Flexible piezoresistive sensing array based on triangular truss grid structure weft knitting spacer fabric

Abstract

The invention belongs to the technical field of flexible sensing, and discloses a flexible piezoresistive sensing array based on a triangular truss grid structure weft knitting spacer fabric, which is of a five-layer composite structure integrally woven and formed through a weft knitting process. The first packaging layer, the first electrode layer, the spacer fabric spacer layer, the second electrode layer and the second packaging layer are sequentially arranged from top to bottom; the first packaging layer and the second packaging layer are formed by weaving insulating yarns and are respectively an upper surface layer and a lower surface layer of the spacer fabric; the spacer fabric spacer layer is of a three-dimensional elastic supporting structure and comprises a plurality of first spacer layer transverse rows and a plurality of second spacer layer transverse rows which are formed by alternately weaving the upper face layer and the lower face layer of the spacer fabric through tucking. The first spacing layer transverse rows and the second spacing layer transverse rows are arranged in the spacing fabric in a staggered mode and are sequentially connected end to end to form a transverse row crossing cross-linked type triangular truss grid structure. The flexible piezoresistive sensing array provided by the invention has high structural integrity and long-term stability.

Description

Technical Field

[0001] The present invention belongs to the field of flexible sensing technology, and in particular relates to a flexible piezoresistive sensing array based on a weft-knitted spacer fabric with a triangular truss grid structure. Background Art

[0002] Piezoresistive array sensors are based on the piezoresistive effect of materials (the physical property that resistance changes 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 a packaging layer. They are widely used in areas such as detecting occupant presence in car seats, capturing physiological signals 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 base layer need to be processed step by step through coating, lamination, and other processes, which are prone to stratification and lack long-term stability; (3) The multi-layer stacking structure hinders air and moisture exchange, and long-term wear can easily cause skin discomfort.

[0004] To overcome these shortcomings, researchers have begun 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) proposes a piezoresistive array sensor composed of three fabric layers (electrode layer–piezoresistive layer–electrode layer) laminated with thermoplastic polyurethane (TPU). However, the multilayer lamination process is complex, and the sensor suffers from poor flexibility and air permeability. Patent CN202110657122.8 discloses an array sensor based on double-layer fabric lamination, forming sensing units by cross-stacking fabrics containing unidirectional electrodes. However, this method still relies on stacking multiple layers of fabric, resulting in poor long-term sensor stability. Furthermore, the multilayer structure is thick, resulting in poor flexibility and air permeability. Patent CN202011220793.X realizes a multi-layer fabric sensor array through bonding and sewing processes. However, its stacked structure leads to degraded flexibility, low interface bonding strength, insufficient long-term stability, and low air permeability due to the multi-layer dense structure.

[0005] The array sensors with multi-layer fabric structures mentioned above have the following shortcomings: (1) Structural non-integration: the electrode layer and the piezoresistive layer cannot be integrally formed through a textile process and must rely on a subsequent composite or bonding process, resulting in high process complexity and increased costs; (2) Performance-comfort contradiction: the multi-layer stacking or composite structure sacrifices the inherent breathability and softness of the textile substrate; (3) Insufficient long-term stability: the bonding interface is prone to stratification under dynamic pressure, resulting in deterioration of signal stability.

[0006] In response to the shortcomings of array sensors with multi-layer fabric structures, researchers have shifted their research focus to the development of textile-based array sensors with integrated weaving molding processes. For example, patent application CN202311511898.4 discloses a piezoresistive array sensor based on a single-layer fabric. Both the transverse and longitudinal electrodes are woven using a knitted floating wire process, and are electrically connected through a piezoresistive sensitive layer between the electrodes. Although the floating wire electrode structure simplifies the manufacturing process, the electrode layer and the piezoresistive sensitive layer are physically separated structures, which are prone to slippage under load, seriously restricting the stability of the sensor. Patent CN202310420626.7 and Reference 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 from conductive yarns, and the spacer layer is a piezoresistive sensitive layer. However, the sensing units can only be arranged along the longitudinal direction of the fabric, making it impossible to construct a two-dimensional in-plane array (such as a 4×4 array). This cannot meet the requirements for two-dimensional pressure distribution detection in scenarios such as smart mattresses and robot tactile skin. In addition, the piezoresistive sensitive yarns in adjacent horizontal rows in the piezoresistive sensitive layer are not physically connected, and the contact and separation between the yarns during compression are 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. Conductive yarns are introduced into the fabric through localized yarn-insertion technology to form sensing units, and the middle layer uses weft-inserted bulked yarns as a dielectric layer. However, the weft-inserted yarns are arranged in isolation, and random contact and separation during compression lead to large capacitance fluctuations and insufficient sensor stability. Patent CN202311563830.0 discloses a flexible fabric sensor based on warp-knitted spacer fabric. It uses braiding and weft-insertion to integrate longitudinal and transverse electrodes into the upper and lower layers of the fabric, and uses polyester / nylon monofilament to weave a spacer layer. Pressure-resistance response is achieved through electrode contact and separation. However, this technology has the following defects: it relies on a "switch-type" sensing mechanism of electrode contact and separation, which triggers a resistance response only under higher pressure and is completely ineffective for tiny pressures (such as human breathing and pulse); the resistance change 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 externally led through reserved conductive yarns, which require an additional insulating coating layer to prevent short circuits, and its long-term reliability is insufficient.

[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 realize the integrated weaving of the packaging layer, electrode layer and piezoresistive sensitive layer without the need for post-compounding, and fundamentally solve the defect of insufficient long-term stability of the existing technology. Summary of the Invention

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

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] The flexible piezoresistive sensing array based on a triangular truss grid structure weft-knitted spacer fabric is a five-layer composite structure woven and formed in one piece through a weft knitting process. From top to bottom, it consists of a first packaging layer, a first electrode layer, a spacer fabric spacer layer, a second electrode layer, and a second packaging layer.

[0011] 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;

[0012] The first electrode layer comprises a plurality of independent first electrodes along the longitudinal direction of the spacer fabric, and the second electrode layer comprises a plurality of independent second electrodes along the lateral 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 packaging layer, and the second electrode layer is integrally embedded in the second packaging layer.

