Flexible piezoresistive sensor array based on triangular truss mesh structure weft-knitted spacer fabric

Abstract

The present application belongs to the technical field of flexible sensing, and discloses a flexible piezoresistive sensing array based on a triangular truss grid structure weft-knitted spacer fabric, which is a five-layer composite structure integrally formed through a weft-knitting process, and sequentially comprises a first encapsulation layer, a first electrode layer, a spacer fabric spacing layer, a second electrode layer and a second encapsulation layer from top to bottom; the first encapsulation layer and the second encapsulation layer are knitted from insulating yarns and serve as upper and lower layers of the spacer fabric respectively; the spacer fabric spacing layer is a three-dimensional elastic support structure, and comprises a plurality of first spacer layer courses and a plurality of second spacer layer courses alternately knitted through tuck stitches on the upper and lower layers of the spacer fabric; the first spacer layer courses and the second spacer layer courses are staggered with each other in the spacer fabric and are sequentially connected at the head and tail to form a triangular truss grid structure in a cross-course crosslinking mode. The flexible piezoresistive sensing array of the present application has high structural integrity and long-term stability.

Description

Technical Field

[0001] This invention belongs to the field of flexible sensing technology, specifically relating to a flexible piezoresistive sensing array based on a weft-knitted spacer fabric with a triangular truss grid structure. Background Technology

[0002] Piezoresistive array sensors are based on the piezoresistive effect of materials (the physical property of resistance changing with pressure). They achieve high-precision detection of dynamic pressure distribution through arrayed multi-point sensing units. Their core structure consists of a conductive electrode layer, a piezoresistive sensitive layer, and an encapsulation layer. They are widely used in fields such as occupant presence detection in automobile seats, physiological signal capture in health monitoring equipment, and tactile bionic skin for robots.

[0003] Traditional piezoresistive array sensors are usually made of silicon-based or thin film materials, which have the following problems: (1) The rigid structure makes it difficult to fit complex curved surfaces (such as human joints), resulting in poor wearing comfort; (2) The sensing layer, electrode layer and substrate layer need to be processed step by step through coating, bonding and other processes, which are easy to delaminate and have insufficient long-term stability; (3) The multi-layer stacked structure hinders the exchange of air and moisture, and long-term wear can easily cause skin discomfort.

[0004] To overcome the aforementioned shortcomings, researchers began exploring textile-based piezoresistive array sensors. For example, Reference 1 (3DKnITS: Three-dimensional digital knitting of intelligent textile sensor for activity recognition and biomechanical monitoring, in Proc. 44th Annu.Int. Conf. IEEE Eng. Med. Biol. Soc.(EMBC), Jul. 2022, pp. 2403–2409) proposed a piezoresistive array sensor composed of three layers of fabric (electrode layer – piezoresistive layer – electrode layer) composited with thermoplastic polyurethane (TPU). However, the multilayer composite process is complex, resulting in poor sensor flexibility and breathability. Patent CN202110657122.8 discloses an array sensor based on double-layer fabric bonding, forming sensing units by cross-stacking fabrics containing unidirectional electrodes. However, this method still relies on multilayer fabric stacking, leading to poor long-term sensor stability, and the multilayer structure is thick, resulting in poor flexibility and breathability. Patent CN202011220793.X achieves a multi-layer fabric sensing array through bonding and sewing processes. However, its layered structure leads to deterioration of flexibility, low interfacial bonding strength, insufficient long-term stability, and low air permeability due to its dense multi-layer structure.

[0005] The array sensor with the multi-layer fabric structure mentioned above has the following shortcomings: (1) Non-integrated structure: The electrode layer and the piezoresistive layer cannot be integrally formed by textile process and need to rely on subsequent composite or bonding process, resulting in high process complexity and increased cost; (2) Performance-comfort contradiction: The multi-layer stacked or composite structure sacrifices the inherent breathability and softness of the textile substrate; (3) Insufficient long-term stability: The bonding interface is prone to delamination under dynamic pressure, resulting in deterioration of signal stability.

[0006] To address the shortcomings of array sensors with multi-layered fabric structures, researchers have shifted their focus to developing textile-based array sensors using integrated knitting processes. For example, patent application CN202311511898.4 discloses a piezoresistive array sensor based on a single-layer fabric, where both the transverse and longitudinal electrodes are woven using a knitted float yarn process, and electrical connection is achieved through a piezoresistive sensitive layer between the electrodes. Although the float electrode structure simplifies the manufacturing process, the electrode layer and the piezoresistive sensitive layer are physically separate structures, making them prone to slippage under load, which severely restricts the stability of the sensor. Patent CN202310420626.7 and Document 2 (Three-directional spacer-knitted piezoresistant strain and pressure sensor for electronic integration and on-body applications [J]. ACS Appl Mater Interfaces, 2023, 15(47): 55009–5502) disclose a piezoresistive sensor and array based on weft-knitted spacer fabric. The upper and lower surfaces are electrode layers woven with conductive yarns, and the spacer layer is a piezoresistive sensitive layer. However, its sensing units can only be arranged along the longitudinal direction of the fabric, and it cannot construct a two-dimensional in-plane array (such as a 4×4 array), which cannot meet the needs of two-dimensional pressure distribution detection in scenarios such as smart mattresses and robotic tactile skin. In addition, there is no physical connection between adjacent rows of piezoresistive sensitive yarns in the piezoresistive sensitive layer. During compression, the contact-separation between the yarns is highly random, resulting in large resistance fluctuations and insufficient sensor stability. Patent CN202010114973.3 discloses a capacitive flexible fabric sensor based on a weft-knitted jacquard structure. It introduces conductive yarns into the fabric to form sensing units through partial yarn-addition technology, with the middle layer using weft-inserted bulky yarn as the dielectric layer. However, the isolated arrangement of the weft yarns leads to random contact-separation during compression, resulting in large capacitance fluctuations and insufficient sensor stability. Patent CN202311563830.0 discloses a flexible fabric sensor based on a warp-knitted spacer fabric. It integrates longitudinal and transverse electrodes on the upper and lower layers of the fabric using chain knitting and weft insertion, and uses polyester / nylon monofilaments to weave spacer layers, achieving a pressure-resistance response through electrode contact-separation. However, this technology has the following drawbacks: it relies on a "switch-type" sensing mechanism that separates electrode contacts, which only triggers a resistance response under high pressure and is completely ineffective under minute pressures (such as human breathing and pulse); the resistance variation range is narrow, and the signal resolution and stability are insufficient, making it difficult to meet the needs of high-precision scenarios such as medical monitoring; in addition, the electrode signal is led out through a reserved conductive yarn, which requires an additional insulating layer to prevent short circuits, resulting in insufficient reliability in long-term use.

[0007] Therefore, it is of great significance to study a flexible piezoresistive sensing array based on a triangular truss grid structure weft-knitted spacer fabric, which can achieve the integrated weaving of the encapsulation layer, electrode layer and piezoresistive sensitive layer without the need for subsequent composite processing, and fundamentally solve the defect of insufficient long-term stability of existing technologies. Summary of the Invention

[0008] The purpose of this invention is to solve the problems existing in the prior art and provide a flexible piezoresistive sensing array based on a weft-knitted spacer fabric with a triangular truss grid structure.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] The flexible piezoresistive sensing array based on the triangular truss grid structure weft-knitted spacer fabric is a five-layer composite structure woven in one piece by weft knitting process, consisting of a first encapsulation layer, a first electrode layer, a spacer fabric spacer layer, a second electrode layer, and a second encapsulation layer from top to bottom.

[0011] The first encapsulation layer and the second encapsulation layer are woven from insulating yarns and are respectively the upper and lower layers of the spacer fabric;

[0012] The first electrode layer includes a plurality of independent first electrodes along the longitudinal direction of the spacer fabric, and the second electrode layer includes a plurality of independent second electrodes along the transverse direction of the spacer fabric. The first electrode layer and the second electrode layer are woven from conductive yarns. The first electrode layer is integrally embedded in the first encapsulation layer, and the second electrode layer is integrally embedded in the second encapsulation layer.

[0013] The spacer fabric spacer layer is a three-dimensional elastic support structure, comprising multiple first spacer layer rows and multiple second spacer layer rows formed by alternating weaving loops on the upper and lower layers of the spacer fabric; the first spacer layer rows and the second spacer layer rows are arranged alternately in the spacer fabric and are connected end to end to form a cross-linked triangular truss grid structure.

