Self-calibration flexible pressure sensing equipment

Abstract

The invention discloses a self-calibration flexible pressure sensing device, which comprises a first conductor and a second conductor which are in a strip-shaped, strip-shaped or linear structure and both have a piezoresistive effect. The isolating layer is arranged between the first conductor and the second conductor, and through holes or long grooves with continuous through holes are distributed in the surface of the isolating layer; and an encapsulation layer covering the first conductor and the second conductor. According to the embodiment of the invention, a dual-core layer piezoresistive structure and a through hole type isolation layer design are adopted, the dual-core layer design covers a range from small pressure to large pressure, the range limitation of a single material is broken through, and a dynamic self-calibration technology is combined, so that multi-parameter integrated detection of pressure magnitude, position and width is realized; the sensor array has the advantages of self-adaption to environment change, wide-range detection, multi-scene applicability and the like, the sensor for realizing the functions only needs four wires, complex wiring of the sensor array is avoided, miniaturization and flexibility are facilitated, a narrow strip-shaped flexible structure is adopted as a whole, and flexible arrangement of sensor tracks and garment integration are facilitated.

Description

Technical Field

[0001] The embodiments of the present invention relate to, but are not limited to, the field of flexible electronic sensor technology, and in particular to a self-calibrating flexible pressure sensing device. Background Technology

[0002] Flexible pressure sensors, as a core component of flexible electronics technology, are widely used in smart wearable devices, medical rehabilitation monitoring, industrial robot tactile sensing and other fields. With the development of IoT and AI technologies, the market has put forward higher requirements for the multi-parameter detection capability, environmental adaptability and range of sensors. However, traditional piezoresistive sensors have the following technical problems: (1) Poor environmental adaptability: The resistance value of piezoresistive materials is significantly affected by temperature or other physical quantities, requiring additional compensation circuits or algorithms, which increases the complexity of the system; (2) Range limitation: A single piezoresistive material is difficult to cover the wide range of pressure requirements from small pressure (e.g., 0.1N) to large pressure (e.g., 100N); (3) Single detection parameter: Most sensors can only output the pressure magnitude and cannot simultaneously obtain information such as contact position and force width; (4) High structural complexity: To achieve multi-parameter detection, array design or increase the number of wires is required, which is not conducive to miniaturization and flexibility; (5) Bulk size: Most sensors are in the form of flexible thin films, which makes it difficult to achieve yarn-type or narrow strip flexible structures, which is not conducive to the flexible arrangement of sensor trajectories and clothing integration. Summary of the Invention

[0003] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0004] This invention provides a self-calibrating flexible pressure sensing device, which adopts a dual-core layer piezoresistive structure and a perforated isolation layer design. The dual-core layer design covers a pressure range from low to high, breaking through the range limitations of a single material. Combined with dynamic self-calibration technology, it achieves integrated detection of multiple parameters such as pressure magnitude, position, and width. It has the advantages of adapting to environmental changes, wide range detection, and applicability to multiple scenarios. Moreover, the sensor that achieves the above functions only requires four wires, avoiding the complex wiring of the sensor array, which is conducive to miniaturization and flexibility. The overall narrow and long strip flexible structure is conducive to the flexible arrangement of sensor trajectories and integration into clothing.

[0005] A first aspect of the present invention provides a self-calibrating flexible pressure sensing device, comprising: The first and second conductors are in the form of strips, strips or lines, and both have piezoresistive effect; An isolation layer is disposed between the first conductor and the second conductor, and its surface is distributed with through holes or long grooves with continuous through holes. An encapsulation layer covers the first conductor and the second conductor; The first conductor has a first left-end wire 1L and a first right-end wire 1R led out from its two ends; the second conductor has a second left-end wire 2L and a second right-end wire 2R led out from its two ends; the resistance between the first left-end wire 1L and the first right-end wire 1R is R. 1L1R The resistance value between the second left terminal 2L and the second right terminal 2R is R. 2L2R The resistance value between the first left-end wiring and the second left-end wiring is R. 1L2L The resistance value between the first right-end wiring and the second right-end wiring is R. 1R2R ; When the external force is less than the set threshold F0, the first conductor and the second conductor have no electrical contact, and the resistance value R between the first left-end wiring and the second left-end wiring is... 1L2L The resistance R between the first right-end connection and the second right-end connection is infinite. 1R2R It is infinite; When the external force is greater than or equal to the set threshold F0, the first conductor and the second conductor make contact through the through hole or long groove of the isolation layer, and the resistance value R between the first left-end wiring and the second left-end wiring is... 1L2L The abrupt change to a non-infinite value results in the resistance value R between the first right-end connection and the second right-end connection. 1L2L The mutation changes to a non-infinite value; Based on the four resistance values ​​R of the dynamic scan 1L1R R 2L2R R 1L2L R 1R2R In addition, a three-dimensional database of physical quantities under different environments is used to obtain the pressure magnitude, pressing position, and pressing width W of the pressing point.

[0006] In some embodiments, the pressing position is calculated using the following formula: When the pressing point is close to the first left end wiring, R 1L2L ≈0, R 1R2R ≈R 1L1R + R 2L2R ; When the pressing point is close to the first right-end wiring, R 1R2R ≈0, R 1L2L ≈R 1L1R + R 2L2R ; When the pressing point is located at the midpoint, R 1L2L ≈R 1R2R ≤0.5(R 1L1R + R 2L2R ); When the pressing point is located elsewhere, according to R 1L2L and R1R2R The pressing position is determined by the proportional relationship.

[0007] In some embodiments, the pressing width W is calculated using the following formula: When pressing a single point with a narrow range, R 1L2L + R 1R2R ≈R 1L1R + R 2L2R The pressing width is very small, W≈0; When pressing a single point with wide amplitude, R W = 0.5×(R) 1L1R + R 2L2R (R 1L2L + R 1R2R )), R W The value is positively correlated with the press width W.

[0008] In some embodiments, the construction steps of the three-dimensional database include: First, the threshold F0 is calibrated to determine the condition of R under different environmental physical quantities. 1L2L R 1R2R The magnitude of the pressure corresponding to the sudden change to non-infinity; Under different environmental physical quantities, the conduction threshold pressure F0 corresponds to the same conduction pressure. When environmental physical quantities change, single-point narrow-amplitude pressure, single-point medium-amplitude pressure, and single-point wide-amplitude pressure are applied to the sensor respectively, according to R. 1L1R R 2L2R R 1L2L R 1R2R A three-dimensional database of environmental physical quantities, width, and piezoresistive equations was constructed based on the relationship between pressure magnitude and pressing width W.

[0009] In some embodiments, the pressure magnitude and pressure location of the press are detected through the following steps: When R 1L2L R 1R2R When the mutation becomes non-infinite, record R at this time. 1L1R R 2L2R Match the environmental physical quantities and call the first piezoresistive equation corresponding to the environmental physical quantities; Calculate R W = 0.5×(R) 1L1R + R 2L2R (R) 1L2L + R 1R2R Match the press width and call the second piezoresistive equation corresponding to the press width; The pressure magnitude and pressing position are calculated based on the first and second piezoresistive equations.

[0010] In some embodiments, the piezoresistive materials of the first conductor and the second conductor are uniformly distributed, and the piezoresistive material comprises: Polymer composite materials containing conductive particles; Blended yarns of conductive and non-conductive fibers, or multifilaments of conductive fibers, or yarns spun from fibers containing conductive particles, or yarns with conductive materials distributed on their surface. Intrinsically conductive nanofibers prepared by electrospinning and polymer nanofibers filled with conductive phases; Elastomers filled with liquid metal microfluidics or with attached liquid metal; Intrinsically conductive polymer materials, as well as their composites with conventional polymer materials, and their composites with conductive particles; Materials exhibiting piezoresistive effect include materials whose internal contact area changes or whose structural contact area changes when subjected to pressure, resulting in a change in resistance.

[0011] In some embodiments, the isolation layer is an elastic polymer material, including polyurethane, silicone or thermoplastic elastomer acrylic resin, epoxy resin, phenolic resin, polyester, polyester fiber, nylon, acrylic fiber, polypropylene fiber, vinylon, chlorofiber and their composite materials; the encapsulation layer is polyurethane, silicone, styrene-ethylene-butene-styrene block copolymer.