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

[0014] The plurality of first electrodes in the first electrode layer and the plurality of second electrodes in the second electrode layer form a plurality of intersection regions on the spacer fabric, the plurality of intersection regions constituting a plurality of piezoresistive sensing regions A, the spacer layer of the spacer fabric being provided with piezoresistive sensitive regions A1 in the piezoresistive sensing regions A, the resistance value of the piezoresistive sensitive regions A1 varying 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 packaging layer and the second packaging layer constitute a non-piezoresistive sensing area B. The spacer fabric spacer layer is provided with a non-piezoresistive sensitive area B1 in the non-piezoresistive sensing area B. The non-piezoresistive sensitive area B1 is used to isolate adjacent piezoresistive sensing areas A and lay signal wires.

[0016] As the preferred technical solution:

[0017] In the flexible piezoresistive sensing array based on the weft-knitted spacer fabric with a triangular truss grid structure as described above, the piezoresistive sensitive area A1 is formed by knitting conductive yarns. The conductive yarns are knitted twice in a row through alternating tucking to form a cross-row cross-linked triangular truss grid structure, and the first electrode layer and the second electrode layer are simultaneously connected.

[0018] The non-piezoresistive sensitive area B1 is formed by weaving insulating yarn, or not weaving. The latter is divided into two situations. 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] The flexible piezoresistive sensing array based on the triangular truss grid structure weft-knitted spacer fabric as described above, in the piezoresistive sensing area A, the structures of the first encapsulation layer and the second encapsulation layer are one or more of a plain stitch and a variable plain stitch;

[0020] In the non-piezoresistive sensing area B, the structures of the first packaging layer and the second packaging layer are one or more of plain stitch, variable plain stitch, rib and mesh; the rib structure can reduce the thickness of the fabric in this area, and the mesh structure can greatly improve the air permeability and moisture permeability of the fabric.

[0021] In the flexible piezoresistive sensing array based on the triangular truss grid structure weft-knitted spacer fabric described above, the plurality of independent first electrodes in the first electrode layer and along the longitudinal direction of the spacer fabric are integrally embedded in the first packaging layer using one or a combination of a plating weave, a tuck weave, and a warp weave;

[0022] The plurality of independent second electrodes in the second electrode layer and along the horizontal direction of the spacer fabric are integrally embedded in the second packaging layer in a manner of one or a combination of a plating weave and a tuck weave.

[0023] In the flexible piezoresistive sensing array based on weft-knitted spacer fabric as described above, 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 metal conductive yarns, carbon-based conductive yarns, conductive polymer yarns, and conductive material-plated yarns. The resistance of the electrode yarns is 0.01 to 2 Ω / cm.

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

[0025] As described above, the flexible piezoresistive sensing array based on the weft-knitted spacer fabric with a triangular truss grid structure, the insulating yarns for weaving the first packaging layer, the second packaging layer and the non-piezoresistive sensitive area B1 of the spacer fabric spacer layer are independently selected from one or more of cotton, wool, silk, linen, polyester, nylon, acrylic, chlorofiber, chloroacrylic, polypropylene, vinylon, spandex, glass fiber, aramid, polyimide fiber, acrylic pre-oxidized yarn, viscose, Tencel, lyocell, modal, acetate fiber and cuprammonium fiber.

[0026] As described above, the flexible piezoresistive sensing array based on the triangular truss grid structure weft-knitted spacer fabric 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 sensor array based on the triangular truss grid structure weft-knitted spacer fabric as described above has a baseline resistance change rate of no more than 5% in a zero-pressure state after 100,000 cycles of compression under cyclic compression test conditions with a pressure amplitude of 0 to 50 kPa.

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

[0029] The weaving method of the piezoresistive sensing area A is: three types of yarns are used for weaving, wherein the three types of yarns are insulating yarn, electrode yarn and piezoresistive sensitive yarn, and the weaving process is:

[0030] Step 1: The insulating yarn is knitted on the first needle bed in a plain or modified plain stitch to form an insulating row of the first encapsulation layer; the electrode yarn is knitted in a plating stitch or a tuck stitch and is integrally embedded in the insulating row to form an electrode row of the first electrode layer;

[0031] Step 2: The piezoresistive sensitive yarn is alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form a first spacer layer row of the spacer fabric spacer layer;

[0032] Step 3: The insulating yarn is knitted on the second needle bed in a plain stitch or a modified plain stitch to form an insulating row of the second encapsulation layer; the electrode yarn is knitted in a plating stitch or a tuck stitch and is integrally embedded in the insulating row to form an electrode row of the second electrode layer;

[0033] Step 4: The piezoresistive sensitive yarn is alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form a second spacer layer row of the spacer fabric spacer layer;

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

[0035] The non-piezoresistive sensing area B is braided using two types of yarns, the two types of yarns being an insulating yarn and an electrode yarn, and the braiding method is as follows:

[0036] The insulating yarn is knitted on the first needle bed and the second needle bed in a plain stitch, a modified plain stitch, a rib or a mesh structure to form insulating rows of the first encapsulation layer and the second encapsulation layer;

[0037] When the insulating yarn is knitted in a plain stitch or a modified plain stitch on the first needle bed and the second needle bed, the spacer fabric spacer layer is formed by knitting another insulating yarn in alternating tuck stitches on the first needle bed and the second needle bed, or is not knitted to form an air layer structure;

[0038] When the insulating yarn is knitted in a rib or mesh structure on the first needle bed and the second needle bed, the spacer fabric spacer layer is not knitted;

[0039] In the longitudinal direction of the fabric, the electrode yarn is integrally embedded in the insulating row of the first packaging layer in a manner of one or more combinations of a plating weave, a tuck weave, and a warp weave, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the longitudinal direction of the fabric;

[0040] In the horizontal direction of the fabric, the electrode yarn is embedded in the insulating horizontal row of the second packaging layer in a manner of one or a combination of a plating yarn and a tuck loop structure, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the horizontal direction of the fabric.

