A hierarchical spiral micro-bump piezoresistive pressure sensor

Abstract

The application belongs to the technical field of flexible sensor, and particularly relates to a hierarchical spiral micro-protrusion piezoresistive pressure sensor; wherein from top to bottom, an upper packaging layer, a flexible electrode assembly, a piezoresistive layer and a lower packaging layer are sequentially connected; the flexible electrode assembly is arranged on the piezoresistive layer and comprises a flexible substrate, a first electrode and a second electrode arranged on the flexible substrate; the piezoresistive layer comprises a disc base, a plurality of micro-protrusions arranged on the disc base and connecting ribs connecting the micro-protrusions; the micro-protrusion structure with hierarchical variation characteristics is arranged, and the plurality of micro-protrusions are connected by using the connecting structure, so that the piezoresistive layer forms a continuous structure network, and the detection of the resistance change signal under the pressure is realized by combining the flexible electrode assembly.

Description

Technical Field

[0001] This invention belongs to the field of flexible sensor technology, specifically relating to a hierarchical spiral micro-protrusion piezoresistive pressure sensor. Background Technology

[0002] With the development of flexible electronics technology, smart wearable devices and human-computer interaction technology, flexible pressure sensors, due to their softness, flexibility and ability to adapt to complex curved structures, have great application demand in fields such as electronic skin, human motion detection, intelligent robot tactile perception and flexible detection equipment.

[0003] Currently, flexible pressure sensors mainly include capacitive pressure sensors, resistive pressure sensors, piezoelectric pressure sensors, and triboelectric pressure sensors. Among them, piezoresistive pressure sensors are widely used in the field of flexible pressure detection because of their relatively simple structure, easy implementation of detection circuits, and ability to detect pressure signals by adjusting the sensitive material and structural form.

[0004] Existing flexible piezoresistive pressure sensors typically achieve the conversion of pressure signals into resistance change signals by setting microstructures on the surface of an elastic substrate or sensitive material. When the sensor is subjected to external pressure, the microstructures deform, which in turn causes changes in the conductive network inside the sensitive material or changes in the contact state between the electrodes and the sensitive layer.

[0005] However, there is still room for further optimization in existing flexible piezoresistive pressure sensors based on microstructure design.

[0006] On the one hand, the sensitive microstructures in some existing microstructure pressure sensors are usually arranged in a regular array, such as columnar array, conical array or periodic lattice structure. Each microstructure unit is relatively independent. When subjected to pressure, there is still room for improvement in the stress transmission relationship between microstructures and the overall structural synergy.

[0007] On the other hand, some existing microstructures use repeating unit structures of the same size. Under different pressure conditions, the deformation states of each microstructure are relatively similar, making it difficult to form a stress process with hierarchical variation characteristics.

[0008] In addition, some existing piezoresistive pressure sensors lack continuous connection structures between microstructures, which limits the structural continuity and conductive path connection relationships within the sensitive layer.

[0009] Therefore, there is a need to provide a new flexible piezoresistive pressure sensor structure. By designing microstructures with hierarchical variation characteristics and the connection method between microstructures, the piezoresistive layer can form a continuous structure, thereby meeting the application requirements of flexible pressure detection. Summary of the Invention

[0010] To address the problems of limited microstructure arrangement, insufficient interconnection between microstructures, and limited ability to coordinate structural changes during pressure application in existing flexible piezoresistive pressure sensors, this invention provides a hierarchical spiral micro-protrusion piezoresistive pressure sensor. By setting up a micro-protrusion structure with hierarchical variation characteristics and connecting multiple micro-protrusions using a connecting structure, the piezoresistive layer forms a continuous structural network. Combined with a flexible electrode assembly, it enables the detection of resistance change signals under pressure.