[0012] In some embodiments, the processing method of the sensing device includes at least one of spinning technology, yarn spinning technology, printing technology, coating technology, microfluidic technology, sewing and embroidery, and bonding combination.

[0013] In some embodiments, the first conductor and the second conductor are linear in shape, and are arranged in parallel or intertwined; the first conductor and the second conductor are not electrically connected when there is no external force, and are electrically connected when the external force reaches F0.

[0014] In some embodiments, the encapsulation layer completely encapsulates the first conductor, and simultaneously completely encapsulates the second conductor and the isolation layer; or, the encapsulation layer does not completely encapsulate the first conductor, the second conductor, and the isolation layer, but only adheres to the upper surface of the first conductor and the lower surface of the second conductor.

[0015] This invention provides a self-calibrating flexible pressure sensing device, comprising: a first conductor and a second conductor, which are strip-shaped, strip-shaped, or linear in structure and both exhibit piezoresistive effect; an isolation layer disposed between the first conductor and the second conductor, the surface of which is distributed with through holes or elongated grooves with continuous through holes; and an encapsulation layer covering the first conductor and the second conductor; a first left-end wiring 1L and a first right-end wiring 1R are led out from both ends of the first conductor, and a second left-end wiring 2L and a second right-end wiring 2R are led out from both ends of the second conductor; the resistance value between the first left-end wiring 1L and the first right-end wiring 1R is R. 1L1R The resistance value between the second left terminal 2L and the second right terminal 2R is R. 2L2R The resistance value between the first left-hand wire and the second left-hand wire is R. 1L2L The resistance value between the first right-end wiring and the second right-end wiring is R. 1R2R When the external force is less than the set threshold F0, the first conductor and the second conductor have no electrical contact, and the resistance value R between the first left-end wiring and the second left-end wiring is [value missing]. 1L2L The resistance R between the first right-hand connection and the second right-hand connection is infinite. 1R2R The resistance is infinite; when the external force is greater than or equal to the set threshold F0, the first conductor and the second conductor make contact through the through-hole or long slot of the isolation layer, and the resistance value R between the first left end wire and the second left end wire is infinite. 1L2L The abrupt change to a non-infinite value indicates the resistance R between the first right-hand connection and the second right-hand connection. 1L2L The abrupt change results in a non-infinite value; based on the four resistance values ​​R from the dynamic scan. 1L1R R 2L2R R 1L2L R 1R2R The invention utilizes a three-dimensional database of physical quantities under different environments to obtain the pressure magnitude, pressing position, and pressing width W at the pressing point. Based on this, the self-calibrating flexible pressure sensing device of this invention adopts a dual-core layer piezoresistive structure and a perforated isolation layer design. The dual-core layer design covers a range from low to high pressure, breaking through the range limitations of a single material. Combined with dynamic self-calibration technology, it achieves integrated detection of multiple parameters, including pressure magnitude, position, and width. It has advantages such as adaptability to environmental changes, wide range detection, and applicability to multiple scenarios. Moreover, the sensor that achieves the above functions only requires four wires, avoiding the complex wiring of sensor arrays, which is conducive to miniaturization and flexibility. The overall narrow and long strip flexible structure is conducive to the flexible arrangement of sensor trajectories and integration into clothing.

[0016] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0017] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the technical solutions of the present invention, and do not constitute a limitation on the technical solutions of the present invention.

[0018] Figure 1A A longitudinal cross-sectional structural diagram of a self-calibrating flexible pressure sensing device provided in an embodiment of the present invention; Figure 1B This is a schematic cross-sectional view of a self-calibrating flexible pressure sensing device provided in an embodiment of the present invention. Figure 1C This is a top view of the isolation layer provided in an embodiment of the present invention; Figure 1D This is a side view of the isolation layer provided in an embodiment of the present invention; Figure 2 Typical topographic figures of the piezoresistive equations for the first and second conductors provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a first conductor and a second conductor without electrical contact according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a structure in which a first conductor and a second conductor are in contact through a long groove in an isolation layer, according to an embodiment of the present invention. Figure 5 This is a schematic diagram of the structure of a self-calibrating flexible pressure sensing device provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of a self-calibrating flexible pressure sensing device provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of a self-calibrating flexible pressure sensing device provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the structure of a self-calibrating flexible pressure sensing device provided in an embodiment of the present invention; Figure 9 This is a schematic diagram of the structure of a self-calibrating flexible pressure sensing device provided in an embodiment of the present invention; Figure 10 This is a schematic diagram of the structure of a self-calibrating flexible pressure sensing device provided in an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] It should be understood that in the description of the embodiments of the present invention, "multiple" (or "amounts") means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. If "first," "second," etc., are used in the description, they are only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0021] Flexible pressure sensors, as a core component of flexible electronics technology, are widely used in smart wearable devices, medical rehabilitation monitoring, industrial robot tactile sensing and other fields. With the development of IoT and AI technologies, the market has put forward higher requirements for the multi-parameter detection capability, environmental adaptability and range of sensors. However, traditional piezoresistive sensors have the following technical problems: (1) Poor environmental adaptability: The resistance value of piezoresistive materials is significantly affected by temperature or other physical quantities, requiring additional compensation circuits or algorithms, which increases the complexity of the system; (2) Range limitation: A single piezoresistive material is difficult to cover the wide range of pressure requirements from small pressure (e.g., 0.1N) to large pressure (e.g., 100N); (3) Single detection parameter: Most sensors can only output the pressure magnitude and cannot simultaneously obtain information such as contact position and force width; (4) High structural complexity: To achieve multi-parameter detection, array design or increase the number of wires is required, which is not conducive to miniaturization and flexibility; (5) Bulk size: Most sensors are in the form of flexible thin films, which makes it difficult to achieve yarn-type or narrow strip flexible structures, which is not conducive to the flexible arrangement of sensor trajectories and clothing integration.

[0022] To address the aforementioned technical problems, this invention provides a self-calibrating flexible pressure sensing device, comprising: a first conductor and a second conductor, both having a strip, band, or line structure and exhibiting piezoresistive effect; an isolation layer disposed between the first conductor and the second conductor, with through holes or elongated grooves having continuous through holes distributed on its surface; and an encapsulation layer covering the first conductor and the second conductor; a first left-end wiring 1L and a first right-end wiring 1R are led out from both ends of the first conductor, and a second left-end wiring 2L and a second right-end wiring 2R are led out from both ends of the second conductor; the resistance value between the first left-end wiring 1L and the first right-end wiring 1R is R. 1L1R The resistance value between the second left terminal 2L and the second right terminal 2R is R. 2L2R The resistance value between the first left-hand wire and the second left-hand wire is R. 1L2L The resistance value between the first right-end wiring and the second right-end wiring is R. 1R2R When the external force is less than the set threshold F0, the first conductor and the second conductor have no electrical contact, and the resistance value R between the first left-end wiring and the second left-end wiring is [value missing]. 1L2L The resistance R between the first right-hand connection and the second right-hand connection is infinite. 1R2RThe resistance is infinite; when the external force is greater than or equal to the set threshold F0, the first conductor and the second conductor make contact through the through-hole or long slot of the isolation layer, and the resistance value R between the first left end wire and the second left end wire is infinite. 1L2L The abrupt change to a non-infinite value indicates the resistance R between the first right-hand connection and the second right-hand connection. 1L2L The abrupt change results in a non-infinite value; based on the four resistance values ​​R from the dynamic scan. 1L1R R 2L2R R 1L2L R 1R2R The invention utilizes a three-dimensional database of physical quantities under different environments to obtain the pressure magnitude, pressing position, and pressing width W at the pressing point. Based on this, the self-calibrating flexible pressure sensing device of this invention adopts a dual-core layer piezoresistive structure and a perforated isolation layer design. The dual-core layer design covers a range from low to high pressure, breaking through the range limitations of a single material. Combined with dynamic self-calibration technology, it achieves integrated detection of multiple parameters, including pressure magnitude, position, and width. It has advantages such as adaptability to environmental changes, wide range detection, and applicability to multiple scenarios. Moreover, the sensor that achieves the above functions only requires four wires, avoiding the complex wiring of sensor arrays, which is conducive to miniaturization and flexibility. The overall narrow and long strip flexible structure is conducive to the flexible arrangement of sensor trajectories and integration into clothing.

