Wireless Flexible Sensing System for Real-time Monitoring of Shield Segment Deformation and Its Preparation Method

Abstract

The present invention discloses a wireless flexible sensing system for real-time monitoring of shield segment deformation and a preparation method thereof. The sensing system includes: a first base and a second base, which are respectively arranged at two different radial positions on the inner side of the shield segment; a deformation housing, with two ends respectively connected to the first base and the second base; a rigid sheet, with two ends respectively connected to the first base and the second base, and the rigid sheet is bent into an arch shape by the first base and the second base, and the protruding direction of the rigid sheet is opposite to the protruding direction of the shield segment; a flexible groove induction film, which is arranged on the rigid sheet and is used to sense the deformation of the rigid sheet; a power supply collector, which is arranged in the deformation housing and is electrically connected to the flexible groove induction film. When the shield segment deforms, the deformation housing, the rigid sheet and the flexible groove induction film all deform accordingly. This is not only suitable for monitoring small strain amounts, but also capable of allowing monitoring of large strain amounts, with a wider working range and being able to instantaneously monitor the occurrence of sudden large deformations.

Description

Technical Field

[0001] The present invention relates to the technical field of shield segment detection, and particularly relates to a wireless flexible sensing system for real-time monitoring of shield segment deformation and a preparation method thereof. Background Art

[0002] Shield segments are the main assembled components in shield construction, and are the innermost barrier of the tunnel, bearing the functions of resisting soil pressure, groundwater pressure and some special loads. Shield segments are the permanent lining structure of shield tunnels, and the quality of shield segments is directly related to the overall quality and safety of the tunnel, affecting the waterproof performance and durability of the tunnel. During the construction of important sections such as shield launching, receiving, passing through ventilation shafts and connecting channels, the force on the segment structure will change, resulting in segment deformation. In severe cases, it will lead to tunnel water and sand gushing, water and mud inrush or even tunnel failure, causing catastrophic safety accidents. Therefore, the monitoring of the lining segments during shield construction is essential.

[0003] At present, the monitoring of segment structure deformation mainly adopts two methods: manual measurement and automated monitoring. Manual measurement mainly involves workers using portable collectors to collect segment stress data, and comparing the recorded data with safety values to achieve the safety monitoring of segments. Although this method is economical, it cannot monitor the deformation and stress of segments in real time and continuously, resulting in untimely monitoring and a lag in judging the engineering safety. Automated monitoring uses transmission optical cables to connect the sensors arranged inside the segments with the collectors on the ground, and the processing terminal makes an analysis and judgment. Although this method can monitor in real time, the wiring is complicated and not conducive to the construction.

[0004] Generally, in the ideal state of segment deformation monitoring, it is hoped that the deformation can be detected earlier, so that a response plan can be made earlier. In the prior art, the two methods of manual measurement and automated monitoring are difficult to detect small deformation signals, resulting in insufficient timeliness of shield segment monitoring.

[0005] Therefore, the prior art still needs to be improved and developed. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a wireless flexible sensing system for real-time monitoring of shield segment deformation and a preparation method thereof, aiming at solving the problem of insufficient timeliness of shield segment monitoring in the prior art.

[0007] The technical solution adopted by the present invention to solve the technical problem is as follows:

[0008] A wireless flexible sensing system for real-time monitoring of shield segment deformation, which includes:

[0009] The first base and the second base are respectively arranged at two different radial positions inside the shield segment;

[0010] A deformable housing, with two ends respectively connected to the first base and the second base;

[0011] A rigid sheet, with two ends respectively connected to the first base and the second base. The rigid sheet is bent into an arch shape by the first base and the second base, and the protruding direction of the rigid sheet is opposite to the protruding direction of the shield segment;

[0012] A flexible groove induction film, arranged on the rigid sheet and used for sensing the deformation of the rigid sheet;

[0013] A power supply collector, arranged on the deformable housing and electrically connected to the flexible groove induction film.

[0014] For the real-time monitoring wireless flexible sensing system for shield segment deformation, wherein the flexible groove induction film includes:

[0015] A flexible composite layer, on the side of the flexible composite layer facing away from the rigid sheet, there are a number of micro-nano grooves, and the micro-nano grooves extend along the axial direction of the shield segment;

[0016] A conductive layer, distributed inside and at the edges of the micro-nano grooves;

[0017] Wherein, the flexible composite layer includes: an insulating matrix and micro-nano conductive materials dispersed in the insulating matrix;

[0018] The conductive layer is electrically connected to the power supply collector.

