Single-electrode friction nano-generator flexible pressure sensor and preparation method and application thereof

Abstract

The invention relates to the field of flexible pressure sensors, and discloses a single-electrode friction nano-generator flexible pressure sensor and a preparation method and application thereof, and the method comprises the steps: taking friction electronegative fasciated yarns as weft yarns, taking friction electronegative material filaments as warp yarns, and weaving to form a friction electronegative fabric; the triboelectric fabric is woven by using nylon filaments as warp yarns and weft yarns at the same time; nylon is adopted as sewing lines of sewing points, and the friction electronegative fabric and the friction electropositive fabric which are laid and matched up and down are connected through the sewing points, so that flexible pressure sensing is formed. Compared with a contact-separation mode, a transverse sliding mode and an independent friction layer mode, the single-electrode design mode of the sensor is simple in structure, the wiring requirement is simplified, and the complexity of an array is remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the field of flexible pressure sensors, and particularly to a single-electrode triboelectric nanogenerator flexible pressure sensor, its preparation method and application. Background Art

[0002] In recent years, the applied research of flexible wearable pressure sensors in the field of medical monitoring has been continuously deepening and approaching maturity. Compared with those devices used to monitor vital signs in the current medical system, wearable flexible pressure sensors have many significant advantages, such as small size, easy to carry, can be worn on the body, and also have the characteristic of self-driving. With the rapid development of modern technology and the continuous improvement of people's living standards, real-time monitoring of human movement health and pulse signals plays an increasingly crucial role in disease diagnosis, rehabilitation treatment, and health assessment, and related monitoring devices are also moving more and more towards the direction of miniaturization and multi-functionality, which are exactly the requirements that such long-term monitoring devices need to meet currently. To achieve real-time monitoring of human movement health, the key problems to be solved urgently include ensuring the sensitivity of the sensor, guaranteeing the sustainability of power supply, and the wearability of the device. And one effective solution is to design a single-electrode triboelectric nanogenerator. Based on the coupling effect of triboelectrification and electrostatic induction, the triboelectric nanogenerator can convert mechanical energy in the environment (such as various energy forms like human movement mechanical energy, sound energy, etc.) into electrical energy, with a relatively high energy conversion efficiency, and can effectively convert pressure signals into electrical signals. Therefore, as the principle basis for preparing flexible pressure sensors, and then realizing real-time monitoring of human movement health, this is undoubtedly a practical way to prepare flexible pressure sensors for monitoring movement signals. At the same time, pressure sensors based on triboelectricity also have the characteristics of a wide range of material selectivity, light texture, and diverse structural design forms. The single-electrode triboelectric flexible pressure sensor has many excellent characteristics such as good softness, breathability, washability, durability, and dyeability. And the single-electrode triboelectric nanogenerator plantar pressure sensor array can monitor the plantar pressure distribution in real time and has extensive and important applications in many fields. In the field of human movement monitoring, it can accurately record the changes in plantar pressure during exercise, provide scientific data support for athletes' training, and help them optimize their sports performance and prevent sports injuries; in gait analysis, by accurately analyzing the plantar pressure distribution, it can provide detailed gait information for researchers and help them deeply understand the human movement pattern and biomechanical characteristics; in the field of medical rehabilitation, the plantar pressure sensor array can be used to assist doctors in diagnosing and treating patients' foot diseases, such as diabetic foot, flat feet, etc., and provide key basis for formulating rehabilitation plans. Applying it to the monitoring of human movement signals can realize the regulation and control of human exercise volume, provide valuable reference materials for sports health and medical diagnosis, etc., and has very important research significance.