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

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) The flexible piezoresistive sensing array of the present invention is based on a triangular truss grid structure weft-knitted spacer fabric. The piezoresistive sensitive yarn is embedded in the electrode layer by two consecutive alternating knitted loops to form a cross-row cross-linked triangular truss grid structure, which gives the sensor excellent compression resilience and structural stability. By constructing a triangular truss grid conductive network, the piezoresistive sensitive yarn is dynamically reconstructed when under pressure, and the reconstruction rate of the conductive path is greatly improved, which 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 a cyclic compression test with a pressure amplitude of 0~50 kPa, the baseline resistance change rate of the sensor does not exceed 5% after 100,000 compression cycles.

[0044] (2) The flexible piezoresistive sensing array of the present invention, which is based on a triangular truss grid structure weft-knitted spacer fabric, simultaneously weaves the electrode layer, the piezoresistive sensitive layer and the packaging layer through the weft knitting process, breaking through the bottleneck problem of interface stratification in the traditional step-by-step composite process, supports the customization of non-uniform arrays (such as gradient density distribution) and seamless fitting with special-shaped surfaces, and integrates process and function, providing a mass-producible technical solution for scenarios such as wearable devices, smart homes and robot tactile perception. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the structural decomposition of the flexible piezoresistive sensor array according to Example 1 of the present invention;

[0046] Figure 2 Schematic diagram of the decomposition of the knitted structure of the flexible piezoresistive sensor array according to Example 1 of the present invention;

[0047] Figure 3 Schematic diagram of the knitted structure of a sensing unit in the flexible piezoresistive sensing array according to Example 1 of the present invention;

[0048] Figure 4 Schematic diagram of the knitted structure of the cross-row cross-linked triangular truss grid structure according to Example 1 of the present invention;

[0049] Figure 5This is a schematic diagram of functional partitions of the flexible piezoresistive sensing array according to Example 1 of the present invention; Figure 5 In the figure, A represents the piezoresistive sensing area A, and B represents the non-piezoresistive sensing area B;

[0050] Figure 6 This is a schematic diagram of the functional divisions of the flexible piezoresistive sensing array spacer fabric spacer layer of Example 1 of the present invention; Figure 6 In the figure, A1 represents the piezoresistive sensitive area A1, and B1 represents the non-piezoresistive sensitive area B1;

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

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

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

[0054] Figure 10 Schematic diagram of the weaving process of the flexible piezoresistive sensor array according to Example 1 of the present invention;

[0055] Figure 11 This is a knitting diagram of a weft-knitted spacer fabric with a cross-row cross-linked triangular truss grid structure according to Example 1 of the present invention;

[0056] Figure 12 Schematic diagram of the structural decomposition of the flexible piezoresistive sensor array according to Example 2 of the present invention;

[0057] Figure 13 Schematic diagram of the structural decomposition of the flexible piezoresistive sensor array according to Example 3 of the present invention;

[0058] Figure 14 Schematic diagram of the structural decomposition of the flexible piezoresistive sensor array according to Example 4 of the present invention;

[0059] Figure 15 This is a knitting diagram of a weft-knitted spacer fabric with a cross-row cross-linked triangular truss grid structure according to Example 4 of the present invention;

[0060] Among them, 1 is the first packaging layer; 2 is the first electrode layer; 3 is the spacer fabric spacer layer, 3-1 is the first spacer layer horizontal row, 3-2 is the second spacer layer horizontal row; 4 is the second electrode layer; 5 is the second packaging layer. DETAILED DESCRIPTION

[0061] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

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

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

[0064] Water vapor transmission rate: tested according to GB / T 12704.1-2009 standard.

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

[0066] Step 1: Initial resistance measurement;

[0067] The sensor was balanced for 24 hours at a temperature of 20 ± 2°C and a relative humidity of 65 ± 2%. The sensor resistance was then measured at zero pressure and recorded as (3 measurements, take the arithmetic mean);

[0068] Step 2: Load cycle test;

[0069] Pressure amplitude: 0~50 kPa;

[0070] Number of cycles: 100,000 times;

[0071] Step 3: Resistance measurement after recovery and cyclic compression;

[0072] After the cyclic compression test, the sensor was left to stand for 2 hours in an environment with a temperature of 20 ± 2°C and a relative humidity of 65 ± 2%. The sensor resistance was then measured at zero pressure and recorded as (3 measurements, take the arithmetic mean);

[0073] Step 4: Calculate the baseline resistance change rate as follows:

[0074]

[0075] Example 1

[0076] Flexible piezoresistive sensing array based on triangular truss grid structure weft knitted spacer fabric, such as Figures 1-3 As shown, it is a five-layer composite structure integrally woven by a weft knitting process, which comprises, from top to bottom, a first packaging layer 1, a first electrode layer 2, a spacer fabric spacer layer 3, a second electrode layer 4, and a second packaging 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 comprises a plurality of independent first electrodes along the longitudinal direction of the spacer fabric, which are integrally embedded in the first packaging layer 1 using a plating weave;

[0079] like Figure 8 As shown, the second electrode layer 4 woven from electrode yarns comprises a plurality of independent second electrodes arranged along the horizontal direction of the spacer fabric, and is integrally embedded in the second packaging layer 5 using a plating weave;

[0080] like Figure 4 As shown, the spacer fabric spacer layer 3 is a three-dimensional elastic support structure, consisting of a plurality of first spacer layer rows 3-1 and a plurality of second spacer layer rows 3-2 formed by alternately weaving tuck 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 staggered in the spacer fabric and connected end to end to form a cross-row cross-linked triangular truss grid structure;

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

[0082] like Figure 9 and Figure 10 As shown, the piezoresistive sensitive area A1 is formed by weaving piezoresistive sensitive yarns. The piezoresistive sensitive yarns are knitted twice in a row through alternating knitting to form a triangular truss grid structure that is cross-row cross-linked and synchronously connects 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 is provided with 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 route signal wires.

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

[0085] In the piezoresistive sensing area 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 area B, the structure of the first encapsulation layer 1 and the second encapsulation layer 5 is a flat needle structure;

[0087] The flexible piezoresistive sensing array based on the triangular truss grid structure weft-knitted spacer fabric is knitted using a 14-needle knitting computerized flat knitting machine equipped with two needle beds. The specific preparation steps for the piezoresistive sensing area A and the non-piezoresistive sensing area B are as follows:

[0088] (1) Material selection;

[0089] Insulation yarn: 2 pieces of 200D polyester;

[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 sheath-core conductive yarn, manufacturer: Haining Taierxin New Materials Co., Ltd., linear density 100D, resistance 1000000 Ω / cm.