[0019] For the real-time monitoring wireless flexible sensing system for shield segment deformation, wherein the micro-nano conductive material uses graphene.

[0020] For the real-time monitoring wireless flexible sensing system for shield segment deformation, wherein the conductive layer is selected from at least one of a carbon conductive material layer, a metal material layer, a transition metal carbide material layer, a polymer conductive material layer, and a conductive composite material layer.

[0021] For the real-time monitoring wireless flexible sensing system for shield segment deformation, wherein the deformable housing includes:

[0022] A first rigid outer shell, arranged on the first base;

[0023] A second rigid outer shell, arranged on the second base;

[0024] A flexible and elastic outer shell, with two ends respectively connected to the first rigid outer shell and the second rigid outer shell;

[0025] Among them, the power supply collector is arranged on the first rigid housing or the second rigid housing.

[0026] The real-time monitoring wireless flexible sensing system for shield segment deformation, wherein the flexible elastic material of the flexible elastic housing is selected from thermoplastic elastomer or thermoplastic vulcanizate, and the thermoplastic elastomer is selected from at least one of silicone rubber, epoxy resin, thermoplastic polyurethane, polydimethylsiloxane, and styrene.

[0027] A preparation method of the real-time monitoring wireless flexible sensing system for shield segment deformation as described in any one of the above, which includes the steps:

[0028] Prepare a flexible groove induction film;

[0029] Assemble the flexible groove induction film on a rigid sheet, and assemble the power supply collector on a deformation housing;

[0030] Assemble the rigid sheet equipped with the flexible groove induction film and the deformation housing equipped with the power supply collector on a first base and a second base, and electrically connect the power supply collector and the flexible groove induction film to obtain a real-time monitoring wireless flexible sensing system for shield segment deformation.

[0031] The preparation method of the real-time monitoring wireless flexible sensing system for shield segment deformation, wherein the preparation of the flexible groove induction film includes:

[0032] Dissolve graphene in a solvent to obtain a graphene solution;

[0033] Add an insulating material to the graphene solution to obtain a mixed solution; wherein, the mass ratio of graphene to the insulating material is 1:2 - 4;

[0034] Heat and cure the mixed solution into a film to obtain a flexible composite layer;

[0035] Form micro-nano grooves on the flexible composite layer;

[0036] Form a conductive layer on the micro-nano grooves to obtain a flexible groove induction film.

[0037] The preparation method of the real-time monitoring wireless flexible sensing system for shield segment deformation, wherein after forming micro-nano grooves on the flexible composite layer, the flexible composite layer with micro-nano grooves is pre-stretched, the number of pre-stretching times is a preset number, and the elongation rate of pre-stretching is 200% - 400%.

[0038] The preparation method of the real-time monitoring wireless flexible sensing system for shield segment deformation, wherein the forming of the conductive layer on the micro-nano grooves to obtain a flexible groove induction film includes:

[0039] A conductive layer is formed by sputtering metal ions on the surface of the micro-nano grooves on the pre-stretched flexible composite layer, and a conductive tape is connected to the conductive layer to obtain a flexible groove induction film.

[0040] Beneficial effects: When the shield segment deforms, the deformed shell, the rigid sheet, and the flexible groove induction film all deform accordingly. This is not only suitable for monitoring small strain amounts but also allows for monitoring of large strain amounts, with a wider working range and the ability to instantaneously monitor sudden large deformations. The flexible groove induction film is attached to the arched rigid sheet, which can endow the flexible groove induction film with a larger frequency response bandwidth, enhance the high-frequency response characteristics of the flexible groove induction film, and also improve the sensitive response performance of the flexible groove induction film. In short, the real-time deformation monitoring wireless flexible sensing system for shield segments in this application can timely monitor small deformation signals of the shield segments, so as to make corresponding countermeasures in advance and prevent problems before they occur. Brief Description of the Drawings

[0041] Figure 1 is a schematic structural diagram of the real-time deformation monitoring wireless flexible sensing system for shield segments in an embodiment of the present invention.

[0042] Figure 2 is a schematic structural diagram of the flexible groove induction film in an embodiment of the present invention.

