot achieve changes in size and electrode size. The manufactured sensor is only adapted to a single specific object; another example is that the patent document with the application number 202010136656.1 discloses a nested capacitance tomography sensor and an image data acquisition method. Its sensor structure is fixed and cannot measure multiple measured objects without damaging the structure of the measured object itself, and it is only applicable to the measurement of cylindrical structures. It can be seen that in the field of capacitance tomography, the existing technology usually customizes sensors of specific sizes according to specific requirements. Therefore, it is only applicable to specific measurement objects or application scenarios, and its versatility is limited; at the same time, although traditional electrode materials (such as metals and carbon-based materials) have excellent conductivity, they have limitations such as high rigidity, non-adjustable morphology, and poor environmental adaptability, and cannot meet the requirements for dynamically adjusting the shape and position of the electrodes.

[0005] In response to the problems in the related art, no effective solution has been proposed yet. Summary of the Invention

[0006] (1) Technical problems to be solved

[0007] In view of the deficiencies of the prior art, the present invention provides a capacitance tomography sensor and a detection method based on a magnetorheological fluid electrode, which can achieve general measurement of planes and quasi-cylinders of different sizes, and innovatively introduces magnetorheological fluid with liquid properties to replace traditional metal electrodes, thereby solving the problem that capacitance tomography in the prior art needs to customize specific sensors according to specific requirements.

[0008] (2) Technical solutions

[0009] To achieve the above advantages of being able to perform general measurement on planes and quasi-cylinders of different sizes and innovatively introducing magnetorheological fluid with liquid properties to replace traditional metal electrodes, the specific technical solutions adopted by the present invention are as follows:

[0010] According to one aspect of the present invention, there is provided a capacitance tomography sensor based on a magnetorheological fluid electrode, including:

[0011] A strip-shaped main body for forming a sensor that can be circumferentially extended and retracted; the strip-shaped main body is made of a flexible film material, and the strip-shaped main body is a double-layer non-closed structure, and the double-layer non-closed structure includes an inflation layer and an electrode layer;

[0012] An isolation strip group for setting the position and width of a preset electrode area inside the electrode layer. The isolation strip group includes several used isolation strips and unused isolation strips;

[0013] A number of magnetorheological fluid electrodes, which are used as electrodes with magnetic field response characteristics. The magnetorheological fluid electrodes are made by injecting magnetorheological fluid into a preset electrode area between adjacent used isolation strips;

[0014] A number of telescopic buckles and vacuum suction cups, which are used to fix the sensor on the object to be measured.

[0015] Furthermore, inflation valves are arranged at the top of both ends of the inflation layer to ensure the airtightness of the inflation layer; a flexible support is arranged at the bottom end of the electrode layer, and the cross-section of the flexible support is set as a U-shaped structure; a number of permanent magnets are embedded inside the top of the flexible support, and the permanent magnets are used to cooperate with the used isolation strips to stimulate the magnetic change of the magnetorheological fluid; an interval area is arranged between adjacent magnetorheological fluid electrodes in the electrode layer, and the interval area uses air as a filling medium.

[0016] Furthermore, a flexible circuit board is arranged on the used isolation strip, and an electromagnetic coil is arranged on the surface of the flexible circuit board by printing; the electromagnetic coil is used to cooperate with the electrode layer to solidify the magnetorheological fluid electrode; the magnetic field response characteristics of the magnetorheological fluid electrode include: the viscosity increases and presents a solid state under the action of an external magnetic field, and returns to a flowing state after the external magnetic field is removed; the structures of the used isolation strip and the unused isolation strip are the same.

[0017] Furthermore, an axial scale is engraved at one end of the inflation layer, and a circumferential scale is engraved at the top end of the electrode layer; the axial scale and the circumferential scale are used to adjust the position of the isolation strip and serve as a reference for observing whether the width and height of each electrode are consistent.

[0018] Furthermore, a flexible slide rail is fixedly arranged in the middle of the outer side of the inflation layer, and a number of first rings are sleeved outside the flexible slide rail; suction cup support frames are fixedly arranged on both sides of the top end and both sides of the bottom end of the first ring, and one end of the suction cup support frame is fixedly connected with the vacuum suction cup, which is used to realize the position adjustment of the vacuum suction cup through the flexible slide rail.

[0019] Furthermore, the sensor has two installation methods: a column-like structure and a planar structure. The column-like structure is fixed by telescopic buckles and vacuum suction cups, and the planar structure is fixed by vacuum suction cups.

[0020] Furthermore, it also includes a wire and a wire bundling band; the wire is used to connect the excitation source, and the wire bundling band is used to bundle and store the wire.

[0021] According to another aspect of the present invention, a capacitance tomography detection method based on magnetorheological fluid electrodes is also provided. The capacitance tomography detection method based on magnetorheological fluid electrodes includes:

[0022] S1. Based on the application scenario requirements, determine the number of used isolation strips, the number of magnetorheological fluid electrodes, and the width of the interval area;

[0023] S2. Select the corresponding installation method according to the type of the object to be measured, fix the sensor on the object to be measured, and adjust the position of the used isolation strip by using the circumferential scale and the axial scale. Inject the magnetorheological fluid between adjacent used isolation strips to form a magnetorheological fluid electrode.