[0014] Multiple first electrodes in the first electrode layer and multiple second electrodes in the second electrode layer form multiple intersection regions on the spacer fabric. The multiple intersection regions constitute multiple piezoresistive sensing regions A. The spacer fabric spacer layer provides a piezoresistive sensitive region A1 in the piezoresistive sensing region A. The resistance value of the piezoresistive sensitive region A1 changes with pressure.

[0015] The non-intersecting areas of the multiple first electrodes in the first electrode layer and the multiple second electrodes in the second electrode layer on the spacer fabric, as well as the non-electrode areas of the first encapsulation layer and the second encapsulation layer, constitute a non-piezoresistive sensing region B. The spacer fabric spacer layer has a non-piezoresistive sensitive region B1 in the non-piezoresistive sensing region B. The non-piezoresistive sensitive region B1 is used to isolate the adjacent piezoresistive sensing region A and to lay signal wires.

[0016] As a preferred technical solution:

[0017] As described above, the flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric has a piezoresistive sensitive area A1 formed by woven conductive yarn. The conductive yarn is woven into a cross-column cross-linked triangular truss mesh structure by two consecutive alternating knitting loops, and the first electrode layer and the second electrode layer are connected synchronously.

[0018] The non-piezoresistive sensitive area B1 is formed by weaving insulating yarn, or not woven. The latter is divided into two cases: the first is that the spacer layer is not woven in this area, and the upper and lower layers of the spacer fabric are separated in this area to form an air layer structure; the second is that the spacer layer is not woven in this area, and the upper and lower layers of the spacer fabric are interwoven in this area to form a rib or mesh structure.

[0019] As described above, in the flexible piezoresistive sensing array based on the weft-knitted spacer fabric of the triangular truss grid structure, the structure of the first encapsulation layer and the second encapsulation layer in the piezoresistive sensing region A is one or more of plain knit and variable plain knit structures.

[0020] In the non-piezoresistive sensing region B, the structure of the first encapsulation layer and the second encapsulation layer is one or more of plain knit, variable plain knit, rib, and mesh structures; wherein the rib structure can reduce the thickness of the fabric in this region, while the mesh structure can significantly improve the air permeability and moisture permeability of the fabric.

[0021] As described above, in the flexible piezoresistive sensing array based on the triangular truss grid structure weft knitted spacer fabric, multiple independent first electrodes in the first electrode layer along the longitudinal direction of the spacer fabric are integrally embedded in the first encapsulation layer in one or a combination of two of the following: yarn filling structure, tucked structure, and warp filling structure.

[0022] Multiple independent second electrodes in the second electrode layer, which are spaced along the transverse direction of the fabric, are integrally embedded in the second encapsulation layer using one or a combination of yarn-padded and tucked weave structures.

[0023] As described above, in the flexible piezoresistive sensing array based on weft-knitted spacer fabric, the conductive yarns that knit the first electrode layer and the second electrode layer are referred to as electrode yarns. The electrode yarns are one or more of metal conductive yarns, carbon-based conductive yarns, conductive polymer yarns, and yarns coated with conductive materials. The resistance of the electrode yarns is 0.01~2 Ω / cm.

[0024] As described above, in the flexible piezoresistive sensing array based on weft-knitted spacer fabric, the conductive yarn that weaves the piezoresistive sensitive region A1 is referred to as the piezoresistive sensitive yarn. The piezoresistive sensitive yarn is one or more of the following: metal conductive yarn, carbon-based conductive yarn, conductive polymer yarn, and conductive material-plated yarn. The resistance of the piezoresistive sensitive yarn is 1000~1000000 Ω / cm.

[0025] The flexible piezoresistive sensing array based on the weft-knitted spacer fabric of the triangular truss grid structure described above uses insulating yarns that are independently selected from one or more of the following: cotton, wool, silk, linen, polyester, nylon, acrylic, chlorofiber, acrylic-chlorofiber, polypropylene, vinylon, spandex, glass fiber, aramid, polyimide fiber, acrylic pre-oxidized yarn, viscose, Tencel, Lyocell, Modal, cellulose acetate, and cuprammonium fiber.

[0026] The flexible piezoresistive sensing array based on the weft-knitted spacer fabric of the triangular truss grid structure described above has a thickness of 1~10 mm, an air permeability of ≥300 mm / s, and a moisture permeability of ≥200 g / (m²•24h).

[0027] The flexible piezoresistive sensing array based on the weft-knitted spacer fabric of the triangular truss grid structure, as described above, has a baseline resistance change rate of no more than 5% after 100,000 cycles of compression under cyclic compression test conditions with a pressure amplitude of 0~50 kPa and zero pressure.

[0028] The flexible piezoresistive sensing array based on the weft-knitted spacer fabric of the triangular truss mesh structure, as described above, is knitted using a flat knitting machine equipped with two needle beds.

[0029] The piezoresistive sensing region A is prepared by weaving three types of yarn: insulating yarn, electrode yarn, and piezoresistive sensitive yarn. The weaving process is as follows:

[0030] Step 1: The insulating yarn is woven in plain knit or modified plain knit on the first needle bed to form an insulating row of the first encapsulation layer; the electrode yarn is woven in a padded or tucked structure and is integrally embedded in the insulating row to form an electrode row of the first electrode layer.

[0031] Step 2: The pressure-sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, to form the first spacer layer row of the spacer layer of the spacer fabric;

[0032] Step 3: The insulating yarn is woven in plain knit or modified plain knit on the second needle bed to form an insulating row of the second encapsulation layer; the electrode yarn is woven in a padded or tucked structure and is integrally embedded in the insulating row to form an electrode row of the second electrode layer.

[0033] Step 4: The pressure-sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, to form the second spacer layer row of the spacer fabric.

[0034] Repeat steps 1 to 4 until the weaving of the piezoresistive sensing area A is complete;

[0035] The non-piezoresistive sensing region B is prepared by weaving two types of yarn, namely insulating yarn and electrode yarn, and the weaving method is as follows:

[0036] The insulating yarn is woven in plain stitch, varied plain stitch, rib or mesh structure in the first and second needle beds to form the insulating rows of the first and second encapsulation layers;

[0037] When the insulating yarn is woven in plain knit or a modified plain knit structure on the first and second needle beds, the spacer fabric spacer layer is formed by alternately looping another insulating yarn on the first and second needle beds, or not woven to form an air layer structure.

[0038] When the insulating yarn is woven in a rib or mesh structure in the first and second needle beds, the spacer fabric spacer layer is not woven.

[0039] In the warp direction of the fabric, the electrode yarn is integrally embedded in the insulating row of the first encapsulation layer in one or more combinations of yarn-adding structure, tuck structure and warp-lining structure, and serves as a signal wire to connect two adjacent piezoresistive sensing areas in the warp direction of the fabric.

[0040] In the transverse direction of the fabric, the electrode yarn is integrally embedded in the insulating transverse of the second encapsulation layer using one or a combination of yarn-adding and loop-knitting structures, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the transverse direction of the fabric.

[0041] Based on the above weaving method, the number and spatial distribution of the piezoresistive sensing area are precisely controlled through the weaving process, and a sensing array containing multiple independent longitudinal first electrodes and multiple independent transverse second electrodes is directly woven. The intersection nodes of the first and second electrodes form multiple independent piezoresistive sensing units, constituting a highly integrated piezoresistive sensing system, thus completing the weaving of a flexible piezoresistive sensing array based on a weft-knitted spacer fabric with a triangular truss grid structure.

[0042] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0043] (1) The present invention provides a flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric. By embedding the piezoresistive sensitive yarn into the electrode layer by knitting it in two consecutive alternating loops, a cross-linked triangular truss mesh structure is formed, which gives the sensor excellent compression resilience and structural stability. By constructing a triangular truss mesh conductive network, the dynamic contact reorganization of the piezoresistive sensitive yarn under pressure greatly improves the conductive path reconstruction rate, effectively reduces the contact resistance fluctuation amplitude of the sensing unit, solves the signal drift problem caused by yarn slippage in traditional fabric sensors, and achieves ultra-stable sensing performance under dynamic load. Under cyclic compression test with pressure amplitude of 0~50 kPa, after 100,000 compression cycles, the baseline resistance change rate of the sensor does not exceed 5%.

[0044] (2) The present invention provides a flexible piezoresistive sensing array based on a triangular truss grid structure weft-knitted spacer fabric. By weft knitting process, the electrode layer, piezoresistive sensitive layer and encapsulation layer are woven simultaneously, breaking through the interface layering bottleneck problem of traditional step-by-step composite process. It supports the customization of non-uniform arrays (such as gradient density distribution) and seamless bonding with irregular curved surfaces. The process-function integration provides a mass-producible technical solution for wearable devices, smart homes and robot tactile perception scenarios. Attached Figure Description

[0045] Figure 1 This is an exploded view of the flexible piezoresistive sensing array according to Embodiment 1 of the present invention;

[0046] Figure 2 This is an exploded view of the knitted structure of the flexible piezoresistive sensing array in Embodiment 1 of the present invention;

[0047] Figure 3 This is a schematic diagram of the knitted structure of a sensing unit in the flexible piezoresistive sensing array of Embodiment 1 of the present invention.