[0043] Figure 3 is a schematic structural diagram of the real-time deformation monitoring wireless flexible sensing system for shield segments under tensile stress in an embodiment of the present invention.

[0044] Figure 4 is a schematic structural diagram of the real-time deformation monitoring wireless flexible sensing system for shield segments under compressive stress in an embodiment of the present invention.

[0045] Figure 5 is a schematic structural diagram of the flexible groove induction film in different states in an embodiment of the present invention.

[0046] Figure 6 is a schematic structural diagram of the micro-nano grooves in an embodiment of the present invention.

[0047] Figure 7 is a graph showing the change trends of the resistance change rate and elongation rate of the real-time deformation monitoring wireless flexible sensing system for shield segments in an embodiment of the present invention.

[0048] Figure 8 is a principle block diagram of the flexible groove induction film and the power supply collector in an embodiment of the present invention.

[0049] Description of the Reference Numerals:

[0050] 10. Shield segment; 21. First base; 22. Second base; 23. Bolt; 31. First rigid housing; 32. Second rigid housing; 33. Flexible elastic housing; 40. Rigid sheet; 50. Flexible groove induction film; 51. Flexible composite layer; 511. Micro-nano groove; 52. Conductive layer; 60. Power supply collector; 61. Power module; 62. Acquisition module; 621. ADC module; 622. MCU module; 63. Wireless module; 70. Electric wire. Detailed implementation manners

[0051] To make the objectives, technical solutions and advantages of the present invention clearer and more definite, the present invention will be further described in detail below with reference to the accompanying drawings and by way of examples. It should be understood that the specific examples described herein are only for explaining the present invention and are not used to limit the present invention.

[0052] Please refer to Figures 1 - 8 , and the present invention provides some embodiments of a wireless flexible sensing system for real-time monitoring of shield segment deformation.

[0053] As Figure 1 shown, the wireless flexible sensing system for real-time monitoring of shield segment deformation of the present invention includes:

[0054] A first base 21 and a second base 22, which are respectively arranged at two different radial positions on the inner side of the shield segment 10;

[0055] A deformation housing, with two ends respectively connected to the first base 21 and the second base 22;

[0056] A rigid sheet 40, with two ends respectively connected to the first base 21 and the second base 22. The rigid sheet 40 is bent into an arch shape by the first base 21 and the second base 22, and the protruding direction of the rigid sheet 40 is opposite to the protruding direction of the shield segment 10;

[0057] A flexible groove induction film 50, which is arranged on the rigid sheet 40 and is used to sense the deformation of the rigid sheet 40;

[0058] A power supply collector 60, which is arranged on the deformation housing and is electrically connected to the flexible groove induction film 50 (for example, the electrical connection can be achieved by using an electric wire 70).

[0059] Specifically, the shield segment 10 is usually arc-shaped. There can be multiple shield segments 10 on each cross-section. The first base 21 and the second base 22 are located at different positions on the cross-section of the shield segment 10, and the first base 21 and the second base 22 respectively correspond to different radial positions. The first base 21 and the second base 22 can be arranged on the same shield segment 10 or on different shield segments 10. The first base 21 and the second base 22 can be fixed to the shield segment 10 by bolts 23 or screws. For example, they can be connected and installed in the form of screw nuts through threaded holes, can be directly installed with the nuts of the shield segment 10, or can be directly tightened on the surface of the shield segment 10 in the form of screws. Since the tightening force is much greater than the deformation force of the deformed housing, this fixing method is more convenient, not affected by the nut spacing of the shield segment 10, can greatly simplify the volume of the wireless sensing system device, and achieve miniaturization. The deformed housing can deform and recover deformation. The rigid sheet 40 and the flexible groove sensing film 50 are both located inside the deformed housing. The rigid sheet 40 is kept bent in an arched state under the extrusion of the first base 21 and the second base 22, and the rigid sheet 40 can deform within a certain range. The flexible groove sensing film 50 is flexible and can generate deformation. The deformation position of the deformed housing corresponds to the position of the flexible groove sensing film 50. When the shield segment 10 deforms, the deformed housing, the rigid sheet 40, and the flexible groove sensing film 50 all deform accordingly. This is not only suitable for monitoring small strain amounts but also allows monitoring of large strain amounts, has a wider working range, and can instantaneously monitor the occurrence of sudden large deformations. The flexible groove sensing film 50 is attached to the arched rigid sheet 40. The rigid sheet 40 can endow the flexible groove sensing film 50 with a larger frequency response bandwidth, enhance the high-frequency response characteristics of the flexible groove sensing film 50, and at the same time can also improve the sensitive response performance of the flexible groove sensing film 50. In summary, the real-time monitoring wireless flexible sensing system for shield segment deformation in this application can timely monitor the smaller deformation signals of the shield segment 10, so as to make a response plan in advance and prevent problems before they occur.