[0024] S3. Fill the inflation layer with gas through the inflation valve, check the uniformity of the sensor expansion with reference to the circumferential scale and the axial scale, make the magnetorheological fluid electrode fit the object to be measured, and start the electromagnetic coil on the used isolation strip to generate an external magnetic field in cooperation with the permanent magnet inside the electrode layer to solidify the magnetorheological fluid electrode.

[0025] S4. Connect the excitation source with a wire, apply an electrical signal to excite the magnetorheological fluid electrode, collect the capacitance signal through the data acquisition unit, and reconstruct the spatial distribution of the dielectric constant in the region by combining the sensitive field model and the inversion algorithm to obtain the imaging of the internal structure of the object to be measured.

[0026] Further, filling the inflation layer with gas through the inflation valve, checking the uniformity of the sensor expansion with reference to the circumferential scale and the axial scale, making the magnetorheological fluid electrode fit the object to be measured, and starting the electromagnetic coil on the used isolation strip to generate an external magnetic field in cooperation with the permanent magnet inside the electrode layer to solidify the magnetorheological fluid electrode includes:

[0027] S31. Based on the type of the object to be measured, control the liquid level height of the magnetorheological fluid electrode with reference to the axial scale to ensure that the liquid level heights in each magnetorheological fluid electrode are the same.

[0028] S32. Fill the inflation layer with gas through the inflation valve, check the expansion of each part of the sensor with reference to the circumferential scale and the axial scale, make the magnetorheological fluid electrode fit the object to be measured, and fix the sensor.

[0029] S33. Use the electromagnetic coil on the used isolation strip and the permanent magnet embedded in the flexible support to work together to generate an external magnetic field, so that the magnetorheological fluid electrode is solidified under the action of the magnetic field and its conductivity is enhanced, and a stable electrode structure is obtained.

[0030] Further, the expression of the spatial distribution of the dielectric constant in the region is:

[0031]

[0032] In the formula, C represents the capacitance value; Q represents the electric charge quantity; V represents the potential difference between the two electrodes forming the capacitor; ε(x, y) represents the dielectric constant distribution in the sensing field; φ(x, y) represents the potential distribution; Γ represents the electrode surface.

[0033] (III) Beneficial effects

[0034] Compared with the prior art, the present invention provides a capacitance tomography sensor and a detection method based on a magneto-variable fluid electrode, having the following beneficial effects:

[0035] (1) The present invention adopts a special electrode material, magnetorheological fluid, and an air-filled fitting method, enabling the liquid electrode to perfectly and fully fit the surface of the object to be measured, breaking through the limitation of the rigidity of traditional sensors; combined with the design of a strip-shaped non-closed structure, the sensor can adapt to various shapes of objects to be measured such as planes and quasi-cylindrical bodies, greatly expanding the scope of application scenarios and solving the limitation of traditional capacitance tomography technology that requires customizing specific sensors according to specific requirements.

[0036] (2) The present invention solves the problem that existing sensors have a fixed structure and are only applicable to specific measurement scenarios. By adjusting the effective use lengths of the electrode layer and the air-filled layer, changing the electrode width and spacing by adjusting the position of the isolation strip, and changing the electrode height by adjusting the liquid level height of the magnetorheological fluid, the general measurement of objects of different sizes and shapes is realized.

[0037] (3) The present invention first applies the intelligent material, magneto-variable fluid, as the electrode material of the capacitance sensor. Under the action of a magnetic field, it can change from a liquid state to a solid state within an extremely short time. By adjusting the composition, the conductivity of the electrode material can be adjusted to adapt to the measurement requirements. Moreover, the liquid electrode material can better fit the surface of the object to be measured, realizing the adaptability of the sensor to different measurement environments; the liquid injection - magnetic field curing characteristics of the magnetorheological fluid enable it to accurately fill the preset electrode area, and under the action of the expansion pressure of the air-filled layer, it fully fits the object to be measured. After forming a stable fit, it is cured by a magnetic field to form a stable electrode structure, further reducing the interference of edge effects on the measurement results, improving the accuracy of the reconstructed image, and improving the quality of the measurement signal.

[0038] (4) The combination of the strip-shaped non-closed structure and the fixing component of the present invention can achieve rapid installation. Combined with the setting of circumferential and axial scales, high-precision positioning is realized, enabling the sensor to be precisely adjusted and installed according to the characteristics of the object to be measured; through the combined fixing method of a telescopic buckle and a vacuum suction cup, it is ensured that the sensor is stably attached to the surface of the object to be measured, while ensuring that the electrode gaps at the head and tail connections are consistent with other parts; the installation process does not require damaging the object to be measured, meeting the requirements of industrial sites for immediate measurement, realizing portable and non-destructive rapid measurement, and greatly improving the practicality and application scope of the sensor.