[0048] Figure 4 This is a schematic diagram of the knitted structure of the cross-row cross-linked triangular truss mesh structure of Embodiment 1 of the present invention;

[0049] Figure 5This is a schematic diagram of the functional partitioning of the flexible piezoresistive sensing array in Embodiment 1 of the present invention; Figure 5 In the diagram, A represents the piezoresistive sensing region A, and B represents the non-piezoresistive sensing region B.

[0050] Figure 6 This is a schematic diagram of the functional partitioning of the spacer fabric of the flexible piezoresistive sensing array in Embodiment 1 of the present invention. Figure 6 In the diagram, A1 represents the piezoresistive sensitive region A1, and B1 represents the non-piezoresistive sensitive region B1;

[0051] Figure 7 This is a schematic diagram of the weaving of the first electrode layer and the first encapsulation layer of the flexible piezoresistive sensing array according to Embodiment 1 of the present invention;

[0052] Figure 8 This is a schematic diagram of the weaving of the second electrode layer and the second encapsulation layer of the flexible piezoresistive sensing array in Embodiment 1 of the present invention;

[0053] Figure 9 This is a schematic diagram of the weaving of the spacer fabric of the flexible piezoresistive sensing array in Embodiment 1 of the present invention;

[0054] Figure 10 This is a schematic diagram of the weaving process of the flexible piezoresistive sensing array in Embodiment 1 of the present invention;

[0055] Figure 11 This is a weaving diagram of the cross-row cross-linked triangular truss mesh structure weft-knitted spacer fabric of Embodiment 1 of the present invention;

[0056] Figure 12 This is an exploded view of the flexible piezoresistive sensing array according to Embodiment 2 of the present invention;

[0057] Figure 13 This is an exploded view of the flexible piezoresistive sensing array according to Embodiment 3 of the present invention;

[0058] Figure 14 This is an exploded view of the flexible piezoresistive sensing array according to Embodiment 4 of the present invention;

[0059] Figure 15 This is a weaving diagram of the cross-row cross-linked triangular truss mesh structure weft-knitted spacer fabric of Embodiment 4 of the present invention;

[0060] Wherein, 1 is the first encapsulation layer; 2 is the first electrode layer; 3 is the spacer fabric spacer layer; 3-1 is the first spacer layer row; 3-2 is the second spacer layer row; 4 is the second electrode layer; and 5 is the second encapsulation layer. Detailed Implementation

[0061] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0062] The performance index testing method of this invention is as follows:

[0063] Air permeability: Tested according to GB / T5453-1997 standard.

[0064] Moisture permeability: Tested according to GB / T 12704.1-2009 standard.

[0065] The method for testing the baseline resistance change rate is as follows:

[0066] Step 1: Initial resistance measurement;

[0067] The sensor was equilibrated for 24 hours at a temperature of 20 ± 2℃ and a relative humidity of 65 ± 2%. The sensor resistance was then measured under zero pressure and recorded as follows. (Three measurements were taken, and the arithmetic mean was used).

[0068] Step 2: Load Cyclic Test;

[0069] Pressure range: 0~50 kPa;

[0070] Loop count: 100,000;

[0071] Step 3: Restore and measure the resistance after cyclic compression;

[0072] After the cyclic compression test, the sensor was left to stand for 2 hours at a temperature of 20 ± 2℃ and a relative humidity of 65 ± 2%. Then, the sensor resistance was measured under zero pressure and recorded as follows. (Three measurements were taken, and the arithmetic mean was used).

[0073] Step 4: Calculation of baseline resistance change rate, the calculation method is as follows:

[0074]

[0075] Example 1

[0076] Flexible piezoresistive sensing array based on weft-knitted spacer fabric with triangular truss grid structure, such as Figures 1-3 As shown, the five-layer composite structure is integrally woven by weft knitting process, and from top to bottom are the first encapsulation layer 1, the first electrode layer 2, the spacer fabric spacer layer 3, the second electrode layer 4, and the second encapsulation layer 5.

[0077] The first encapsulation layer 1 and the second encapsulation layer 5 are woven from insulating yarns and are the upper and lower layers of the spacer fabric, respectively.

[0078] like Figure 7 As shown, the first electrode layer 2, woven from electrode yarns, contains multiple independent first electrodes spaced along the longitudinal direction of the fabric, and is integrally embedded in the first encapsulation layer 1 using a yarn-filling structure.

[0079] like Figure 8 As shown, the second electrode layer 4, woven from electrode yarns, contains multiple independent second electrodes arranged along the transverse direction of the spaced fabric, and is integrally embedded in the second encapsulation layer 5 using a yarn-filling structure.

[0080] like Figure 4 As shown, the spacer fabric spacer layer 3 is a three-dimensional elastic support structure, consisting of multiple first spacer layer rows 3-1 and multiple second spacer layer rows 3-2 formed by alternating weaving loops on the upper and lower layers of the spacer fabric; the first spacer layer rows 3-1 and the second spacer layer rows 3-2 are arranged alternately in the spacer fabric and are connected end to end to form a cross-row cross-linked triangular truss grid structure.

[0081] like Figure 5 and Figure 6 As shown, multiple first electrodes in the first electrode layer 2 and multiple second electrodes in the second electrode layer 4 form multiple intersection regions on the spacer fabric, and the multiple intersection regions constitute multiple piezoresistive sensing regions A; the spacer fabric spacer layer 3 has a piezoresistive sensitive region A1 in the piezoresistive sensing region A, and the resistance value of the piezoresistive sensitive region A1 changes with the pressure.

[0082] like Figure 9 and Figure 10 As shown, the piezoresistive sensitive area A1 is woven from piezoresistive sensitive yarn. The piezoresistive sensitive yarn is woven into a cross-sectional cross-linked triangular truss grid structure by knitting the loops twice in succession, and simultaneously connecting the first electrode layer 2 and the second electrode layer 4.

[0083] The non-intersecting areas of the multiple first electrodes in the first electrode layer 2 and the multiple second electrodes in the second electrode layer 4 on the spacer fabric, as well as the non-electrode areas of the first encapsulation layer 1 and the second encapsulation layer 5, constitute a non-piezoresistive sensing area B. The spacer fabric spacer layer 3 provides a non-piezoresistive sensitive area B1 in the non-piezoresistive sensing area B. The non-piezoresistive sensitive area B1 is used to isolate the adjacent piezoresistive sensing area A and to lay signal wires.

[0084] The non-piezoresistive sensitive area B1 is not woven;

[0085] In the piezoresistive sensing region A, the structure of the first encapsulation layer 1 and the second encapsulation layer 5 is a flat needle structure.

[0086] In the non-piezoresistive sensing region B, the structure of the first encapsulation layer 1 and the second encapsulation layer 5 is a flat needle structure.

[0087] The aforementioned flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric was woven using a computerized flat knitting machine with two needle beds. The machine gauge was 14 gauge. The specific fabrication steps for the piezoresistive sensing region A and the non-piezoresistive sensing region B are as follows:

[0088] (1) Material selection;

[0089] Insulating yarn: 2 strands of polyester with a linear density of 200 D;

[0090] Electrode yarn: silver-plated nylon, manufacturer: Qingdao Tianyin Textile Technology Co., Ltd., linear density 280 D, resistance 2 Ω / cm;

[0091] Piezoresistive sensitive yarn: Polyester core conductive yarn, manufacturer: Haining Taixin New Material Co., Ltd., linear density 100D, resistance 1,000,000 Ω / cm.

[0092] (2) The weaving method for the piezoresistive sensing region A is as follows: it is prepared by weaving three types of yarn, namely insulating yarn, electrode yarn and piezoresistive sensitive yarn, such as Figure 11 As shown, the weaving process of the piezoresistive sensing region A is as follows:

[0093] Step 1: The insulating yarn is woven in plain stitch on the first needle bed to form an insulating row of the first encapsulation layer 1; the electrode yarn is woven in a padded stitch and is integrally embedded in the insulating row to form an electrode row of the first electrode layer 2.

[0094] Step 2: The pressure-sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, to form the first spacer layer row 3-1 of the spacer layer 3 of the spacer fabric.