[0092] (2) The weaving method of the piezoresistive sensing area A is: three types of yarns are used for weaving, and the three types of yarns are insulating yarn, electrode yarn and piezoresistive sensitive yarn, such as Figure 11 As shown, the weaving process of the piezoresistive sensing area A is:

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

[0094] Step 2: The piezoresistive sensitive yarn is alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form a first spacer layer row 3 - 1 of the spacer fabric spacer layer 3 ;

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

[0096] Step 4: The piezoresistive sensitive yarn is alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form the second spacer layer row 3 - 2 of the spacer fabric spacer layer 3 ;

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

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

[0099] The insulating yarn is knitted in a plain stitch on the first needle bed and the second needle bed to form insulating rows of the first encapsulation layer and the second encapsulation layer;

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

[0101] In the longitudinal direction of the fabric, the electrode yarn is embedded in the insulating row of the first packaging layer using a plating yarn structure, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the longitudinal direction of the fabric;

[0102] In the fabric row direction, the electrode yarn is embedded in the insulating row of the second packaging layer using a plating yarn structure, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the fabric row direction;

[0103] According to the above-mentioned weaving method, the number and spatial distribution of piezoresistive sensing areas are precisely controlled through the weaving program, and a sensing array consisting of 4 columns of longitudinal first electrodes and 4 rows of transverse second electrodes is directly woven. Its cross nodes form 16 independent piezoresistive sensing units, constituting a highly integrated 4×4 piezoresistive sensing system.

[0104] The flexible piezoresistive sensing array based on a 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 a cyclic compression test with a pressure amplitude of 0-50 kPa, after 100,000 cycles of compression, the baseline resistance change rate in the zero-pressure state was 4.3%.

[0105] Comparative Example 1

[0106] The flexible piezoresistive sensing array based on weft-knitted spacer fabric is basically the same as Example 1, except that the weaving method of its piezoresistive sensing area is different from that of Example 1. Its piezoresistive sensing area is woven using the traditional weaving method of weft-knitted spacer fabric, so no cross-row cross-linked triangular truss grid structure is formed, and the piezoresistive sensitive yarns between adjacent rows have no physical connection with each other.

[0107] The weaving method of the piezoresistive sensing area is: three types of yarns are used for weaving, and the three yarns are insulating yarn, electrode yarn and piezoresistive sensitive yarn. The weaving process is:

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

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

[0110] Step 3: The piezoresistive sensitive yarn is alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form a first spacer layer row of the spacer fabric spacer layer;

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

[0112] The piezoresistive sensor array has a thickness of 4 mm, an air permeability of 520 mm / s, and a moisture permeability of 310 g / (m²•24h). Under a cyclic compression test with a pressure amplitude of 0 to 50 kPa, the baseline resistance change rate in the zero-pressure state was 21.3% after 100,000 cycles of compression.

[0113] Comparing Comparative Example 1 with Example 1 reveals that the air and moisture permeability of the piezoresistive sensor array in Comparative Example 1 have improved, but its stability has significantly decreased. This is because the number and density of piezoresistive sensitive yarns in the spacer fabric spacer layer in Comparative Example 1 are reduced, resulting in improved air and moisture permeability. However, Comparative Example 1 is woven using a traditional weft-knitted spacer fabric weaving method, which does not form a triangular truss grid structure that crosses rows and crosses them. The piezoresistive sensitive yarns between adjacent rows are not physically connected, resulting in a high degree of randomness in the contact and separation between the yarns during compression. Furthermore, the spacer layer yarn structure is unstable, causing slippage during compression, resulting in large resistance fluctuations and reduced long-term stability of the sensor.

[0114] Example 2

[0115] Flexible piezoresistive sensing array based on triangular truss grid structure weft knitted spacer fabric, such as Figure 12 As shown, it is a five-layer composite structure integrally woven by a weft knitting process, which comprises, from top to bottom, a first packaging layer 1, a first electrode layer 2, a spacer fabric spacer layer 3, a second electrode layer 4, and a second packaging 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 comprises a plurality of independent first electrodes arranged along the longitudinal direction of the spacer fabric, and is integrally embedded in the first packaging layer 1 using a plating weave and a lining weave;

[0118] The second electrode layer 4 woven from electrode yarns comprises a plurality of independent second electrodes arranged along the horizontal direction of the spacer fabric, and is integrally embedded in the second packaging layer 5 using a plating weave;

[0119] The spacer fabric spacer layer 3 is a three-dimensional elastic support structure, consisting of a plurality of first spacer layer rows 3-1 and a plurality of second spacer layer rows 3-2, formed by alternately weaving tuck 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 staggered in the spacer fabric and connected end to end to form a cross-row cross-linked triangular truss grid structure.

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

[0121] The piezoresistive sensitive area A1 is formed by weaving piezoresistive sensitive yarns. The piezoresistive sensitive yarns are knitted twice in a row, forming a cross-row cross-linked triangular truss grid structure, and synchronously connecting the first electrode layer 2 and the second electrode layer 4.

[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 is provided with 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 route signal wires.

