High-sensitivity aerogel sensor device based on multi-scale integrated structure

Abstract

A high-sensitivity aerogel sensor device based on a multi-scale integrated structure comprises a sensing array integrated structure connected to the outside through a communication and electrical bus, the communication and electrical bus is connected with a column control multiplexer and a row control multiplexer, and the column control multiplexer and the row control multiplexer are connected with a main control chip; the sensing array integrated structure comprises positioning bearing foam, upper and lower insulating packaging plastic films connected with the upper and lower parts of the positioning bearing foam, and a side surface connected with a side surface anti-corrosion layer, and the positioning bearing foam wraps special structured pressure sensing aerogel; the upper surface and the lower surface of the special structured pressure sensing aerogel are connected with a column common electrode and a row common electrode through an upper electrode strengthening layer and a lower electrode strengthening layer, the column common electrode is connected with a column control multiplexer, and the row common electrode is connected with a row control multiplexer; according to the invention, the microstructure and the macrostructure are synergistically optimized, so that the mechanical property, the sensing sensitivity and the long-term stability are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of aerogel sensors, and particularly relates to a high-sensitivity aerogel sensor device based on a multi-scale integrated structure. Background Art

[0002] With the rapid development of flexible electronic technologies, flexible sensors with high sensitivity and wide dynamic range have shown broad application prospects in the fields of health monitoring, intelligent robots, artificial intelligence, etc. Aerogels are widely used in the manufacture of flexible pressure sensors due to their ultra-light mass, high porosity, and excellent compression performance.

[0003] To further improve performance, an important research and development direction for current flexible piezoresistive sensors is to achieve the design and manufacture of the hierarchical structures of materials, including multi-faceted structural designs at multiple levels such as micro and macro levels, which are of great value in improving performance and promoting application innovation. At the microscale, micro-nano structures can significantly enhance the sensing sensitivity of the sensor to small pressures (such as physiological signals) through local deformation; while at the macro level, the flexible substrate endows the sensor with the ability to deform over a large range, not only broadening the detection range but also improving mechanical stability, thus achieving a wide-range response from small stress to large stress.

[0004] On this basis, if the synergistic effect between different-scale structures can be achieved, it will not only help improve the device's fast response ability to dynamic signals but also significantly enhance the cyclic stability of the sensor under complex working conditions such as repeated compression and bending. On the other hand, with the development of flexible electronic technologies, the demand for personalized customization is increasing day by day. If the microstructural functional materials with excellent performance can be custom-designed into macrostructures, the adaptability of flexible wearable sensors in specific working environments can be further improved, while meeting the personalized needs of different people, and thus significantly expanding the value and potential of flexible electronic devices in sensing applications.

[0005] However, in terms of the sensing structure design, existing aerogel sensors usually show significant limitations. First of all, the macroscopic structure design is relatively single, and most of them adopt uniform blocky or disordered foam-like structures (Wang Q, Chen A, Gu H, et al. Highly interconnected porous PDMS / CNTs sandwich sponges with anti-icing / deicing microstructured surfaces [J]. Journal of Materials Science, 2021, 56(20): 11723-11735.; Schuler F, Schamel D, Salonen A, et al. Synthesis of macroporous polystyrene by the polymerization of foamed emulsions [J]. Angew Chem Int Ed Engl, 2012, 51(9): 2213-7.), lacking optimization for different stress ranges. In this homogeneous structure, when stressed, the deformation modes of each part are similar, making it difficult to achieve precise stress regulation, resulting in unstable sensitivity performance of the sensor under different loading conditions. In addition, the microscopic pore structure and macroscopic structure of the sensing structure in such sensors are often independent of each other. Although the sensitivity can be improved by optimizing the pore size and network distribution, due to the lack of collaborative design with the macroscopic structure, the improvement of the comprehensive performance of the sensor is limited. Under high load or long-term use, existing aerogel sensors are prone to irreversible structural collapse, leading to the decline of sensing performance and affecting their repeated service life.

