Knitted fabric flexible capacitive sensor

Abstract

The invention relates to a knitted fabric flexible capacitive sensor, which comprises a planar first knitted fabric layer, a planar second knitted fabric layer and a middle layer, the first knitted fabric layer and the second knitted fabric layer are connected with each other by weaving spacing yarns therebetween, and the spacing yarns form a middle layer; the first knitted fabric layer and the second knitted fabric layer are formed by intermeshing conductive yarns; the spacer yarns are insulated elastic yarns and are connected with the first knitted fabric layer and the second knitted fabric layer in a tucking manner. The knitted fabric flexible capacitive sensor is integrally formed, simple in structure, good in stretchability and compressibility, capable of detecting compression loads or stretching loads and outputting specific numerical values of the loads, and capable of being widely applied to the fields of human motion monitoring, human-computer interaction and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of textile strain and pressure sensors, and in particular relates to a knitted fabric flexible capacitive sensor. Background Art

[0002] With the rapid development of wearable artificial intelligence devices, flexible sensors have gradually shown broad application prospects in the fields of human motion monitoring, electronic skin and human-computer interaction due to their advantages such as stretchability and light weight. According to the sensing principle, flexible sensors are divided into resistive sensors, piezoelectric sensors and capacitive sensors. Among them, capacitive sensors have the advantages of high sensitivity, short response time, wide detection range and strong environmental adaptability, and have a wide range of applications.

[0003] Knitted fabrics have good extensibility and elasticity. When a knitted fabric flexible capacitive sensor with a multi-layer composite structure of conductive yarn and insulating elastic yarn is subjected to a compressive load, the distance between the first knitted fabric layer and the second knitted fabric layer changes, causing a change in capacitance, making it a capacitive pressure sensor. When subjected to a tensile load, the surface area of ​​the first knitted fabric layer and the second knitted fabric layer changes, and at the same time, the distance between the first knitted fabric layer and the second knitted fabric layer changes, which together cause a change in capacitance, making it a capacitive strain sensor.

[0004] Knitted fabric flexible capacitive sensors are soft, breathable, stretchable, and easier to integrate with other carriers (such as clothing, seat cushions, gloves, etc.), which greatly improves the comfort of wearable artificial intelligence devices. Among them, the integration method of knitted fabric flexible capacitive sensors is direct weaving, pasting or other methods.

[0005] The document (Batch Fabrication of Customizable Silicone-Textile Composite Capacitive Strain Sensors for Human Motion Tracking [J]. Advanced Materials Technologies, 2017: 1700136.) discloses a capacitive sensor, in which the electrode layer is a highly stretchable silver-plated knitted fabric, and the upper and lower electrode layers are separated by a silicone elastomer as a dielectric, which has high linearity, low hysteresis and high sensitivity. However, its multi-layer structure requires specific tools for multiple coatings and drying, and the manufacturing process is complicated. Because the sensor needs to coat and dry the silver-plated knitted fabric as the electrode layer multiple times to bond the dielectric layer and the electrode layer, the sensor cannot be directly woven into the carrier and can only be integrated by hand sewing.

[0006] Patent CN106884257A discloses a weft knitted fabric strain sensor, including a sensing area and a connection area, wherein the sensing area is composed of a plain-stitched yarn coil woven with a conductive face yarn and an elastic ground yarn, and the conductive yarn in the sensing area is in a bent structure; the connection area is located on both sides of the sensing area, and is composed of a plain-stitched yarn coil with a face yarn and an elastic yarn as the ground yarn. The sensor is a resistive strain sensor with high sensitivity, can be knitted on a machine, and can be directly woven into a carrier. However, the sensor can only detect tensile loads, but not compressive loads.

[0007] Patent CN114111878A discloses a capacitive sensor, including a first conductive layer, a second conductive layer, an electromagnetic shielding element, and a spacer fabric. The spacer fabric is arranged between the first conductive layer and the second conductive layer and has a first thickness. The capacitive sensor can be in the form of a flexible capacitive sensing pad, and a detection signal is generated when the spacer fabric is compressed to the second thickness through a capacitive detection circuit. The sensor can only detect the presence of a pressure load above a specific value, and cannot detect the specific value of the pressure load. At the same time, the spacer fabric only serves as a dielectric layer to separate the first conductive layer from the second conductive layer.