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

[0124] In the piezoresistive sensing area A, the structure of the first packaging layer and the second packaging layer is a 1+1 changing flat needle structure;

[0125] In the non-piezoresistive sensing area B, the structure of the first packaging layer and the second packaging layer is a 1+1 changing flat needle structure;

[0126] The flexible piezoresistive sensing array based on the triangular truss grid structure weft-knitted spacer fabric is knitted using a 14-needle knitting computerized flat knitting machine equipped with two needle beds. The specific preparation steps for the piezoresistive sensing area A and the non-piezoresistive sensing area B are as follows:

[0127] (1) Material selection;

[0128] Insulation yarn: 2 pieces of 200D polyester;

[0129] Electrode yarn: 9 twisted copper wires with a diameter of 0.03 mm and a resistance of 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 slurry. 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: three types of yarns are used for weaving, and the three types of yarns are insulating yarn, electrode yarn and piezoresistive sensitive yarn. The weaving process is:

[0132] Step 1: The insulating yarn is knitted on the first needle bed in a 1+1 plain stitch to form an insulating row of the first encapsulation layer; the electrode yarn is knitted in a plating stitch and integrally embedded in the insulating row to form an electrode row of the first electrode layer;

[0133] Step 2: The piezoresistive sensitive yarn is alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form a first spacer layer row of the spacer fabric spacer layer;

[0134] Step 3: The insulating yarn is knitted on the second needle bed in a 1+1 plain stitch to form an insulating row of the second encapsulation layer; the electrode yarn is knitted in a plating stitch and is integrally embedded in the insulating row to form an electrode row of the second electrode layer;

[0135] Step 4: The piezoresistive sensitive yarn is alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form a second spacer layer row of the spacer fabric spacer layer;

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

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

[0138] The insulating yarn is knitted on the first needle bed and the second needle bed in a 1+1 alternating plain stitch to form insulating rows of the first encapsulation layer and the second encapsulation layer;

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

[0140] In the longitudinal direction of the fabric, the electrode yarn is embedded in the insulating horizontal row of the first packaging layer using the lining warp tissue, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the longitudinal direction of the fabric;

[0141] In the fabric row direction, the electrode yarn is embedded in the insulating row of the second packaging layer using a plating yarn structure, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the fabric row direction;

[0142] According to the above-mentioned weaving method, the number and spatial distribution of piezoresistive sensing areas are precisely controlled through the weaving program, and a sensing array consisting of 4 columns of longitudinal first electrodes and 4 rows of transverse second electrodes is directly woven. Its cross nodes form 16 independent piezoresistive sensing units, constituting a highly integrated 4×4 piezoresistive sensing system.

[0143] The flexible piezoresistive sensing array based on a 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 a cyclic compression test with a pressure amplitude of 0-50 kPa, after 100,000 cycles of compression, the baseline resistance change rate in the zero-pressure state was 4.8%.

[0144] Example 3

[0145] Flexible piezoresistive sensing array based on triangular truss grid structure weft knitted spacer fabric, such as Figure 13 As shown, it is a five-layer composite structure integrally woven by a weft knitting process, which comprises, from top to bottom, a first packaging layer 1, a first electrode layer 2, a spacer fabric spacer layer 3, a second electrode layer 4, and a second packaging 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 comprises a plurality of independent first electrodes arranged along the longitudinal direction of the spacer fabric, and is integrally embedded in the first packaging layer 1 using a plating weave;

[0148] The second electrode layer 4 woven from electrode yarns comprises a plurality of independent second electrodes arranged along the horizontal direction of the spacer fabric, and is integrally embedded in the second packaging layer 5 using a plating weave;

[0149] The spacer fabric spacer layer 3 is a three-dimensional elastic support structure, consisting of a plurality of first spacer layer rows 3-1 and a plurality of second spacer layer rows 3-2, formed by alternately weaving tuck 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 staggered in the spacer fabric and connected end to end to form a cross-row cross-linked triangular truss grid structure.

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

[0151] The piezoresistive sensitive area A1 is formed by weaving piezoresistive sensitive yarns. The piezoresistive sensitive yarns are knitted twice in a row, forming a cross-row cross-linked triangular truss grid structure, and synchronously connecting the first electrode layer 2 and the second electrode layer 4.

[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 is provided with 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 route signal wires.

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

[0154] In the piezoresistive sensing area A, the structure of the first packaging layer and the second packaging layer is a flat needle structure;

[0155] In the non-piezoresistive sensing area B, the structures of the first encapsulation layer and the second encapsulation layer are mesh structures;

[0156] The flexible piezoresistive sensor array based on the triangular truss grid structure weft-knitted spacer fabric is knitted using a knitting computerized flat knitting machine equipped with two needle beds. The machine gauge of the computerized flat knitting machine is 18 needles. The specific preparation steps of the piezoresistive sensing area A and the non-piezoresistive sensing area B are as follows:

[0157] (1) Material selection;

[0158] Insulation yarn: nylon, linear density 210 D;

[0159] Electrode yarn: 7 twisted copper wires with a diameter of 0.03 mm and a resistance of 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 slurry. 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: three types of yarns are used for weaving, and the three types of yarns are insulating yarn, electrode yarn and piezoresistive sensitive yarn. The weaving process is:

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

[0163] Step 2: The piezoresistive sensitive yarn is alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form a first spacer layer row of the spacer fabric spacer layer;

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

[0165] Step 4: The piezoresistive sensitive yarn is alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form a second spacer layer row of the spacer fabric spacer layer;

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

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

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

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

[0170] In the longitudinal direction of the fabric, the electrode yarn is embedded in the insulating row of the first packaging layer using a plating yarn structure, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the longitudinal direction of the fabric;

[0171] In the fabric row direction, the electrode yarn is embedded in the insulating row of the second packaging layer using a plating yarn structure, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the fabric row direction;

[0172] According to the above-mentioned weaving method, the number and spatial distribution of piezoresistive sensing areas are precisely controlled through the weaving program, and a sensing array consisting of 4 columns of longitudinal first electrodes and 4 rows of transverse second electrodes is directly woven. Its cross nodes form 16 independent piezoresistive sensing units, constituting a highly integrated 4×4 piezoresistive sensing system.

[0173] The flexible piezoresistive sensing array based on a 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 a cyclic compression test with a pressure amplitude of 0-50 kPa, after 100,000 cycles of compression, the baseline resistance change rate in the zero-pressure state was 4.9%.