[0011] To achieve the above objectives, the technical solution of the present invention is implemented as follows: A hierarchical spiral micro-protrusion piezoresistive pressure sensor includes: The layers arranged from top to bottom are: an upper encapsulation layer, a flexible electrode assembly, a piezoresistive layer, and a lower encapsulation layer; wherein: The flexible electrode assembly is disposed on one side of the piezoresistive layer and includes a flexible substrate, a first electrode and a second electrode disposed on the same side surface of the flexible substrate, an insulating gap being provided between the first electrode and the second electrode, the first electrode being connected to a first lead-out terminal, and the second electrode being connected to a second lead-out terminal. The piezoresistive layer includes a disk substrate, a central micro-protrusion disposed at the center of the disk substrate, a plurality of micro-protrusions, and connecting ribs connecting the plurality of micro-protrusions. Multiple micro-protrusions are distributed on the disk substrate according to a preset arrangement path with the central micro-protrusion as the center, and the multiple micro-protrusions have size variation characteristics from the central region of the disk substrate to the outer region; The connecting ribs include in-track connecting ribs and cross-track connecting ribs. The in-track connecting ribs are used to connect adjacent micro-protrusions on the same arrangement path, and the cross-track connecting ribs are used to connect micro-protrusions between two adjacent arrangement paths.

[0012] The central micro-protrusion is located at the center of the disk base. Multiple micro-protrusions are arranged along multiple concentric annular paths with the center of the disk base as the center. The diameter of each annular path increases gradually from the inside to the outside. The same-track connecting rib connects adjacent micro-protrusions on the same annular path. The cross-track connecting rib obliquely and alternately connects micro-protrusions between two adjacent annular paths. The micro-protrusions include a hemispherical top and a cylindrical bottom connected sequentially from top to bottom; the height and diameter of the cylindrical bottom increase progressively from the inner annular path to the outer annular path; and the height and diameter of each micro-protrusion located on the same annular path are the same.

[0013] The disc base, the central micro-protrusion, the micro-protrusion, and the connecting rib are integrally formed.

[0014] The first electrode and the second electrode have the same shape, and the second electrode is arranged 180° rotated relative to the first electrode around the center of the flexible substrate.

[0015] The first electrode and the second electrode have the same structure, each consisting of a first arc-shaped electrode segment, a second arc-shaped electrode segment, a third arc-shaped electrode segment, a fourth arc-shaped electrode segment, a fifth arc-shaped electrode segment, and a sixth arc-shaped electrode segment arranged in sequence. One end of two adjacent arc-shaped electrode segments is connected in series via an edge arc-shaped electrode segment, and the other end of two adjacent arc-shaped electrode segments is connected in series via an inner edge arc-shaped electrode segment, so that the six arc-shaped electrode segments are connected as one unit.

[0016] The piezoresistive layer is made of a flexible conductive composite material, which includes an elastic matrix material and conductive fillers dispersed in the elastic matrix material; the elastic matrix material is silicone, and the conductive fillers include graphene and carbon nanotubes.

[0017] The flexible substrate is made of TPU flexible material, and the first electrode and the second electrode are formed by conductive silver paste disposed on the flexible substrate.

[0018] The flexible electrode assembly is disposed above the piezoresistive layer. The first electrode and the second electrode are in contact with the side of the micro-protrusion away from the disk substrate. The disk substrate is located on the side of the micro-protrusion away from the flexible electrode assembly and is fixedly connected to the lower encapsulation layer.

[0019] The beneficial effects of this invention are: This invention creates a spiral hierarchical distribution of microstructures in the piezoresistive layer by setting microprotrusions with dimensional variation characteristics, which is beneficial for forming structural differences between different regions.

[0020] This invention distributes multiple micro-protrusions according to a preset arrangement path, giving the microstructures in the piezoresistive layer a certain spatial arrangement pattern, which is beneficial for enriching the connection forms between microstructures.

[0021] This invention creates a continuous connection structure between multiple micro-protrusions by setting connecting ribs. The same-track connecting ribs are used to maintain the connection relationship in the same arrangement direction, and the cross-track connecting ribs are used to enhance the connection relationship between different areas, which is beneficial to maintaining the structural continuity of the piezoresistive layer.

[0022] This invention reduces the problem of assembling and connecting multiple independent microstructures by setting the disk base, micro-protrusions and connecting ribs as an integral structure.

[0023] This invention uses a flexible electrode assembly and a piezoresistive layer that work together to allow external pressure to cause structural changes in the piezoresistive layer, and achieves pressure detection by measuring the resistance change between the first electrode and the second electrode.

[0024] This invention employs a flexible substrate and a flexible packaging structure, giving the pressure sensor a flexible structural feature that facilitates its application in flexible detection scenarios. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the structure of the first electrode and the second electrode of the present invention; Figure 3 This is a schematic diagram of the structure of the first electrode of the present invention; Figure 4 This is a top view of the piezoresistive layer of the present invention. Figure 5 This is a schematic diagram of the overall three-dimensional structure of the piezoresistive layer of the present invention; Figure 6 This is a partial structural schematic diagram of the piezoresistive layer of the present invention; Figure 7 This is a partially enlarged structural diagram of the micro-protrusions and connecting ribs of the present invention.