[0008] Patent CN210014750U discloses a capacitive elastic strain sensor, which uses elastic textile material as a matrix and can be integrated into a wearable device to detect stress and strain such as stretching and bending of the body, including an elastic bonding layer, a first conductive layer, a second conductive layer, an elastic dielectric layer and an elastic packaging layer. The sensor has a low thickness, thereby improving its wearability and comfort. Although the sensor uses elastic textile material as a matrix, its moisture absorption and air permeability are poor compared to knitted fabric sensors, and it cannot be integrated into a carrier by direct weaving.

[0009] Therefore, it is of great significance to study a high-sensitivity sensor that is easy to integrate and can accurately detect the size of tensile load or compressive load to solve the problems existing in the prior art. Summary of the invention

[0010] The purpose of the present invention is to solve the problems existing in the prior art and to provide a knitted fabric flexible capacitive sensor.

[0011] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0012] A knitted fabric flexible capacitive sensor, comprising a planar first knitted fabric layer, a planar second knitted fabric layer and an intermediate layer;

[0013] The first knitted fabric layer and the second knitted fabric layer are connected to each other by weaving spacer yarns therebetween, and the spacer yarns constitute the intermediate layer;

[0014] The first knitted fabric layer and the second knitted fabric layer are both formed by mutually interlacing conductive yarns;

[0015] The spacer yarn is an insulating elastic yarn, and connects the first knitted fabric layer and the second knitted fabric layer in the form of a tuck.

[0016] As the preferred technical solution:

[0017] In the above-mentioned flexible capacitive sensor for knitted fabrics, the tucks are full-needle tucks or every other-needle tucks.

[0018] As described above, a knitted fabric flexible capacitive sensor, the conductive yarn is one or more of metal-based conductive yarn, carbon-based conductive yarn and conductive polymer yarn; the present invention only lists common conductive yarns, and other yarns that can achieve this function are also suitable for the present invention.

[0019] In the knitted fabric flexible capacitive sensor as described above, the insulating elastic yarn is spandex, latex yarn or thermoplastic elastomer yarn.

[0020] A knitted fabric flexible capacitive sensor as described above, wherein the thermoplastic elastomer yarn is a polyester thermoplastic elastomer, a polystyrene thermoplastic elastomer, a polyolefin thermoplastic elastomer, a polydiene thermoplastic elastomer, a polyvinyl chloride thermoplastic elastomer, a polyurethane thermoplastic elastomer, a polyamide thermoplastic elastomer, a polyorganofluorine thermoplastic elastomer, a polysilicone thermoplastic elastomer or a polyethylene thermoplastic elastomer polyester yarn, polyamide yarn, organic fluorine yarn, polyolefin yarn or a mixed multifilament thereof; the present invention only lists common substances that can be used to make insulating elastic yarns, and other substances that can achieve this function are also suitable for the present invention.

[0021] After the thermoplastic elastomer yarn is woven between the first knitted fabric layer and the second knitted fabric layer, the thermoplastic elastomer yarn is melted by heat pressing to form an elastic body block material.

[0022] A knitted fabric flexible capacitive sensor as described above, wherein the linear density of the conductive yarn is 22-280 dtex, and the linear density of the insulating elastic yarn is 22-280 dtex;

[0023] The thickness of the first knitted fabric layer is 1-3 mm, the thickness of the second knitted fabric layer is 1-3 mm, and the thickness of the middle layer is 1-3 mm.

[0024] A knitted fabric flexible capacitive sensor as described in any one of the above items, wherein the knitted fabric flexible capacitive sensor can be used to detect a tensile load or a compressive load;

[0025] Under a tensile load, the surface areas of the first knitted fabric layer and the second knitted fabric layer in the knitted fabric flexible capacitive sensor change, and at the same time, the distance between the first knitted fabric layer and the second knitted fabric layer changes, causing the capacitance to change;

[0026] Under a compressive load, the distance between the first knitted fabric layer and the second knitted fabric layer in the knitted fabric flexible capacitive sensor changes, causing the capacitance to change.