[0039] (5) Except for the electrode material, the inflatable layer, the isolation strip group, the scale, and the inflation valve of the present invention are all made of non-conductive materials, effectively suppressing the interference of external stray capacitance on the signal to be measured and improving the accuracy of signal acquisition; through the precise design of the circumferential scale and the axial scale, it is possible to visually observe whether the length and width of each electrode are consistent, whether the gap ratio is the same, and whether the liquid level height remains consistent, facilitating rapid adjustment and calibration by the operator, ensuring the consistency and reliability of the measurement results; in addition, the uniform expansion design of the inflatable layer, combined with the scale reference, ensures uniform force on each part of the sensor, guarantees the consistency of electrode fitting, and further improves the accuracy of image reconstruction. Description of the Drawings

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0041] Figure 1 It is a schematic structural diagram of a capacitance tomography sensor based on a magnetorheological fluid electrode for detecting a columnar structure according to an embodiment of the present invention;

[0042] Figure 2 It is a schematic structural diagram of the inflatable layer in a capacitance tomography sensor based on a magnetorheological fluid electrode according to an embodiment of the present invention;

[0043] Figure 3 It is a schematic structural diagram of the electrode layer in a capacitance tomography sensor based on a magnetorheological fluid electrode according to an embodiment of the present invention;

[0044] Figure 4 It is a schematic structural diagram of a capacitance tomography sensor based on a magnetorheological fluid electrode for detecting a planar structure according to an embodiment of the present invention;

[0045] Figure 5 It is a schematic structural diagram of another angle of a capacitance tomography sensor based on a magnetorheological fluid electrode for detecting a planar structure according to an embodiment of the present invention;

[0046] Figure 6 It is a schematic partial structural diagram of a capacitance tomography sensor based on a magnetorheological fluid electrode according to an embodiment of the present invention;

[0047] Figure 7 It is a front view of the partial structure of a capacitance tomography sensor based on a magnetorheological fluid electrode according to an embodiment of the present invention;

[0048] Figure 8It is a schematic flowchart of a capacitance tomography detection method based on a magneto-variable fluid electrode according to an embodiment of the present invention;

[0049] Figure 9 It is a specific implementation diagram of a capacitance tomography detection method based on a magneto-variable fluid electrode according to an embodiment of the present invention.

[0050] In the figure:

[0051] 1. Inflation valve; 2. Inflation layer; 3. Electrode layer; 4. Used isolation strip; 5. Magnetorheological fluid electrode; 6. Spacing area; 7. Axial scale; 8. Circumferential scale; 9. Vacuum chuck; 10. Wire; 11. Non-effective measurement area; 12. Unused isolation strip; 13. Flexible support; 14. Object to be measured; 15. Retractable buckle; 16. Wire bundling strap; 17. Flexible slide rail; 18. Suction cup support frame; 19. Area without magnetorheological fluid filled. Detailed implementation manners

[0052] To further illustrate each embodiment, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. They are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principle of the embodiments. With reference to these contents, those of ordinary skill in the art should be able to understand other possible implementation manners and the advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are usually used to represent similar components.

[0053] According to an embodiment of the present invention, a capacitance tomography sensor and a detection method based on a magneto-variable fluid electrode are provided.

[0054] Now, the present invention will be further described in conjunction with the accompanying drawings and specific implementation manners. As Figures 1-7 shown, according to an embodiment of the present invention, a capacitance tomography sensor based on a magneto-variable fluid electrode is provided, including:

[0055] A strip-shaped main body for forming a sensor that can be circumferentially retractably extended; the strip-shaped main body is made of a flexible thin film material, and the strip-shaped main body is a double-layer non-closed structure, and the double-layer non-closed structure includes an inflation layer 2 and an electrode layer 3;

[0056] An isolation strip group for setting the position and width of a preset electrode area inside the electrode layer 3, and the isolation strip group includes a plurality of used isolation strips 4 and unused isolation strips 12;

[0057] A plurality of magnetorheological fluid electrodes 5 for serving as electrodes with magnetic field response characteristics, and the magnetorheological fluid electrodes 5 are made by injecting magnetorheological fluid into the preset electrode area between adjacent used isolation strips 4;

[0058] A number of telescopic fasteners 15 and vacuum suckers 9 are used to fix the sensor on the object to be measured 14.

[0059] Specifically, the present invention proposes a capacitance tomography sensor using magnetorheological fluid as the electrode material, which can achieve universal measurement of planes and quasi-cylindrical bodies of different sizes, and innovatively introduces the magnetorheological fluid with liquid properties to replace the traditional metal electrodes, solving the problem that the capacitance tomography technology needs to customize specific sensors according to specific requirements.

[0060] Specifically, the magnetorheological fluid material is used to replace the traditional conductive metal (such as copper) as the magnetorheological fluid electrode 5. This material has rheological properties, that is, under the action of a magnetic field, the viscosity of the magnetorheological fluid rapidly increases until it solidifies, and the conductivity increases; after the magnetic field action disappears, it can return to the liquid state again, so it has fast reversibility.