[0023] The main structure of this invention is composed of flexible materials and is functionally divided into a first conductor, a second conductor, an isolation layer, and an encapsulation layer. The first and second conductors are strip-shaped, ribbon-shaped, or linear, both exhibiting piezoresistive effect. The isolation layer is located between the first and second conductors and has through-holes or elongated grooves with continuous through-holes on its surface. The encapsulation layer covers the first and second conductors. A first left-end wire 1L and a first right-end wire 1R are led out from both ends of the first conductor, and a second left-end wire 2L and a second right-end wire 2R are led out from both ends of the second conductor. The resistance value between the first left-end wire 1L and the first right-end wire 1R is R. 1L1R The resistance value between the second left terminal 2L and the second right terminal 2R is R. 2L2R The resistance value between the first left-hand wire and the second left-hand wire is R. 1L2L The resistance value between the first right-end wiring and the second right-end wiring is R. 1R2R When the external force is less than the set threshold F0, the first conductor and the second conductor have no electrical contact, and the resistance value R between the first left-end wiring and the second left-end wiring is [value missing]. 1L2L The resistance R between the first right-hand connection and the second right-hand connection is infinite. 1R2R The resistance is infinite; when the external force is greater than or equal to the set threshold F0, the first conductor and the second conductor make contact through the through-hole or long slot of the isolation layer, and the resistance value R between the first left end wire and the second left end wire is infinite. 1L2L The abrupt change to a non-infinite value indicates the resistance R between the first right-hand connection and the second right-hand connection.1L2L The abrupt change results in a non-infinite value; based on the four resistance values ​​R from the dynamic scan. 1L1R R 2L2R R 1L2L R 1R2R In addition, a three-dimensional database of physical quantities under different environments is used to obtain the pressure magnitude, pressing position, and pressing width W of the pressing point.

[0024] It is understood that this invention can be applied to multiple fields, including but not limited to: medical and health: intelligent rehabilitation monitoring, physiological signal acquisition, wearable medical devices; industrial manufacturing: robot tactile perception, precision assembly force control, industrial equipment pressure monitoring; consumer electronics: intelligent wearable devices (such as gloves, insoles), flexible input devices, virtual reality interaction; smart home: smart home textiles (mattresses, sofas), smart car interiors (seats, steering wheels), Internet of Things sensor networks; special applications: smart textile toys, motion monitoring equipment, aerospace flexible sensing systems.

[0025] Understandably, the pressure point is calculated using the following formula: When the pressing point is close to the first left end wiring, R 1L2L ≈0, R 1R2R ≈R 1L1R + R 2L2R ; When the pressing point is close to the first right end wiring, R 1R2R ≈0, R 1L2L ≈R 1L1R + R 2L2R ; When the pressure point is at the midpoint, R 1L2L ≈R 1R2R ≤0.5(R 1L1R + R 2L2R ); When the pressure point is elsewhere, according to R 1L2L and R 1R2R The proportional relationship is used to determine the pressing position.

[0026] Understandably, the press width W is calculated using the following formula: When pressing a single point with a narrow range, R 1L2L + R 1R2R ≈R 1L1R + R 2L2R The pressing width is very small, W≈0; When pressing a single point with wide amplitude, R W = 0.5×(R) 1L1R + R 2L2R (R 1L2L + R 1R2R )), RW The value is positively correlated with the press width W.

[0027] Understandably, the steps involved in constructing a 3D database include: First, the threshold F0 is calibrated to determine the condition of R under different environmental physical quantities. 1L2L R 1R2R The magnitude of the pressure corresponding to the sudden change to non-infinity; Under different environmental physical quantities, the conduction threshold pressure F0 corresponds to the same conduction pressure, that is, the force divided by the force area is the same; or the change of conduction pressure with this physical quantity is at least 20 times smaller than the change of piezoresistive effect with this physical quantity; that is, compared to the piezoresistive effect being severely affected by this environmental physical quantity, the conduction pressure is basically unaffected by this environmental physical quantity. When environmental physical quantities (temperature (sensor temperature drift), humidity (sensor humidity drift), time (sensor zero-point drift), etc.) change, for example, if the environmental physical quantity is temperature, then at multiple temperature points (e.g., 10℃, 20℃, 30℃, 40℃, 50℃), single-point narrow-amplitude pressing (e.g., width < 5mm), single-point medium-amplitude pressing (e.g., width 5mm), and single-point wide-amplitude pressing (e.g., width > 5mm) are applied to the sensor, according to R... 1L1R R 2L2R R 1L2L R 1R2R A three-dimensional database of environmental physical quantities, width, and piezoresistive equations was constructed based on the relationship between pressure magnitude and pressing width W.

[0028] Understandably, the pressure applied and the location of the press are determined through the following steps: When R 1L2L R 1R2R When the mutation becomes non-infinite, record R at this time. 1L1R R 2L2R Match the environmental physical quantities and call the first piezoresistive equation corresponding to the environmental physical quantities; Calculate R W = 0.5×(R) 1L1R + R 2L2R (R) 1L2L + R 1R2R Match the press width and call the second piezoresistive equation corresponding to the press width; The pressure magnitude and pressing position are calculated based on the first and second piezoresistive equations.

[0029] It is understandable that the piezoresistive material of the first conductor and the second conductor is uniformly distributed (i.e., the piezoresistive coefficient is the same at all locations of the first conductor or the second conductor), and is selected from one of the following combinations: Polymer composite materials containing conductive particles, such as carbon nanotubes / styrene-ethylene-butene-styrene block copolymer (SEBS), graphene / polyurethane, and silver nanowires / silicone. Blended yarns of conductive and non-conductive fibers, or multifilaments of conductive fibers, or yarns spun from fibers containing conductive particles, or yarns with conductive materials distributed on their surface. Intrinsically conductive nanofibers and polymer nanofibers filled with conductive phases prepared by electrospinning, including fiber bundles and fiber webs; Elastomers filled with liquid metal microfluidics or with attached liquid metal; Intrinsically conductive polymer materials, their composites with conventional polymer materials, and their composites with conductive particles; Other materials exhibiting a generalized piezoresistive effect include those whose internal contact area changes or whose structural contact area changes when subjected to pressure, resulting in a change in resistance.

[0030] Understandably, the isolation layer is made of elastic polymer materials, such as polyurethane, silicone, or thermoplastic elastomers with good elasticity; or acrylic resin, epoxy resin, phenolic resin, polyester, nylon, acrylic fiber, polypropylene, vinylon, and chlorofiber with lower elasticity, or their composite materials.

[0031] It is understandable that the encapsulation layer is made of polyurethane, silicone, styrene-ethylene-butene-styrene block copolymer, etc., and the material of the encapsulation layer can be the same as that of the isolation layer.

[0032] It is understandable that the processing methods for sensing devices can include spinning technology, yarn spinning technology, printing technology, coating technology, microfluidics technology, sewing and embroidery, bonding and assembly, etc. Specific processing methods include, but are not limited to: dry spinning, wet spinning, melt spinning, electrospinning, preform thermal drawing, yarn blending, covered yarn, core-spun yarn, coated yarn, ply yarn doubling, template injection molding, 3D printing, screen printing, perforated plate printing, thin film cutting and bonding, embroidery and sewing, microfluidics technology, etc.

[0033] Understandably, the first and second conductors are linear in shape (slender strips, ribbons, or linear structures), arranged parallel to each other or intertwined. The geometry and spatial arrangement of the isolation layer are flexible, but it must ensure that the first and second conductors are not electrically connected when there is no external force, and are electrically connected after the external force reaches F0. The encapsulation layer can completely enclose the first conductor, the second conductor, and the isolation layer. Alternatively, the encapsulation layer may not completely cover the first and second conductors and the isolation layer, but only adhere to the upper surface of the first conductor and the lower surface of the second conductor. The cross-section of the sensing device can be of any shape, such as circular, elliptical, square, rectangular, rhomboid, triangular, petal-shaped, fiber bundle morphology, and other geometric shapes.

[0034] Understandably, when pressure sensing devices with slender strip, ribbon, or linear structures are placed on fabrics or clothing, the sensor's main structure can take on any geometric shape, which can be customized according to user needs, such as straight lines, wavy lines, curves, triangles, or other geometric patterns. The first conductor, second conductor, insulating layer, and encapsulation layer are all flexible materials, and they are combined into a yarn-like or strip-shaped main structure. Therefore, they possess the advantages of being soft, flexible, washable, and tumble-dryable, characteristic of apparel textiles.