[0027] The knitted fabric flexible capacitive sensor as described above can withstand a tensile stress of 0.01 to 300 N in a 50% tensile strain range and a compressive stress of 0.1 to 4×10 5 Pa of pressure.

[0028] A knitted fabric flexible capacitive sensor as described above, wherein the sensitivity range of the knitted fabric flexible capacitive sensor is 1 to 2;

[0029] After one knitted fabric flexible capacitive sensor is cut into a plurality of capacitive sensors of the same shape, under the same tensile load or compressive load, the cut capacitive sensors have consistent baseline capacitance values ​​and consistent sensitivities.

[0030] The principle of the present invention is as follows:

[0031] In the present invention, the first knitted fabric layer and the second knitted fabric layer are formed by mutually interlacing conductive yarns, and serve as the first electrode layer and the second electrode layer respectively; the middle layer is composed of insulating elastic yarn, and the first knitted fabric layer and the second knitted fabric layer are connected by tucking in the knitting process, serving as a dielectric layer. Under tensile load, the surface area of ​​the first knitted fabric layer and the second knitted fabric layer changes, and the distance between the first knitted fabric layer and the second knitted fabric layer also changes, which together cause the capacitance to change; under compressive load, the distance between the first knitted fabric layer and the second knitted fabric layer changes, causing the capacitance to change. The unique three-layer composite structure allows the two electrode layers to have a specific initial spacing, so that the knitted fabric flexible capacitive sensor obtains a stable capacitance base value; the insulating elastic yarn is used as the spacer yarn of the knitted spacer fabric, so that the knitted fabric flexible capacitive sensor obtains a higher sensitivity. At the same time, the first knitted fabric layer and the second knitted fabric layer of the knitted fabric flexible capacitive sensor are mutually interlaced by the coils formed by the conductive yarn to form a conductive network, so that the sensor can be cut into any shape and retain a high sensitivity.

[0032] Beneficial effects:

[0033] (1) The knitted fabric flexible capacitive sensor of the present invention is integrally formed and has good weavability. It can be integrated into a carrier by direct weaving or other methods and has a simple structure.

[0034] (2) A knitted fabric flexible capacitive sensor of the present invention has good stretchability and compressibility, can detect compressive load or tensile load, and output the specific value of the load (by detecting the change of capacitance value, and then after data processing, the specific load value corresponding to different capacitance values ​​can be obtained); it can be applied to the fields of human motion monitoring, human-computer interaction, etc.

[0035] (3) The knitted fabric flexible capacitive sensor of the present invention uses insulating elastic yarn as the middle layer, namely the dielectric layer, which gives the sensor higher sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the front coil structure of the knitted fabric flexible capacitive sensor of the present invention;

[0037] Figure 2 It is a schematic diagram of the cross-sectional structure of the knitted fabric flexible capacitive sensor after heat pressing treatment of the present invention;

[0038] Figure 3 It is a working principle diagram of the knitted fabric flexible capacitive sensor of the present invention before and after compression load; Figure 3 (a) is the working principle diagram of the knitted fabric flexible capacitive sensor before compression load. Figure 3 (b) is a working principle diagram of the knitted fabric flexible capacitive sensor before and after compression load; wherein S is the surface area, d is the distance between the first knitted fabric layer and the second knitted fabric layer before compression, and d0 is the distance between the first knitted fabric layer and the second knitted fabric layer after compression;

[0039] Figure 4 It is a working principle diagram of the knitted fabric flexible capacitive sensor of the present invention before and after stretching load; Figure 4 (a) is the working principle diagram of the knitted fabric flexible capacitive sensor before tensile load. Figure 4 (b) is a working principle diagram of the knitted fabric flexible capacitive sensor after stretching load; wherein S is the surface area, d is the distance between the first knitted fabric layer and the second knitted fabric layer before stretching, d0 is the distance between the first knitted fabric layer and the second knitted fabric layer after stretching; S0 is the surface area after stretching;

[0040] Among them, 1 is the first knitted fabric layer, 2 is the second knitted fabric layer, and 3 is the middle layer. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0042] The test methods involved in the performance indicators of the present invention are as follows:

[0043] The knitted fabric flexible capacitive sensor of the present invention is placed in the middle of the pressure head / chuck of the YG028 fabric strength meter. A conductive yarn is led out from the first knitted fabric layer and the second knitted fabric layer of the sensor to connect the two electrode chucks of the TH283X series compact LCR digital bridge to form a complete conductive path. During the test, the digital bridge monitors and records the capacitance value change of the sensor in real time, and the fabric strength meter monitors the tensile stress / pressure change of the sensor in real time.