[0006] In addition, the sensing structures of existing aerogel sensors generally do not introduce gradient structure design (Xu X, Du J, Cao Q, et al. Digitization of Free-Shapable Graphene Foam with Damage Tolerance[J]. Advanced Functional Materials, 2023, 33(21).; Liu J, Zhang X, Liu J, et al. 3D Printing of Anisotropic Piezoresistive Pressure Sensors for Directional Force Perception[J]. Adv Sci(Weinh), 2024, 11(24): e2309607.), resulting in poor adaptability under different stress conditions. Due to the uniform overall structure, the deformation modes of each region after being stressed are relatively consistent, and it is impossible to form optimized regulation for different mechanical environments. In the low-stress range, the sensor may exhibit low sensitivity, while in the high-stress range, it may be damaged due to excessive stress on local structures, limiting the dynamic range of the sensor. At the same time, the stress mode of the uniform structure often leads to large-area deformation of the sensing material, making the sensor prone to fatigue damage after long-term use and reducing its durability. Due to the lack of gradient design, the functions of existing sensors are often relatively single, and it is difficult to simultaneously achieve high sensitivity and wide dynamic range, restricting their applications in multiple scenarios.

[0007] Finally, the existing designs for sensing structures often neglect the supporting development of functions such as pressure bearing and large-area array sensing in practical applications (Kim H-G, Hajra S, Lee H, et al. Additively Manufactured Mechanical Metamaterial-Based Pressure Sensor with Tunable Sensing Properties for Stance and Motion Analysis[J]. Advanced Engineering Materials, 2023, 25(14).;), resulting in many problems such as high application thresholds and low customization levels for flexible piezoresistive sensors based on new sensing structures. The design of sensor devices mostly remains at the principle stage, lacking systematic construction and optimization of device packaging and load bearing.

[0008] In summary, there are still many deficiencies in the sensing structure design of current aerogel sensors, mainly manifested as problems such as single macroscopic structure, lack of collaborative optimization between microscopic and macroscopic structures, uncontrollable stress mode, easy damage to the structure, and insufficient adaptability; at the same time, there is a lack of systematic packaging and other designs for large-area array sensor devices. The above problems limit the further development and application of aerogel sensors. It is urgent to optimize the sensing structure design to improve its mechanical properties, sensing sensitivity, and long-term stability, and on this basis, form a more mature and complete large-area sensor device. Summary of the Invention

[0009] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a high-sensitivity aerogel sensor device based on a multi-scale integrated structure, with collaborative optimization of the microscopic and macroscopic structures to improve its mechanical properties, sensing sensitivity, and long-term stability.

[0010] To achieve the above purpose, the present invention provides the following technical solutions:

[0011] A high-sensitivity aerogel sensor device based on a multi-scale integrated structure includes a communication and electrical bus 13 connected to an external circuit and a computer. The communication and electrical bus 13 is connected through a first column wire bundle 9-1, a first row wire bundle 12-1, a column control multiplexer 8, and a row control multiplexer 11 to supply power to the internal pins of the column control multiplexer 8 and the row control multiplexer 11; the column control multiplexer 8 and the row control multiplexer 11 are connected to a main control chip 10 through a second column wire bundle 9-2 and a second row wire bundle 12-2, for supplying power from the column control multiplexer 8 and the row control multiplexer 11 to the main control chip 10, and at the same time controlling the pin gating of the column control multiplexer 8 and the row control multiplexer 11 through the main control chip 10; the column control multiplexer 8, the row control multiplexer 11, and the sensing array integrated structure are connected.

[0012] The communication and electrical bus 13 includes bidirectional communication lines and electrical lines to realize the electrical and communication paths of the sensing array integrated structure.

[0013] The described integrated structure of the sensing array includes a positioning and bearing foam 3, with upper and lower longitudinal fixing layers 4 fixedly connected above and below the positioning and bearing foam 3. An upper and lower insulating encapsulation plastic film 1 is connected to the outside of the upper and lower longitudinal fixing layers 4, and a side corrosion prevention layer 2 is connected to the side of the positioning and bearing foam 3. The positioning and bearing foam 3 encloses a specially structured pressure sensing aerogel 14. At the same time, the positioning and bearing foam 3 fills the gaps of the specially structured pressure sensing aerogel 14. The upper and lower surfaces of the specially structured pressure sensing aerogel 14 are connected to a column common electrode 5 and a row common electrode 6 through upper and lower electrode strengthening layers 7. The column common electrode 5 is connected to a column control multiplexer 8, and the row common electrode 6 is connected to a row control multiplexer 11. By regularly selecting rows and columns, sequential measurement of the sensing points in the array is achieved.

[0014] The described specially structured pressure sensing aerogel 14 is formed by integrating a macroscopic truss structure or a macroscopic curved surface structure and an internal microscopic lamellar structure. The macroscopic truss structure is composed of multiple support units, and each support unit constructs a spatial framework through an interleaved arrangement. The macroscopic curved surface structure is composed of repeated arrangements of minimum curved surface structure units.