[0027] In the diagram: 1. Lower encapsulation layer; 2. Upper encapsulation layer; 3. Electrode assembly; 31. Flexible substrate; 32. First electrode; 321. First arc-shaped electrode segment; 322. Second arc-shaped electrode segment; 323. Third arc-shaped electrode segment; 324. Fourth arc-shaped electrode segment; 325. Fifth arc-shaped electrode segment; 326. Sixth arc-shaped electrode segment; 33. Second electrode; 34. First lead-out terminal; 35. Second lead-out terminal; 36. Insulating gap; 4. Piezoresistive layer; 41. Disk substrate; 42. Micro-protrusion; 421. Minimum micro-protrusion; 422. Maximum micro-protrusion; 43. Connecting rib; 431. Same-track connecting rib; 432. Cross-track connecting rib. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1

[0029] A hierarchical spiral micro-protrusion piezoresistive pressure sensor, such as Figure 1-7 As shown, in this embodiment, the pressure sensor has a disk-shaped structure, including: an upper encapsulation layer 2, a flexible electrode assembly 3, a piezoresistive layer 4, and a lower encapsulation layer 1 arranged sequentially from top to bottom; wherein, the upper encapsulation layer 2 and the lower encapsulation layer 1 are respectively disposed on both sides of the pressure sensor for encapsulating and protecting the internal structure. Specifically, the upper encapsulation layer 2 is fixed to the flexible electrode assembly 3, and the lower encapsulation layer 1 is fixed to the bottom of the piezoresistive layer 4.

[0030] Preferably, the pressure sensor has an overall diameter of approximately 15 mm and an overall thickness of approximately 0.5 mm.

[0031] The flexible electrode assembly 3 is disposed on the piezoresistive layer 4 and includes a flexible substrate 31, a first electrode 32 and a second electrode 33 disposed on the same side surface of the flexible substrate 31. An insulating gap 36 is provided between the first electrode 32 and the second electrode 33. The first electrode 32 is connected to a first lead-out terminal 34, and the second electrode 33 is connected to a second lead-out terminal 35.

[0032] The flexible substrate 31 has a certain degree of flexibility, enabling the flexible electrode assembly 3 to adapt to the overall bending or deformation of the sensor. Specifically, the flexible substrate 31 is a flexible thin film, the main part of which is a circular thin film, and the two ends of the circular thin film extend outward to form strip-shaped thin films.

[0033] Flexible electrode assembly structure: The flexible substrate 31 is used to support the first electrode 32 and the second electrode 33. The first electrode 32 and the second electrode 33 are both disposed on a circular thin film of the flexible substrate 31 and are located in the same plane.

[0034] The first electrode 32 and the second electrode 33 have the same structure, both being arc-shaped spiral structures. In one embodiment: The first electrode 32 includes a plurality of arc-shaped electrode segments arranged in the radial direction of the flexible substrate 31. Each arc-shaped electrode segment extends from the outer periphery of the electrode to the central region in stages and is spaced apart, so that the first electrode 32 forms a multi-turn spiral conductive structure. The second electrode 33 has the same shape and size as the first electrode 32, and the second electrode 33 is arranged 180° around the center of the sensor relative to the first electrode 32.

[0035] An insulating gap 36 is provided between the first electrode 32 and the second electrode 33 to prevent direct electrical connection between the two electrodes. The first lead-out terminal 34 and the second lead-out terminal 35 are used to connect to an external detection circuit.