[0044] During the test, the pressure head of the testing instrument YG028 fabric strength tester used completely covers the sensor, that is, during the compression process, the sensor is evenly stressed and slight changes in the surface area can be ignored.

[0045] (1) Tensile stress: The tensile stress to which the present invention is subjected during the test is directly measured by a YG028 fabric strength tester.

[0046] (2) Pressure: The pressure to which the present invention is subjected during the test cannot be directly measured, but the pressure can be directly measured, so its value can be directly calculated by a theoretical formula, which is as follows:

[0047] ;

[0048] in, is the pressure; F is the pressure applied; S is the force-bearing area, i.e. the surface area.

[0049] (3) Sensitivity: The sensitivity of the present invention cannot be directly measured, but the change in capacitance during the test can be directly measured, so its value can be directly calculated by a theoretical formula, which is as follows:

[0050] ;

[0051] in, is the capacitance value after load; is the capacitance value in the initial state; For strain.

[0052] Example 1

[0053] A knitted fabric flexible capacitive sensor is knitted using 280D silver wire as conductive yarn and 120D spandex as spacer yarn using a computer flat knitting machine (machine number: 14). The first pass is a loop of the silver wire on the front needle bed, the second pass is a loop of the silver wire on the rear needle bed, and the third pass is a full-needle tuck of spandex. The above three passes are woven to form a fabric row, that is, every three passes are a knitting cycle.

[0054] like Figure 1As shown, the knitted fabric flexible capacitive sensor obtained by weaving includes a planar first knitted fabric layer 1, a planar second knitted fabric layer 2 and an intermediate layer 3; the first knitted fabric layer 1 and the second knitted fabric layer 2 are both formed by mutually interlacing silver threads, the intermediate layer 3 is woven from elastic yarn spandex, the first knitted fabric layer 1 and the second knitted fabric layer 2 are connected by full needle tucking, and at the same time, the elastic yarn spandex of the intermediate layer 3 tightens the first knitted fabric layer 1 and the second knitted fabric layer 2; the first knitted fabric layer 1 and the second knitted fabric layer 2 serve as electrode layers of the knitted fabric flexible capacitive sensor, and the intermediate layer 3 serves as a dielectric layer of the knitted fabric flexible capacitive sensor;

[0055] The thickness of the first knitted fabric layer 1 is 1.42 mm, the thickness of the second knitted fabric layer 2 is 1.42 mm, and the thickness of the intermediate layer 3 is 2.37 mm;

[0056] The weight of the knitted flexible capacitive sensor is 354g / m 2 The horizontal density is 14.3 columns / inch and the vertical density is 12.6 rows / inch.

[0057] Knitted fabric flexible capacitive sensors can be used to detect tensile or compressive loads;

[0058] like Figure 4 As shown, under the tensile load, the surface areas of the first knitted fabric layer and the second knitted fabric layer in the knitted fabric flexible capacitive sensor change, and at the same time, the distance between the first knitted fabric layer and the second knitted fabric layer changes, causing the capacitance to change;

[0059] like Figure 3 As shown, under the compressive load, the distance between the first knitted fabric layer and the second knitted fabric layer in the knitted fabric flexible capacitive sensor changes, causing the capacitance to change;

[0060] The knitted fabric flexible capacitive sensor can withstand a tensile stress of 0.01~300N in the range of 50% tensile strain and a compressive stress of 0.1~3.2×10 5 The sensitivity of the knitted flexible capacitive sensor is 1.23; after 10,000 cycles of compression or stretching, the repeatability error δ R压缩 = 3.74%, δ R拉伸 = 3.21%, showing excellent cycle stability and dynamic durability;

[0061] After a knitted flexible capacitive sensor is cut into multiple capacitive sensors of the same shape, under the same tensile load or compressive load, the cut capacitive sensors have consistent baseline capacitance values ​​and consistent sensitivity.