[0061] Specifically, the sensor is fixed on the surface of the object to be measured 14 on a plane or quasi-cylindrical body through the telescopic fasteners 15 and the vacuum suckers 9. The size and spacing of the sensor electrodes are determined by the axial scale 7 and the circumferential scale 8, and then the sensitive field of the sensor is quickly calculated for convenient real-time imaging, solving the problem of inability to quickly image in the case of measuring the position of the plane or quasi-cylindrical body measurement area.

[0062] Specifically, the present invention uses magnetorheological fluid as the electrode material. Utilizing its rheological properties, after presetting the number and position of the used isolation strips 4 through the axial scale 7 and the circumferential scale 8, the magnetorheological fluid is filled into the preset electrode area, and the preset electrode area can be filled without gaps; after injection, an inert gas is filled into the gas-filled layer 2 to ensure that the magnetorheological fluid electrode 5 fits the object to be measured 14 as much as possible, and then the magnetic field is applied to solidify the magnetorheological fluid, realizing high-precision fitting with the object to be measured 14.

[0063] Specifically, the present invention determines the diameter of the quasi-cylindrical body according to the axial scale 7, thereby calculating the electrode height under the optimal size ratio, and then adjusting the liquid level height of the magnetorheological fluid to change the electrode height, solving the influence of the edge effect on the measurement result of the quasi-cylindrical body.

[0064] Specifically, as Figure 1 shown, the non-effective measurement area 11 (that is, the non-effective measurement area is the remaining unused part after the circumferential length direction of the sensor completely covers the object to be measured) can be retracted and extended.

[0065] Specifically, based on the magnetic field response characteristics of the magnetorheological fluid, the present invention can prepare magnetorheological fluids with different components as electrodes according to the different requirements of the object to be measured 14 for the electrode material, which can be personalized to meet the needs of different scenarios while improving the measurement accuracy and quality. Moreover, the circumferential length of the sensor can be made into an infinitely retractable length, so it can wrap or cover the surface of cylindrical objects or planar objects to be measured, realizing portable measurement without damaging the object to be measured 14 due to cutting the cylindrical pipeline.

[0066] In one embodiment, inflation valves 1 are provided at both top ends of the inflation layer 2 to ensure the airtightness of the inflation layer 2; a flexible support 13 is provided at the bottom end of the electrode layer 3, and the cross-section of the flexible support 13 is set as a U-shaped structure; several permanent magnets are embedded inside the top of the flexible support 13, and the permanent magnets are used to cooperate with the used isolation strip 4 to stimulate the magnetic change of the magnetorheological fluid; an interval region 6 is provided between adjacent magnetorheological fluid electrodes 5 in the electrode layer 3, and the interval region 6 uses air as the filling medium.

[0067] Specifically, the present invention changes the number of electrodes by setting the used isolation strip 4, slides the used isolation strip 4 at both ends of the same electrode to change the width of the magnetorheological fluid electrode 5, and combines with changing the liquid level height of the magnetorheological fluid to change the electrode height, so as to design specific electrode arrangement modes and electrode sizes for objects to be measured 14 of different sizes.

[0068] In one embodiment, a flexible circuit board is provided on the used isolation strip 4, and an electromagnetic coil is provided on the surface of the flexible circuit board by printing; the electromagnetic coil is used to cooperate with the electrode layer 3 to solidify the magnetorheological fluid electrode 5; the magnetic field response characteristics of the magnetorheological fluid electrode 5 include: the viscosity increases and presents a solid state under the action of an external magnetic field, and returns to a flowing state after the external magnetic field is removed; the structures of the used isolation strip 4 and the unused isolation strip 12 are the same.

[0069] Specifically, the present invention adopts a silicon-based composite elastomer ring-shaped liquid-phase isolation and sealing device: glass fiber or ceramic particles are added to the basic silicone to increase the hardness, so that the silicone matrix has both flexibility and a certain degree of rigidity, and it is made into strips for the used isolation strip 4 and the unused isolation strip 12 for controlling the electrode width and electrode length of the present invention. The structures of the used isolation strip 4 and the unused isolation strip 12 are the same, and a flexible circuit board printed with an electromagnetic coil is pasted on each isolation strip.

[0070] In one embodiment, an axial scale 7 is engraved at one end of the inflation layer 2, and a circumferential scale 8 is engraved at the top end of the electrode layer 3; the axial scale 7 and the circumferential scale 8 are used to adjust the position of the isolation strip and serve as a reference for observing whether the widths and heights of each electrode are consistent.

[0071] In one embodiment, a flexible slide rail 17 is fixedly arranged in the middle of the outer side of the inflatable layer 2, and a plurality of first rings are sleeved outside the flexible slide rail 17; suction cup support frames 18 are fixedly arranged on both sides of the top end and both sides of the bottom end of the first ring, and one end of the suction cup support frame 18 is fixedly connected to the vacuum suction cup 9, so as to realize the position adjustment of the vacuum suction cup 9 through the flexible slide rail 17.