[0060] The power collector 60 is used to supply power to the flexible groove sensing membrane 50 and collect the sensing data of the flexible groove sensing membrane 50. The power collector 60 includes: a power module 61 and a collection module 62. The power module 61 can use a lithium battery, such as a polymer core lithium battery or a button battery. The collection module 62 includes an ADC module 621 and an MCU module 622. The power collector 60 transmits data wirelessly. For example, the wireless transmission data can use at least one of Bluetooth, wireless WiFi, and ZigBee. The power collector 60 can also include: a wireless module 63. The wireless module 63 can use a Bluetooth module, a wireless WiFi module, or a ZigBee module. The wireless module 63 transmits the data to the receiving end (for example, a PC end). Data is transmitted in the form of wireless communication, and a small battery is used for power supply. The power of signal collection and transmission is small. Under the sampling frequency of 1Hz, it can be used for the entire shield construction period (>3 years) without replacing the power supply module, which greatly simplifies the volume and wiring troubles of the sensor system.

[0061] The rigid sheet 40 is made of a rigid material, and the rigid material is selected from a metal material, a metal compound material, a ceramic material, and a glass material. The metal material may be an alloy material.

[0062] In a preferred implementation of the embodiment of the present invention, Figure 2 As shown, the flexible groove sensing film 50 includes:

[0063] A flexible composite layer 51, wherein a plurality of micro-nano grooves 511 are provided on a side of the flexible composite layer 51 away from the rigid sheet 40, and the micro-nano grooves 511 extend along the axial direction of the shield segment 10;

[0064] The conductive layer 52 is distributed inside and around the micro-nano groove 511;

[0065] The flexible composite layer 51 includes: an insulating matrix and micro-nano conductive materials dispersed in the insulating matrix; and the conductive layer 52 is electrically connected to the power collector 60 .

[0066] Specifically, micro-nano grooves 511 are provided on the upper side of the flexible composite layer 51. The lower side of the flexible composite layer 51 is connected to the rigid sheet 40, which can be adhesively connected specifically. The flexible composite layer 51 and the rigid sheet 40 are insulated from each other. The conductive layer 52 is laid on the upper surface of the flexible composite layer 51 and the walls of the micro-nano grooves 511, presenting an undulating wave-like structure as a whole. The micro-nano conductive materials in the flexible composite layer 51 are uniformly dispersed in the insulating matrix, and the micro-nano conductive materials essentially form a three-dimensional porous structure. The insulating matrix fills the pore structure and wraps these micro-nano conductive materials. The conductive layer 52 and the flexible composite layer 51 have different resistivity and different resistance change ranges. Under the same deformation condition, the conductive layer 52 and the flexible composite layer 51 form different resistance changes.

[0067] The micro-nano grooves 511 can greatly improve the response of electrical signals, and can convert weak strain excitation into resistance or voltage signal output to issue a warning signal in time. The flexible composite layer 51 has flexibility and can deform and recover from deformation. When the shield segment 10 deforms, the rigid sheet 40 also deforms. The deformation of the flexible groove sensing film 50 not only includes the deformation of the conductive layer 52 caused by the change in the width of the groove, but also the tensile deformation or extrusion deformation of the flexible composite layer 51. When the flexible composite layer 51 undergoes tensile deformation or extrusion deformation, the distance between two adjacent micro-nano conductive materials changes. If the distance between two adjacent micro-nano conductive materials is within the preset distance, due to the tunneling effect, an electron channel is still formed between the two adjacent micro-nano conductive materials; if the distance between two adjacent micro-nano conductive materials is greater than the preset distance, an open circuit is formed between the two adjacent micro-nano conductive materials. Considering that two adjacent micro-nano conductive materials can be adjacent in the length direction or in the thickness direction, when the flexible composite layer 51 is stretched, the distance between two adjacent micro-nano conductive materials in the length direction may increase, and the distance between two adjacent micro-nano conductive materials in the thickness direction and width direction may decrease. The flexible composite layer 51 as a whole shows an increase in resistance; when the flexible composite layer 51 is extruded, the distance between two adjacent micro-nano conductive materials in the length direction may decrease, and the distance between two adjacent micro-nano conductive materials in the thickness direction and width direction may increase. The flexible composite layer 51 as a whole shows a decrease in resistance. In short, when the flexible composite layer 51 deforms, its resistance changes, and the amount of deformation of the flexible composite layer 51 can be reflected by the change amount of the resistance.