[0062] Example 2

[0063] A knitted flexible capacitive sensor is basically the same as Example 1, except that the conductive yarn is 95D / 12f C / PET multifilament (the mass fraction of C is 30.51%), the spacer yarn is 60D latex yarn, and it is woven using a computer flat knitting machine (machine number: 20).

[0064] like Figure 1 As shown, the knitted fabric flexible capacitive sensor obtained by weaving includes a planar first knitted fabric layer 1, a planar second knitted fabric layer 2 and an intermediate layer 3; the first knitted fabric layer 1 and the second knitted fabric layer 2 are both formed by mutually interlacing C / PET multifilaments, the intermediate layer 3 is woven by latex yarns, the first knitted fabric layer 1 and the second knitted fabric layer 2 are connected by full needle tucking, and at the same time, the latex yarns of the intermediate layer 3 tighten the first knitted fabric layer 1 and the second knitted fabric layer 2; the first knitted fabric layer 1 and the second knitted fabric layer 2 serve as electrode layers of the knitted fabric flexible capacitive sensor, and the intermediate layer 3 serves as a dielectric layer of the knitted fabric flexible capacitive sensor;

[0065] The thickness of the first knitted fabric layer 1 is 1.33 mm, the thickness of the second knitted fabric layer 2 is 1.33 mm, and the thickness of the intermediate layer 3 is 1.75 mm;

[0066] The weight of the knitted flexible capacitive sensor is 297g / m 2 The horizontal density is 20.4 columns / inch and the vertical density is 16.3 rows / inch.

[0067] Knitted fabric flexible capacitive sensors can be used to detect tensile or compressive loads;

[0068] like Figure 4 As shown, under the tensile load, the surface areas of the first knitted fabric layer and the second knitted fabric layer in the knitted fabric flexible capacitive sensor change, and at the same time, the distance between the first knitted fabric layer and the second knitted fabric layer changes, causing the capacitance to change;

[0069] like Figure 3 As shown, under the compressive load, the distance between the first knitted fabric layer and the second knitted fabric layer in the knitted fabric flexible capacitive sensor changes, causing the capacitance to change;

[0070] The knitted fabric flexible capacitive sensor can withstand a tensile stress of 0.01~240N in the range of 50% tensile strain and a compressive stress of 0.1~2.3×10 5 The sensitivity of the knitted flexible capacitive sensor is 1.13; after 10,000 cycles of compression or stretching, the repeatability error δ R压缩 = 2.78%, δ R拉伸 = 2.59%, showing excellent cycle stability and dynamic durability;

[0071] After a knitted flexible capacitive sensor is cut into multiple capacitive sensors of the same shape, under the same tensile load or compressive load, the cut capacitive sensors have consistent baseline capacitance values ​​and consistent sensitivity.

[0072] Example 3

[0073] A knitted fabric flexible capacitive sensor is provided, wherein 75D / 40f Cu / PAN multifilament (Cu mass fraction is 32.2%) is used as conductive yarn and 115D TPU is used as spacer yarn, and the knitting is performed by using a computer flat knitting machine (machine number: 20), wherein the first pass is formed by the Cu / PAN multifilament in the front needle bed, the second pass is formed by the Cu / PAN multifilament in the rear needle bed, and the third and fourth passes are formed by the spacer yarn with each needle being gathered, and the above four passes are knitted to form a fabric row, that is, every four passes are a knitting cycle; after the knitting is removed from the machine, the knitted fabric is hot-pressed at 180°C for 1 minute by using a flat hot press machine to melt the TPU into an elastic block material;