[0036] The first electrode 32 includes multiple arc-shaped electrode segments connected sequentially along a spiral direction. Specifically, the first electrode 32 includes a first arc-shaped electrode segment 321, a second arc-shaped electrode segment 322, a third arc-shaped electrode segment 323, a fourth arc-shaped electrode segment 324, a fifth arc-shaped electrode segment 325, and a sixth arc-shaped electrode segment 326, wherein the first arc-shaped electrode segment 321, the second arc-shaped electrode segment 322, the third arc-shaped electrode segment 323, the fourth arc-shaped electrode segment 324, the fifth arc-shaped electrode segment 325, and the sixth arc-shaped electrode segment 326 are arranged sequentially in the radial direction and extend in a circumferentially curved manner, with the ends of adjacent arc-shaped electrode segments connected to each other, thereby forming a continuous spiral conductive path; specifically: The first electrode 32 and the second electrode 33 have the same structure, each consisting of a first arc-shaped electrode segment 321, a second arc-shaped electrode segment 322, a third arc-shaped electrode segment 323, a fourth arc-shaped electrode segment 324, a fifth arc-shaped electrode segment 325 and a sixth arc-shaped electrode segment 326 arranged in sequence. One end of two adjacent arc-shaped electrode segments is connected in series via an edge arc-shaped electrode segment, and the other end of two adjacent arc-shaped electrode segments is connected in series via an inner edge arc-shaped electrode segment, so that the six arc-shaped electrode segments are connected as one unit. The end of the first arc-shaped electrode segment 321 of the first electrode 32 is connected to the first lead-out terminal 34 via an electrode lead; the end of the first arc-shaped electrode segment 321 of the second electrode 33 is connected to the second lead-out terminal 35 via an electrode lead. The first lead-out end 34 and the second lead-out end 35 are respectively disposed on the two strip films of the flexible substrate 31; The electrode leads connecting the end of the first arc-shaped electrode segment 321 to the first lead-out end 34 are arranged on the circular film and a corresponding strip film of the flexible substrate 31; the electrode leads connecting the end of the first arc-shaped electrode segment 321 to the second lead-out end 35 are arranged on the circular film and another corresponding strip film of the flexible substrate 31.

[0037] An insulating gap 36 is formed between all the inner arc-shaped electrode segments of the first electrode 32 and all the inner arc-shaped electrode segments of the second electrode 33; and, all the inner arc-shaped electrode segments of the first electrode 32 and the second electrode 33 are geometrically located on the same circumference, so as to jointly define a circle in the overall outline.

[0038] Similarly, all the edge arc-shaped electrode segments of the first electrode 32 and the second electrode 33 are geometrically located on the same circumference, so that each edge arc-shaped electrode segment together defines a circular trajectory on the overall outline.

[0039] The above structure enables the first electrode 32 and the second electrode 33 to form an interleaved electrode structure covering the detection area.

[0040] Piezoresistive layer structure: The piezoresistive layer 4 is disposed on one side of the flexible electrode assembly 3. For example... Figures 6-7 As shown, the piezoresistive layer 4 includes: a disk substrate 41; a central micro-protrusion disposed at the center of the disk substrate 41; a plurality of micro-protrusions 42 disposed on the disk substrate 41; and connecting ribs 43 connecting the plurality of micro-protrusions 42.

[0041] The disk substrate 41 has a disk-shaped structure and serves as the basic load-bearing structure for the piezoresistive layer 4. Multiple micro-protrusions 42 are disposed on one side surface of the disk substrate 41 and distributed on the disk substrate 41 according to a preset arrangement path.

[0042] In a preferred embodiment, the central micro-protrusion is located at the center of the disk base 41, that is, the center of the cylindrical bottom surface of the central micro-protrusion coincides with the center point of the top surface of the disk base 41. Multiple micro-protrusions 42 are arranged along multiple concentric annular paths centered on the center of the upper surface of the disk base 41. The diameter of each annular path increases progressively from the inside out. Each annular path is formed by sequentially connecting the centers of the cylindrical bottom surfaces of the micro-protrusions 42. The connecting ribs 431 connect adjacent micro-protrusions 42 on the same annular path; that is, each micro-protrusion 42 on the same annular path is sequentially connected by the connecting ribs 431. The cross-rail connecting ribs 432 obliquely and alternately connect micro-protrusions 42 between adjacent annular paths. Each micro-protrusion 42 is connected to adjacent micro-protrusions 42 on its inner annular path and adjacent micro-protrusions 42 on its outer annular path via the cross-rail connecting ribs 432. Cross-rail connecting ribs 432 are also provided between the outermost micro-protrusions 42 and the edge of the disk base 41.

[0043] In other words, multiple micro-protrusions 42 located on the same annular path are connected in series by the same track connecting ribs 431; and each of the same track connecting ribs 431 is located on the same circumference in geometric position to jointly form an annular path.

[0044] Micro-protrusion hierarchical structure: The micro-protrusions 42 include: a minimum micro-protrusion 421 configured as the smallest in size on the annular path located at the very center of the central region; and a maximum micro-protrusion 422 configured as the largest in size on the annular path located at the very edge of the peripheral region.