[0095] Step 3: The insulating yarn is woven in plain stitch on the second needle bed to form an insulating row of the second encapsulation layer 5; the electrode yarn is woven in a padded stitch and is integrally embedded in the insulating row to form an electrode row of the second electrode layer 4.

[0096] Step 4: The pressure-sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, to form the second spacer layer row 3-2 of the spacer layer 3 of the spacer fabric.

[0097] Repeat steps 1 to 4 until the weaving of the piezoresistive sensing area A is complete;

[0098] (3) The non-piezoresistive sensing region B is prepared by weaving two types of yarn, namely insulating yarn and electrode yarn, and the weaving method is as follows:

[0099] The insulating yarn is woven in plain stitch on the first and second needle beds to form insulating rows of the first and second encapsulation layers;

[0100] The spacer fabric spacer layer is not woven, forming an air layer structure;

[0101] In the warp direction of the fabric, the electrode yarn is integrally embedded in the insulating row of the first encapsulation layer using a yarn-adding structure, and serves as a signal wire to connect two adjacent piezoresistive sensing areas in the warp direction of the fabric.

[0102] In the transverse direction of the fabric, the electrode yarn is integrally embedded in the insulating transverse of the second encapsulation layer using a yarn-adding structure, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the transverse direction of the fabric.

[0103] Based on the above weaving method, the number and spatial distribution of the piezoresistive sensing area are precisely controlled through the weaving process, and a sensing array containing 4 columns of vertical first electrodes and 4 rows of horizontal second electrodes is directly woven. The intersection nodes form 16 independent piezoresistive sensing units, constituting a highly integrated 4×4 piezoresistive sensing system.

[0104] The flexible piezoresistive sensing array based on the triangular truss grid structure weft knitted spacer fabric has a thickness of 3 mm, an air permeability of 400 mm / s, and a moisture permeability of 250 g / (m²•24h). Under cyclic compression tests with a pressure amplitude of 0~50 kPa, after 100,000 cycles of compression, the baseline resistance change rate under zero pressure is 4.3%.

[0105] Comparative Example 1

[0106] The flexible piezoresistive sensing array based on weft-knitted spacer fabric is basically the same as in Example 1, except that the weaving method of its piezoresistive sensing area is different from that in Example 1. Its piezoresistive sensing area is woven using the traditional weft-knitted spacer fabric weaving method, so no cross-column cross-linked triangular truss grid structure is formed, and the piezoresistive sensitive yarns between adjacent columns are not physically connected to each other.

[0107] The weaving method for its piezoresistive sensing area is as follows: it is prepared by weaving three types of yarn, namely insulating yarn, electrode yarn, and piezoresistive sensitive yarn. The weaving process is as follows:

[0108] Step 1: The insulating yarn is woven in plain stitch on the first needle bed to form an insulating row of the first encapsulation layer; the electrode yarn is woven in a padded stitch and is integrally embedded in the insulating row to form an electrode row of the first electrode layer.

[0109] Step 2: The insulating yarn is woven in plain knit on the second needle bed to form an insulating row of the second encapsulation layer; the electrode yarn is woven in a padded knit and integrally embedded in the insulating row to form an electrode row of the second electrode layer.

[0110] Step 3: The pressure-sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, to form the first spacer layer row of the spacer layer of the spacer fabric;

[0111] Repeat steps 1-3 until the weaving of the piezoresistive sensing area is complete.

[0112] The thickness of the piezoresistive sensing array is 4 mm, the air permeability is 520 mm / s, and the moisture permeability is 310 g / (m²•24h). Under cyclic compression tests with a pressure amplitude of 0~50 kPa, after 100,000 cycles of compression, the baseline resistance change rate under zero pressure is 21.3%.

[0113] Comparing Comparative Example 1 and Example 1, it can be found that the air permeability and moisture permeability of the piezoresistive sensor array in Comparative Example 1 are improved, but its stability is significantly reduced. This is because the number and density of piezoresistive sensitive yarns in the spacer fabric spacer layer of Comparative Example 1 are reduced, thus improving air permeability and moisture permeability. However, Comparative Example 1 uses a traditional weft-knitted spacer fabric weaving method, which does not form a cross-column cross-linked triangular truss grid structure. The piezoresistive sensitive yarns between adjacent columns have no physical connection, resulting in strong randomness in yarn contact and separation during compression. Furthermore, the spacer layer yarn structure has poor stability, causing slippage during compression, leading to large resistance fluctuations and a decrease in the long-term stability of the sensor.

[0114] Example 2

[0115] Flexible piezoresistive sensing array based on weft-knitted spacer fabric with triangular truss grid structure, such as Figure 12 As shown, the five-layer composite structure is integrally woven by weft knitting process, and from top to bottom are the first encapsulation layer 1, the first electrode layer 2, the spacer fabric spacer layer 3, the second electrode layer 4, and the second encapsulation layer 5.

[0116] The first encapsulation layer 1 and the second encapsulation layer 5 are woven from insulating yarns and are the upper and lower layers of the spacer fabric, respectively.

[0117] The first electrode layer 2, woven from electrode yarns, contains multiple independent first electrodes spaced along the longitudinal direction of the fabric, and is integrally embedded in the first encapsulation layer 1 using a yarn-filling structure and a warp-lining structure.

[0118] The second electrode layer 4, woven from electrode yarns, contains multiple independent second electrodes arranged along the transverse direction of the spaced fabric, and is integrally embedded in the second encapsulation layer 5 using a yarn-filling structure.

[0119] The spacer fabric spacer layer 3 is a three-dimensional elastic support structure, consisting of multiple first spacer layer rows 3-1 and multiple second spacer layer rows 3-2 formed by alternating weaving loops on the upper and lower layers of the spacer fabric; the first spacer layer rows 3-1 and the second spacer layer rows 3-2 are arranged alternately in the spacer fabric and are connected end to end to form a cross-row cross-linked triangular truss grid structure.

[0120] Multiple first electrodes in the first electrode layer 2 and multiple second electrodes in the second electrode layer 4 form multiple intersection regions on the spacer fabric. The multiple intersection regions constitute multiple piezoresistive sensing regions A. The spacer fabric spacer layer 3 has a piezoresistive sensitive region A1 in the piezoresistive sensing region A. The resistance value of the piezoresistive sensitive region A1 changes with pressure.

[0121] The piezoresistive sensitive area A1 is woven from piezoresistive sensitive yarn; using piezoresistive sensitive yarn, a cross-sectional cross-linked triangular truss grid structure is woven by two consecutive alternating knitting loops, and the first electrode layer 2 and the second electrode layer 4 are connected simultaneously.

[0122] The non-intersecting areas of the multiple first electrodes in the first electrode layer 2 and the multiple second electrodes in the second electrode layer 4 on the spacer fabric, as well as the non-electrode areas of the first encapsulation layer 1 and the second encapsulation layer 5, constitute a non-piezoresistive sensing area B. The spacer fabric spacer layer 3 provides a non-piezoresistive sensitive area B1 in the non-piezoresistive sensing area B. The non-piezoresistive sensitive area B1 is used to isolate the adjacent piezoresistive sensing area A and to lay signal wires.

[0123] The non-piezoresistive sensitive area B1 is not woven;

[0124] In the piezoresistive sensing region A, the structure of the first encapsulation layer and the second encapsulation layer is a 1+1 variable flat needle structure.

[0125] In the non-piezoresistive sensing region B, the structure of the first encapsulation layer and the second encapsulation layer is a 1+1 variable flat needle structure.

[0126] The aforementioned flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric was woven using a computerized flat knitting machine with two needle beds. The machine gauge was 14 gauge. The specific fabrication steps for the piezoresistive sensing region A and the non-piezoresistive sensing region B are as follows:

[0127] (1) Material selection;

[0128] Insulating yarn: 2 strands of polyester with a linear density of 200 D;

[0129] Electrode yarn: 9 strands of copper wire with a diameter of 0.03 mm twisted together, resistance 0.03 Ω / cm;

[0130] Piezoresistive sensitive yarn: Graphene carbon nanotube composite conductive fiber, made of nylon stretched textured yarn coated with graphene carbon nanotube conductive paste, manufacturer: Beijing Tanyang Technology Co., Ltd., linear density 350 D, resistance 1000 Ω / cm.

[0131] (2) The weaving method of the piezoresistive sensing area A is as follows: it is prepared by weaving three kinds of yarn, namely insulating yarn, electrode yarn and piezoresistive sensitive yarn. The weaving process is as follows:

[0132] Step 1: The insulating yarn is woven in a 1+1 variation plain knit weave on the first needle bed to form an insulating row of the first encapsulation layer; the electrode yarn is woven in a padded weave and is integrally embedded in the insulating row to form an electrode row of the first electrode layer.