[0072] Specifically, the vacuum suction cup 9 is used to cooperate with the retractable buckle 15 to fix the sensor and the object to be measured 14 together, and is a suction cup made of rubber that can be sealed and airtight. Each vacuum suction cup 9 is connected by a suction cup support frame 18 and can move on the sensor structure through the flexible slide rail 17 (that is, the flexible slide rail is made of a non-conductive silicon-based composite elastic material and cooperates with the suction cup support frame).

[0073] Specifically, a total of four suction cup support frames 18 on both sides of the top end and both sides of the bottom end of each first ring are distributed in an X shape. One end of the suction cup support frame 18 is fixedly welded to the first ring, and the other end of the suction cup support frame 18 is fixedly connected to the middle of one side of the vacuum suction cup 9.

[0074] In one embodiment, the sensor has two installation methods: a column-like structure and a planar structure. The column-like structure is fixed by the retractable buckle 15 and the vacuum suction cup 9, and the planar structure is fixed by the vacuum suction cup 9.

[0075] Specifically, the retractable buckle 15 is made of a plastic notch connecting spring with good rigidity, and the spring is coated with insulating paint. When the type of the object to be measured 14 is a column-like structure, a second ring can also be sleeved in the middle of the spring of the retractable buckle 15, and the second ring is sleeved into the first ring, so as to move the vacuum suction cup 9 along the flexible slide rail 17 through the retractable buckle 15 and the suction cup support frame 18, and adjust the position of the vacuum suction cup 9 on the sensor.

[0076] In one embodiment, it further includes a wire 10 and a wire bundling band 16; the wire 10 is used to connect the excitation source, and the wire bundling band 16 is used to bundle and store the wire 10.

[0077] Specifically, the wire bundling band 16 is an insulating tie made of nylon and is commonly used for bundling general-purpose wires.

[0078] Specifically, the present invention proposes a variable-size ECT sensor using smart material magnetorheological fluid as the electrode material. The working principle of the present invention is as follows: First, a polypropylene film with a certain flexibility and not easily damaged is selected as the main material of the sensor structure, and it is made into a strip-shaped non-closed structure with two internal spaces, which has the characteristic of circumferentially retractable extension. One layer serves as the inflatable layer 2, on which an inflation valve 1 is made, and it is required to ensure good airtightness of the inflatable layer 2 at any time. The other layer is the electrode layer 3 with an upper-open and lower-closed structure. The lower end of this structure is designed with a flexible support 13, and a permanent magnet is embedded on the flexible support 13 to cooperate with the electromagnetic coil on the used isolation strip 4. The isolation strip group is used to set the position and width of the preset electrode in the electrode layer 3. Then, magnetorheological fluid is injected between the used isolation strips 4 of the preset electrode to generate the magnetorheological fluid electrode 5. The interval area 6 (pole gap) between adjacent electrodes is air, and no components are injected. The used isolation strip 4 is made of a flexible circuit board printed with an electromagnetic coil for exciting the magnetic change of the magnetorheological fluid. The inflatable layer 2 is engraved with an axial scale 7, and the electrode layer 3 is engraved with a circumferential scale 8, which are used to adjust the position of the used isolation strip 4, determine the electrode position and size, serve as a reference for observing whether the width and height of each electrode are the same, and at the same time check the expansion degree of the inflatable layer 2 to ensure the same force condition everywhere. A telescopic buckle 15 and a vacuum suction cup 9 are set to fix the sensor on the measured object 14.

[0079] As Figure 8 shown in Figure 9 According to another embodiment of the present invention, a capacitance tomography detection method based on a magnetorheological fluid electrode is also provided. The capacitance tomography detection method based on a magnetorheological fluid electrode includes:

[0080] S1. Based on the application scenario requirements, determine the number of used isolation strips 4, the number of magnetorheological fluid electrodes 5, and the width of the interval area 6;

[0081] S2. Select the corresponding installation method according to the type of the measured object 14, fix the sensor on the measured object 14, and use the circumferential scale 8 and the axial scale 7 to adjust the position of the used isolation strip 4, and inject magnetorheological fluid between adjacent used isolation strips 4 to form the magnetorheological fluid electrode 5;

[0082] S3. Inflate the inflatable layer 2 through the inflation valve 1, check the expansion uniformity of the sensor with reference to the circumferential scale 8 and the axial scale 7, make the magnetorheological fluid electrode 5 fit the measured object 14, and start the electromagnetic coil on the used isolation strip 4 to cooperate with the permanent magnet inside the electrode layer 3 to generate an external magnetic field to solidify the magnetorheological fluid electrode 5;

[0083] S4. Connect the excitation source using the wire 10, apply an electrical signal to excite the magnetorheological fluid electrode 5, collect the capacitance signal through the data acquisition unit, and reconstruct the spatial distribution of the dielectric constant in the region by combining the sensitive field model and the inversion algorithm to obtain the imaging of the internal structure of the object under test 14.