[0045] The micro-protrusion 42 includes a hemispherical top and a cylindrical bottom connected sequentially from top to bottom; the height and diameter of the cylindrical bottom increase progressively from the inner annular path to the outer annular path; and the height and diameter of each micro-protrusion 42 located on the same annular path are the same.

[0046] The disk base 41, the central micro-protrusion, the micro-protrusion 42, and the connecting rib 43 are integrally formed. Specifically, the bottom of the disk base 41 (the end not connected to the micro-protrusion 42) is in contact with the lower encapsulation layer 1.

[0047] In this embodiment: the smallest micro-protrusion 421 has a diameter of 0.05 mm and a height of 0.075 mm; the largest micro-protrusion 422 has a diameter of 0.7 mm and a height of 0.65 mm.

[0048] Through the above-mentioned dimensional changes, the micro-protrusions 42 in different regions have different structural dimensional characteristics.

[0049] Connecting rib structure: The connecting ribs 43 are disposed among the multiple micro-protrusions 42 to connect the multiple micro-protrusions 42 and form a continuous structure. The connecting ribs 43 include: in-track connecting ribs 431 and cross-track connecting ribs 432. The in-track connecting ribs 431 connect adjacent micro-protrusions 42 on the same arrangement path to maintain the continuous connection of the micro-protrusions 42 along the arrangement direction. The cross-track connecting ribs 432 connect micro-protrusions 42 on adjacent arrangement paths between different arrangement regions to enhance the connection between micro-protrusions in different regions. Through the combined action of the in-track connecting ribs 431 and the cross-track connecting ribs 432, the multiple micro-protrusions 42 form a structural network with multi-directional connections. The cross-track connecting ribs 432 connect different spiral regions.

[0050] In this embodiment, the connecting rib 43 adopts an approximately cylindrical structure. The diameter of the connecting rib 43 is approximately 0.05 mm.

[0051] Through the combined action of the same-track connecting rib 431 and the cross-track connecting rib 432, a multi-directional connection network is formed inside the pressure resistance layer 4.

[0052] Materials and manufacturing structure: In one embodiment, the flexible substrate 31 is made of TPU flexible material.

[0053] The first electrode 32 and the second electrode 33 are formed using stretchable conductive silver paste disposed on a flexible substrate 31. The piezoresistive layer 4 is made of a flexible conductive composite material. Preferably, the piezoresistive layer 4 is formed by combining an elastic matrix material and a conductive filler, wherein: the elastic matrix material includes silicone; the conductive filler includes graphene and carbon nanotubes. Silicone serves as the elastic matrix material; graphene and carbon nanotubes serve as the conductive fillers. The disk substrate 41, the micro-protrusions 42, and the connecting ribs 43 are formed integrally.

[0054] Assembly relationship: The flexible electrode assembly 3 is disposed above the piezoresistive layer 4. The first electrode 32 and the second electrode 33 are in contact with the side of the central micro-protrusion and micro-protrusion 42 away from the disk substrate 41. The disk substrate 41 is located on the side of the micro-protrusion 42 away from the flexible electrode assembly 3 and is fixedly connected to the lower encapsulation layer 1. The upper encapsulation layer 2, the flexible electrode assembly 3, the piezoresistive layer 4, and the lower encapsulation layer 1 together form the layered structure of the pressure sensor.

[0055] In the assembled state: the upper encapsulation layer 2 and the lower encapsulation layer 1 limit and protect the internal structure, ensuring stable contact between the flexible electrode assembly 3 and the piezoresistive layer 4. At the same time, the upper encapsulation layer 2 and the lower encapsulation layer 1 do not apply a preset compressive load to the micro-protrusion 42, keeping the micro-protrusion 42 in its initial structural state.

[0056] Work process: When using this invention, an external electrical detection device needs to be connected in parallel with the circuit. When measuring the voltage across the sensor, the external electrical detection device is connected in parallel with the sensor of this invention. When measuring the current across the sensor, the external electrical detection device is connected in series with the sensor of this invention.

[0057] If the sensor of the present invention is subjected to pressure, the resistance of the sensing layer will change. When the output voltage of the external circuit is constant, the current or voltage in the circuit will change, which can be measured by an external electrical detection device. The voltage or current signal output by the external electrical detection device is collected to determine the equivalent resistance between the first electrode 32 and the second electrode 33.