[0003] However, there are many deficiencies in existing plantar pressure sensors at the technical level. Currently, most plantar pressure sensors adopt a multi-electrode design scheme, which makes the wiring of the sensor array extremely complex. The complex wiring not only increases the difficulty and cost of the manufacturing process, but also easily causes interference and loss during signal transmission, thereby affecting the performance and stability of the sensor. At the same time, the multi-electrode design scheme results in high power consumption of the sensor, which greatly limits the battery life of the device in some application scenarios with strict power consumption requirements, such as long-term use of wearable devices. In addition, due to the unique curved shape of the sole, extremely high requirements are imposed on the flexibility and conformability of the sensor. Ordinary plantar pressure sensors are difficult to ensure high-precision monitoring while meeting good flexibility and conformability, and cannot closely fit the complex curved surface of the sole, resulting in the accuracy and reliability of the monitoring data being affected. This not only fails to provide accurate and effective data support for related fields, but also restricts to a certain extent the application of plantar pressure sensors in more scenarios.

[0004] In practical applications, plantar pressure sensors also need to meet a series of strict requirements. For example, they should meet the requirements of ergonomic design to ensure that they do not cause discomfort to users during long-term wearing and use; at the same time, they should achieve low-power operation to extend the service time of the device; and they should have the characteristics of being easy to manufacture, reducing production costs, and improving production efficiency, so as to achieve large-scale commercial applications. However, the current technical status is difficult to fully meet these requirements, and there is an urgent need for a new technical solution to solve the above problems in order to promote the further development of plantar pressure sensors in the fields of human motion monitoring, gait analysis, medical rehabilitation, etc. Therefore, it is of great practical significance and urgent need to develop a new type of plantar pressure sensor. Summary of the Invention

[0005] The present invention aims to solve the deficiencies of the existing technology and provides a single-electrode triboelectric nanogenerator flexible pressure sensor, which is used as a flexible pressure sensor array for monitoring human plantar signals. By optimizing the materials and structural design methods, the sensor array has the advantages of high sensitivity, low power consumption, easy manufacturing, etc., and at the same time can adapt to the complex curved surface of the sole and has good flexibility and wearability.

[0006] To achieve the above object, on the one hand, the present invention provides a preparation method for a single-electrode triboelectric nanogenerator flexible pressure sensor, which includes the following steps:

[0007] S1. Use filaments of triboelectric negative materials to wrap conductive yarns to form triboelectric negative wrapped yarns, and then use the triboelectric negative wrapped yarns as weft yarns and filaments of triboelectric negative materials as warp yarns to weave a triboelectric negative fabric;

[0008] S2. A triboelectrically positive fabric is woven using nylon filaments as both warp and weft yarns.

[0009] S3. A suture thread made of nylon is used at the suture points to connect the triboelectrically negative fabric and the triboelectrically positive fabric laid one above the other through multiple suture points. In the natural state, the triboelectrically negative fabric and the triboelectrically positive fabric do not contact each other, forming a single - electrode triboelectric nanogenerator flexible pressure sensor with a conductive yarn as the electrode.

[0010] As a further preferred technical solution of the present invention, the triboelectrically negative material is any one or a mixture of several of polyvinylidene fluoride, polystyrene, polyurethane, polyvinylidene fluoride - hexafluoropropylene, polytrifluoroethylene, polyvinylidene fluoride - chlorotrifluoroethylene ether, polyethersulfone, polyvinylidene fluoride - trifluoroethylene, fluorinated polyetherimide, polycarbonate, and polyimide.

[0011] As a further preferred technical solution of the present invention, the conductive yarn is made of at least one of conductive fabric, copper, silver, silver nanowire, copper alloy, gold, aluminum, iron, aluminum alloy, carbon fiber, graphite, graphene, and carbon nanotube.

[0012] As a further preferred technical solution of the present invention, the conductive yarn is an aluminum wire yarn with a diameter of 0.05 - 0.3 mm.

[0013] As a further preferred technical solution of the present invention, in steps S1 and S2, the weaving process is a fabric of the woven fabric type with a structure where warp and weft yarns are vertically interlaced by a rapier loom; and / or, the size range of the triboelectrically negative fabric is 3 - 8 cm × 3 - 8 cm, and the size range of the triboelectrically positive fabric is not less than that of the triboelectrically negative fabric.