[0035] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0036] Example 1 This embodiment provides a self-calibrating flexible pressure sensing device, which is made of carbon nanotubes and polyurethane materials through a preform thermal stretching process. Figure 1A This is a longitudinal cross-sectional view of the sensing device. Figure 1B This is a cross-sectional view of the sensing device. The entire sensing device consists of a first conductor 1, an insulating layer 2, a second conductor 3, and an encapsulation layer 4. Both the first conductor 1 and the second conductor 3 are made of carbon nanotubes and polyurethane composite materials, exhibiting piezoresistive effect. They are both elongated strips with rectangular cross-sections. The amount of carbon nanotubes added to the first conductor 1 and the second conductor 3 differs, and the elastic modulus of the polyurethane used also differs. The insulating layer 2 is made of polyurethane, consisting of a series of long strips along the longitudinal direction (top view) and discontinuous rectangles along the transverse direction (bottom view). Essentially, the insulating layer 2 is composed of a series of rectangular cross-section strips that do not touch each other (leaving gaps / grooves), much like multiple chopsticks arranged parallel without contact. The top and side views of the insulating layer 2 are shown below. Figure 1C and Figure 1D ,in, Figure 1C This is a top view, showing a series of long strips. Figure 1D This is a side view (cross-sectional view), showing the approximate relationship between the thickness and width of the isolation layer and the gaps. Therefore, isolation layer 2 can separate conductors 1 and 3, while the long grooves between the strips allow the first conductor 1 and the second conductor 3 to make electrical contact with each other when pressed down. Isolation layer 2 has at least one long groove, ensuring that conductors 1 and 3 can make electrical contact, i.e., conductors 1 and 3 are connected, with a threshold pressure of F0. Encapsulation layer 4 is made of polyurethane. The first conductor 1 has a first left-end wire 1L and a first right-end wire 1R led out from both ends; the second conductor 3 has a second left-end wire 2L and a second right-end wire 2R led out from both ends; as... Figure 3 As shown, the resistance between the first left-end wiring and the first right-end wiring is denoted as R. 1L1R The resistance between the second left-end wiring and the second right-end wiring is denoted as R. 2L2R The resistance between the first left-hand connection and the second left-hand connection is denoted as R. 1L2LThe resistance between the first right-end connection and the second right-end connection is denoted as R. 1R2R .

[0037] Work style: When the external force is less than the set threshold F0, the first conductor 1 and the second conductor 3 have no electrical contact, and the resistance R between the first left-end wiring and the second left-end wiring is... 1L2L Infinite ( Figure 3 The resistance R between the first right-end wiring and the second right-end wiring 1R2R Infinite ( Figure 3 ); When the external force is greater than or equal to F0, the first conductor 1 and the second conductor 3 make contact through the long groove of the isolation layer 2, and the resistance R between the first left end wire and the second left end wire is... 1L2L The mutation becomes a non-infinite value ( Figure 4 The resistance R between the first right-end wiring and the second right-end wiring 1R2R The mutation becomes a non-infinite value ( Figure 4 ); Dynamically scan four resistance values ​​R 1L1R R 2L2R R 1L2L R 1R2R By combining environmental physical quantities (such as temperature) and comprehensive calibration data of the pressing width, the pressure magnitude, location, and width can be deduced.

[0038] Calibration steps: Step 1: First, calibrate F0, that is, determine the value of R under different environmental physical quantities. 1L2L R 1R2R The magnitude of the pressure when the value abruptly changes from infinity to non-infinity; Step 2: When the environmental physical quantity changes, such as temperature, apply single-point narrow-range pressure (e.g., width < 5mm), single-point medium-range pressure (e.g., width 5mm), and single-point wide-range pressure (e.g., width > 5mm) to the sensor at multiple temperature points (e.g., 10℃, 20℃, 30℃, 40℃, 50℃), and measure R. 1L1R R 2L2R R 1L2L R 1R2R A three-dimensional database of temperature-width-piezoresistive equations was established to study the relationship between pressure and width.

[0039] Pressing position: When the pressing point is close to the first left end wiring, R 1L2L ≈0, R 1R2R ≈R 1L1R + R 2L2R ; When the pressing point is close to the first right end wiring, R 1R2R ≈0,R 1L2L≈R 1L1R + R 2L2R ; When the pressure point is at the midpoint, R 1L2L ≈R 1R2R ≤0.5(R 1L1R + R 2L2R ); When the pressure point is elsewhere, via R 1L2L and R 1R2R The specific pressing position is determined by the proportional relationship. It should be noted that the contact resistance of the first conductor 1 and the second conductor 3 is assumed to be zero here.

[0040] Press width W: When pressing a single point with a narrow range, R 1L2L + R 1R2R ≈R 1L1R + R 2L2R The pressing width is very small, W≈0 ( Figure 4 (The image above) When pressing a single point, not a narrow range, R W = 0.5×(R) 1L1R + R 2L2R (R) 1L2L + R 1R2R )), R W The value is positively correlated with the press width W. Figure 4 (See the image below).

[0041] It should be noted that this assumes good contact and zero contact resistance throughout the contact area between the first conductor 1 and the second conductor 3, i.e., within the pressing width W. Therefore, dashed lines represent numerous contact points. According to the law of minimum energy, R... 1L2L This is equal to the sum of the resistance of the first conductive portion of W (excluding the leftmost part) and the resistance of the second conductive portion of W (excluding the leftmost part). That is, measuring R... 1L2L At that time, the current does not flow through the interior of W, but only through the leftmost side of W.

[0042] Detection pressure: Step 1: When R 1L2L R 1R2R When the mutation becomes non-infinite, record R at this time. 1L1R R 2L2R Match environmental physical quantities (such as temperature values) and call the corresponding piezoresistive equations for the environmental physical quantities; Step 2: Calculate R W = 0.5×(R) 1L1R + R 2L2R (R) 1L2L + R1R2R ), obtain the pressing width W, match the pressing width and call the corresponding piezoresistive equation; Step 3: Combine the equations from Step 1 and Step 2 to calculate the magnitude and location of the pressure.

[0043] Wide pressure range: The typical piezoresistive equations for the first conductor 1 and the second conductor 3 in this embodiment are as follows: Figure 2 As shown, f AB For the piezoresistive equation of the first conductor 1, f CD This is the piezoresistive equation for the second conductor 3. Due to differences in the amount of carbon nanotubes added and the type and modulus of polyurethane, their piezoresistive equations have no overlapping operating regions. The first conductor 1 focuses on low-pressure measurements, while the second conductor 3 focuses on high-pressure measurements. It should be noted that F in the figure... critical This refers to F0 mentioned earlier. It should be noted that the pressure measurement range of the sensing device in this embodiment does not necessarily have to be greater than or equal to F0. When the pressure is less than F0, it can still be measured using the piezoresistive equation f of the first conductor 1. AB Pressure measurement is achieved, but at this time, the pressure location and pressure width cannot be determined, nor can environmental physical quantities be compensated.

[0044] Processing method: (1) Prefabricated body processing Material Preparation: Conductor Materials: Both the first conductor 1 and the second conductor 3 use thermoplastic polyurethane (TPU) as the matrix, with 5-15 wt% and 2-8 wt% of multi-walled carbon nanotubes (MWCNTs) added respectively. High conductivity (surface resistance ≤1 kΩ / sq) and medium conductivity (10 kΩ / sq-100 kΩ / sq) composite masterbatches are prepared by melt blending using a twin-screw extruder. Isolation Layer Material: 5% silica nanoparticles are added to pure TPU to enhance melt strength. Longitudinal strip-shaped preforms are fabricated using micro / nano molds, with a discontinuous rectangular cross-section (groove height and width 50-200 μm, spacing 100-500 μm) to ensure physical isolation between the strips while leaving gaps (see...). Figure 1C and Figure 1D Encapsulation layer material: Low-hardness TPU (Shore A60-80) extruded into thin-walled tubular preforms to protect the internal structure.