[0015] The thickness of the lamellae of the microscopic lamellar structure is at the micron level. The size parameters of the rod diameter or wall thickness of the support units are at the millimeter level, forming a continuous support network and maintaining overall stability under stress.

[0016] The layout of the macroscopic truss structure shows a gradient change, that is, along a specific direction, the distribution density of the support units gradually changes; or the layout of the macroscopic curved surface structure shows a gradient change, that is, along a specific direction, the curvature and orientation of the support units gradually change; or the overall structure type shows a gradient change, that is, along a specific direction, the shape of the support units themselves changes layer by layer. The gradient changes of the macroscopic truss structure and the macroscopic curved surface structure provide different deformation response characteristics in different pressure regions, showing non-linear piezoresistive response characteristics.

[0017] The macroscopic truss structure or the macroscopic curved surface structure matches the microscopic lamellar structure. A high-density microscopic lamellar structure is used in high stress concentration regions to improve the overall sensitivity, and at the same time, a low-density microscopic lamellar structure is used in low stress regions to increase signal stability.

[0018] The manufacturing method of the described specially structured pressure sensing aerogel 14 includes the following steps:

[0019] 1) Preparation of a soluble photosensitive resin mold: Through the PμSL stereolithography 3D printing process, a resin device with a target macroscopic structure is printed using a soluble photosensitive resin to prepare a soluble photosensitive resin mold with a specific structural design.

[0020] 2) Preparation of paraffin mold: After the soluble photosensitive resin mold is printed and cleaned, it is placed into the pre-melted paraffin until completely submerged, and then vacuum treatment is carried out until the paraffin solidifies;

[0021] 3) Removal of soluble photosensitive resin mold: Open several openings of the paraffin wrapped with the soluble photosensitive resin mold and place the whole into flowing lye to dissolve the internal resin, forming a paraffin mold with the target structure. A liquid convection device is used to achieve the flow of the lye;

[0022] 4) Preparation of precursor solution: Add PAA milk fiber and triethylamine to deionized water to form a PAA solution. The mass ratio of PAA milk fiber to triethylamine is 1:1, and the final concentration range of PAA milk fiber in the PAA solution is within 20 - 100 mg / mL; Then add conductive filler to the PAA solution and disperse it fully by ultrasonic treatment. The final concentration range of the conductive filler in the solution is within 4 - 100 mg / mL;

[0023] 5) Pouring of precursor solution into paraffin mold: The PAA and conductive filler mixed solution (precursor solution) prepared in step 4) is poured into the paraffin mold prepared in step 3), and then vacuum treatment is carried out;

[0024] 6) Forming of conductive filler aerogel: After the treatment is completed, the whole is placed into a freeze dryer for unidirectional freeze-drying forming;

[0025] 7) Removal of paraffin mold: After the forming is completed, the whole device is taken out and the paraffin is removed by heating. It is placed in hot water for heating. After the paraffin melts, it will automatically float to the water surface and separate from the device, thus obtaining the special structured pressure sensing aerogel 14.

[0026] The conductive filler is a micro-nano material with conductive properties, including graphene, carbon nanotubes, carbon nanosheets, MXene, etc.

[0027] In step 3), the lye is one or both of KOH solution and NaOH solution.

[0028] The minimum structural rod diameter of the special structured pressure sensing aerogel 14 prepared in step 7) reaches 150 μm.

[0029] Compared with the prior art, the present invention has the following technical effects:

[0030] (A) The present invention adopts a cross-scale structural integrated design, combining a macroscopic truss structure or a macroscopic curved surface structure with a microscopic lamellar structure, effectively improving the sensitivity of the sensor. The macroscopic truss structure or the macroscopic curved surface structure optimizes the overall stress distribution, enabling the sensor to generate more obvious deformations at key nodes when externally loaded, thereby improving the signal output accuracy of the sensor; while the microscopic lamellar structure further enhances the formation of the internal conductive network and improves the stability of the signal output.

[0031] (B) By adopting a gradient macroscopic structure design, the sensor has adjustable response characteristics at different pressure stages, realizing a special performance curve, such as the plateau stage in the piezoresistive curve. This structure can adapt to different mechanical environment requirements, ensuring high sensitivity in the low-pressure region and avoiding signal saturation in the high-pressure region, improving the measurement range and adaptability of the sensor.

[0032] (C) While maintaining high sensitivity, the present invention can still maintain relatively high structural stability. The macroscopic structure provides excellent load-bearing capacity, and the internal microscopic lamellar structure disperses stress, making the sensor less likely to suffer from structural collapse or performance degradation during long-term use, thus extending its service life.