[0014] As a further preferred technical solution of the present invention, the nylon filament has a diameter of 0.06 - 0.18 mm and a specification of 50D / 2 ply - 120D / 3 ply.

[0015] On the other hand, according to the present invention, the present invention also provides a single - electrode triboelectric nanogenerator flexible pressure sensor.

[0016] On another aspect, according to the present invention, the present invention also provides an application of a single - electrode triboelectric nanogenerator flexible pressure sensor as a pressure sensor.

[0017] As a further preferred technical solution of the present invention, using the single - electrode triboelectric nanogenerator flexible pressure sensor as a sensing unit, a sensing array is composed of multiple such sensing units.

[0018] As a further preferred technical solution of the present invention, the sensing array is applied to the front and rear soles of the human foot to monitor the pressure signals of foot movement in real time.

[0019] The power generation principle of the single-electrode triboelectric nanogenerator flexible pressure sensing of the present invention is based on the coupling effect of triboelectrification and electrostatic induction. Its working process is divided into two stages: contact and separation. In the contact stage, when two fabric layers come into contact, due to the triboelectrification effect, equal amounts of opposite charges will be carried on their surfaces respectively. At this time, the charges on the surface of the first fabric are bound, and the charges on the second fabric can move freely. In the separation stage, when the two fabric layers are separated, the bound charges of the first fabric will induce opposite charges in the electrode. Due to electrostatic induction, a potential difference is formed between the electrode and the second friction layer, driving free electrons to flow in the external circuit and generating current. When the two fabric layers come into contact again, the potential difference disappears and the electrons flow in the reverse direction, forming an alternating current.

[0020] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0021] 1) Compared with the contact-separation mode, the lateral sliding mode, and the independent friction layer mode, the single-electrode design mode of the present invention has a simple structure, simplifies the wiring requirements, significantly reduces the complexity of the sensing array, not only has a low cost, but also can improve human comfort when applied to human foot movement monitoring;

[0022] 2) The positive friction layer of the present invention innovatively selects commercial nylon, which brings many significant advantages. Compared with some traditional positive electrode materials, commercial nylon has incomparable economy. Its cost is low, greatly reducing the raw material procurement cost, making it possible to mass-produce this triboelectric nanogenerator, effectively enhancing the market competitiveness of the product. At the same time, the easy availability of commercial nylon is a major highlight. As a material widely circulated in the market, it does not require a complex procurement process. Whether it is a small-scale trial production by a research institution or an industrial mass production by an enterprise, it can be easily obtained, effectively ensuring the continuity of research and production. It is worth mentioning that ordinary nylon socks in daily life can also be used as ideal alternatives, which not only further proves the convenience of material acquisition, but also integrates the environmental protection concept into it, realizing the secondary utilization of waste items, and broadening the road for the popularization and application of this triboelectric nanogenerator from the source. This innovative application of materials undoubtedly injects new vitality into the field of triboelectric nanogenerators and is expected to open up a broader development space;

[0023] 3) The flexible pressure sensing of the present invention can adapt to the complex curved surface of the sole, has extremely high flexibility and conformability, can improve the comfort of human wear, and can comprehensively and accurately collect the pressure signals of the human sole by forming a sensing array. Description of the Drawings

[0024] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0025] Figure 1 It is a schematic structural diagram of the triboelectric negative fabric for flexible pressure sensing of a single-electrode triboelectric nanogenerator prepared in Example 1. It is a fabric with warp and weft yarns vertically interlaced, showing triboelectric positivity. It uses a triboelectric negative wrapping yarn as the weft yarn and PVDF filaments as the warp yarn.

[0026] Figure 2 It is a partially enlarged schematic diagram of the triboelectric negative fabric prepared in Example 1. Among them, 1 is PVDF filament, 2 is aluminum wire yarn completely wrapped by PVDF filament, and the triboelectric negative wrapping yarn composed of PVDF filament 1 and aluminum wire yarn 2 is used as the weft yarn of the triboelectric negative fabric.