[0068] Such as Figure 5 and Figure 6As shown, the micro-nano grooves 511 are arranged in sequence along the width direction of the micro-nano grooves 511, and the length direction of the micro-nano grooves 511 is consistent with the axial direction of the shield segment 10. When the shield segment 10 deforms, the rigid sheet 40 and the flexible composite layer 51 also deform, then the width of the micro-nano grooves 511 changes, and the distance s between the conductive layers 52 on the two groove walls of the micro-nano grooves 511 changes, which also causes the resistance of the conductive layer 52 to change.

[0069] The forming method of the micro-nano grooves 511 includes at least one of photolithography, 3D printing, laser etching, structure template method, and mechanical cutting method. As Figure 6 shown, the width δ of the micro-nano grooves 511 is at the micro-nano level, and the depth d of the micro-nano grooves 511 is at the micro-nano level. The angle θ of the sharp corners of the micro-nano grooves 511 is 1° to 20°. The length of the micro-nano grooves 511 can be determined as needed.

[0070] In a preferred implementation manner of the embodiment of the present invention, the micro-nano conductive material is graphene.

[0071] Specifically, the micro-nano conductive material can be graphene. For example, single-layer graphene is used, and each sheet of graphene is used as a conductive unit. When the insulating matrix is stretched, when the insulating matrix is stimulated by tensile stress, due to the Poisson's ratio effect, the thickness of the insulating matrix decreases and the width shrinks along the direction perpendicular to the stretching, and separation may occur between two originally contacting graphene conductive units, and two originally spaced graphene conductive units may approach each other. When the insulating matrix is compressed, when the insulating matrix is stimulated by compressive stress, due to the Poisson's ratio effect, the thickness of the insulating matrix increases and the width increases along the direction perpendicular to the compression, and contact may occur between two originally spaced graphene conductive units, and two originally approaching graphene conductive units may separate from each other.

[0072] In a preferred implementation manner of the embodiment of the present invention, the conductive layer 52 is selected from at least one of a carbon conductive material layer, a metal material layer, a transition metal carbide material layer, a polymer conductive material layer, and a conductive composite material layer.

[0073] Specifically, when the shield segment 10 deforms, the conductive layers 52 on the two groove walls of the micro-nano grooves 511 are in contact with or separated from each other. Then the surface of the conductive layer 52 has good conductivity. When the conductive layers 52 on the groove walls of the micro-nano grooves 511 are in contact with or separated from each other, the resistance of the conductive layer 52 changes greatly.

[0074] The carbon conductive material of the carbon conductive material layer is selected from at least one of carbon nanotubes, graphene, and carbon black. The metal material of the metal material layer is selected from one of gold, silver, copper, and platinum. The transition metal carbide material of the transition metal carbide material layer is selected from two-dimensional metal carbides and nitrides (MXene). The polymer conductive material of the polymer conductive material layer is selected from poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT:PSS). The conductive composite material in the conductive composite material layer is selected from at least one of a composite material of a conductive material and a polymer material, a conductive hydrogel, and an ion gel.

[0075] In a preferred implementation manner of the embodiment of the present invention, as Figure 1 shown, the deformed housing includes:

[0076] A first rigid outer shell 31 disposed on the first base 21;

[0077] A second rigid outer shell 32 disposed on the second base 22;

[0078] A flexible elastic outer shell 33, with both ends respectively connected to the first rigid outer shell 31 and the second rigid outer shell 32;

[0079] Wherein, the power supply collector 60 is disposed on the first rigid outer shell 31 or the second rigid outer shell 32.