[0033] (D) The electrical, load-bearing, and encapsulation part structures of the complete sensor are designed and constructed in a complete manner, which can fully demonstrate the performance advantages of the special structured pressure-sensing aerogel. Moreover, targeted design is carried out according to the characteristics of the large-area flexible piezoresistive sensor, effectively avoiding common defects such as easy misalignment of sensing points, unstable electrode connection, and susceptibility to environmental factors in flexible piezoresistive sensors, greatly reducing the application threshold of the flexible piezoresistive sensor with a new sensing structure.

[0034] (E) The manufacturing method of the special structured pressure-sensing aerogel of the present invention combines the indirect 3D printing process of soluble photosensitive resin with the unidirectional freeze-drying aerogel forming process, effectively solving the problem of easy mismatch between processes and between processes and materials in traditional cross-scale manufacturing, and can realize the integrated molding of the cross-scale integrated structure through a simple method with little damage to the material.

[0035] (F) The manufacturing method of the special structured pressure-sensing aerogel of the present invention introduces an indirect 3D printing process. By means of paraffin casting, the dependence on the material forming ability is significantly reduced, enabling the minimum rod diameter of the aerogel material to reach 150 μm. At the same time, various complex three-dimensional structures such as lattices, octagonal trusses, and diamonds can be manufactured, achieving a technological breakthrough in the structuring of conductive fillers.

[0036] (G) The manufacturing method of the special structured pressure sensing aerogel of the present invention realizes an ordered arrangement of lamellar microstructures inside the aerogel through the unidirectional freeze-drying technique. This structure not only further enhances the flexibility and light weight characteristics of the material, but also, due to the lamellar structure being more sensitive to external forces and more prone to compression, greatly improves the sensitivity of the sensor. The arranged lamellar structure undergoes relatively regular strain changes during compression, which can enhance the stability of the sensing signal. Description of the Drawings

[0037] Figure 1 It is an isometric structure schematic diagram of an embodiment of the present invention.

[0038] Figure 2 It is an isometric structure schematic diagram of the longitudinal integration of a single sensing unit of an embodiment of the present invention.

[0039] Figure 3 It is an SEM image of the microscopic lamellar structure of an embodiment of the present invention.

[0040] Figure 4 It is a preparation flow chart of the structured graphene aerogel of an embodiment of the present invention.

[0041] Figure 5 It is an SEM image of the rod structure of the structured graphene aerogel of an embodiment of the present invention.

[0042] Figure 6 It is the strain-piezoresistive sensing signal one of the structured graphene aerogel of an embodiment of the present invention.

[0043] Figure 7 It is the stress-piezoresistive sensing signal two of the structured graphene aerogel of an embodiment of the present invention.

[0044] Wherein: 1 - upper and lower insulating encapsulation plastic films, 2 - side corrosion protection layer, 3 - positioning and bearing foam, 4 - upper and lower longitudinal fixing layers, 5 - column common electrode, 6 - row common electrode, 7 - upper and lower electrode strengthening layers, 8 - column control multiplexer, 9-1 - first column wire bundle, 9-2 - second column wire bundle, 10 - main control chip, 11 - row control multiplexer, 12-1 - first row wire bundle, 12-2 - second row wire bundle, 13 - communication and electrical bus, 14 - special structured pressure sensing aerogel. Detailed Embodiment

[0045] The present invention will be described in detail below in conjunction with embodiments and drawings. It should be noted that the present invention is not limited to the following embodiments, and all equivalent transformations made on the basis of the technical solutions of this application fall within the protection scope of the present invention.

[0046] As Figure 1 - Figure 2As shown in the figure, a high-sensitivity aerogel sensor device based on a multi-scale integrated structure is used to measure large-area high-precision pressure signals on the installation surface, including a communication and electrical bus 13 connected to an external circuit and a computer. The external circuit and the computer are used to read, perform subsequent processing analysis, and save the sensing data. The communication and electrical bus 13 includes bidirectional communication lines and electrical lines to implement the electrical and communication channels of the sensing array integrated structure. The communication and electrical bus 13 is connected through the first column wire bundle 9-1, the first row wire bundle 12-1, the column control multiplexer 8, and the row control multiplexer 11, and powers the internal pins of the column control multiplexer 8 and the row control multiplexer 11. The column control multiplexer 8 and the row control multiplexer 11 are connected to the main control chip 10 through the second column wire bundle 9-2 and the second row wire bundle 12-2, which is used to supply power from the column control multiplexer 8 and the row control multiplexer 11 to the main control chip 10. At the same time, the main control chip 10 controls the pin gating of the column control multiplexer 8 and the row control multiplexer 11. The column control multiplexer 8, the row control multiplexer 11, and the sensing array integrated structure are connected.

