A flexible thin-film foot energy harvesting and lower limb varicose vein monitoring device

Abstract

A flexible thin-film foot energy harvesting and lower limb varicose vein monitoring device belongs to the field of self-powered and sensor technology. It includes a flexible foot energy harvester located on the sole of a shoe, an energy storage device, and a flexible PVDF piezoelectric material array varicose vein monitoring strap for lower limb binding. The flexible foot energy harvester is electrically connected to the energy storage device, and the energy storage device is electrically connected to the monitoring strap. The flexible PVDF piezoelectric material array varicose vein monitoring strap is a sensing device based on BaTiO3 / PVDF piezoelectric composite material, capable of receiving and displaying the varicose vein status of the lower limbs. The energy of the flexible PVDF piezoelectric material array varicose vein monitoring strap is collected by the flexible foot energy harvester and stored in the storage device. This device achieves efficient mechanical energy-to-electrical energy conversion and high-sensitivity varicose vein monitoring, significantly advancing the fields of self-powered, sensor technology, and wearable piezoelectric technology.

Description

Technical Field

[0001] This invention belongs to the field of self-powered and sensor technology, specifically relating to the design and fabrication of a flexible piezoelectric wearable energy harvesting and venous pressure sensor. Background Technology

[0002] With the rapid development of smart interconnection technology, the emergence of flexible electronic devices, and the rise of wearable technology, monitoring human movement and physiological health using flexible wearable sensors attached to the skin has become a research hotspot. However, most flexible wearable physical sensors rely on external power sources for energy and signal transmission. The large size, inconvenience, short lifespan, and difficulty in replacement of external power supplies limit the daily application of flexible wearable sensors. With the development of piezoelectric energy harvesting and storage technology, utilizing piezoelectric materials as energy harvesters to collect energy generated by human life activities and power flexible wearable sensors represents a promising prospect for realizing self-powered sensor networks for personal healthcare. This is particularly important in the context of my country's aging population, where real-time health monitoring of the elderly is crucial.

[0003] In energy harvesting materials, piezoelectric materials are commonly used as the medium for converting external forces into electrical energy, utilizing the piezoelectric effect to generate charge. There are many types of piezoelectric materials, such as piezoelectric single crystals, piezoelectric ceramics, piezoelectric polymers (e.g., polyvinylidene fluoride (PVDF)), and piezoelectric composites. Each of these materials has its own characteristics. Piezoelectric single crystals and ceramics possess excellent piezoelectric properties and high electromechanical conversion efficiency, resulting in high energy harvesting efficiency for energy harvesters made from them. However, these piezoelectric materials have poor flexibility and cannot be bent, significantly limiting their application in wearable devices. PVDF, on the other hand, possesses flexibility, a property that brittle and hard crystals lack. As a highly flexible plastic film, PVDF is easily formed into devices of various shapes, readily conforming to objects. Furthermore, PVDF piezoelectric elements are highly stable to humidity, temperature, and chemical substances, making them particularly suitable for wearable applications for energy harvesting and signal acquisition. However, PVDF has a low piezoelectric coefficient and low energy conversion efficiency, requiring the design of efficient structures to improve the conversion efficiency of PVDF piezoelectric devices. Array-based piezoelectric PVDF sensors can acquire external vibration signals to the maximum extent and in all directions. BaTiO3 and BaTi2O5, as common and high-performance piezoelectric ceramic fillers, can be combined with PVDF to obtain BaTiO3 / PVDF and BaTi2O5 / PVDF composites with even better piezoelectric properties and higher sensitivity. The piezoelectric composite materials BaTiO3 / PVDF and BaTi2O5 / PVDF, combining electromechanical conversion properties with flexibility, have become the best choice for manufacturing wearable human sensors. Summary of the Invention

[0004] The purpose of this invention is to provide a human foot energy harvester based on flexible wearable piezoelectric technology and a lower limb varicose vein monitoring system based on flexible piezoelectric materials. The energy harvester is used to convert the mechanical energy of the human foot into electrical energy to provide energy for the varicose vein monitoring sensor in the ankle. The lower limb varicose vein acoustic monitoring system can accurately and in real time monitor the condition of the lower limb veins.