[0074] like Figure 2 As shown, the knitted fabric flexible capacitive sensor obtained after weaving and hot pressing includes a planar first knitted fabric layer 1, a planar second knitted fabric layer 2 and an intermediate layer 3; the first knitted fabric layer 1 and the second knitted fabric layer 2 are both formed by mutually interlacing Cu / PAN multifilaments, the intermediate layer 3 is woven by elastic yarn TPU, the first knitted fabric layer 1 and the second knitted fabric layer 2 are connected by spacer needle tucking, and at the same time, the elastic yarn TPU of the intermediate layer 3 tightens the first knitted fabric layer 1 and the second knitted fabric layer 2; the first knitted fabric layer 1 and the second knitted fabric layer 2 serve as electrode layers of the knitted fabric flexible capacitive sensor, and the intermediate layer 3 serves as a dielectric layer of the knitted fabric flexible capacitive sensor;

[0075] The thickness of the first knitted fabric layer 1 is 1.21 mm, the thickness of the second knitted fabric layer 2 is 1.21 mm, and the thickness of the intermediate layer 3 is 1.85 mm;

[0076] The weight of the fabric flexible capacitive sensor is 249g / m 2 The horizontal density is 19.2 columns / inch and the vertical density is 20.3 rows / inch.

[0077] Knitted fabric flexible capacitive sensors can be used to detect tensile or compressive loads;

[0078] Under the tensile load, the surface areas of the first knitted fabric layer and the second knitted fabric layer in the knitted fabric flexible capacitive sensor change, and at the same time, the distance between the first knitted fabric layer and the second knitted fabric layer changes, causing the capacitance to change;

[0079] Under the compressive load, the distance between the first knitted fabric layer and the second knitted fabric layer in the knitted fabric flexible capacitive sensor changes, causing the capacitance to change;

[0080] The knitted fabric flexible capacitive sensor can withstand a tensile stress of 0.01~300N in the range of 50% tensile strain and a compressive stress of 0.1~2.37×10 5 The sensitivity range of the knitted flexible capacitive sensor is 1.56; after 10,000 cycles of compression or stretching, the repeatability error δ R压缩 = 3.05%, δ R拉伸 = 2.87%, showing excellent cycle stability and dynamic durability;

[0081] After a knitted flexible capacitive sensor is cut into multiple capacitive sensors of the same shape, under the same tensile load or compressive load, the cut capacitive sensors have consistent baseline capacitance values ​​and consistent sensitivity.

[0082] Example 4

[0083] A knitted fabric flexible capacitive sensor is basically the same as Example 3, except that the spacer yarn is a 75D / 12f polyester / polyamide multifilament (mass ratio is 55:45).

[0084] like Figure 1 As shown, the knitted fabric flexible capacitive sensor obtained after weaving and hot pressing includes a planar first knitted fabric layer 1, a planar second knitted fabric layer 2 and an intermediate layer 3; the first knitted fabric layer 1 and the second knitted fabric layer 2 are both formed by mutually interlacing silver threads, the intermediate layer 3 is woven by polyester / polyamide multifilaments, the first knitted fabric layer 1 and the second knitted fabric layer 2 are connected by full needle tucking, and at the same time, the intermediate layer 3 polyester / polyamide multifilaments tighten the first knitted fabric layer 1 and the second knitted fabric layer 2; the first knitted fabric layer 1 and the second knitted fabric layer 2 serve as electrode layers of the knitted fabric flexible capacitive sensor, and the intermediate layer 3 serves as a dielectric layer of the knitted fabric flexible capacitive sensor;

[0085] The thickness of the first knitted fabric layer 1 is 1.42 mm, the thickness of the second knitted fabric layer 2 is 1.42 mm, and the thickness of the intermediate layer 3 is 1.29 mm;

[0086] The weight of the knitted flexible capacitive sensor is 313g / m 2 The horizontal density is 14.2 columns / inch and the vertical density is 12.3 rows / inch.