[0133] Step 2: The pressure-sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, to form the first spacer layer row of the spacer layer of the spacer fabric;

[0134] Step 3: The insulating yarn is woven in a 1+1 variation plain knit weave on the second needle bed to form an insulating row of the second encapsulation layer; the electrode yarn is woven with a padding weave and is integrally embedded in the insulating row to form an electrode row of the second electrode layer.

[0135] Step 4: The pressure-sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, to form the second spacer layer row of the spacer fabric.

[0136] Repeat steps 1 to 4 until the weaving of the piezoresistive sensing area A is complete;

[0137] (3) The non-piezoresistive sensing region B is prepared by weaving two types of yarn, namely insulating yarn and electrode yarn, and the weaving method is as follows:

[0138] The insulating yarn is woven in a 1+1 variation plain knit structure on the first and second needle beds to form the insulating rows of the first and second encapsulation layers.

[0139] The spacer fabric spacer layer is not woven, forming an air layer structure;

[0140] In the warp direction of the fabric, the electrode yarn is integrally embedded in the insulating row of the first encapsulation layer using a lining weave, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the warp direction of the fabric.

[0141] In the transverse direction of the fabric, the electrode yarn is integrally embedded in the insulating transverse of the second encapsulation layer using a yarn-adding structure, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the transverse direction of the fabric.

[0142] Based on the above weaving method, the number and spatial distribution of the piezoresistive sensing area are precisely controlled through the weaving process, and a sensing array containing 4 columns of vertical first electrodes and 4 rows of horizontal second electrodes is directly woven. The intersection nodes form 16 independent piezoresistive sensing units, constituting a highly integrated 4×4 piezoresistive sensing system.

[0143] The flexible piezoresistive sensing array based on the triangular truss grid structure weft-knitted spacer fabric has a thickness of 4.2 mm, an air permeability of 350 mm / s, and a moisture permeability of 260 g / (m²•24h). Under cyclic compression tests with a pressure amplitude of 0~50 kPa, after 100,000 cycles of compression, the baseline resistance change rate under zero pressure is 4.8%.

[0144] Example 3

[0145] Flexible piezoresistive sensing array based on weft-knitted spacer fabric with triangular truss grid structure, such as Figure 13 As shown, the five-layer composite structure is integrally woven by weft knitting process, and from top to bottom are the first encapsulation layer 1, the first electrode layer 2, the spacer fabric spacer layer 3, the second electrode layer 4, and the second encapsulation layer 5.

[0146] The first encapsulation layer 1 and the second encapsulation layer 5 are woven from insulating yarns and are the upper and lower layers of the spacer fabric, respectively.

[0147] The first electrode layer 2, woven from electrode yarns, contains multiple independent first electrodes spaced along the longitudinal direction of the fabric, and is integrally embedded in the first encapsulation layer 1 using a yarn-filling structure.

[0148] The second electrode layer 4, woven from electrode yarns, contains multiple independent second electrodes arranged along the transverse direction of the spaced fabric, and is integrally embedded in the second encapsulation layer 5 using a yarn-filling structure.

[0149] The spacer fabric spacer layer 3 is a three-dimensional elastic support structure, consisting of multiple first spacer layer rows 3-1 and multiple second spacer layer rows 3-2 formed by alternating weaving loops on the upper and lower layers of the spacer fabric; the first spacer layer rows 3-1 and the second spacer layer rows 3-2 are arranged alternately in the spacer fabric and are connected end to end to form a cross-row cross-linked triangular truss grid structure.

[0150] Multiple first electrodes in the first electrode layer 2 and multiple second electrodes in the second electrode layer 4 form multiple intersection regions on the spacer fabric. The multiple intersection regions constitute multiple piezoresistive sensing regions A. The spacer fabric spacer layer 3 has a piezoresistive sensitive region A1 in the piezoresistive sensing region A. The resistance value of the piezoresistive sensitive region A1 changes with pressure.

[0151] The piezoresistive sensitive area A1 is woven from piezoresistive sensitive yarn; using piezoresistive sensitive yarn, a cross-sectional cross-linked triangular truss grid structure is woven by two consecutive alternating knitting loops, and the first electrode layer 2 and the second electrode layer 4 are connected simultaneously.

[0152] The non-intersecting areas of the multiple first electrodes in the first electrode layer 2 and the multiple second electrodes in the second electrode layer 4 on the spacer fabric, as well as the non-electrode areas of the first encapsulation layer 1 and the second encapsulation layer 5, constitute a non-piezoresistive sensing area B. The spacer fabric spacer layer 3 provides a non-piezoresistive sensitive area B1 in the non-piezoresistive sensing area B. The non-piezoresistive sensitive area B1 is used to isolate the adjacent piezoresistive sensing area A and to lay signal wires.

[0153] The non-piezoresistive sensitive area B1 is not woven;

[0154] In the piezoresistive sensing region A, the structure of the first and second encapsulation layers is a flat needle structure;

[0155] In the non-piezoresistive sensing region B, the structure of the first and second encapsulation layers is a mesh structure.

[0156] The aforementioned flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric was woven using a computerized flat knitting machine with two needle beds. The machine's gauge was 18 gauge. The specific fabrication steps for the piezoresistive sensing region A and the non-piezoresistive sensing region B are as follows:

[0157] (1) Material selection;

[0158] Insulating yarn: Nylon, linear density 210 D;

[0159] Electrode yarn: 7 strands of copper wire with a diameter of 0.03 mm twisted together, resistance 0.05 Ω / cm;

[0160] Piezoresistive sensitive yarn: Graphene carbon nanotube composite conductive fiber, made of nylon stretched textured yarn coated with graphene carbon nanotube conductive paste, manufacturer: Beijing Tanyang Technology Co., Ltd., linear density 280 D, resistance 5000 Ω / cm.

[0161] (2) The weaving method of the piezoresistive sensing area A is as follows: it is prepared by weaving three kinds of yarn, namely insulating yarn, electrode yarn and piezoresistive sensitive yarn. The weaving process is as follows:

[0162] Step 1: The insulating yarn is woven in plain stitch on the first needle bed to form an insulating row of the first encapsulation layer; the electrode yarn is woven in a padded stitch and is integrally embedded in the insulating row to form an electrode row of the first electrode layer.

[0163] Step 2: The pressure-sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, to form the first spacer layer row of the spacer layer of the spacer fabric;

[0164] Step 3: The insulating yarn is woven in plain stitch on the second needle bed to form an insulating row of the second encapsulation layer; the electrode yarn is woven in a padded stitch and is integrally embedded in the insulating row to form an electrode row of the second electrode layer.

[0165] Step 4: The pressure-sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, to form the second spacer layer row of the spacer fabric.

[0166] Repeat steps 1 to 4 until the weaving of the piezoresistive sensing area A is complete;

[0167] (3) The non-piezoresistive sensing region B is prepared by weaving two types of yarn, namely insulating yarn and electrode yarn, and the weaving method is as follows:

[0168] The insulating yarn is woven in a mesh structure in the first and second needle beds to form insulating rows of the first and second encapsulation layers;

[0169] The spacer fabric spacer layer is not woven;

[0170] In the warp direction of the fabric, the electrode yarn is integrally embedded in the insulating row of the first encapsulation layer using a yarn-adding structure, and serves as a signal wire to connect two adjacent piezoresistive sensing areas in the warp direction of the fabric.

[0171] In the transverse direction of the fabric, the electrode yarn is integrally embedded in the insulating transverse of the second encapsulation layer using a yarn-adding structure, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the transverse direction of the fabric.

[0172] Based on the above weaving method, the number and spatial distribution of the piezoresistive sensing area are precisely controlled through the weaving process, and a sensing array containing 4 columns of vertical first electrodes and 4 rows of horizontal second electrodes is directly woven. The intersection nodes form 16 independent piezoresistive sensing units, constituting a highly integrated 4×4 piezoresistive sensing system.

[0173] The flexible piezoresistive sensing array based on the triangular truss grid structure weft-knitted spacer fabric has a thickness of 2 mm, an air permeability of 800 mm / s, and a moisture permeability of 790 g / (m²•24h). Under cyclic compression tests with a pressure amplitude of 0~50 kPa, after 100,000 cycles of compression, the baseline resistance change rate under zero pressure is 4.9%.

[0174] Example 4

[0175] Flexible piezoresistive sensing array based on weft-knitted spacer fabric with triangular truss grid structure, such as Figure 14As shown, the five-layer composite structure is integrally woven by weft knitting process, and from top to bottom are the first encapsulation layer 1, the first electrode layer 2, the spacer fabric spacer layer 3, the second electrode layer 4, and the second encapsulation layer 5.