[0080] Specifically, when the shield segment 10 deforms, the deformed housing deforms accordingly, which may be a local area deformation. For example, as Figure 1 , Figure 3 and Figure 4 shown, the flexible elastic outer shell 33 deforms, and the first rigid outer shell 31 and the second rigid outer shell 32 basically do not deform. The flexible elastic outer shell 33 is located at the corresponding position of the flexible groove induction film 50.

[0081] In a preferred implementation manner of the embodiment of the present invention, the flexible elastic material of the flexible elastic outer shell 33 is selected from thermoplastic elastomers or thermoplastic vulcanizates, and the thermoplastic elastomers are selected from at least one of silicone rubber, epoxy resin, thermoplastic polyurethane, polydimethylsiloxane, and styrene.

[0082] Specifically, the flexible elastic outer shell 33 can be made of thermoplastic elastomers or thermoplastic vulcanizates. The first rigid outer shell 31 and the second rigid outer shell 32 can be made of nylon fiber-reinforced materials. The flexible elastic outer shell 33 and the first rigid outer shell 31, the second rigid outer shell 32 can be adhesively connected.

[0083] Based on the shield segment deformation real-time monitoring wireless flexible sensing system described in any of the above embodiments, the present invention also provides a preferred embodiment of a preparation method of a shield segment deformation real-time monitoring wireless flexible sensing system:

[0084] The preparation method of the wireless flexible sensing system for real-time monitoring of the deformation of shield segments in the embodiments of the present invention includes the following steps:

[0085] Step S100: Prepare a flexible groove induction film;

[0086] Step S200: Assemble the flexible groove induction film on a rigid sheet, and assemble a power supply collector on a deformation housing;

[0087] Step S300: Assemble the rigid sheet with the flexible groove induction film and the deformation housing with the power supply collector on a first base and a second base, and electrically connect the power supply collector and the flexible groove induction film to obtain the wireless flexible sensing system for real-time monitoring of the deformation of shield segments.

[0088] Specifically, first prepare a flexible groove induction film, then bond the flexible groove induction film on a rigid sheet, install the power supply collector on the deformation housing, then install the rigid sheet on the first base and the second base, install the deformation housing on the first base and the second base, and finally electrically connect the power supply collector and the flexible groove induction film (for example, electrical connection can be achieved by using wires) to obtain the wireless flexible sensing system for real-time monitoring of the deformation of shield segments. Assemble the wireless flexible sensing system for real-time monitoring of the deformation of shield segments on the shield segments, and the shield segments can be monitored in real time.

[0089] Step S100 specifically includes:

[0090] Step S110: Dissolve graphene in a solvent to obtain a graphene solution;

[0091] Step S120: Add an insulating material to the graphene solution to obtain a mixed solution; wherein, the mass ratio of graphene to the insulating material is 1:2 to 4;

[0092] Step S130: Heat and cure the mixed solution into a film to obtain a flexible composite layer;

[0093] Step S140: Form micro-nano grooves on the flexible composite layer;

[0094] Step S150: Form a conductive layer on the micro-nano grooves to obtain a flexible groove induction film.

[0095] Specifically, a certain amount of graphene is dissolved in a solvent, stirred and mixed evenly to obtain a graphene solution. Then a certain amount of rubber powder is added to the graphene solution, stirred and mixed evenly and ultrasonicated to obtain a mixed solution, the mixed solution is poured into a mold (such as a glass container) and heated, and the rubber is cured into a film to obtain a flexible composite layer. Micro-nano grooves are laser cut on the flexible composite layer, the width of the micro-nano grooves is 10μm to 60μm, the depth of the micro-nano grooves is 5μm to 30μm, the spacing between two adjacent micro-nano grooves is 80μm to 200μm, and the number of micro-nano grooves is 50 to 200. A conductive layer is formed in the area where the micro-nano grooves are located by sputtering to obtain a flexible groove sensing film.

[0096] After the micro-nano grooves are formed on the flexible composite layer, the flexible composite layer formed with the micro-nano grooves is pre-stretched, the number of pre-stretching is a preset number, and the elongation of the pre-stretching is 200% to 400%. In order to improve the yield rate of the flexible groove sensing membrane, after the micro-nano grooves are formed on the flexible composite layer, the flexible composite layer is pre-stretched a preset number of times. Through pre-stretching, the tensile properties of the flexible composite layer can be detected, and the wireless flexible sensing system for real-time monitoring of shield segment deformation is not easily damaged by stretching, which is conducive to improving the service life of the wireless flexible sensing system for real-time monitoring of shield segment deformation. Specifically, after pre-stretching, the conductive layer is formed. When the flexible groove sensing membrane is deformed during use, the conductive layer is not easily damaged by stretching, thereby improving the service life.