[0005] The technical solution to achieve the purpose of this invention is as follows:

[0006] A flexible thin-film foot energy harvesting and lower limb varicose vein monitoring device is characterized by comprising a flexible foot energy harvester (1) located on the sole of a shoe, an energy storage device (2), and a flexible PVDF piezoelectric material array varicose vein monitoring strap (3) for lower limb binding; the flexible foot energy harvester is electrically connected to the energy storage device, and the energy storage device is electrically connected to the monitoring strap; the flexible PVDF piezoelectric material array varicose vein monitoring strap is a sensing device based on BaTiO3 / PVDF piezoelectric composite material, capable of receiving and displaying the varicose vein condition of the lower limbs. The energy of the flexible PVDF piezoelectric material array varicose vein monitoring strap is collected by the flexible foot energy harvester and stored in the storage device.

[0007] The flexible foot energy harvester (1) of the shoe sole has two layers, with the lower surface of the upper layer and the upper surface of the lower layer both having a serrated structure. The BaTi2O5 / PVDF piezoelectric composite material is located between the upper and lower serrations. There is a protrusion and a depression between the upper and lower serrations to increase the deformation of the BaTi2O5 / PVDF piezoelectric composite material and collect more energy. The thickness of the flexible BaTi2O5 / PVDF composite piezoelectric film material is 50μm. Multiple flexible BaTi2O5 / PVDF composite piezoelectric film materials can be spliced ​​or stacked. All BaTi2O5 / PVDF in the insole are connected in parallel.

[0008] The lower layer is a base (11), and the upper layer is a load-bearing element (13). An arc-shaped spring (12) is provided between the two ends or around the upper and lower layers. A BaTi2O5 / PVDF composite piezoelectric film material (14) is placed between the base and the load-bearing element. A groove is provided on the upper surface of the base, within which the load-bearing element, arc-shaped spring, and BaTi2O5 / PVDF composite piezoelectric film material are located. The groove also serves to limit the movement of the load-bearing element, arc-shaped spring, and BaTi2O5 / PVDF composite piezoelectric film material, allowing the load-bearing element to move only up and down relative to the base, forming an encapsulated energy harvester component. The lower end face of the load-bearing element and the upper end face of the inner cavity of the base are both serrated structures, with the pointed tip of the load-bearing element facing the recess of the base, creating an interlaced structure between the base and the load-bearing element.

[0009] The flexible PVDF piezoelectric material array varicose vein monitoring strap (3) for lower limb binding consists of a signal acquisition module, an information processing module, and an information transmission module. The signal acquisition module is electrically connected to the information processing module, and the information processing module is electrically connected to the information transmission module. The information transmission module is composed of a Bluetooth module and a mobile terminal, which transmits the data processed by the signal processing module to the mobile terminal via Bluetooth, and the data is presented on the mobile terminal.

[0010] The signal acquisition module includes a BaTiO3 / PVDF piezoelectric composite material sensing module and a preamplifier. The BaTi2O5 / PVDF piezoelectric composite material sensing module includes a rectangular array (31) composed of 4 rows and 4 columns of BaTi2O5 / PVDF piezoelectric composite materials, and each unit of the array has an electrode wire led out.

[0011] The information processing module includes components such as filters and analog-to-digital converters (ADCs) to convert the signals collected by the sensors into digital signals and accurately extract the collected information.

[0012] The information processing module uses big data and artificial intelligence algorithms to transform the physiological state of the human body, especially the condition of varicose veins in the lower limbs. For example, the condition of varicose veins can be determined by checking the blood pressure signal in the ankle.

[0013] The significant advantages of this invention compared to existing technologies are:

[0014] (1) By connecting the base and the load-bearing element through the bow-shaped spring, the mechanical energy can be converted into electrical energy by applying pressure to the load-bearing element through the kinetic energy of the foot. When no force is applied, the bow-shaped spring will bounce the load-bearing component up, and the flexible PVDF piezoelectric material will return to its original state.