[0174] Example 4

[0175] Flexible piezoresistive sensing array based on triangular truss grid structure weft knitted spacer fabric, such as Figure 14As shown, it is a five-layer composite structure integrally woven by a weft knitting process, which comprises, from top to bottom, a first packaging layer 1, a first electrode layer 2, a spacer fabric spacer layer 3, a second electrode layer 4, and a second packaging 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 comprises a plurality of independent first electrodes arranged along the longitudinal direction of the spacer fabric, and is integrally embedded in the first packaging layer 1 using a tuck stitch;

[0178] The second electrode layer 4 woven from electrode yarns comprises a plurality of independent second electrodes arranged along the horizontal direction of the spacer fabric, and is integrally embedded in the second packaging layer 5 using a tuck stitch;

[0179] The spacer fabric spacer layer 3 is a three-dimensional elastic support structure, consisting of a plurality of first spacer layer rows 3-1 and a plurality of second spacer layer rows 3-2, formed by alternately weaving tuck 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 staggered in the spacer fabric and connected end to end to form a cross-row cross-linked triangular truss grid structure.

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

[0181] The piezoresistive sensitive area A1 is formed by weaving piezoresistive sensitive yarns. The piezoresistive sensitive yarns are knitted twice in a row, forming a cross-row cross-linked triangular truss grid structure, and synchronously connecting the first electrode layer 2 and the second electrode layer 4.

[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 is provided with 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 route signal wires.

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

[0184] In the piezoresistive sensing area A, the structure of the first packaging layer and the second packaging layer is a flat needle structure;

[0185] In the non-piezoresistive sensing area B, the structure of the first encapsulation layer and the second encapsulation layer is a ribbed structure;

[0186] The flexible piezoresistive sensing array based on the triangular truss grid structure weft-knitted spacer fabric is knitted using a 14-needle knitting computerized flat knitting machine equipped with two needle beds. The specific preparation steps for the piezoresistive sensing area A and the non-piezoresistive sensing area B are as follows:

[0187] (1) Material selection;

[0188] Insulation yarn: 4 strands of 140D nylon;

[0189] Electrode yarn: 9 twisted copper wires with a diameter of 0.03 mm and a resistance of 0.03 Ω / cm;

[0190] Piezoresistive sensitive yarn: Polyester sheath-core conductive stretch yarn, manufacturer: Beijing Tanyang Technology Co., Ltd., linear density 160D, resistance 500,000 Ω / cm.

[0191] (2) The weaving method of the piezoresistive sensing area A is: three types of yarns are used for weaving, and the three types of yarns are insulating yarn, electrode yarn and piezoresistive sensitive yarn, such as Figure 15 As shown, the weaving process is:

[0192] Step 1: The insulating yarn is knitted on the first needle bed in a plain stitch to form an insulating row of the first encapsulation layer; the electrode yarn is knitted in a tuck stitch and is integrally embedded in the insulating row to form an electrode row of the first electrode layer;

[0193] Step 2: The piezoresistive sensitive yarn is alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form a first spacer layer row of the spacer fabric spacer layer;

[0194] Step 3: The insulating yarn is knitted on the second needle bed in a plain stitch to form an insulating row of the second encapsulation layer; the electrode yarn is knitted in a tuck stitch and is integrally embedded in the insulating row to form an electrode row of the second electrode layer;

[0195] Step 4: The piezoresistive sensitive yarn is alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form a second spacer layer row of the spacer fabric spacer layer;

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

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

[0198] The insulating yarn is knitted in a rib structure on the first needle bed and the second needle bed to form insulating rows of the first encapsulation layer and the second encapsulation layer;

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

[0200] In the longitudinal direction of the fabric, the electrode yarn is embedded in the insulating horizontal row of the first packaging layer using a tuck stitch and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the longitudinal direction of the fabric.

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

[0202] According to the above-mentioned weaving method, the number and spatial distribution of piezoresistive sensing areas are precisely controlled through the weaving program, and a sensing array consisting of 4 columns of longitudinal first electrodes and 4 rows of transverse second electrodes is directly woven. Its cross nodes form 16 independent piezoresistive sensing units, constituting a highly integrated 4×4 piezoresistive sensing system.

[0203] The flexible piezoresistive sensing array based on a 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 a cyclic compression test with a pressure amplitude of 0-50 kPa, after 100,000 cycles of compression, the baseline resistance change rate in the zero-pressure state was 4.2%.

[0204] Example 5

[0205] The flexible piezoresistive sensing array based on a triangular truss grid structure weft-knitted spacer fabric is a five-layer composite structure woven and formed in one piece through a weft knitting process. From top to bottom, it consists of a first packaging layer, a first electrode layer, a spacer fabric spacer layer, a second electrode layer, and a second packaging layer.

[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 comprises a plurality of independent first electrodes arranged along the longitudinal direction of the spacer fabric, and is integrally embedded in the first packaging layer using a plating yarn structure;

[0208] The second electrode layer woven from electrode yarns comprises a plurality of independent second electrodes arranged along the horizontal direction of the spacer fabric, and is integrally embedded in the second packaging layer using a plating yarn structure;

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

[0210] The plurality of first electrodes in the first electrode layer and the plurality of second electrodes in the second electrode layer form a plurality of intersection regions on the spacer fabric, wherein the plurality of intersection regions constitute a plurality of piezoresistive sensing regions A; the spacer fabric spacer layer is provided with 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 formed by weaving piezoresistive sensitive yarns. The piezoresistive sensitive yarns are knitted twice in a row, forming a cross-row cross-linked triangular truss grid structure, and synchronously connecting the first electrode layer 2 and the second electrode layer 4.

[0212] The non-intersecting areas of the plurality of first electrodes in the first electrode layer and the plurality of 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 is provided with 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 weaving insulating yarn;

[0214] In the piezoresistive sensing area A, the structure of the first packaging layer and the second packaging layer is a flat needle structure;

[0215] In the non-piezoresistive sensing area B, the structure of the first encapsulation layer and the second encapsulation layer is a flat needle structure;

[0216] The flexible piezoresistive sensing array based on the triangular truss grid structure weft-knitted spacer fabric is knitted using a 10-needle knitting machine equipped with two needle beds. The specific preparation steps for the piezoresistive sensing area A and the non-piezoresistive sensing area 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 twisted copper wires with a diameter of 0.05 mm and a resistance of 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: three types of yarns are used for weaving, and the three types of yarns are insulating yarn, electrode yarn and piezoresistive sensitive yarn. The weaving process is:

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

[0224] Step 2: The piezoresistive sensitive yarn is alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form the first spacer layer row of the spacer fabric spacer layer. The insulating yarn II is used as the plating yarn of the piezoresistive sensitive yarn and is knitted synchronously with the piezoresistive sensitive yarn.