[0027] Figure 3 It is a schematic structural diagram of the triboelectric positive fabric for flexible pressure sensing of a single-electrode triboelectric nanogenerator prepared in Example 1. It is a fabric with warp and weft yarns vertically interlaced, showing triboelectric negativity. It uses nylon as the warp and weft yarns of the fabric respectively.

[0028] Figure 4 It is a schematic diagram of the sole sensing array prepared in Example 1. Among them, 3 is the triboelectric positive fabric, 4 is the triboelectric negative fabric. On the triboelectric positive fabric 3, multiple triboelectric negative fabrics 4 are respectively placed at the front sole and the heel to form a sensing array.

[0029] Figure 5 It is the result of the 35N pressure monitored by the flexible pressure sensing of the single-electrode triboelectric nanogenerator of the present invention

[0030] Figure 6 It is the result of the 100N pressure monitored by the flexible pressure sensing of the single-electrode triboelectric nanogenerator of the present invention.

[0031] Figure 7 It is the result of the front sole movement monitored by the flexible pressure sensing of the single-electrode triboelectric nanogenerator of the present invention.

[0032] Figure 8 It is the result of the heel movement monitored by the flexible pressure sensing of the single-electrode triboelectric nanogenerator of the present invention.

[0033] The realization of the object, functional features and advantages of the present invention will be further described in conjunction with the embodiments with reference to the accompanying drawings. Specific Embodiments

[0034] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0035] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which the present invention pertains. The test reagents used in the following embodiments are all conventional biochemical reagents unless otherwise specified; the experimental methods are all conventional methods unless otherwise specified.

[0036] Example 1

[0037] A preparation method for a single-electrode triboelectric nanogenerator flexible pressure sensor, the specific steps are as follows:

[0038] Step 1: Prepare a triboelectric negative wrapping yarn

[0039] Use polyvinylidene fluoride (PVDF) filaments to wrap an aluminum wire yarn (diameter 0.1 mm) to form a triboelectric negative wrapping yarn. Among them, the wrapping process is realized by a wrapping machine, and the aluminum wire yarn is used as an electrode;

[0040] Step 2: Use the triboelectric negative wrapping yarn as the weft yarn and PVDF filaments as the warp yarn, and weave through a rapier loom to form a triboelectric negative fabric (as shown in Figure 1 and 2 ), the total number of shuttles is 2, the weft density is 300 (per 10 cm), and the weaving speed is 23 (wefts / min);

[0041] Step 3: Use nylon filaments as both the warp yarn and the weft yarn, and weave through a rapier loom to form a triboelectric positive fabric (as shown in Figure 3 ), the total number of shuttles is 2, the weft density is 300 (per 10 cm), and the weaving speed is 23 (wefts / min);

[0042] Step 4: As shown in Figure 4 , cut the above-mentioned triboelectric positive fabric into an insole shape, and lay multiple triboelectric negative fabrics with a size of 5 cm × 5 cm at the forefoot and heel of the insole on the triboelectric positive fabric respectively to form a sensing array with each triboelectric negative fabric as a unit; as shown in Figure 4 , 3 represents the triboelectric positive fabric, and 4 represents the triboelectric negative fabric. Among them, the triboelectric negative fabric and the triboelectric positive fabric are connected by a plurality of stitching points, and in the natural state, the two layers of fabrics do not contact each other, and they can contact each other after being subjected to external pressure; the stitching points use nylon as the sewing thread and are fixed and connected by a flat sewing method. Without affecting the comfort, a small amount of hot melt adhesive is also used to separate the two layers of fabrics, further ensuring that the two layers of fabrics do not contact each other in the natural state.

[0043] As shown inFigure 5 The electrical performance output of the sensor under a pressure of 35 N is shown. The maximum voltage can reach 1.4 V, and the signal is stable. Figure 6 The electrical performance output under a pressure of 100 N is shown. The maximum voltage can reach 1.8 V, and the signal is stable; its signal frequency is 1.5 Hz, which can meet the motion frequency monitoring of basic human movements. It can be seen from the data graph that this single-electrode triboelectric nanogenerator flexible pressure sensor can achieve different responses to different pressures. Therefore, it can achieve real-time monitoring of the front and rear heels of the human body.