[0047] Referring to Figure 1 , Figure 2 , the described sensing array integrated structure is composed of upper and lower insulating encapsulation plastic films 1, side corrosion protection layers 2, positioning and bearing foams 3, upper and lower longitudinal fixing layers 4, column common electrodes 5, row common electrodes 6, upper and lower electrode strengthening layers 7, and special structured pressure-sensing aerogels 14. The upper and lower parts of the positioning and bearing foam 3 are connected to the upper and lower longitudinal fixing layers 4. The outside of the upper and lower longitudinal fixing layers 4 is connected to the upper and lower insulating encapsulation plastic films 1. The upper and lower longitudinal fixing layers 4 ensure the high-strength combination of the entire longitudinal integrated structure and avoid device damage in large-pressure measurement scenarios. The upper and lower insulating encapsulation plastic films 1 achieve overall protection and electrical isolation encapsulation of the internal structure. The side of the positioning and bearing foam 3 is connected to the side corrosion protection layer 2, and the side corrosion protection layer 2 realizes the anti-corrosion protection of the positioning and bearing foam 3.

[0048] A single sensing point of the sensing array integrated structure is as Figure 2As shown in the figure, the sensing unit in the upper left corner (first column, first row) of the sensing array integrated structure is wrapped with a special structured pressure sensing aerogel 14 in the positioning bearing foam 3. The special structured pressure sensing aerogel 14 is composed of a macroscopic truss structure and a microscopic lamellar structure. The macroscopic truss structure is composed of multiple supporting units (cylindrical as a whole). Each supporting unit constructs a space skeleton in a staggered arrangement. This structure ensures that the positioning bearing foam 3 can bear pressure together with the special structured pressure sensing aerogel 14 to achieve an auxiliary bearing function, thereby avoiding the special structured pressure sensing aerogel 14 from reaching the upper limit of deformation too early, thereby increasing its sensing range in disguise. At the same time, the positioning bearing foam 3 is filled in each special structure. In the gaps between the structured pressure sensing aerogels 14, the relative positions of the multiple special structured pressure sensing aerogels 14 are ensured not to change, thereby enhancing the position accuracy of large-area pressure sensing; the upper and lower surfaces of the special structured pressure sensing aerogels 14 are connected to the column common electrode 5 and the row common electrode 6 through the upper and lower electrode strengthening layers 7, and the upper and lower electrode strengthening layers 7 realize a stable connection between the special structured pressure sensing aerogels 14 and the column common electrode 5 and the row common electrode 6, thereby avoiding signal fluctuations caused by electrode problems; the column common electrode 5 is connected to the column control multiplexer 8, and the row common electrode 6 is connected to the row control multiplexer 11, and the sequential measurement of the sensing points in the array is realized by regularly selecting the rows and columns. It should be emphasized that in this embodiment, Figure 1 The 3*3 sensor array integrated structure shown in the figure is for illustration only. The number of sensor points can be increased or decreased arbitrarily (such as 4*4, 10*10), and the sensor array integrated structure can meet its adaptability.

[0049] Figure 2 The special structured pressure sensing aerogel 14 shown is only a schematic structure. All other similar structures (including grid structures, curved structures, random structures, etc. and the aforementioned gradient structures) can be manufactured using the above-mentioned manufacturing method and replaced with the special structured pressure sensing aerogel 14.

[0050] like Figure 3 As shown, the internal material of the special structured pressure sensing aerogel 14 is not a homogeneous entity, but is composed of a microscopic lamellar structure with a thickness of the lamellar at the micron level, which enables the sensor to have highly sensitive sensing performance. At the same time, the microscopic lamellar structure provides a large specific surface area, so that the electron transmission path can be dynamically adjusted according to the external force, thereby improving the stability of the signal output.

[0051] like Figure 4 As shown, the manufacturing method of the special structured pressure sensing aerogel 14 of this embodiment is as follows:

[0052] 1) Preparation of a soluble photosensitive resin mold: Using the PμSL light-curing 3D printing process, a resin device with a target macrostructure is printed using soluble photosensitive resin. The target macrostructure is the final macrostructure to be formed, such as a truss structure or a curved surface structure. If a gradient structure is required, the printed model can be modified to a gradient structure model. The soluble photosensitive resin is poured into the resin tank of the light-curing 3D printer, and the position of the work platform and release film is adjusted to ensure accurate optical and mechanical focus. Subsequently, process parameters such as print layer thickness, exposure time, and light intensity are set on the printer. The resin is gradually stacked and formed by UV light exposure and curing layer by layer, ultimately preparing a soluble photosensitive resin mold with a specific structural design.