[0087] Knitted fabric flexible capacitive sensors can be used to detect tensile or compressive loads;

[0088] like Figure 4 As shown, under the tensile load, the surface areas of the first knitted fabric layer and the second knitted fabric layer in the knitted fabric flexible capacitive sensor change, and at the same time, the distance between the first knitted fabric layer and the second knitted fabric layer changes, causing the capacitance to change;

[0089] like Figure 3 As shown, under the compressive load, the distance between the first knitted fabric layer and the second knitted fabric layer in the knitted fabric flexible capacitive sensor changes, causing the capacitance to change;

[0090] The knitted fabric flexible capacitive sensor can withstand a tensile stress of 0.01~300N in the range of 50% tensile strain and a compressive stress of 0.1~3.4×10 5 The sensitivity of the knitted flexible capacitive sensor is 1.17; after 10,000 cycles of compression or stretching, the repeatability error δ R压缩 = 4.04%, δ R拉伸 = 3.87%, showing excellent cycle stability and dynamic durability;

[0091] After a knitted flexible capacitive sensor is cut into multiple capacitive sensors of the same shape, under the same tensile load or compressive load, the cut capacitive sensors have consistent baseline capacitance values ​​and consistent sensitivity.

Claims

1. A knitted fabric flexible capacitive sensor, characterized by: comprising a planar first knitted fabric layer, a planar second knitted fabric layer and an intermediate layer; The first knitted fabric layer and the second knitted fabric layer are connected to each other by weaving spacer yarns therebetween, the spacer yarns constituting the intermediate layer; The first knitted fabric layer and the second knitted fabric layer are both formed by mutually interlacing conductive yarns; The spacer yarn is an insulating elastic yarn, and connects the first knitted fabric layer and the second knitted fabric layer in the form of tuck loops.

2. The knitted fabric flexible capacitive sensor according to claim 1, characterized in that: The tuck stitches are full needle tuck stitches or every other needle tuck stitches.

3. The knitted fabric flexible capacitive sensor according to claim 1, characterized in that: The conductive yarn is one or more of metal-based conductive yarn, carbon-based conductive yarn and conductive polymer yarn.

4. The knitted fabric flexible capacitive sensor according to claim 1, characterized in that: The insulating elastic yarn is spandex, latex yarn or thermoplastic elastomer yarn.

5. The knitted fabric flexible capacitive sensor according to claim 4, characterized in that: The thermoplastic elastomer yarn is polyester thermoplastic elastomer, polystyrene thermoplastic elastomer, polyolefin thermoplastic elastomer, polydiene thermoplastic elastomer, polyvinyl chloride thermoplastic elastomer, polyurethane thermoplastic elastomer, polyamide thermoplastic elastomer, polyorganofluorine thermoplastic elastomer, polyorganosilicone thermoplastic elastomer, polyethylene thermoplastic elastomer or a mixed multifilament thereof; After the thermoplastic elastomer yarn is woven between the first knitted fabric layer and the second knitted fabric layer, the thermoplastic elastomer yarn is melted by heat pressing to form an elastomer block material.

6. The knitted fabric flexible capacitive sensor according to claim 1, characterized in that: The linear density of the conductive yarn is 22-280 dtex, and the linear density of the insulating elastic yarn is 22-280 dtex; The thickness of the first knitted fabric layer is 1-3 mm, the thickness of the second knitted fabric layer is 1-3 mm, and the thickness of the intermediate layer is 1-3 mm.

7. The knitted fabric flexible capacitive sensor according to any one of claims 1 to 6, characterized in that: The knitted fabric flexible capacitive sensor can be used to detect tensile load or compressive load; Under a tensile load, the surface areas of the first knitted fabric layer and the second knitted fabric layer in the knitted fabric flexible capacitive sensor change, and simultaneously the distance between the first knitted fabric layer and the second knitted fabric layer changes, causing the capacitance to change; Under a compressive load, the distance between the first knitted fabric layer and the second knitted fabric layer in the knitted fabric flexible capacitive sensor changes, causing the capacitance to change.

8. The knitted fabric flexible capacitive sensor according to claim 7, characterized in that: The knitted fabric flexible capacitive sensor can withstand a tensile stress of 0.01 to 300 N within a 50% tensile strain range and a compressive stress of 0.1 to 4 × 10 5 Pa pressure.

9. The knitted fabric flexible capacitive sensor according to claim 1, characterized in that: The sensitivity range of the knitted fabric flexible capacitive sensor is 1~2; After one knitted fabric flexible capacitive sensor is cut into multiple capacitive sensors of the same shape, under the same tensile load or compressive load, the cut capacitive sensors have consistent baseline capacitance values ​​and consistent sensitivities.

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