[0058] The external electrical detection device is an electrometer, or it can be other electrical detection equipment with corresponding voltage and current detection functions; the detection excitation can be a voltage excitation method or a current excitation method.

[0059] In the initial no-load state, the upper encapsulation layer 2, flexible electrode assembly 3, piezoresistive layer 4, and lower encapsulation layer 1 maintain their initial assembly state. The micro-protrusions 42, connecting ribs 43, and disk substrate 41 are in their initial form, and the first electrode 32 and the second electrode 33 form an initial conductive contact with the piezoresistive layer 4. The first lead 34 and the second lead 35 are respectively connected to the positive and negative terminals of an external circuit. The external circuit provides a detection excitation between the first electrode 32 and the second electrode 33, and the initial equivalent resistance between the first electrode 32 and the second electrode 33 is obtained through an external electrical detection device. .

[0060] When external pressure is applied to the upper encapsulation layer 2, the upper encapsulation layer 2 deforms, causing the flexible substrate 31 and the first electrode 32 and the second electrode 33 disposed on the flexible substrate 31 to move towards the piezoresistive layer 4, so that the first electrode 32 and the second electrode 33 apply pressure to the central micro-protrusion and the micro-protrusion 42 in the piezoresistive layer 4. The external pressure is transmitted to the lower encapsulation layer 1 along the direction of the upper encapsulation layer 2, the flexible substrate 31, the first electrode 32 and the second electrode 33, the central micro-protrusion, the micro-protrusion 42, the connecting rib 43 and the disk substrate 41.

[0061] Under external pressure, the micro-protrusions 42 undergo compressive deformation, and the connecting ribs 43 integrally connected to the micro-protrusions 42 subsequently undergo bending, compression, or tensile deformation. Since the height and diameter of the micro-protrusions 42 gradually increase from the center region of the sensor to the outer region, micro-protrusions 42 at different locations exhibit different deformation responses under external pressure. Micro-protrusions 42 on adjacent tracks are connected by cross-track connecting ribs 432, and adjacent micro-protrusions 42 on the same track are connected by same-track connecting ribs 431, thus forming an interconnected conductive network through multiple micro-protrusions 42, same-track connecting ribs 431, and cross-track connecting ribs 432.

[0062] The piezoresistive layer 4 is made of conductive composite material. When the micro-protrusions 42 and connecting ribs 43 deform, the relative positions, contact states, and spacing of the conductive fillers inside the piezoresistive layer 4 change, thereby causing changes in the connection state and equivalent conductivity of the conductive pathways inside the piezoresistive layer 4. At the same time, the deformation of the micro-protrusions 42 under pressure changes the contact state between them and the first electrode 32 and the second electrode 33. The combined effect of the changes in the resistance of the piezoresistive layer 4 and the changes in the contact state between the electrodes and the piezoresistive layer 4 causes a change in the overall equivalent resistance between the first electrode 32 and the second electrode 33.

[0063] An external electrical detection device performs real-time or periodic detection of the electrical parameters between the first electrode 32 and the second electrode 33. When a voltage excitation method is used, a predetermined detection voltage is applied between the first electrode 32 and the second electrode 33, and the corresponding current is detected by the external electrical detection device. The current equivalent resistance is determined based on the detection voltage and the detection current. When a current excitation method is used, a predetermined detection current is applied between the first electrode 32 and the second electrode 33, and the corresponding voltage is detected by the external electrical detection device. The current equivalent resistance is determined based on the detection voltage and the detection current.

[0064] Before formal use, multiple known pressure values ​​are applied to the pressure sensor using a standard pressure loading device, and the equivalent resistance values ​​between the first electrode 32 and the second electrode 33 are recorded under each known pressure condition to establish a calibration correspondence between the pressure values ​​and the equivalent resistance values. The calibration correspondence is determined based on actual test results, and its specific form is not limited.

[0065] During actual pressure testing, when the external pressure changes, the micro-protrusions 42, connecting ribs 43, and the internal conductive network of the piezoresistive layer 4 change accordingly, causing a corresponding change in the equivalent resistance between the first electrode 32 and the second electrode 33. The external electrical detection device detects the current equivalent resistance, and the pressure value corresponding to the current equivalent resistance is determined according to the pre-established pressure-resistance calibration relationship, thereby realizing the detection of external pressure.