[0053] 2) Preparation of paraffin mold: After the soluble photosensitive resin mold is printed and cleaned, melted paraffin is placed in it until it is completely immersed. Vacuum treatment is then performed to ensure that the paraffin fully fills the small structures and ensures the molding of structural details. The paraffin is then allowed to solidify.

[0054] 3) Removal of the soluble photosensitive resin mold: The paraffin wax containing the soluble photosensitive resin mold is opened several times and the entire mold is placed in a flowing alkali solution to dissolve the resin inside. The openings are to allow the resin to contact and dissolve with the alkali solution, forming a paraffin mold with the target structure. A liquid convection device can be used to achieve the flow of the alkali solution.

[0055] 4) Preparation of a precursor solution: PAA emulsion and triethylamine are added to deionized water to form a PAA solution, with a mass ratio of PAA emulsion to triethylamine of 1:1. Depending on the desired material properties, the final concentration of the PAA emulsion in the PAA solution can range from 20 to 100 mg / mL, with a higher concentration resulting in a lower porosity of the resulting material. Graphene is then added to the PAA solution and thoroughly ultrasonically dispersed. Depending on the desired material properties, the final concentration of the graphene in the solution can range from 4 to 100 mg / mL, with a higher concentration resulting in a lower resistivity of the resulting material.

[0056] 5) Pouring the precursor solution into the paraffin mold: The PAA and graphene mixed solution (precursor solution) prepared in step 4) is poured into the paraffin mold prepared in step 3) and then vacuumed to fill in the structural details;

[0057] 6) Forming of graphene aerogel: After the treatment is completed, the whole is placed in a freeze dryer for unidirectional freeze drying and forming. The growth direction of the ice crystals is the arrangement direction of the material microstructure. The freeze drying temperature is -50°C and the time is 48 hours.

[0058] 7) Removal of paraffin mold: After the forming is completed, the whole device is taken out and the paraffin is removed by heating. It can be placed in hot water for heating. After the paraffin melts, it will automatically float to the water surface and separate from the device, and the special structured pressure sensing aerogel 14 is obtained.

[0059] In the above preparation method, graphene as the conductive filler can be arbitrarily replaced by other micro-nano materials with conductive properties, such as carbon nanotubes, carbon nanosheets, MXene, etc.

[0060] In step 3), the lye is one or both of KOH solution and NaOH solution; in step 3), the liquid convection device is a small water pump or a similar device; in step 7), the minimum structural rod diameter of the prepared special structured pressure sensing aerogel 14 reaches 150 μm; in step 4) of this embodiment, the final concentration of PAA filaments in the PAA solution is 25 mg / mL; in step 5) of this embodiment, the final concentration of graphene is 10 mg / mL.

[0061] Refer to Figure 5 , Figure 5 is the SEM image of the truss structure of the structured graphene aerogel rod in the embodiment of the present invention. It can be seen that the prepared structured PI aerogel has a complete truss structure. The micro-rods of the truss structure present an ordered lamellar structure formed by the growth of ice crystals guided by a unidirectional temperature gradient inside, and all the lamellae are arranged in the same direction. On the surface of the micro-pore wall, graphene sheets are evenly distributed, which helps to construct a stable and continuous conductive network. The SEM image characterization proves that this process can realize the manufacture of PI / graphene aerogel integrating macroscopic truss and microscopic lamellar structures. The multi-level structure not only enhances the coupling effect between different scale structures, but also significantly improves the response sensitivity and detection ability of the material to pressure signals.

[0062] Refer to Figure 6 , Figure 6 is the strain-piezoresistive sensing signal 1 of the structured graphene aerogel in the embodiment of the present invention. The macroscopic structure type is an octagonal truss structure, and the characterization method is the piezoresistive signal curve of the device during the slow compression to 70% strain at a constant speed using a tensile machine. It can be seen that during the compression process of 70% strain, the resistance change rate gradually increases with the increase of strain, and the strain factor GF can reach 7.31 under small strain; under 70% large strain, the resistance still changes linearly with strain and no saturation occurs. It proves that it has high sensitivity to small strain and can realize large strain detection.