[0097] Step S150 specifically includes:

[0098] Step S151, performing metal ion sputtering on the surface of the pre-stretched flexible composite layer where the micro-nano grooves are located to form a conductive layer, and connecting a conductive tape on the conductive layer to obtain a flexible groove sensing film.

[0099] The conductive layer may be a metal particle conductive layer, and the metal particle conductive layer may be formed by sputtering coating. Specific embodiment 1

[0101] (1) adding a certain amount of single-layer graphene powder into toluene solvent and stirring for 2 hours using a stirrer;

[0102] (2) adding the rubber SEPS-4052 powder to the graphene solution stirred in step (1), and stirring again to fully dissolve the single-layer graphene powder and the rubber SEPS-4052 powder in toluene, and the mass of the graphene accounts for 25% of the total mass of the graphene and the rubber;

[0103] (3) The stirred mixed solution was subjected to ultrasonic oscillation for 1 hour, then poured into a glass container, placed on a heating table, and heated at a constant temperature of 25° C. for 24 hours to solidify into a film with a film thickness of about 0.15 mm;

[0104] (4) After film formation, use a laser marking machine to cut the film, and the cutting size is 40 mm × 4 mm;

[0105] (5) Using a femtosecond laser device, on the cut film, process a micro-nano groove structure through a fast scanning mode, the groove pitch is 100 μm, the groove width is about 40 μm, the depth is about 20 μm, and the number of grooves is 100;

[0106] (6) Perform 300% pre-stretching on the cut film 50 times;

[0107] (7) Use a sputtering coater to perform silver ion sputtering on the surface of the pre-stretched film above to form a conductive silver layer with uniform thickness;

[0108] (8) Stick conductive tapes on both ends of the sample with the conductive silver layer, and evenly apply conductive silver paste at the joint between the conductive tape and the sample, and place it on a heating table to heat at 80 °C for 1 hour for drying;

[0109] (9) Obtain a thin film sample with a composite conductive functional layer.

[0110] In a flexible composite layer formed with rubber as the matrix and graphene as the micro-nano conductive material, its resistance change can be attributed to the change of the graphene conduction path. The prepared flexible composite layer can be understood as a composite material of graphene and rubber. Regarding a single two-dimensional graphene sheet as a single conductive unit, when the flexible substrate is stimulated by tensile stress, due to the Poisson ratio effect, the thickness of the flexible substrate decreases and the width shrinks along the direction perpendicular to the tensile direction. Separation occurs between two originally contacting graphene conductive units. The separated distance is either sufficient to form an open circuit or still within the range of triggering the tunneling effect, and both of these will affect the resistance.

[0111] Due to the sputtering of a conductive silver layer on the micro-nano groove surface, silver nanoparticles are distributed on the two inclined surfaces (i.e., the groove walls) of the micro-nano groove. Especially the silver nanoparticles deposited at the bottom of the micro-nano groove, when subjected to tensile external force, the silver nanoparticles at the bottom will suffer a tearing effect, that is, the silver nanoparticles originally in contact at the bottom of the groove will be forced to separate by the tensile force, the inclined surface of the micro-nano groove opens, and the distance between the stacked silver nanoparticles on both sides of the bottom inclined surface increases, resulting in a reduction in the electron conduction path. Correspondingly, when subjected to compressive external force, the inclined surfaces of the micro-nano groove approach, the distance between the stacked silver nanoparticles on both sides of the bottom inclined surface decreases, and the silver nanoparticles that were not in contact on the inclined surface originally come into contact, resulting in an increase in the number of electron conduction paths, thereby affecting the magnitude of the resistance.

[0112] The combined effect of the above two mechanisms is to cause a change in the number of electron conduction paths, thereby resulting in a change in the thin-film resistance. The synergistic effect between the two mechanisms can significantly enhance the sensitivity characteristics of the flexible trench induction film.