[0084] In one embodiment, gas is filled into the inflatable layer 2 through the inflation valve 1, the expansion uniformity of the sensor is inspected with reference to the circumferential scale 8 and the axial scale 7, the magnetorheological fluid electrode 5 is made to fit the object under test 14, and the electromagnetic coil on the used isolation strip 4 is activated to generate an external magnetic field in cooperation with the permanent magnet inside the electrode layer 3 to solidify the magnetorheological fluid electrode 5, including:

[0085] S31. Based on the type of the object under test 14, control the liquid level height of the magnetorheological fluid electrode 5 with reference to the axial scale 7 to ensure that the liquid level heights in each magnetorheological fluid electrode 5 are the same;

[0086] S32. Fill gas into the inflatable layer 2 through the inflation valve 1, inspect the expansion of each part of the sensor with reference to the circumferential scale 8 and the axial scale 7, make the magnetorheological fluid electrode 5 fit the object under test 14, and fix the sensor;

[0087] S33. Use the electromagnetic coil on the used isolation strip 4 and the permanent magnet embedded in the flexible support 13 to work together to generate an external magnetic field, so that the magnetorheological fluid electrode 5 is solidified and its conductivity is enhanced under the action of the magnetic field to obtain a stable electrode structure.

[0088] Specifically, first, according to the requirements of the application scenario, determine the number of used isolation strips 4, the number and width of the magnetorheological fluid electrodes 5, and the interval region 6 between adjacent electrodes, and place the used isolation strips 4 on the electrode layer 3 at the pre-calculated distance. For different types of objects under test 14: for the columnar-like structure, after placement, the sensor is initially fixed on the object under test 14 with the telescopic buckle 15 and the vacuum chuck 9, and for the planar structure, it is initially fixed on the object under test 14 with the vacuum chuck 9. The two installation methods are respectively applicable to the scenarios where the object under test is a columnar-like and a planar structure; the most core difference between the two methods lies in the electrode array method and the form used for fixation (as described above).

[0089] Specifically, then, the position of the used isolation strip 4 is adjusted again with the help of the circumferential scale 8 on the electrode layer. After adjustment, magnetorheological fluid is added into the preset electrode area in the middle of the used isolation strip 4 to generate the magnetorheological fluid electrode 5. The liquid level height is set according to different scenarios, and with the help of the axial scale 7, the liquid level height in each electrode is ensured to be consistent; the interval area 6 between adjacent electrodes is air and no components are injected. After injecting the magnetorheological fluid, the position of the used isolation strip 4 is finely adjusted again with reference to the axial scale 7 and the circumferential scale 8 to ensure that the lengths and widths of different electrodes are equal, the gap ratios are the same, and the liquid level heights are the same. Gas is filled into the inflation layer 2 through the inflation valve 1 to make the inner magnetorheological fluid electrode 5 better fit the object to be measured 14. With reference to the circumferential scale 8 and the axial scale 7, it is checked whether the expansion of each part of the sensor is equal and the external forces in each part are the same, especially paying attention to the connection part where the head and tail are joined. After checking, the sensor is finally fixed. The electromagnetic coil on the flexible circuit board fixed on the used isolation strip 4 is started, and it works together with the permanent magnet embedded in the flexible support 13 to solidify the magnetorheological fluid.

[0090] Specifically, finally, after the electromagnetic coil and the permanent magnet cooperate, an electrical signal is given through the wire 10 connected to the excitation source (all wires are bundled and stored by the wire bundling band 16) to excite the magnetorheological fluid electrode 5. The capacitance signal is collected by relying on the data acquisition unit. Combining the sensitive field model built in advance in equal proportion and the traditional inversion algorithm, the spatial distribution of the dielectric constant in the region is reconstructed and presented in an image manner.

[0091] It should be noted that, mathematically, the imaging problem can be expressed as a non - linear inverse problem, and the expression is:

[0092] C = S(ε)+δ;

[0093] In the formula, C represents the measured capacitance vector, ε represents the dielectric constant distribution, and δ represents the measurement noise. Due to the weak non - linear characteristics of the sensitive field S and the ill - posedness of the inverse problem, traditional linear inversion algorithms (such as the linear back - projection method) are difficult to achieve high - precision reconstruction; in addition, the capacitance measurement signal is weak (usually at the femto - farad level), vulnerable to parasitic capacitance and environmental noise interference, which poses harsh requirements on the signal - to - noise ratio (SNR) of the hardware circuit.

[0094] Specifically, in the present invention, the expression for the spatial distribution of the dielectric constant in the region is:

[0095]

[0096] In the formula, C represents the capacitance value; Q represents the electric charge; V represents the potential difference between the two electrodes forming the capacitor; ε(x,y) represents the dielectric constant distribution in the sensing field; φ(x,y) represents the potential distribution; Γ represents the electrode surface.