[0063] Refer to Figure 7 , Figure 7This is the second stress-piezoresistive sensing signal of the structured graphene aerogel in the embodiment of the present invention. The macroscopic structure type is an octagonal truss structure, and the characterization method is the piezoresistive signal curve of the device during the process of slowly compressing it to a stress of 250 KPa at a constant speed using a tensile machine. It can be seen that as the stress increases, the resistance change rate gradually increases, and the trend gradually slows down. The maximum sensitivity S can reach 3.56 kPa -1 , which is suitable for the detection of small stresses.

[0064] The working principle of the present invention is as follows:

[0065] Initial state: When no external force is applied, the microscopic lamellar structure of the special structured pressure sensing aerogel 14 is in a stable arrangement state, and the overall conductive network maintains the initial connection. At this time, the initial resistance of the special structured pressure sensing aerogel 14 remains at a specific value, and the output signal remains stable.

[0066] External force action and strain perception: When an external force (such as pressure or strain) is applied to the sensor, the macroscopic truss structure or curved surface structure deforms, resulting in stress concentration in local areas; at the same time, the microscopic lamellar structure undergoes interlayer slip under the action of pressure, causing a dynamic adjustment of the contact state of the internal conductive network, resulting in a change in the overall resistance of the special structured pressure sensing aerogel 14.

[0067] Resistance change and signal output: Since the resistance of the special structured pressure sensing aerogel 14 has a non-linear relationship with strain, as the external force increases, the overall resistance of the special structured pressure sensing aerogel 14 changes accordingly, and an electrical signal is formed and output according to the external measurement circuit. The electrical signal can be collected, amplified, and converted by a subsequent signal processing circuit, and finally used for sensing data analysis in practical applications.

[0068] Recovery and stability adjustment: When the external force is removed, the special structured pressure sensing aerogel 14 gradually returns to the initial state relying on the elastic recovery characteristics of the macroscopic gradient structure design and the microscopic lamellar structure; the gradient macroscopic structure ensures the controllability of the deformation in different pressure regions, while the reasonable layout of the microscopic lamellar structure optimizes the signal recovery characteristics, enabling the sensor to maintain high stability and reliability during long-term repeated use.

[0069] By combining the indirect 3D printing process of soluble photosensitive resin with the unidirectional freeze-drying aerogel forming process, the present invention proposes a cross-scale manufacturing method for a structurally designable special structured pressure-sensing aerogel, effectively solving the problem of easy mismatch between processes and between processes and materials in traditional cross-scale manufacturing, capable of achieving high-precision and high-quality complex three-dimensional structure forming, and having good structural design flexibility; due to the introduction of the indirect 3D printing process, the dependence on the material forming ability is significantly reduced, enabling the minimum rod diameter to reach 150 μm, and at the same time capable of manufacturing various complex three-dimensional structures such as lattices, octagonal trusses, and diamonds; through the unidirectional freeze-drying technology, an orderly arranged lamellar microstructure can also be formed inside the aerogel, not only further enhancing the flexibility and light-weight characteristics of the material, but also significantly improving the sensitivity of the sensor because the lamellar structure is more sensitive to external forces and more prone to compression; the finally prepared cross-scale structured aerogel sensing material has the advantages of high sensitivity, wide stress response range, light weight, softness, good air permeability, etc., significantly enhancing the application performance and environmental adaptability of the flexible piezoresistive sensor in wearable devices.

Claims

1. A highly sensitive aerogel sensor device based on a multi-scale integrated structure, including a communication and electrical bus (13) connected to an external circuit and a computer, characterized in that: The communication and electrical bus (13) is connected through the first column wire bundle (9-1), the first row wire bundle (12-1), the column control multiplexer (8), and the row control multiplexer (11) to supply power to the internal pins of the column control multiplexer (8) and the row control multiplexer (11); the column control multiplexer (8) and the row control multiplexer (11) are connected through the second column wire bundle (9-2), the second row wire bundle (12-2), and the main control chip (10) to supply power from the column control multiplexer (8) and the row control multiplexer (11) to the main control chip (10), and at the same time control the pin gating of the column control multiplexer (8) and the row control multiplexer (11) through the main control chip (10). The column control multiplexer (8) and the row control multiplexer (11) are connected to the sensing array integrated structure.

2. The device according to claim 1, characterized in that: The communication and electrical bus (13) contains bidirectional communication lines and electrical lines to realize the electrical and communication paths of the sensing array integrated structure.