[0176] The first encapsulation layer 1 and the second encapsulation layer 5 are woven from insulating yarns and are the upper and lower layers of the spacer fabric, respectively.

[0177] The first electrode layer 2, woven from electrode yarns, contains multiple independent first electrodes spaced along the longitudinal direction of the fabric, and is integrally embedded in the first encapsulation layer 1 using a loop weave.

[0178] The second electrode layer 4, woven from electrode yarns, contains multiple independent second electrodes arranged along the transverse direction of the spaced fabric, and is integrally embedded in the second encapsulation layer 5 using a loop weave.

[0179] The spacer fabric spacer layer 3 is a three-dimensional elastic support structure, consisting of multiple first spacer layer rows 3-1 and multiple second spacer layer rows 3-2 formed by alternating weaving loops on the upper and lower layers of the spacer fabric; the first spacer layer rows 3-1 and the second spacer layer rows 3-2 are arranged alternately in the spacer fabric and are connected end to end to form a cross-row cross-linked triangular truss grid structure.

[0180] Multiple first electrodes in the first electrode layer 2 and multiple second electrodes in the second electrode layer 4 form multiple intersection regions on the spacer fabric. The multiple intersection regions constitute multiple piezoresistive sensing regions A. The spacer fabric spacer layer 3 has a piezoresistive sensitive region A1 in the piezoresistive sensing region A. The resistance value of the piezoresistive sensitive region A1 changes with pressure.

[0181] The piezoresistive sensitive area A1 is woven from piezoresistive sensitive yarn; using piezoresistive sensitive yarn, a cross-sectional cross-linked triangular truss grid structure is woven by two consecutive alternating knitting loops, and the first electrode layer 2 and the second electrode layer 4 are connected simultaneously.

[0182] The non-intersecting areas of the multiple first electrodes in the first electrode layer 2 and the multiple second electrodes in the second electrode layer 4 on the spacer fabric, as well as the non-electrode areas of the first encapsulation layer 1 and the second encapsulation layer 5, constitute a non-piezoresistive sensing area B. The spacer fabric spacer layer 3 provides a non-piezoresistive sensitive area B1 in the non-piezoresistive sensing area B. The non-piezoresistive sensitive area B1 is used to isolate the adjacent piezoresistive sensing area A and to lay signal wires.

[0183] The non-piezoresistive sensitive area B1 is not woven;

[0184] In the piezoresistive sensing region A, the structure of the first and second encapsulation layers is a flat needle structure;

[0185] In the non-piezoresistive sensing region B, the structure of the first and second encapsulation layers is a ribbed structure.

[0186] The aforementioned flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric was woven using a computerized flat knitting machine with two needle beds. The machine gauge was 14 gauge. The specific fabrication steps for the piezoresistive sensing region A and the non-piezoresistive sensing region B are as follows:

[0187] (1) Material selection;

[0188] Insulating yarn: 4 strands of nylon with a linear density of 140 D;

[0189] Electrode yarn: 9 strands of copper wire with a diameter of 0.03 mm twisted together, resistance 0.03 Ω / cm;

[0190] Piezoresistive sensitive yarn: Polyester core conductive elastic yarn, manufacturer: Beijing Tanyang Technology Co., Ltd., linear density 160D, resistance 500000 Ω / cm.

[0191] (2) The weaving method for the piezoresistive sensing region A is as follows: it is prepared by weaving three types of yarn, namely insulating yarn, electrode yarn and piezoresistive sensitive yarn, such as Figure 15 As shown, the weaving process is as follows:

[0192] Step 1: The insulating yarn is woven in plain stitch on the first needle bed to form an insulating row of the first encapsulation layer; the electrode yarn is tucked in loop and embedded in the insulating row to form an electrode row of the first electrode layer.

[0193] Step 2: The pressure-sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, to form the first spacer layer row of the spacer layer of the spacer fabric;

[0194] Step 3: The insulating yarn is woven in plain knit on the second needle bed to form an insulating row of the second encapsulation layer; the electrode yarn is tucked in a loop and embedded in the insulating row to form an electrode row of the second electrode layer.

[0195] Step 4: The pressure-sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, to form the second spacer layer row of the spacer fabric.

[0196] Repeat steps 1 to 4 until the weaving of the piezoresistive sensing area A is complete;

[0197] (3) The non-piezoresistive sensing region B is prepared by weaving two types of yarn, namely insulating yarn and electrode yarn, and the weaving method is as follows:

[0198] The insulating yarn is woven in a rib structure in the first and second needle beds to form insulating rows of the first and second encapsulation layers;

[0199] The spacer fabric spacer layer is not woven;

[0200] In the warp direction of the fabric, the electrode yarn is embedded in the insulating row of the first encapsulation layer using a loop weave and serves as a signal wire to connect two adjacent piezoresistive sensing areas in the warp direction of the fabric.

[0201] In the transverse direction of the fabric, the electrode yarn is embedded in the insulating transverse of the second encapsulation layer using a loop weave and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the transverse direction of the fabric.

[0202] Based on the above weaving method, the number and spatial distribution of the piezoresistive sensing area are precisely controlled through the weaving process, and a sensing array containing 4 columns of vertical first electrodes and 4 rows of horizontal second electrodes is directly woven. The intersection nodes form 16 independent piezoresistive sensing units, constituting a highly integrated 4×4 piezoresistive sensing system.

[0203] The flexible piezoresistive sensing array based on the triangular truss grid structure weft-knitted spacer fabric has a thickness of 4.1 mm, an air permeability of 450 mm / s, and a moisture permeability of 360 g / (m²•24h). Under cyclic compression tests with a pressure amplitude of 0~50 kPa, after 100,000 cycles of compression, the baseline resistance change rate under zero pressure is 4.2%.

[0204] Example 5

[0205] The flexible piezoresistive sensing array based on the triangular truss grid structure weft-knitted spacer fabric is a five-layer composite structure woven in one piece by weft knitting process, consisting of a first encapsulation layer, a first electrode layer, a spacer fabric spacer layer, a second electrode layer, and a second encapsulation layer from top to bottom.

[0206] The first encapsulation layer and the second encapsulation layer are woven from insulating yarns and are the upper and lower layers of the spacer fabric, respectively.

[0207] The first electrode layer, woven from electrode yarns, contains multiple independent first electrodes spaced along the longitudinal direction of the fabric, which are integrally embedded in the first encapsulation layer using a yarn-filling structure.

[0208] The second electrode layer, woven from electrode yarns, contains multiple independent second electrodes arranged along the transverse direction of the spaced fabric, and is integrally embedded in the second encapsulation layer using a yarn-filling structure.

[0209] The spacer fabric spacer layer is a three-dimensional elastic support structure, consisting of multiple first spacer layer rows and multiple second spacer layer rows formed by alternating weaving loops on the upper and lower layers of the spacer fabric; the first spacer layer rows and the second spacer layer rows are arranged alternately in the spacer fabric and are connected end to end to form a cross-linked triangular truss grid structure.

[0210] Multiple first electrodes in the first electrode layer and multiple second electrodes in the second electrode layer form multiple intersection regions on the spacer fabric, and the multiple intersection regions constitute multiple piezoresistive sensing regions A; the spacer fabric spacer layer has a piezoresistive sensitive region A1 in the piezoresistive sensing region A, and the resistance value of the piezoresistive sensitive region A1 changes with pressure.

[0211] The piezoresistive sensitive area A1 is woven from piezoresistive sensitive yarn; using piezoresistive sensitive yarn, a cross-sectional cross-linked triangular truss grid structure is woven by two consecutive alternating knitting loops, and the first electrode layer 2 and the second electrode layer 4 are connected simultaneously.

[0212] The non-intersecting areas of the multiple first electrodes in the first electrode layer and the multiple second electrodes in the second electrode layer on the spacer fabric, as well as the non-electrode areas of the first encapsulation layer 1 and the second encapsulation layer, constitute a non-piezoresistive sensing area B. The spacer fabric spacer layer provides a non-piezoresistive sensitive area B1 in the non-piezoresistive sensing area B. The non-piezoresistive sensitive area B1 is used to isolate the adjacent piezoresistive sensing area A and to lay signal wires.

[0213] The non-piezoresistive sensitive area B1 is formed by braiding insulating yarn;

[0214] In the piezoresistive sensing region A, the structure of the first and second encapsulation layers is a flat needle structure;

[0215] In the non-piezoresistive sensing region B, the structure of the first and second encapsulation layers is a flat needle structure.