[0097] For the convenience of understanding the technical solution of the present invention, the structure and working principle of the present invention will be specifically described as follows in combination with specific embodiments:

[0098] The capacitance tomography sensor based on a magnetorheological fluid electrode provided by the present invention has an overall structure composed of five parts: an isolation strip group, a magnetorheological fluid electrode 5, an inflation layer 2, a scale, a flexible support 13, and a fixing component. Among them, the isolation strip group includes used isolation strips 4 and unused isolation strips 12, which are used to separate adjacent magnetorheological fluid electrodes 5; the flexible support 13 is fixed at the bottom of the electrode layer 3; the scale includes an axial scale 7 and a circumferential scale 8, which cooperate with the inflation layer 2 to check the force conditions at various places, and at the same time cooperate with the used isolation strips 4 to ensure that the length, width of each magnetorheological fluid electrode 5 and the gap ratio of the interval area 6 are the same; the magnetorheological fluid electrode 5 is attached to the inflation layer 2; the fixing component includes a telescopic buckle 15 and a vacuum suction cup 9, which are used to fix the overall structure of the sensor on the object to be measured 14.

[0099] During use, first, according to the size and shape of the object to be measured 14, determine the number of used isolation strips 4, the number and width of the magnetorheological fluid electrodes 5, and the distance of the interval area 6 between adjacent electrodes, and place the used isolation strips 4 on the electrode layer 3 at the pre-calculated distance. To avoid edge effects, calculate the height of the magnetorheological fluid according to the optimal aspect ratio of the electrode size, and then fill the preset electrode area in the electrode layer 3 with liquid to form the magnetorheological fluid electrode 5, while the area not filled with magnetorheological fluid 19 (that is, the area not filled with magnetorheological fluid is the area between adjacent electrodes, this area is the pole gap, and it is air) remains empty. After the liquid filling is completed, the operator can observe the axial scale 7 and the circumferential scale 8 to ensure that the lengths of different magnetorheological fluid electrodes 5 are equal and the gap ratios are the same, and fill the liquid again according to needs to ensure that the liquid surface height remains consistent and the same as the preset.

[0100] In the present invention, an inflation layer 2 made of polypropylene film is provided, and inflation valves 1 are provided at both top ends thereof to ensure the airtightness of the inflation layer 2. Inert gas is filled into the inflation layer 2 through the inflation valve 1 to make the inflation layer 2 expand and apply a uniform pressure to the magnetorheological fluid electrode 5, ensuring that the liquid magnetorheological fluid electrode 5 fully adheres to the surface of the object to be measured 14. At the same time, the operator can observe the axial scale 7 and the circumferential scale 8 to check whether the force conditions at various places are consistent after inflation to ensure the measurement accuracy.

[0101] The fixing component is divided into a height-adjustable telescopic buckle 15 and a vacuum suction cup 9. The two are connected by a suction cup support frame 18 and installed on a flexible slide rail 17 outside the sensor. A number of first loops are sleeved outside the flexible slide rail 17, so that the vacuum suction cup 9 can move along the flexible slide rail 17 to adjust its position. This design ensures that the sensor can be stably fixed on the surface of the object to be measured 14, and at the same time, by proper extrusion, it ensures that the spacing area 6 at the head and tail connection is consistent with the spacing areas 6 at other positions, improving the measurement accuracy.

[0102] During actual measurement, the operation steps are as follows: First, preset the number and position of the used isolation strips 4 according to the measurement requirements. Then, inject the magnetorheological fluid electrode material into the preset electrode area in the middle of the used isolation strips 4 to form the magnetorheological fluid electrodes 5. The spacing area 6 between adjacent electrodes is air, and no material is injected. After injection, inert gas is filled into the inflation layer 2 through the inflation valve 1, so that the inflation layer 2 expands to uniformly squeeze the electrode layer 3, ensuring that the magnetorheological fluid electrodes 5 are closely attached to the surface of the object to be measured 14. After completing the above steps, the electromagnetic coil of the flexible circuit board on the used isolation strip 4 is started, and at the same time, it cooperates with the permanent magnet embedded in the flexible support 13 to form a stable background magnetic field to work together with the electromagnetic coil, so that the magnetorheological fluid solidifies and its conductivity increases under the action of the magnetic field, thereby forming a stable electrode structure, reducing the overall energy consumption, and improving the measurement accuracy.

[0103] The wire 10 is connected to the left end of each magnetorheological fluid electrode 5 as a shielded signal wire. All the wires 10 are bundled and stored by a wire bundling strap 16, thereby ensuring the connection between the magnetorheological fluid electrodes 5 and the data acquisition instrument, so that the magnetorheological fluid electrodes 5 can upload the measurement data in real time. The system quickly calculates the sensitive field by combining the capacitance data obtained after exciting the magnetorheological fluid electrodes 5 with the position parameters of the circumferential scale 8 and the axial scale 7, and reconstructs the image to achieve real-time imaging.