[0045] Co-extrusion composite molding: A multi-channel co-extruder is used, and the layers are aligned and laminated in the following order: "first conductor 1 → isolation layer 2 → second conductor 3 → encapsulation layer 4". The width of the isolation layer 2 should be slightly wider than that of the first conductor 1 and the second conductor 3 to avoid incorrect conduction. The extrusion temperature is controlled at 180-200℃ (above the melting point of TPU but below the oxidation temperature of MWCNTs) to ensure uniform material flow. Output structure: The final product is a tubular or flat strip preform. The internal conductors 1 and 2 are rectangular strips (width 0.5-2 mm, thickness 50-200 μm). Transverse grooves are left between the strips of the isolation layer, and the encapsulation layer completely encapsulates the entire structure.

[0046] (2) Implementation of hot drawing process The preform is preheated as a whole using infrared heating or hot air circulation, with the temperature set at 200℃ (balancing TPU melt flowability and MWCNTs thermal stability). The draw ratio is set to 3-5 times (adjusted according to the target fiber diameter), and the stretching speed is 50-200 mm / min. High-speed stretching can reduce TPU crystallinity and improve fiber flexibility. Immediately after stretching, the preform is rapidly cooled in a water-cooling bath (15-20℃) to fix the long groove structure and prevent bending or shrinkage deformation of the long strips caused by air cooling.

[0047] Example 2 Referring to Figure 1, this embodiment provides a self-calibrating flexible pressure sensing device. The main body is made of graphene / polyether block amide (PEBA) material, which is prepared by a continuous composite wet spinning process. The specific steps are as follows: First, a first-stage spinning process is performed to form a composite structure of a first conductor 1 and an insulating layer 2. The first conductor 1 stock solution is prepared by dissolving PEBA / 5% graphene in formic acid / m-cresol (volume ratio 7:3). This stock solution is extruded using a rectangular spinneret (slit size 0.3mm × 0.08mm) to form a rectangular cross-section fiber. At this point, the first conductor 1 has a width of 0.3 mm and a thickness of 0.08 mm. The insulating layer 2 stock solution is PEBA / 25% polyethylene glycol (PEG) dissolved in formic acid. It is simultaneously extruded through a side-co-extrusion spinneret along one long side (0.3 mm) of the first conductor 1, forming a single-sided composite structure. The insulating layer 2 has a width of 0.33 mm (covering the long side of the first conductor 1 with a 10% margin) and a thickness of 0.03 mm. The extruded fiber is then passed through two coagulation baths. The first bath is 15℃ water / ethanol (volume ratio 8:2) for rapid coagulation, and the second bath is 60℃ hot water (containing 0.5%...). NaOH (flow rate 2 m / s) was used to dissolve the PEG porogen. During the second bath treatment, the fiber residence time was controlled to be 40 seconds, so that a specific structure could be formed in the contact area between the isolation layer 2 and the first conductor 1. After exiting the bath, the fiber was stretched 3.5 times. At this time, the size of the first conductor 1 was adjusted to a width of 0.22 mm and a thickness of 0.05 mm, and the thickness of the isolation layer 2 was uniformly controlled at 0.025 mm. After the second bath treatment and stretching, the isolation layer 2 was dissolved and removed due to the dissolution of the PEG porogen, forming a porous structure with a pore size on the order of 0.5 μm and a porosity of 50%.

[0048] Next, online transition and second-stage spinning are performed to form the second conductor 3 and encapsulation layer 4. The first-stage fiber enters the second-stage spinneret area vertically, pauses for 1.5 seconds in the intermediate air section, and is heated to maintain the fiber surface temperature at 45°C. The second conductor 3 is a PEBA / 12% graphene solution dissolved in formic acid, and the encapsulation layer 4 is a pure PEBA solution dissolved in formic acid. The second conductor 3 is simultaneously extruded on one side of the isolation layer of the composite structure of the first conductor 1 and the isolation layer 2 using a lateral (second conductor 3) and circumferential (encapsulation layer 4) co-extrusion spinneret. Its width is 0.22 mm and its thickness is 0.03 mm, thus forming a three-layer sandwich structure with the first conductor 1. The encapsulation layer 4 has a thickness of 0.015 mm and covers the outer surface of the three-layer sandwich structure. When the PEBA extruded at 65°C comes into contact with the fibers of the three-layer sandwich structure, partial melting and bonding occur to eliminate interface defects. The fibers are then subjected to secondary coagulation in a 25°C water bath and then stretched 2.2 times. The final total fiber width is 0.38 mm and the thickness is 0.095 mm. mm, and the surface roughness Ra of the encapsulation layer 4 is ≤0.08 μm. Finally, post-processing and continuous control are carried out. Before winding, the fiber is dried with hot air at 110℃ for 45 seconds to eliminate internal stress.

[0049] When the sensor is subjected to pressure (≥5 kPa), due to the perforated structure of the isolation layer 2 and the elasticity of all materials, the first conductor 1 and the second conductor 3 make electrical contact. After the pressure is released, the first conductor 1 and the second conductor 3 separate from each other. The calibration process and usage method of this embodiment are similar to those of Embodiment 1.

[0050] Example 3 Please refer to Figure 1. This embodiment provides a fabrication scheme for a self-calibrating flexible pressure sensing device based on melt spinning. The scheme uses polyethylene terephthalate (PET) as the matrix material and silver nanoparticles (AgNP) and carbon black (CB) as conductive fillers, and is achieved through a twin-screw blending-melt spinning-post-processing process.

[0051] Step 1: Raw material pretreatment and blending modification PET chips were dried in a vacuum environment to remove moisture. AgNP particles (50 nm in diameter) and CB particles (30 nm in diameter) were mixed at a mass ratio of 1:3, and 0.5 wt% silane coupling agent KH550 was added. The mixture was then ultrasonically dispersed in an ethanol solution to form a uniform suspension, which was subsequently dried to constant weight to obtain surface-functionalized conductive fillers. The dried PET and conductive fillers were mixed according to the designed ratios: the first conductor 1 was PET / 8% AgNP-CB, and the second conductor 3 was PET / 12% AgNP-CB. Premixing was performed in a high-speed mixer to ensure uniform adhesion of the fillers to the surface of the PET particles.

[0052] Step 2: Twin-screw blending and granulation A co-rotating twin-screw extruder was used, with zone temperatures set at 240℃, 255℃, 270℃, 275℃, and 280℃ for zones one through five, a die temperature of 285℃, and a screw speed of 200 rpm. The premixed material was fed into the screw through a side feed port. In the melting zone, the material was subjected to strong shear force, causing the conductive filler to form a nanoscale dispersion within the PET matrix. The resulting pellets, with a diameter of 3 mm, were then dried in an 80℃ hot air circulating oven for subsequent use.

[0053] Step 3: Melt spinning to prepare fiber structure The dual-spinneret composite spinning technology is adopted, and the main screw (supplying raw materials to the first conductor 1 and the second conductor 3) and the auxiliary screw (supplying raw materials to the isolation layer 2 and the encapsulation layer 4) are independently temperature controlled.

[0054] First conductor 1 spinning: PET / 8% AgNP-CB masterbatch is heated to 290℃ to melt and extruded through a rectangular spinneret (slit size 0.25mm×0.07mm) to form conductive fibers with a width of 0.25mm and a thickness of 0.07mm.

[0055] Preparation of isolation layer 2: Pure PET (with 5% compatibilizer SEBS and polyethylene glycol PEG) was used as raw material, heated to 285℃ to melt, and simultaneously extruded through a side co-extrusion spinneret on one side of the first conductor 1 to form an isolation layer with a width of 0.28 mm (covering the first conductor 1 with a 12% margin) and a thickness of 0.025 mm. During the spinning process, nitrogen gas was introduced for protection to prevent oxidative degradation of PET. At the same time, taking advantage of the phase separation characteristics of PET and PEG during spinning, PEG was allowed to precipitate, leaving voids, forming a uniformly distributed perforated structure with a pore size of 0.5 μm (adjustable according to actual needs) inside the isolation layer 2.

[0056] Spinning of the second conductor 3 and encapsulation layer 4: After being cooled by a 30cm air section, the composite fiber of the first conductor 1 and the insulating layer 2 enters the second spinneret area. The second conductor 3, made of PET / 12% AgNP-CB masterbatch, is extruded through a rectangular spinneret at 292℃ to form conductive fibers with a width of 0.25mm and a thickness of 0.035mm, forming a three-layer sandwich structure together with the first conductor 1 and the insulating layer 2. The encapsulation layer 4, made of pure PET, is circumferentially co-extruded onto the outer surface of the three-layer sandwich structure at 288℃ to form a protective layer with a thickness of 0.015mm. Ultimately, the total fiber width is controlled at 0.4mm and the total thickness at 0.09mm.