[0113] According to the Figure 7 characterization results shown (△R / R0 represents the resistance change rate), the sensitivity of the flexible trench induction film can reach a maximum sensitivity value of 2762.4 within the range of the strain (elongation rate) of 200%. Compared with traditional resistance strain gauges, its detectable strain range has increased significantly, and the sensitivity is more than 500 times that of traditional resistance strain gauges, showing extremely high sensitivity characteristics.

[0114] Figure 8 It is a schematic diagram of the composition of the flexible trench induction film and the power supply acquisition module. The flexible trench induction film and a fixed-value resistor are connected in series to a 3.3V voltage, and the real-time voltage value at both ends of the flexible trench induction film is collected. The ADC module used is LTC1865L, the single-chip microcomputer is STM32L432KC, the wireless module is Bluetooth BT27, and the power supply module is a polymer lithium battery of 4800mAH.

[0115] It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above description, and all such improvements and transformations should fall within the protection scope of the appended claims of the present invention.

Claims

1. A method for preparing a wireless flexible sensing system for real-time monitoring of shield segment deformation, characterized in that: The wireless flexible sensing system for real-time monitoring of shield segment deformation includes: The first base and the second base are respectively arranged at two different radial positions inside the shield segment; A deformable shell, two ends of which are respectively connected to the first base and the second base; A rigid sheet, two ends of which are respectively connected to the first base and the second base, the rigid sheet is bent into an arch shape by the first base and the second base, and a protruding direction of the rigid sheet is opposite to a protruding direction of the shield segment; A flexible groove sensing film is provided on the rigid sheet and is used to sense the deformation of the rigid sheet; A power collector, which is arranged on the deformable shell and is electrically connected to the flexible groove sensing film; The preparation method comprises the steps of: preparing a flexible groove sensing membrane; The flexible groove sensing film is assembled on the rigid sheet, and the power collector is assembled on the deformable shell; A rigid sheet equipped with a flexible groove sensing membrane and a deformable shell equipped with a power collector are assembled on a first base and a second base, and the power collector and the flexible groove sensing membrane are electrically connected to obtain a wireless flexible sensing system for real-time monitoring of shield segment deformation; The method for preparing the flexible groove sensing film comprises: dissolving graphene in a solvent to obtain a graphene solution; Adding an insulating material to the graphene solution to obtain a mixed solution; wherein the mass ratio of the graphene to the insulating material is 1:2-4; heating and curing the mixed solution to form a film to obtain a flexible composite layer; forming micro-nano grooves on the flexible composite layer; forming a conductive layer on the micro-nano groove to obtain a flexible groove sensing film; After the micro-nano grooves are formed on the flexible composite layer, the flexible composite layer formed with the micro-nano grooves is pre-stretched, the number of pre-stretching is a preset number, and the elongation of the pre-stretching is 200% to 400%.

2. The method for preparing the wireless flexible sensor system for real-time monitoring of shield segment deformation according to claim 1 is characterized in that: The step of forming a conductive layer on the micro-nano groove to obtain a flexible groove sensing film comprises: The surface of the pre-stretched flexible composite layer where the micro-nano grooves are located is subjected to metal ion sputtering to form a conductive layer, and a conductive tape is connected to the conductive layer to obtain a flexible groove sensing film.

3. The method for preparing the wireless flexible sensor system for real-time monitoring of shield segment deformation according to claim 1 is characterized in that: The conductive layer is selected from at least one of a carbon conductive material layer, a metal material layer, a transition metal carbide material layer, a polymer conductive material layer, and a conductive composite material layer.

4. The method for preparing the wireless flexible sensor system for real-time monitoring of shield segment deformation according to claim 1 is characterized in that: The deformable shell comprises: A first rigid housing, disposed on the first base; A second rigid housing, disposed on the second base; A flexible shell, two ends of which are respectively connected to the first rigid shell and the second rigid shell; Wherein, the power supply collector is arranged in the first rigid shell or the second rigid shell.

5. The method for preparing the wireless flexible sensor system for real-time monitoring of shield segment deformation according to claim 4 is characterized in that: The flexible and elastic material of the flexible and elastic shell is selected from thermoplastic elastomer or thermoplastic vulcanized rubber, and the thermoplastic elastomer is selected from at least one of silicone rubber, epoxy resin, thermoplastic polyurethane, polydimethylsiloxane, and styrene.

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