[0216] The aforementioned flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric was woven using a computerized flat knitting machine with two needle beds. The machine's gauge was 10 gauge. The specific fabrication steps for the piezoresistive sensing region A and the non-piezoresistive sensing region B are as follows:

[0217] (1) Material selection;

[0218] Insulating yarn I: Nylon, linear density 600 D;

[0219] Insulating yarn II: polyester monofilament, diameter 0.08 mm;

[0220] Electrode yarn: 9 strands of copper wire with a diameter of 0.05 mm twisted together, resistance 0.01 Ω / cm;

[0221] Piezoresistive sensitive yarn: Low-temperature carbonized pre-oxidized yarn, the pre-oxidized yarn is Shanghai Petrochemical 1K pre-oxidized fiber filament, the low-temperature carbonization temperature is 750 ℃, and the resistance is 60000 Ω / cm.

[0222] (2) The weaving method of the piezoresistive sensing area A is as follows: it is prepared by weaving three kinds of yarn, namely insulating yarn, electrode yarn and piezoresistive sensitive yarn. The weaving process is as follows:

[0223] Step 1: Insulating yarn I is woven in plain knit on the first needle bed to form an insulating row of the first encapsulation layer; the electrode yarn is woven in a padded knit and is integrally embedded in the insulating row to form an electrode row of the first electrode layer.

[0224] Step 2: The piezoresistive sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, to form the first interlayer row of the spacer fabric. The insulating yarn II is woven synchronously with the piezoresistive sensitive yarn as a filler yarn.

[0225] Step 3: Insulating yarn I is woven in plain knit on the second needle bed to form an insulating row of the second encapsulation layer; the electrode yarn is woven with a padding structure and is integrally embedded in the insulating row to form an electrode row of the second electrode layer.

[0226] Step 4: The piezoresistive sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, forming the second interlayer row of the interlayer fabric. The insulating yarn II is woven synchronously with the piezoresistive sensitive yarn as a supplementary yarn.

[0227] Repeat steps 1 to 4 until the weaving of the piezoresistive sensing area A is complete;

[0228] (3) The non-piezoresistive sensing region B is prepared by weaving two types of yarn, namely insulating yarn and electrode yarn, and the weaving method is as follows:

[0229] Insulating yarn I is woven in plain stitch on the first and second needle beds;

[0230] The spacer fabric spacer layer is formed by alternately looping insulating yarn II on the first and second needle beds;

[0231] In the warp direction of the fabric, the electrode yarn is integrally embedded in the insulating row of the first encapsulation layer using a yarn-adding structure, and serves as a signal wire to connect two adjacent piezoresistive sensing areas in the warp direction of the fabric.

[0232] In the transverse direction of the fabric, the yarn-filled structure is integrally embedded in the insulating transverse of the second encapsulation layer and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the transverse direction of the fabric.

[0233] Based on the above weaving method, the number and spatial distribution of the piezoresistive sensing area are precisely controlled through the weaving process, and a sensing array containing 6 columns of vertical first electrodes and 6 rows of horizontal second electrodes is directly woven. The intersection nodes form 36 independent piezoresistive sensing units, constituting a highly integrated 6×6 piezoresistive sensing system.

[0234] The flexible piezoresistive sensing array based on the triangular truss grid structure weft-knitted spacer fabric has a thickness of 8 mm, an air permeability of 700 mm / s, and a moisture permeability of 610 g / (m²•24h). Under cyclic compression test conditions with a pressure amplitude of 0~50 kPa, after 100,000 cycles of compression, the baseline resistance change rate under zero pressure is 4.6%.

[0235] Example 6

[0236] The flexible piezoresistive sensing array based on the triangular truss grid structure weft-knitted spacer fabric is a five-layer composite structure woven in one piece by weft knitting process, consisting of a first encapsulation layer, a first electrode layer, a spacer fabric spacer layer, a second electrode layer, and a second encapsulation layer from top to bottom.

[0237] The first encapsulation layer and the second encapsulation layer are woven from insulating yarns and are the upper and lower layers of the spacer fabric, respectively.

[0238] The first electrode layer includes multiple independent first electrodes spaced along the longitudinal direction of the fabric, which are integrally embedded in the first encapsulation layer using a yarn-filling structure.

[0239] The second electrode layer contains multiple independent second electrodes arranged along the transverse direction of the spaced fabric, which are integrally embedded in the second encapsulation layer using a yarn-filling structure.

[0240] The first electrode layer and the second electrode layer are woven from electrode yarns;

[0241] The spacer fabric spacer layer is a three-dimensional elastic support structure, consisting of multiple first spacer layer rows and multiple second spacer layer rows formed by alternating weaving loops on the upper and lower layers of the spacer fabric; the first spacer layer rows and the second spacer layer rows are arranged alternately in the spacer fabric and are connected end to end to form a cross-linked triangular truss grid structure.

[0242] Multiple first electrodes in the first electrode layer and multiple second electrodes in the second electrode layer form multiple intersection regions on the spacer fabric, and the multiple intersection regions constitute multiple piezoresistive sensing regions A; the spacer fabric spacer layer has a piezoresistive sensitive region A1 in the piezoresistive sensing region A, and the resistance value of the piezoresistive sensitive region A1 changes with pressure.

[0243] The piezoresistive sensitive area A1 is woven from piezoresistive sensitive yarn; using piezoresistive sensitive yarn, a cross-sectional cross-linked triangular truss grid structure is woven by two consecutive alternating knitting loops, and the first electrode layer 2 and the second electrode layer 4 are connected simultaneously.

[0244] The non-intersecting areas of the multiple first electrodes in the first electrode layer and the multiple second electrodes in the second electrode layer on the spacer fabric, as well as the non-electrode areas of the first encapsulation layer and the second encapsulation layer, constitute a non-piezoresistive sensing area B. The spacer fabric spacer layer provides a non-piezoresistive sensitive area B1 in the non-piezoresistive sensing area B. The non-piezoresistive sensitive area B1 is used to isolate the adjacent piezoresistive sensing area A and to lay signal wires.

[0245] The non-piezoresistive sensitive area B1 is not woven;

[0246] In the piezoresistive sensing region A, the structure of the first and second encapsulation layers is a flat needle structure;

[0247] In the non-piezoresistive sensing region B, the structure of the first and second encapsulation layers is a ribbed structure.

[0248] The aforementioned flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric was woven using a computerized flat knitting machine with two needle beds. The machine's gauge was 20 gauge. The specific fabrication steps for the piezoresistive sensing region A and the non-piezoresistive sensing region B are as follows:

[0249] (1) Material selection;

[0250] Insulating yarn: Nylon / spandex double-wrapped yarn, manufacturer: Lilong Textile Technology Co., Ltd., the core yarn is spandex with a linear density of 70 D, and both the inner and outer covering yarns are nylon with a linear density of 140 D;

[0251] Electrode yarn: 7 silver-copper alloy nickel-plated wires with a diameter of 0.03 mm and a resistance of 0.05 Ω / cm;

[0252] Piezoresistive sensitive yarn: Polyester core conductive elastic yarn, manufacturer: Beijing Tanyang Technology Co., Ltd., linear density 88 D, resistance 600000 Ω / cm.

[0253] (2) The weaving method of the piezoresistive sensing area A is as follows: it is prepared by weaving three kinds of yarn, namely insulating yarn, electrode yarn and piezoresistive sensitive yarn. The weaving process is as follows:

[0254] Step 1: The insulating yarn is woven in plain stitch on the first needle bed to form an insulating row of the first encapsulation layer; the electrode yarn is woven in a padded stitch and is integrally embedded in the insulating row to form an electrode row of the first electrode layer.

[0255] Step 2: The pressure-sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, to form the first spacer layer row of the spacer layer of the spacer fabric;

[0256] Step 3: The insulating yarn is woven in plain stitch on the second needle bed to form an insulating row of the second encapsulation layer; the electrode yarn is woven in a padded stitch and is integrally embedded in the insulating row to form an electrode row of the second electrode layer.

[0257] Step 4: The pressure-sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, to form the second spacer layer row of the spacer fabric.

[0258] Repeat steps 1 to 4 until the weaving of the piezoresistive sensing area A is complete;

[0259] (3) The non-piezoresistive sensing region B is prepared by weaving two types of yarn, namely insulating yarn and electrode yarn, and the weaving method is as follows:

[0260] The insulating yarn is woven in a rib structure in the first and second needle beds to form insulating rows of the first and second encapsulation layers;

[0261] The spacer fabric spacer layer is not woven;

[0262] In the warp direction of the fabric, the electrode yarn is integrally embedded in the insulating row of the first encapsulation layer using a yarn-adding structure, and serves as a signal wire to connect two adjacent piezoresistive sensing areas in the warp direction of the fabric.