[0057] It should be noted that this embodiment uses a PET substrate with an elastic modulus of 4 GPa, which allows for the measurement of relatively large pressures.

[0058] Example 4

Detailed Example 4-1

[0059] Material preparation and cutting. (1) Conductor material. Both the first conductor 11 and the second conductor 13 are made of homogeneous polyurethane / graphene composite film. The graphene filling amount of the second conductor 13 is 3 times that of the first conductor 11, and the initial resistance difference is significant. The two conductive films are cut into strips (2 mm wide and 50 mm long), one of each. (2) Insulating layer material. The insulating layer 12 is made of warp-knitted spandex mesh with a mesh size of 200 μm × 200 μm (40% porosity), and is cut into strips of the same size as the conductors. (3) Encapsulation layer material. The TPU film is cut into strips with a width of 6 mm and a length of 50 mm (the width is 3 times that of the inner layer structure).

[0060] The first conductor 11 strip is placed on top, with an spandex mesh insulating layer 12 in the middle, and the second conductor 13 strip on the bottom. The three layers are aligned at their ends and stacked together. Optionally, a TPU film strip can be placed in the center to cover the three layers, leaving a 1 mm gap on both sides for heat pressing and bonding to form a closed tubular structure. The TPU film is uniformly heated using a hot air gun (150°C) to melt it and tightly adhere it to the inner layer material. After cooling, excess TPU edges are removed, ultimately obtaining a cross-sectional area with a cross-sectional ratio... Figure 8 The three-layer structure shown is a sensing device with an additional encapsulation layer.

[0061]

Detailed Example 4-2

[0062] It should be noted that in this embodiment, the insulating layer 12 can be fixed to the surface of the second conductor 13 by using a dispensing machine or 3D printing. For example, a polyurethane dot matrix can be fixed to the surface of the second conductor 13 using a dispensing machine, with sufficient distance maintained between each pair of polyurethane dots, which is equivalent to through holes. At the edges where sewing or adhesive bonding is required, the polyurethane dots are densely arranged without gaps, thereby ensuring insulation and effective bonding.

[0063]

Detailed Examples 4-3

[0064] Yarn selection and specifications. The lower and middle layers of the first conductor 11 use conductive polyester / ordinary polyester blended yarn, in which the conductive polyester surface is coated with silver nanoparticles and blended with ordinary polyester in a 1:1 ratio. The yarn fineness is 75D, balancing conductivity, piezoresistive effect, and structural strength. The upper surface layer uses 40D pure polyester yarn to prevent short circuits between the upper layer and other conductive components, serving as an insulating encapsulation function. The insulating layer 12 uses a polyester / spandex core-spun yarn with 20D spandex as the core yarn and 50D polyester wrapped around it. Spandex provides elasticity, while polyester ensures structural strength and stability. The upper and middle layers inside the second conductor 13 are the same as the lower and middle layers of the first conductor 11, using conductive polyester / ordinary polyester blended yarn; the lower surface layer of 13 also uses 40D pure polyester yarn, serving as an insulating protection function.

[0065] Weaving process and yarn count. This equipment uses a computerized flat knitting machine with a multi-needle bed and a complex yarn guiding system for three-dimensional knitting. It uses a total of 6 yarn paths and achieves three-layer structure weaving in one go by precisely controlling the feeding of each yarn path and the movement of the knitting needles.

[0066] The first and second paths are conductive polyester / ordinary polyester blended yarns for the first conductor 11. At the start of weaving, the yarn guide leads it to specific needles on the front needle bed. The front needle bed needles perform loop-gathering and loop-forming actions according to a preset program, forming the middle and lower layer loop structure. During weaving, by adjusting the position of the yarn guide and the yarn tension, the blended yarn is evenly distributed in both the transverse and longitudinal directions, ensuring a uniform and stable conductive layer.

[0067] The third path is made of pure polyester yarn for the first conductor 11. When the middle and lower layers are woven to a certain length, the yarn guide introduces the pure polyester yarn into the front needle bed needles for plain knitting, forming a flat and dense upper surface layer. During weaving, the needle movement and yarn tension are precisely controlled to ensure good connection between the pure polyester yarn and the middle and lower layer blended yarns, forming a complete structure of the first conductor 11.

[0068] The fourth and fifth paths are made of polyester / spandex core-spun yarn for the isolation layer 12. After the first conductor 11 is woven, the position of the computerized flat knitting machine needle bed and the path of the yarn guide are adjusted to introduce the core-spun yarn between the front and rear needle beds. The needles of the front and rear needle beds alternately loop, so that the core-spun yarn forms a mesh structure with regular holes between the two needle beds. The size and shape of the holes are precisely adjusted by controlling the loop height of the needles and the yarn tension to ensure good electrical contact between the first and second conductors when they are under force.

[0069] The sixth thread is pure polyester yarn for the second conductor 13. With the weaving of the insulating layer 12 nearing completion, the yarn guide introduces the pure polyester yarn into the back needle bed, weaving the lower surface layer in plain knit. Subsequently, the yarn guide is switched to introduce the conductive polyester / ordinary polyester blended yarn for the second conductor 13. The back needle bed needles then gather and form loops according to a preset program, creating the middle and upper layer structure. During weaving, it is ensured that each layer transitions smoothly, forming a complete second conductor 13.

[0070] Fabric Structure. In the first conductor 11, the lower and middle layers of conductive polyester / ordinary polyester blended yarn are interwoven to form a thick conductive layer with good piezoresistive characteristics, and the resistance changes under stress. The upper surface layer is made of pure polyester yarn in a plain knit, forming a flat and dense insulating surface to prevent short circuits. The insulating layer 12 adopts a knitted mesh fabric structure, with polyester / spandex core-spun yarn woven in loops on a computerized flat knitting machine, forming diamond or square holes between the front and back needle beds. This structure ensures both the strength and elasticity of the insulating layer, and allows the first and second conductors to contact through the holes under pressure to transmit electrical signals. In the second conductor 13, the lower surface layer is made of pure polyester yarn in a plain knit, which serves as insulation; the upper and middle layers of conductive polyester / ordinary polyester blended yarn are interwoven to form a conductive layer, corresponding to the conductive layer of the first conductor 11, facilitating the formation of a conductive circuit under stress.

[0071] This three-dimensional knitting technology enables the one-time weaving of a long, flexible pressure sensing device. Through the rational selection of yarns, design of the weaving process, and fabric structure, the structure is formed in a single operation. During the weaving process, the yarns in each layer cooperate with each other, forming a stable three-layer structure under the precise control of a computerized flat knitting machine. The resistance of the conductive layers of the first conductor 11 and the second conductor 13 changes under pressure, achieving electrical contact through the holes in the insulating layer 12, thereby enabling the sensing and measurement of pressure magnitude, location, and width. Simultaneously, the pure polyester yarn on the upper surface layer of the first conductor 11 and the lower surface layer of the second conductor 13 acts as an insulating encapsulation layer, eliminating the need for an additional encapsulation layer and simplifying the production process.

[0072]

Detailed Example 4-4

[0073] (1) Preparation of the second conductor 13: First, polyurethane is dissolved in a suitable solvent to prepare a polyurethane solution. Using electrospinning technology, a polyurethane film is spun out. This film serves as the lower structure of the second conductor 13. Next, polyurethane and silver nanowires in a first ratio are thoroughly mixed. The mixed solution is then spun onto the prepared polyurethane film by electrospinning to form the upper structure of the second conductor 13. Thus, the preparation of the second conductor 13 is completed.

[0074] (2) Preparation of isolation layer 12: On the upper surface of the second conductor 13, electrospinning is performed using a polyurethane and PVA solution. After the spun layer has cured, the PVA is removed by water dissolution, thereby forming an isolation layer 12 with a porous structure.

[0075] (3) Preparation of the first conductor 11: On the upper surface of the isolation layer 12, polyurethane and silver nanowires in a second ratio are electrospun to form a mixture layer of polyurethane and silver nanowires. This layer serves as the lower structure of the first conductor 11. Subsequently, the same polyurethane solution used to prepare the lower surface of the second conductor is electrospun to form a polyurethane film, which serves as the upper structure of the first conductor 11. The preparation of the first conductor 11 is now complete.