[0225] Step 3: The insulating yarn I is knitted on the second needle bed in a plain stitch to form an insulating row of the second encapsulation layer; the electrode yarn is knitted in a plating stitch 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 alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form the second spacer layer row of the spacer fabric spacer layer. The insulating yarn II is used as the plating yarn of the piezoresistive sensitive yarn and is knitted synchronously with the piezoresistive sensitive yarn.

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

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

[0229] Insulated yarn I is knitted in a plain stitch on the first and second needle beds;

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

[0231] In the longitudinal direction of the fabric, the electrode yarn is embedded in the insulating row of the first packaging layer using a plating yarn structure, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the longitudinal direction of the fabric;

[0232] In the fabric horizontal direction, the added yarn structure is integrally embedded in the insulating horizontal row of the second packaging layer and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the fabric horizontal direction;

[0233] According to the above-mentioned weaving method, the number and spatial distribution of piezoresistive sensing areas are precisely controlled through the weaving program, and a sensing array consisting of 6 columns of longitudinal first electrodes and 6 rows of transverse second electrodes is directly woven. Its cross nodes form 36 independent piezoresistive sensing units, constituting a highly integrated 6×6 piezoresistive sensing system.

[0234] The flexible piezoresistive sensing array based on a 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 in the zero-pressure state was 4.6%.

[0235] Example 6

[0236] The flexible piezoresistive sensing array based on a triangular truss grid structure weft-knitted spacer fabric is a five-layer composite structure woven and formed in one piece through a weft knitting process. From top to bottom, it consists of a first packaging layer, a first electrode layer, a spacer fabric spacer layer, a second electrode layer, and a second packaging layer.

[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 comprises a plurality of independent first electrodes along the longitudinal direction of the spacer fabric, which are integrally embedded in the first packaging layer using a plating yarn structure;

[0239] The second electrode layer comprises a plurality of independent second electrodes arranged along the horizontal direction of the spacer fabric, and is integrally embedded in the second packaging layer using a plating yarn 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 composed of multiple first spacer layer rows and multiple second spacer layer rows formed by alternating tuck loops on the upper and lower layers of the spacer fabric. The first spacer layer rows and the second spacer layer rows are staggered in the spacer fabric and connected end to end to form a cross-row cross-linked triangular truss grid structure.

[0242] The plurality of first electrodes in the first electrode layer and the plurality of second electrodes in the second electrode layer form a plurality of intersection regions on the spacer fabric, wherein the plurality of intersection regions constitute a plurality of piezoresistive sensing regions A; the spacer fabric spacer layer is provided with 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 formed by weaving piezoresistive sensitive yarns. The piezoresistive sensitive yarns are knitted twice in a row, forming a cross-row cross-linked triangular truss grid structure, and synchronously connecting the first electrode layer 2 and the second electrode layer 4.

[0244] The non-intersecting areas of the plurality of first electrodes in the first electrode layer and the plurality of 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 is provided with 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 route signal wires.

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

[0246] In the piezoresistive sensing area A, the structure of the first packaging layer and the second packaging layer is a flat needle structure;

[0247] In the non-piezoresistive sensing area B, the structure of the first encapsulation layer and the second encapsulation layer is a ribbed structure;

[0248] The flexible piezoresistive sensor array based on the triangular truss grid structure weft-knitted spacer fabric is knitted using a 20-needle knitting computerized flat knitting machine equipped with two needle beds. The specific preparation steps for the piezoresistive sensing area A and the non-piezoresistive sensing area B are as follows:

[0249] (1) Material selection;

[0250] Insulation yarn: Nylon / spandex double-cover yarn, manufacturer: Lilong Textile Technology Co., Ltd., the core yarn is 70D spandex, and the inner and outer covering yarns are both 140D nylon;

[0251] Electrode yarns: 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 sheath-core conductive stretch yarn, manufacturer: Beijing Tanyang Technology Co., Ltd., linear density 88 D, resistance 600,000 Ω / cm.

[0253] (2) The weaving method of the piezoresistive sensing area A is: three types of yarns are used for weaving, and the three types of yarns are insulating yarn, electrode yarn and piezoresistive sensitive yarn. The weaving process is:

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

[0255] Step 2: The piezoresistive sensitive yarn is alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form a first spacer layer row of the spacer fabric spacer layer;

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

[0257] Step 4: The piezoresistive sensitive yarn is alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form a second spacer layer row of the spacer fabric spacer layer;

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

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

[0260] The insulating yarn is knitted in a rib structure on the first needle bed and the second needle bed to form insulating rows of the first encapsulation layer and the second encapsulation layer;

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

[0262] In the longitudinal direction of the fabric, the electrode yarn is embedded in the insulating row of the first packaging layer using a plating yarn structure, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the longitudinal direction of the fabric;

[0263] In the fabric row direction, the electrode yarn is embedded in the insulating row of the second packaging layer using a plating yarn structure, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the fabric row direction;

[0264] According to the above-mentioned weaving method, the number and spatial distribution of piezoresistive sensing areas are precisely controlled through the weaving program, and a sensing array consisting of 6 columns of longitudinal first electrodes and 8 rows of transverse second electrodes is directly woven. Its cross nodes form 48 independent piezoresistive sensing units, constituting a highly integrated 6×8 piezoresistive sensing system.

[0265] The flexible piezoresistive sensing array based on a 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 in the zero-pressure state was 3.9%.