[0066] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the scope of protection of the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, any person skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention within the scope of the technology disclosed in the present invention. These simple modifications are all within the scope of protection of the present invention.

[0067] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0068] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A hierarchical spiral micro-protrusion piezoresistive pressure sensor, characterized in that, include: The layers arranged from top to bottom are: an upper encapsulation layer, a flexible electrode assembly, a piezoresistive layer, and a lower encapsulation layer; wherein: The flexible electrode assembly is disposed on one side of the piezoresistive layer and includes a flexible substrate, a first electrode and a second electrode disposed on the same side surface of the flexible substrate. An insulating gap is provided between the first electrode and the second electrode, and the first electrode is connected to a first lead-out terminal, and the second electrode is connected to a second lead-out terminal. The piezoresistive layer includes a disk substrate, a central micro-protrusion disposed at the center of the disk substrate, a plurality of micro-protrusions, and connecting ribs connecting the plurality of micro-protrusions. Multiple micro-protrusions are distributed on the disk substrate according to a preset arrangement path with the central micro-protrusion as the center, and the multiple micro-protrusions have size variation characteristics from the central region of the disk substrate to the outer region; The connecting ribs include in-track connecting ribs and cross-track connecting ribs. The in-track connecting ribs are used to connect adjacent micro-protrusions on the same arrangement path, and the cross-track connecting ribs are used to connect micro-protrusions between two adjacent arrangement paths.

2. The hierarchical spiral micro-protrusion piezoresistive pressure sensor according to claim 1, characterized in that, The central micro-protrusion is located at the center of the disk base. Multiple micro-protrusions are arranged along multiple concentric annular paths with the center of the disk base as the center. The diameter of each annular path increases gradually from the inside to the outside. The same-track connecting rib connects adjacent micro-protrusions on the same annular path. The cross-track connecting rib obliquely and alternately connects micro-protrusions between two adjacent annular paths.

3. The hierarchical spiral micro-protrusion piezoresistive pressure sensor according to claim 1, characterized in that, The micro-protrusions include a hemispherical top and a cylindrical bottom connected sequentially from top to bottom; the height and diameter of the cylindrical bottom increase progressively from the inner annular path to the outer annular path; and the height and diameter of each micro-protrusion located on the same annular path are the same.

4. The hierarchical spiral micro-protrusion piezoresistive pressure sensor according to claim 1, characterized in that, The disc base, the central micro-protrusion, the micro-protrusion, and the connecting rib are integrally formed.

5. The hierarchical spiral micro-protrusion piezoresistive pressure sensor according to claim 1, characterized in that, The first electrode and the second electrode have the same shape, and the second electrode is arranged 180° rotated relative to the first electrode around the center of the flexible substrate.

6. The hierarchical spiral micro-protrusion piezoresistive pressure sensor according to claim 5, characterized in that, The first electrode and the second electrode have the same structure, each consisting of a first arc-shaped electrode segment, a second arc-shaped electrode segment, a third arc-shaped electrode segment, a fourth arc-shaped electrode segment, a fifth arc-shaped electrode segment, and a sixth arc-shaped electrode segment arranged in sequence. One end of two adjacent arc-shaped electrode segments is connected in series via an edge arc-shaped electrode segment, and the other end of two adjacent arc-shaped electrode segments is connected in series via an inner edge arc-shaped electrode segment, so that the six arc-shaped electrode segments are connected as one unit.

7. The hierarchical spiral micro-protrusion piezoresistive pressure sensor according to claim 1, characterized in that, The piezoresistive layer is made of a flexible conductive composite material, which includes an elastic matrix material and conductive fillers dispersed in the elastic matrix material; the elastic matrix material is silicone, and the conductive fillers include graphene and carbon nanotubes.

8. The hierarchical spiral micro-protrusion piezoresistive pressure sensor according to claim 1, characterized in that, The flexible substrate is made of TPU flexible material, and the first electrode and the second electrode are formed by conductive silver paste disposed on the flexible substrate.

9. The hierarchical spiral micro-protrusion piezoresistive pressure sensor according to claim 1, characterized in that, The flexible electrode assembly is disposed above the piezoresistive layer. The first electrode and the second electrode are in contact with the side of the micro-protrusion away from the disk substrate. The disk substrate is located on the side of the micro-protrusion away from the flexible electrode assembly and is connected to the lower encapsulation layer.

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