3. The device according to claim 1, characterized in that: The sensing array integrated structure includes a positioning and bearing foam (3). The upper and lower parts of the positioning and bearing foam (3) are longitudinally fixedly connected by upper and lower longitudinal fixing layers (4). The outer sides of the upper and lower longitudinal fixing layers (4) are connected to upper and lower insulating encapsulation plastic films (1). The side of the positioning and bearing foam (3) is connected to a side corrosion prevention layer (2); a special structured pressure sensing aerogel (14) is wrapped inside the positioning and bearing foam (3), and at the same time the positioning and bearing foam (3) fills the gaps of the special structured pressure sensing aerogel (14). The upper and lower surfaces of the special structured pressure sensing aerogel (14) are connected to the column common electrode (5) and the row common electrode (6) through upper and lower electrode strengthening layers (7). The column common electrode (5) is connected to the column control multiplexer (8), and the row common electrode (6) is connected to the row control multiplexer (11). The sequential measurement of the sensing points in the array is realized by the regular gating of the rows and columns.

4. The device according to claim 3, characterized in that: The special structured pressure sensing aerogel (14) is integrally formed by a macroscopic truss structure or a macroscopic curved surface structure and an internal microscopic laminated structure; the macroscopic truss structure is composed of multiple support units, and each support unit constructs a spatial framework in a staggered arrangement; the macroscopic curved surface structure is composed of repeated arrangements of minimum curved surface structure units.

5. The device according to claim 4, characterized in that: The thickness of the laminae of the microscopic laminated structure is at the micron level; the size parameters of the rod diameter or wall thickness of the support units are at the millimeter level, forming a continuous support network and maintaining overall stability under stress.

6. The device according to claim 4, characterized in that: The layout of the macroscopic truss structure changes in a gradient, that is, along a specific direction, the distribution density of the support units gradually changes; or the layout of the macroscopic curved surface structure changes in a gradient, that is, along a specific direction, the curvature and orientation of the support units gradually change; or the overall structure type changes in a gradient, that is, along a specific direction, the shape of the support units themselves changes layer by layer; the gradient changes of the macroscopic truss structure and the macroscopic curved surface structure provide different deformation response characteristics in different pressure regions, showing non-linear piezoresistive response characteristics.

7. The device according to claim 4, characterized in that: The macroscopic truss structure or macroscopic curved surface structure matches the microscopic lamellar structure. A high-density microscopic lamellar structure is used in high stress concentration areas to improve overall sensitivity, while a low-density microscopic lamellar structure is used in low stress areas to increase signal stability.

8. A method for manufacturing the special structured pressure sensing aerogel in the device according to any one of claims 3 to 7, comprising the following steps: 1) Preparation of soluble photosensitive resin molds: Using the PμSL light-curing 3D printing process, resin devices with target macrostructures are printed using soluble photosensitive resin to produce soluble photosensitive resin molds with specific structural designs. 2) Preparation of paraffin mold: After the soluble photosensitive resin mold is printed and cleaned, place the pre-melted paraffin wax until it is completely immersed, then vacuum it and wait for the paraffin wax to solidify; 3) Removal of the soluble photosensitive resin mold: The paraffin mold wrapped with the soluble photosensitive resin mold is opened several times and placed in a flowing alkali solution to dissolve the internal resin, forming a paraffin mold with the target structure. A liquid convection device is used to achieve the flow of the alkali solution. 4) Preparation of a precursor solution: Adding PAA emulsion and triethylamine to deionized water to form a PAA solution, wherein the mass ratio of PAA emulsion to triethylamine is 1:1 and the final concentration of the PAA emulsion in the PAA solution is within the range of 20-100 mg / mL; then, adding a conductive filler to the PAA solution and thoroughly ultrasonically dispersing the PAA solution to a final concentration of the conductive filler in the solution is within the range of 4-100 mg / mL; 5) Pouring the precursor solution into the paraffin mold: The PAA and conductive filler mixed solution prepared in step 4), i.e., the precursor solution, is poured into the paraffin mold prepared in step 3) and then vacuumed; 6) Molding of the conductive filler aerogel: After the treatment is completed, the entire aerogel is placed in a freeze dryer for unidirectional freeze drying and molding; 7) Removal of the paraffin mold: After the molding is completed, the device is taken out as a whole and the paraffin is removed by heating. It is then placed in hot water and heated. After the paraffin melts, it will automatically float to the surface of the water and separate from the device, thus obtaining a special structured pressure sensing aerogel (14).

9. The method according to claim 8, characterized in that: The conductive filler is a micro-nano material with conductive properties, including graphene, carbon nanotubes, carbon nanosheets or MXene.

10. The method according to claim 8, characterized in that: The alkali solution in step 3) is one or both of KOH solution and NaOH solution; the special structured pressure sensing aerogel (14) prepared in step 7) has a minimum structure rod diameter of 150 μm.

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