[0076] The pressure sensing device prepared by this method can reach the micrometer level in thickness. Because the fiber is made of elastic material and is at the nanometer and micrometer scale, the device can accurately identify minute pressure changes within 1N. It has great potential for application in fields with extremely high requirements for pressure sensing accuracy, such as electronic skin, smart textiles, and wearables.

[0077] Example 5 refer to Figure 5 This embodiment provides a self-calibrating flexible pressure sensing device based on spinning technology. The device is composed of two yarns, yarn 5 and yarn 6, and the main materials are stainless steel fiber, polyester fiber, spandex fiber and cotton fiber.

[0078] The inner core of yarn 5 is a blended yarn made of stainless steel fibers and polyester fibers. Because stainless steel fibers are conductive, this blended yarn exhibits piezoresistive properties. Yarn 6 is also a blend of stainless steel and polyester fibers, but the proportion of stainless steel fibers differs from that of yarn 5 to achieve different piezoresistive characteristics. Both yarns 5 and 6 have an outer surface wrapped with a layer of spandex and cotton fibers using a wrapping process. Gaps are pre-formed in the wrapping yarn during the spinning process to ensure electrical contact between the two core yarns when the equipment is under pressure. Yarn 5 is a composite yarn of a first conductor and an insulating layer, while yarn 6 is a composite yarn of a second conductor and an insulating layer.

[0079] The spinning process employs a highly efficient combination of ring spinning and wrapping spinning. First, the core yarn is prepared by mixing stainless steel fibers and polyester fibers in a designed ratio through an opening and cleaning process. The mixture is then opened and homogenized using a cotton picker, opener, and blender, and carded into a sliver. Multiple drawing processes are then performed to improve fiber condition. Finally, the yarn undergoes roving and spinning processes, followed by ring spinning to twist it into yarn 5 (core yarn). Yarn 6 is prepared using a similar method, only the stainless steel fiber ratio is adjusted. Next, the wrapping yarn is prepared by mixing spandex and cotton fibers in a specific ratio, followed by opening, cleaning, carding, drawing, and roving processes to create roving. Then, wrapping spinning is performed by simultaneously feeding the core yarn and wrapping roving into the wrapping spinning equipment, causing the wrapping yarn to spirally wrap around the surface of the core yarn to form yarn 5 and yarn 6. Finally, the two yarns are twisted together, with precise control of twist and direction to ensure a tight bond and meet the required gap.

[0080] The combined ring spinning and wrapping spinning process in this embodiment is only one of the implementation methods; other processes can also be used. For example, air-jet spinning can be used to prepare core yarn, which utilizes airflow to cohede and twist the fibers, resulting in high efficiency and wide spinning applicability. Siro spinning can be used to prepare wrapping yarn, where two rovings are fed in parallel during the spinning process, and after drafting and twisting, they are formed into a double-ply yarn, resulting in a more stable structure and more uniform performance.

[0081] It should be noted that this embodiment can also flexibly employ coating processes to impart piezoresistive effect to ordinary yarns. For example, a conductive composite material of carbon nanotubes, graphene, and silicone rubber can be coated onto the surface of cotton yarn, thereby giving the cotton yarn conductivity and piezoresistive effect. After coating and curing of the composite material, an elastic polymer material (such as silicone rubber, fluororubber, polyurethane, polylactic acid, sodium alginate, SEBS, etc.) is applied at specific points to act as an insulator. Finally, the first coated cotton yarn (first conductor + insulator layer) and the second coated cotton yarn (second conductor + insulator layer) are twisted together to form a yarn. Different piezoresistive coefficients can also be obtained in various ways, including, but not limited to, adjusting the type and proportion of conductive particles such as carbon nanotubes, graphene, silver nanowires, and carbon black, as well as adjusting the thickness and shape of the conductive composite material coating. In addition, intrinsically conductive polymers (such as polypyrrole and 3,4-ethylenedioxythiophene) can also be used to impart conductivity and piezoresistive effect to the yarn.

[0082] Example 6 refer to Figure 9 This embodiment provides a self-calibrating flexible pressure sensing device based on a spinning process. The device is shaped like a yarn and has an approximately circular cross-section. From the inside out, the device consists of a first conductor 103, an isolation layer 102, and a second conductor 101.

[0083] The first conductor 103 is made of a blend of stainless steel fiber and nylon fiber. The insulating layer 102 uses polyester fiber filaments as the wrapping material and is wrapped around the surface of the first conductor 103 using a hollow spindle wrapping yarn. The wrapping angle and density can be controlled as needed to ensure effective isolation of the second conductor 101 from the first conductor 103 when there is no external force. The second conductor 101 is a blended yarn of stainless steel fiber and nylon fiber with a different stainless steel filler ratio. 101 is wrapped around the surface of 102 through a doubling twisting process. Yarns 102 and 101 are fed simultaneously into a doubling twister, and the spindle twists the yarn to make 101 tightly wrap 102, forming a complete equipment structure.

[0084] When the equipment is subjected to external force, the second conductor 101 and the first conductor 103 deform and make electrical contact through the insulating layer 102. Due to the piezoresistive effect, the resistance changes, and the magnitude, location, and width of the pressure can be sensed by detecting the amount of resistance change. After the external force is removed, the insulating layer 102 elastically recovers, isolating and insulating 101 and 103, and returning to the initial state.

[0085] It should be noted that the spinning process combined with ring spinning, hollow spindle wrapping spinning, and doubling twisting in this embodiment is only one implementation method; other processes can also be used. (Reference) Figure 10 113 and 111 are prepared using air-jet spinning, which utilizes high-speed jet airflow to stretch and twist fiber bundles, resulting in high production efficiency and less yarn hairiness. The isolation layer 112 can be prepared using friction spinning, where the fibers are condensed and twisted into yarn through friction with a dust cage, which is suitable for wrapping filaments and offers flexible processing.

[0086] Device application integration, reference Figure 6 and Figure 7 The self-calibrating flexible pressure sensing device prepared by spinning process, or according to Examples 1, 2, 3, and 5, is fixed to woven fabric 7 or 9 by sewing process to form a circular or rectangular pressure touch panel. This touch panel can not only identify the pressure of a single point press, but also identify the position and pressure width of the single point press, and has a self-calibration function, that is, realize the synchronous identification of the pressing coordinates, pressure, and width within the circle or rectangle.

[0087] Device application integration, reference Figure 6 and Figure 7The self-calibrating flexible pressure sensing device of Example 1 is sewn onto an elastic knitted fabric 9. Since all materials in Example 1 are elastic and stretchable, and the knitted fabric itself is also stretchable, the two-dimensional knitted fabric 9 can be wrapped around a three-dimensional structure. This allows for the monitoring of pressure magnitude, position, and width on the surface of the three-dimensional structure. Therefore, the pressure sensing device of this invention can be used to manufacture various force, position, and width sensing devices for children's toys, teaching aids, sofa covers, etc., adding a tactile "skin" to the surface of these three-dimensional objects to identify position, pressure, and width, and possessing a self-calibrating function.

[0088] It should be noted that this invention combines a dual-core piezoresistive structure with a perforated insulating layer for use in yarn-type flexible pressure sensing, enabling simultaneous detection of multiple parameters such as pressure, position, and width. This design overcomes the limitations of traditional sensors that only detect single parameters, providing a new solution for flexible electronics technology.

[0089] It should be noted that this invention uses the resistance value corresponding to the conduction pressure threshold F0 to infer physical quantities such as ambient temperature that significantly affect the pressure-resistance equation, thereby achieving dynamic calibration and adaptability of the sensor. This mechanism eliminates the need for external compensation circuits or redundant sensors, significantly reducing system complexity and improving the sensor's environmental adaptability.

[0090] It should be noted that this invention employs a dual-core layer design, requiring only four wires to achieve multi-parameter detection, thus avoiding the complex wiring of sensor arrays. This design facilitates sensor miniaturization and flexibility, reduces manufacturing costs, and improves production efficiency.