[0263] In the transverse direction of the fabric, the electrode yarn is integrally embedded in the insulating transverse of the second encapsulation layer using a yarn-adding structure, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the transverse direction of the fabric.

[0264] Based on the above weaving method, the number and spatial distribution of the piezoresistive sensing area are precisely controlled through the weaving process, and a sensing array containing 6 columns of vertical first electrodes and 8 rows of horizontal second electrodes is directly woven. The intersection nodes form 48 independent piezoresistive sensing units, constituting a highly integrated 6×8 piezoresistive sensing system.

[0265] The flexible piezoresistive sensing array based on the triangular truss grid structure weft-knitted spacer fabric has a thickness of 1 mm, an air permeability of 300 mm / s, and a moisture permeability of 200 g / (m²•24h). Under cyclic compression test conditions with a pressure amplitude of 0~50 kPa, after 100,000 cycles of compression, the baseline resistance change rate under zero pressure is 3.9%.

Claims

1. A flexible piezoresistive sensing array based on a weft-knitted spacer fabric with a triangular truss grid structure, characterized in that: It is a five-layer composite structure woven in one piece by weft knitting process, consisting of, from top to bottom, a first encapsulation layer, a first electrode layer, a spacer fabric layer, a second electrode layer, and a second encapsulation layer. The first encapsulation layer and the second encapsulation layer are woven from insulating yarns and are respectively the upper and lower layers of the spacer fabric; The first electrode layer includes a plurality of independent first electrodes along the longitudinal direction of the spacer fabric, and the second electrode layer includes a plurality of independent second electrodes along the transverse direction of the spacer fabric. The first electrode layer and the second electrode layer are woven from conductive yarns. The first electrode layer is integrally embedded in the first encapsulation layer, and the second electrode layer is integrally embedded in the second encapsulation layer. The spacer fabric spacer layer is a three-dimensional elastic support structure, comprising multiple first spacer layer rows and multiple second spacer layer rows formed by alternating weaving loops on the upper and lower layers of the spacer fabric; the first spacer layer rows and the second spacer layer rows are arranged alternately in the spacer fabric and are connected end to end to form a cross-linked triangular truss grid structure. Multiple first electrodes in the first electrode layer and multiple second electrodes in the second electrode layer form multiple intersection regions on the spacer fabric. The multiple intersection regions constitute multiple piezoresistive sensing regions A. The spacer fabric spacer layer provides a piezoresistive sensitive region A1 in the piezoresistive sensing region A. The resistance value of the piezoresistive sensitive region A1 changes with pressure. The non-intersecting areas of the multiple first electrodes in the first electrode layer and the multiple second electrodes in the second electrode layer on the spacer fabric, as well as the non-electrode areas of the first encapsulation layer and the second encapsulation layer, constitute a non-piezoresistive sensing region B. The spacer fabric spacer layer has a non-piezoresistive sensitive region B1 in the non-piezoresistive sensing region B. The non-piezoresistive sensitive region B1 is used to isolate the adjacent piezoresistive sensing region A and to lay signal wires.

2. The flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric according to claim 1, characterized in that, The piezoresistive sensitive area A1 is woven from conductive yarn. The conductive yarn is knitted into a cross-sectional cross-linked triangular truss grid structure by knitting the yarn twice in a row, and the first electrode layer and the second electrode layer are connected simultaneously. The non-piezoresistive sensitive region B1 is formed by braiding insulating yarn, or it may not be braided.

3. The flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric according to claim 2, characterized in that, In the piezoresistive sensing region A, the structure of the first encapsulation layer and the second encapsulation layer is one or more of a flat needle structure and a modified flat needle structure; In the non-piezoresistive sensing region B, the structure of the first encapsulation layer and the second encapsulation layer is one or more of the following: flat needle, variable flat needle, rib, and mesh structure.

4. The flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric according to claim 3, characterized in that, Multiple independent first electrodes in the first electrode layer, which are spaced along the longitudinal direction of the fabric, are integrally embedded in the first encapsulation layer using one or more combinations of yarn-adding structure, tuck structure and warp-insertion structure. Multiple independent second electrodes in the second electrode layer, which are spaced along the transverse direction of the fabric, are integrally embedded in the second encapsulation layer using one or a combination of yarn-padded and tucked weave structures.

5. The flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric according to claim 4, characterized in that, The conductive yarns used to weave the first electrode layer and the second electrode layer are referred to as electrode yarns. The electrode yarns are one or more of the following: metal conductive yarns, carbon-based conductive yarns, conductive polymer yarns, and yarns coated with conductive materials. The resistance of the electrode yarns is 0.01~2 Ω / cm.

6. The flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric according to claim 5, characterized in that, The conductive yarn that weaves the piezoresistive sensitive region A1 is called the piezoresistive sensitive yarn. The piezoresistive sensitive yarn is one or more of the following: metal conductive yarn, carbon-based conductive yarn, conductive polymer yarn, and yarn coated with conductive material. The resistance of the piezoresistive sensitive yarn is 1000~1000000 Ω / cm.

7. The flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric according to claim 6, characterized in that, The insulating yarns used to weave the first encapsulation layer, the second encapsulation layer, and the non-piezoresistive sensitive region B1 of the spacer fabric layer are independently selected from one or more of the following: cotton, wool, silk, linen, polyester, nylon, acrylic, chlorofiber, acrylic-chlorofiber, polypropylene, vinylon, spandex, glass fiber, aramid, polyimide fiber, acrylic pre-oxidized yarn, viscose, Tencel, Lyocell, Modal, cellulose acetate, and cuprammonium fiber.

8. The flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric according to claim 7, characterized in that, The thickness of the spacer fabric is 1~10 mm, the air permeability is ≥300 mm / s, and the moisture permeability is ≥200 g / (m²•24h).

9. The flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric according to claim 8, characterized in that, Under cyclic compression test conditions with a pressure amplitude of 0~50 kPa, after 100,000 cycles of compression, the baseline resistance change rate under zero pressure does not exceed 5%.

10. The flexible piezoresistive sensing array based on a triangular truss mesh structure weft-knitted spacer fabric according to claim 9, characterized in that, The flexible piezoresistive sensing array based on the triangular truss grid structure weft-knitted spacer fabric is knitted using a flat knitting machine with two needle beds; The piezoresistive sensing region A is prepared by weaving three types of yarn: insulating yarn, electrode yarn, and piezoresistive sensitive yarn. The weaving process is as follows: Step 1: The insulating yarn is woven in plain knit or modified plain knit on the first needle bed to form an insulating row of the first encapsulation layer; the electrode yarn is woven in a padded or tucked structure and is integrally embedded in the insulating row to form an electrode row of the first electrode layer. Step 2: The pressure-sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, to form the first spacer layer row of the spacer layer of the spacer fabric; Step 3: The insulating yarn is woven in plain knit or modified plain knit on the second needle bed to form an insulating row of the second encapsulation layer; the electrode yarn is woven in a padded or tucked structure and is integrally embedded in the insulating row to form an electrode row of the second electrode layer. Step 4: The pressure-sensitive yarn is woven in a tucked structure, alternating between the first and second needle beds, to form the second spacer layer row of the spacer fabric. Repeat steps 1 to 4 until the weaving of the piezoresistive sensing area A is complete; The non-piezoresistive sensing region B is prepared by weaving two types of yarn, namely insulating yarn and electrode yarn, and the weaving method is as follows: The insulating yarn is woven in plain stitch, varied plain stitch, rib or mesh structure in the first and second needle beds to form the insulating rows of the first and second encapsulation layers; When the insulating yarn is woven in plain knit or a modified plain knit structure on the first and second needle beds, the spacer fabric spacer layer is formed by alternately looping another insulating yarn on the first and second needle beds, or not woven to form an air layer structure. When the insulating yarn is woven in a rib or mesh structure in the first and second needle beds, the spacer fabric spacer layer is not woven. In the warp direction of the fabric, the electrode yarn is integrally embedded in the insulating row of the first encapsulation layer using one or a combination of two of the following methods: yarn filling structure, loop structure, and warp lining structure. It also serves as a signal conductor, connecting two adjacent piezoresistive sensing areas in the warp direction of the fabric. In the transverse direction of the fabric, the electrode yarn is integrally embedded in the insulating transverse of the second encapsulation layer using one or a combination of yarn-adding and loop-knitting structures, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the transverse direction of the fabric.

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