[0104] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A capacitance tomography sensor based on a magneto-variable fluid electrode, characterized in that Comprising: A strip-shaped main body for forming a circumferentially retractable and extendable sensor; the strip-shaped main body is made of a flexible film material, and the strip-shaped main body is a double-layer non-closed structure, and the double-layer non-closed structure includes an inflatable layer and an electrode layer; An isolation strip group for setting the position and width of a preset electrode area inside the electrode layer, and the isolation strip group includes a plurality of used isolation strips and unused isolation strips; A plurality of magnetorheological fluid electrodes for serving as electrodes with magnetic field response characteristics, and the magnetorheological fluid electrodes are made by injecting magnetorheological fluid into a preset electrode area between adjacent used isolation strips; A plurality of telescopic buckles and vacuum suction cups for fixing the sensor on the object to be measured.

2. The capacitance tomography sensor based on a magneto-variable fluid electrode according to claim 1, characterized in that, Inflation valves are arranged at the top of both ends of the inflatable layer to ensure the airtightness of the inflatable layer; A flexible support is arranged at the bottom end of the electrode layer, and the cross section of the flexible support is set as a U-shaped structure; A plurality of permanent magnets are embedded in the inner side of the top of the flexible support, and the permanent magnets are used to cooperate with the used isolation strips to stimulate the magnetic change of the magnetorheological fluid; An interval area is arranged between adjacent magnetorheological fluid electrodes in the electrode layer, and the interval area uses air as a filling medium.

3. A capacitance tomography sensor based on a magneto-variable fluid electrode according to claim 1, characterized in that A flexible circuit board is arranged on the used isolation strip, and an electromagnetic coil is arranged on the surface of the flexible circuit board by printing; The electromagnetic coil is used to cooperate with the electrode layer to solidify the magnetorheological fluid electrode; The magnetic field response characteristics of the magnetorheological fluid electrode include: the viscosity increases and presents a solid state under the action of an external magnetic field, and returns to a flowing state after the external magnetic field is removed; The used isolation strips and the unused isolation strips have the same structure.

4. A capacitance tomography sensor based on a magneto-variable fluid electrode according to claim 1, characterized in that, An axial scale is engraved at one end of the inflatable layer, and a circumferential scale is engraved at the top end of the electrode layer; The axial scale and the circumferential scale are used to adjust the position of the isolation strip and serve as a reference for observing whether the width and height of each electrode are consistent.

5. A capacitance tomography sensor based on a magneto-variable fluid electrode according to claim 1, characterized in that, [[ID= ​ 6. The capacitance tomography sensor based on a magneto-variable fluid electrode according to claim 5, wherein, ​ 7. A capacitance tomography sensor based on a magneto-variable fluid electrode according to claim 1, characterized in that, ​ 8. A capacitance tomography detection method based on a magneto-variable fluid electrode, which uses the capacitance tomography sensor based on the magneto-variable fluid electrode described in any one of claims 1-7 to implement capacitance tomography detection, characterized in that, ​ ​ ​ S3. Fill the inflation layer with gas through the inflation valve, check the uniformity of the sensor expansion with reference to the circumferential scale and the axial scale, make the magnetorheological fluid electrode fit the object to be measured, and activate the electromagnetic coil on the used isolation strip to generate an external magnetic field in cooperation with the permanent magnet inside the electrode layer to solidify the magnetorheological fluid electrode; S4. Connect the excitation source with wires, apply an electrical signal to excite the magnetorheological fluid electrode, collect the capacitance signal through the data acquisition unit, and reconstruct the spatial distribution of the dielectric constant in the region by combining the sensitive field model and the inversion algorithm to obtain the imaging of the internal structure of the object to be measured.

9. A capacitance tomography detection method based on a magneto-variable fluid electrode according to claim 8, characterized in that The steps of filling the inflation layer with gas through the inflation valve, checking the uniformity of the sensor expansion with reference to the circumferential scale and the axial scale, making the magnetorheological fluid electrode fit the object to be measured, and activating the electromagnetic coil on the used isolation strip to generate an external magnetic field in cooperation with the permanent magnet inside the electrode layer to solidify the magnetorheological fluid electrode include: S31. Based on the type of the object to be measured, control the liquid level height of the magnetorheological fluid electrode with reference to the axial scale to ensure that the liquid level heights in each magnetorheological fluid electrode are the same; S32. Fill the inflation layer with gas through the inflation valve, check the expansion of each part of the sensor with reference to the circumferential scale and the axial scale, make the magnetorheological fluid electrode fit the object to be measured, and fix the sensor; S33. Use the electromagnetic coil on the used isolation strip and the permanent magnet embedded in the flexible support to work together to generate an external magnetic field, so that the magnetorheological fluid electrode is solidified under the action of the magnetic field and its conductivity is enhanced, and a stable electrode structure is obtained.

10. A capacitance tomography detection method based on a magneto-variable fluid electrode according to claim 8, characterized in that, The expression for the spatial distribution of the dielectric constant in the region is: In the formula, C represents the capacitance value; Q represents the charge quantity; V represents the potential difference between the two electrodes forming the capacitor; ε(x, y) represents the dielectric constant distribution in the sensing field; φ(x, y) represents the potential distribution; Γ represents the electrode surface.

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