Claims

1. A flexible piezoresistive sensing array based on a triangular truss grid structure weft-knitted spacer fabric, characterized by: It is a five-layer composite structure woven into an integral body through a weft knitting process, which comprises, from top to bottom, a first packaging layer, a first electrode layer, a spacer fabric spacer layer, a second electrode layer, and a second packaging layer; 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; The first electrode layer comprises a plurality of independent first electrodes along the longitudinal direction of the spacer fabric, and the second electrode layer comprises a plurality of independent second electrodes along the lateral 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 packaging layer, and the second electrode layer is integrally embedded in the second packaging layer. The spacer fabric spacer layer is a three-dimensional elastic support structure, comprising a plurality of first spacer layer rows and a plurality of second spacer layer rows formed by alternately weaving tuck loops on the upper and lower layers of the spacer fabric; the first spacer layer rows and the second spacer layer rows are staggered in the spacer fabric and connected end to end to form a cross-row cross-linked triangular truss grid structure; The plurality of first electrodes in the first electrode layer and the plurality of second electrodes in the second electrode layer form a plurality of intersection regions on the spacer fabric, the plurality of intersection regions constituting a plurality of piezoresistive sensing regions A, the spacer layer of the spacer fabric being provided with piezoresistive sensitive regions A1 in the piezoresistive sensing regions A, the resistance value of the piezoresistive sensitive regions A1 varying 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 packaging layer and the second packaging layer constitute a non-piezoresistive sensing area B. The spacer fabric spacer layer is provided with a non-piezoresistive sensitive area B1 in the non-piezoresistive sensing area B. The non-piezoresistive sensitive area B1 is used to isolate adjacent piezoresistive sensing areas A and lay signal wires.

2. The flexible piezoresistive sensor array based on triangular truss grid structure weft-knitted spacer fabric according to claim 1, characterized in that: The piezoresistive sensitive area A1 is formed by knitting conductive yarns, and the conductive yarns are knitted twice in a row to form a triangular truss grid structure cross-row cross-linked, and the first electrode layer and the second electrode layer are synchronously connected; The non-piezoresistive sensitive area B1 is formed by weaving insulating yarn, or is not weaved.

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

4. The flexible piezoresistive sensing array based on triangular truss grid structure weft knitted spacer fabric according to claim 3, characterized in that: The plurality of independent first electrodes in the first electrode layer and along the longitudinal direction of the spacer fabric are integrally embedded in the first packaging layer in a manner of one or a combination of two or more of a plating weave, a tuck weave and a warp weave; The plurality of independent second electrodes in the second electrode layer and along the horizontal direction of the spacer fabric are integrally embedded in the second packaging layer in a manner of one or a combination of a plating weave and a tuck weave.

5. The flexible piezoresistive sensor array based on a triangular truss grid 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 metal conductive yarns, carbon-based conductive yarns, conductive polymer yarns, and conductive material-plated yarns. The resistance of the electrode yarns is 0.01 to 2 Ω / cm.

6. The flexible piezoresistive sensor array based on a triangular truss grid structure weft-knitted spacer fabric according to claim 5, characterized in that: The conductive yarn weaving the piezoresistive sensitive area A1 is recorded as piezoresistive sensitive yarn, and the piezoresistive sensitive yarn is one or more of metal conductive yarn, carbon-based conductive yarn, conductive polymer yarn and conductive material-plated yarn, and the resistance of the piezoresistive sensitive yarn is 1000~1000000 Ω / cm.

7. The flexible piezoresistive sensor array based on triangular truss grid structure weft-knitted spacer fabric according to claim 6, characterized in that: The insulating yarns used to weave the first packaging layer, the second packaging layer, and the non-piezoresistive sensitive area B1 of the spacer fabric spacer layer are independently selected from one or more of cotton, wool, silk, linen, polyester, nylon, acrylic, chloroprene, chloroprene, polypropylene, vinylon, spandex, glass fiber, aramid, polyimide fiber, acrylic pre-oxidized yarn, viscose, Tencel, lyocell, modal, acetate fiber, and cuprammonium fiber.

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

9. The flexible piezoresistive sensor array based on a triangular truss grid 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, the baseline resistance change rate in the zero-pressure state does not exceed 5% after 100,000 cycles of compression.

10. The flexible piezoresistive sensing array based on triangular truss grid 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 equipped with two needle beds; The weaving method of the piezoresistive sensing area A is: three types of yarns are used for weaving, wherein the three types of yarns are insulating yarn, electrode yarn and piezoresistive sensitive yarn, and the weaving process is: Step 1: The insulating yarn is knitted on the first needle bed in a plain or modified plain stitch to form an insulating row of the first encapsulation layer; the electrode yarn is knitted in a plating stitch or a tuck stitch and is integrally embedded in the insulating row to form an electrode row of the first electrode layer; Step 2: The piezoresistive sensitive yarn is alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form a first spacer layer row of the spacer fabric spacer layer; Step 3: The insulating yarn is knitted on the second needle bed in a plain stitch or a modified plain stitch to form an insulating row of the second encapsulation layer; the electrode yarn is knitted in a plating stitch or a tuck stitch and is integrally embedded in the insulating row to form an electrode row of the second electrode layer; Step 4: The piezoresistive sensitive yarn is alternately knitted on the first needle bed and the second needle bed in a tuck stitch to form a second spacer layer row of the spacer fabric spacer layer; Repeat steps 1 to 4 until the weaving of the piezoresistive sensing area A is completed; The non-piezoresistive sensing area B is braided using two types of yarns, the two types of yarns being an insulating yarn and an electrode yarn, and the braiding method is as follows: The insulating yarn is knitted on the first needle bed and the second needle bed in a plain stitch, a modified plain stitch, a rib or a mesh structure to form insulating rows of the first encapsulation layer and the second encapsulation layer; When the insulating yarn is knitted in a plain stitch or a modified plain stitch on the first needle bed and the second needle bed, the spacer fabric spacer layer is formed by knitting another insulating yarn in alternating tuck stitches on the first needle bed and the second needle bed, or is not knitted to form an air layer structure; When the insulating yarn is knitted in a rib or mesh structure on the first needle bed and the second needle bed, the spacer fabric spacer layer is not knitted; In the longitudinal direction of the fabric, the electrode yarn is integrally embedded in the insulating row of the first packaging layer using one or a combination of a plating weave, a tuck weave, and a warp weave, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the longitudinal direction of the fabric. In the horizontal direction of the fabric, the electrode yarn is embedded in the insulating horizontal row of the second packaging layer in a manner of one or a combination of a plating yarn and a tuck loop structure, and serves as a signal conductor to connect two adjacent piezoresistive sensing areas in the horizontal direction of the fabric.

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