[0044] As Figure 7 The electrical performance output at the front sole is shown. The maximum peak voltage can reach 6.2 V, and the signal is stable and distortion-free. Figure 8 The electrical performance output of the rear heel is shown. The maximum peak voltage can reach 18 V, and the signal is stable and distortion-free. By comparing the output signals of the front sole and the rear heel, it can be seen that there are significant differences between them. Therefore, this sensor can be used to monitor the human body's motion.

[0045] Although the specific implementation manners of the present invention have been described above, those skilled in the art should understand that these are only examples. Various changes or modifications can be made to this implementation manner without departing from the principle and essence of the present invention. The protection scope of the present invention is only defined by the appended claims.

Claims

1. A method for preparing a single-electrode friction nanogenerator flexible pressure sensor, characterized in that: The following steps are involved: S1. Using filaments of triboelectrically negative materials to coat conductive yarns to form triboelectrically negative wrapped yarns, and then using the triboelectrically negative wrapped yarns as weft yarns and the filaments of triboelectrically negative materials as warp yarns to weave a triboelectrically negative fabric; S2, using nylon filaments as both warp and weft yarns to weave a triboelectrically positive fabric; S3. Use nylon as the suture point to connect the tribo-negative fabric and the tribo-positive fabric laid up and down through multiple suture points. In the natural state, the tribo-negative fabric and the tribo-positive fabric do not contact each other, forming a single-electrode friction nanogenerator flexible pressure sensor with conductive yarn as the electrode.

2. The method for preparing a single-electrode friction nanogenerator flexible pressure sensor according to claim 1, characterized in that: The triboelectrically negative material is any one of polyvinylidene fluoride, polystyrene, polyurethane, polyvinylidene fluoride-hexafluoropropylene, polytrifluoroethylene, polyvinylidene fluoride-trifluorochlorovinyl ether, polyether sulfone, polyvinylidene fluoride-trifluoroethylene, fluorinated polyetherimide, polycarbonate and polyimide, or a mixture of several of them.

3. The method for preparing a single-electrode friction nanogenerator flexible pressure sensor according to claim 1, characterized in that: The conductive yarn is made of at least one of conductive fabric, copper, silver, silver nanowire, copper alloy, gold, aluminum, iron, aluminum alloy, carbon fiber, graphite, graphene, and carbon nanotube.

4. The method for preparing a single-electrode friction nanogenerator flexible pressure sensor according to claim 3, characterized in that: The conductive yarn is aluminum yarn with a diameter of 0.05-0.3 mm.

5. The method for preparing a single-electrode friction nanogenerator flexible pressure sensor according to claim 1, characterized in that: In step S1 and step S2, the weaving process is to use a rapier loom to weave a woven fabric type fabric with a vertically interlaced warp and weft yarn structure; and / or, the size range of the tribo-negative fabric is 3 to 8 cm × 3 to 8 cm, and the size range of the tribo-positive fabric is not less than the size range of the tribo-negative fabric.

6. The method for preparing a single-electrode friction nanogenerator flexible pressure sensor according to claim 1, characterized in that: The diameter of the nylon filament is 0.06-0.18 mm, and the specification is 50D / 2 strands-120D / 3 strands.

7. A single-electrode friction nanogenerator flexible pressure sensor, characterized in that: The method according to claims 1 to 7 is used for preparation.

8. Application of the single-electrode friction nanogenerator flexible pressure sensor as claimed in claim 7 as a pressure sensor.

9. The use according to claim 8, characterized in that: A single-electrode friction nanogenerator flexible pressure sensor is used as a sensing unit, and a sensing array is composed of a plurality of the sensing units.

10. The use according to claim 9, characterized in that: The sensor array is applied to the forefoot and the rear foot of the human body to monitor the pressure signal of the plantar movement in real time.

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