[0091] It should be noted that this invention employs a dual-core layer design to cover a pressure range from low to high, breaking through the range limitations of a single material. Simultaneously, the sensor can detect multiple parameters such as pressure, position, and width, meeting the high requirements of IoT and AI technologies for multi-parameter detection capabilities.

[0092] It should be noted that this invention employs one-step molding technology (such as wet spinning, dry spinning, and preform thermal stretching), simplifying the manufacturing process and reducing manufacturing costs. This process makes the sensor more suitable for flexible applications, such as smart wearable devices and medical rehabilitation monitoring.

[0093] Based on this, compared with the prior art, the self-calibrating flexible pressure sensing device of the present invention has at least the following beneficial effects: (1) Multi-parameter synchronous detection capability: Compared with most sensors in the prior art that can only output pressure magnitude, the present invention can simultaneously acquire information such as contact position and force width, realizing multi-parameter synchronous detection and improving the practicality and application range of the sensor.

[0094] (2) Environmental adaptability and self-adaptability: In view of the problem of poor environmental adaptability of traditional piezoresistive sensors, the present invention realizes the self-adaptability of the sensor through a dynamic calibration mechanism, which can maintain stable detection performance under different environmental conditions without the need for additional compensation circuits or algorithms.

[0095] (3) Simplified structure and miniaturization: The present invention adopts a dual-core layer design, which only requires 4 wires to realize multi-parameter detection, avoiding the complex wiring of sensor arrays. This design is conducive to the miniaturization and flexibility of sensors, enabling sensors to be deployed more flexibly in scenarios such as smart textiles and smart wearable devices.

[0096] (4) Extended range and wide applicability: The dual-core design covers a range from low to high pressure, breaking through the range limitations of a single material. This enables the invention to be widely used in various fields such as smart wearable devices, medical rehabilitation monitoring, and industrial robot tactile sensing, meeting the needs of different scenarios for sensor range and detection accuracy.

[0097] (5) Simplified process and reduced cost: The present invention adopts a one-time molding technology, which simplifies the manufacturing process and reduces manufacturing costs. This advantage makes the present invention more competitive in the market and is conducive to promoting the popularization and application of flexible electronics technology.

[0098] The above provides a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of the present invention.

Claims

1. A self-calibrating flexible pressure sensing device, characterized in that, include: The first and second conductors are in the form of strips, strips or lines, and both have piezoresistive effect; An isolation layer is disposed between the first conductor and the second conductor, and its surface is distributed with through holes or long grooves with continuous through holes. An encapsulation layer covers the first conductor and the second conductor; The first conductor has a first left-end wire 1L and a first right-end wire 1R led out from its two ends; the second conductor has a second left-end wire 2L and a second right-end wire 2R led out from its two ends; the resistance between the first left-end wire 1L and the first right-end wire 1R is R. 1L1R The resistance value between the second left terminal 2L and the second right terminal 2R is R. 2L2R The resistance value between the first left-end wiring and the second left-end wiring is R. 1L2L The resistance value between the first right-end wiring and the second right-end wiring is R. 1R2R ; When the external force is less than the set threshold F0, the first conductor and the second conductor have no electrical contact, and the resistance value R between the first left-end wiring and the second left-end wiring is... 1L2L The resistance R between the first right-end connection and the second right-end connection is infinite. 1R2R It is infinite; When the external force is greater than or equal to the set threshold F0, the first conductor and the second conductor make contact through the through hole or long groove of the isolation layer, and the resistance value R between the first left-end wiring and the second left-end wiring is... 1L2L The abrupt change to a non-infinite value results in the resistance value R between the first right-end connection and the second right-end connection. 1L2L The mutation changes to a non-infinite value; Based on the four resistance values ​​R of the dynamic scan 1L1R R 2L2R R 1L2L R 1R2R In addition, a three-dimensional database of physical quantities under different environments is used to obtain the pressure magnitude, pressing position, and pressing width W of the pressing point.

2. The self-calibrating flexible pressure sensing device according to claim 1, characterized in that, The pressing position is calculated using the following formula: When the pressing point is close to the first left end wiring, R 1L2L ≈0, R 1R2R ≈R 1L1R + R 2L2R ; When the pressing point is close to the first right-end wiring, R 1R2R ≈0, R 1L2L ≈R 1L1R + R 2L2R ; When the pressing point is located at the midpoint, R 1L2L ≈R 1R2R ≤0.5(R 1L1R + R 2L2R ); When the pressing point is located elsewhere, according to R 1L2L and R 1R2R The pressing position is determined by the proportional relationship.

3. The self-calibrating flexible pressure sensing device according to claim 1, characterized in that, The pressing width W is calculated using the following formula: When pressing a single point with a narrow range, R 1L2L + R 1R2R ≈R 1L1R + R 2L2R The pressing width is very small, W≈0; When pressing a single point with wide amplitude, R W = 0.5×(R) 1L1R + R 2L2R (R 1L2L + R 1R2R )), R W The value is positively correlated with the press width W.

4. The self-calibrating flexible pressure sensing device according to claim 1, characterized in that, The steps for constructing the three-dimensional database include: First, the threshold F0 is calibrated to determine the condition of R under different environmental physical quantities. 1L2L R 1R2R The magnitude of the pressure corresponding to the sudden change to non-infinity; Under different environmental physical quantities, the conduction threshold pressure F0 corresponds to the same conduction pressure. When environmental physical quantities change, single-point narrow-amplitude pressure, single-point medium-amplitude pressure, and single-point wide-amplitude pressure are applied to the sensor respectively, according to R. 1L1R R 2L2R R 1L2L R 1R2R A three-dimensional database of environmental physical quantities, width, and piezoresistive equations was constructed based on the relationship between pressure magnitude and pressing width W.

5. The self-calibrating flexible pressure sensing device according to claim 1, characterized in that, The magnitude and location of the pressure applied are detected through the following steps: When R 1L2L R 1R2R When the mutation becomes non-infinite, record R at this time. 1L1R R 2L2R Match the environmental physical quantities and call the first piezoresistive equation corresponding to the environmental physical quantities; Calculate R W = 0.5×(R) 1L1R + R 2L2R (R) 1L2L + R 1R2R Match the press width and call the second piezoresistive equation corresponding to the press width; The pressure magnitude and pressing position are calculated based on the first and second piezoresistive equations.

6. The self-calibrating flexible pressure sensing device according to claim 1, characterized in that, The piezoresistive materials of the first conductor and the second conductor are uniformly distributed, and the piezoresistive material comprises: Polymer composite materials containing conductive particles; Blended yarns of conductive and non-conductive fibers, or multifilaments of conductive fibers, or yarns spun from fibers containing conductive particles, or yarns with conductive materials distributed on their surface. Intrinsically conductive nanofibers prepared by electrospinning and polymer nanofibers filled with conductive phases; Elastomers filled with liquid metal microfluidics or with attached liquid metal; Intrinsically conductive polymer materials, as well as their composites with conventional polymer materials, and their composites with conductive particles; Materials exhibiting piezoresistive effect include materials whose internal contact area changes or whose structural contact area changes when subjected to pressure, resulting in a change in resistance.

7. The self-calibrating flexible pressure sensing device according to claim 1, characterized in that, The isolation layer is an elastic polymer material, including polyurethane, silicone or thermoplastic elastomer acrylic resin, epoxy resin, phenolic resin, polyester, polyester fiber, nylon, acrylic fiber, polypropylene fiber, vinylon, chlorofiber and their composite materials; the encapsulation layer is polyurethane, silicone, styrene-ethylene-butene-styrene block copolymer.

8. The self-calibrating flexible pressure sensing device according to claim 1, characterized in that, The processing method of the sensing device includes at least one of spinning technology, yarn spinning technology, printing technology, coating technology, microfluidic technology, sewing and embroidery, and bonding combination.

9. The self-calibrating flexible pressure sensing device according to claim 1, characterized in that, The first conductor and the second conductor are linear in shape, and are arranged in parallel or intertwined. The first conductor and the second conductor are not electrically connected when there is no external force, and are electrically connected when the external force reaches F0.

10. The self-calibrating flexible pressure sensing device according to claim 1, characterized in that, The encapsulation layer completely encloses the first conductor, and also completely encloses the second conductor and the isolation layer; or, the encapsulation layer does not completely enclose the first conductor, the second conductor and the isolation layer, but only adheres to the upper surface of the first conductor and the lower surface of the second conductor.

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