[0015] (2) By setting a specific toothed cross structure between the base and the load-bearing element, the piezoelectric material can undergo greater shape changes in a limited space;

[0016] (3) By selecting PVDF composite materials composed of two different materials, a higher piezoelectric effect can be achieved;

[0017] (4) By selecting composite materials, flexible piezoelectric materials can achieve the mechanical properties of both piezoelectric ceramic materials (mechanical-electric conversion capability) and polymer materials (high elasticity, tear resistance and impact resistance).

[0018] (5) By making the plug into a standard shape, it can be easily and directly embedded into the sole of the shoe, while ensuring comfort.

[0019] (6) The wrap-around sensor array is made of PVDF flexible material and can be attached to an adhesive tape and wrapped around the ankle to check the blood pressure signal in the ankle.

[0020] (7) After the blood pressure signal is collected and processed by the circuit, it can be transmitted to the back end for display by the data processing module. The system uses the displayed blood pressure information and artificial intelligence to judge and display the varicose veins of the user's lower limbs and give a diagnosis. Attached Figure Description

[0021] Figure 1 Block diagram of the flexible PVDF film foot energy harvesting and varicose vein monitoring system

[0022] Figure 2 Schematic diagram of a flexible BaTiO3 / PVDF piezoelectric composite material sensor array varicose vein monitoring system

[0023] Figure 3 Flexible BaTi2O5 / PVDF Energy Harvesting Sports Insole

[0024] Figure 4 Schematic diagram of the internal structure of the energy harvesting unit

[0025] Figure 5 A flexible, windable BaTiO3 / PVDF piezoelectric composite material sensor array for monitoring varicose veins in the lower extremities. Detailed Implementation

[0026] The specific embodiments described below, with reference to the accompanying drawings, will further clarify the purpose, advantages, and features of the invention. The specific embodiments described below are for illustrative purposes only; any similar technical solutions are within the scope of protection claimed by this invention.

[0027] This invention provides a novel self-powered ankle varicose vein monitoring device based on PVDF piezoelectric composite flexible thin film material for energy harvesting. The composition principle of the entire device is as follows: Figure 1As shown, the flexible plantar energy harvester's core component is an insole with a flexible BaTi2O5 / PVDF composite piezoelectric film. Foot movement causes deformation of the BaTi2O5 / PVDF composite piezoelectric film, creating a potential difference. The energy generated by this potential difference is transmitted to an energy storage device via FPC wires. A bandage for monitoring varicose veins in the ankle incorporates a BaTiO3 / PVDF piezoelectric composite material sensor array to monitor vein pulsation. Each unit of the array has an electrode wire leading out. The signal acquisition module collects and amplifies the electrical signals monitored in the flexible BaTiO3 / PVDF piezoelectric composite material sensor array. The signal acquisition module includes a BaTiO3 / PVDF piezoelectric composite material sensor module and a preamplifier. The information processing module processes the collected data, converting the signals collected by the sensors into digital signals through filtering, AD conversion, and other processes. It accurately extracts the collected information and then uses big data and artificial intelligence algorithms to determine the condition of varicose veins in the lower limbs and provide a diagnosis. The results of the information processing are displayed on the display interface of a mobile device through a wireless transmission channel. All the energy for signal acquisition, information processing, and information transmission is collected by the flexible plantar energy harvester and stored in the storage device.

[0028] Figure 2 This is a schematic diagram of the actual application of the entire flexible film foot energy harvesting and lower limb varicose vein monitoring system. Figure 2 The foot energy harvesting insole worn inside the shoe is a flexible foot energy harvester (1). The collected energy is output and stored in the storage device through the electrode leads. 2 in the figure is a wrap-around BaTiO3 / PVDF lower limb varicose vein monitoring sensor array band. The outer layer of the band is the energy storage. The signal acquisition and processing module is located in the outer, inner or middle layer of the band. Finally, the processing result is transmitted to the mobile device.

[0029] Figure 3 It is a flexible BaTi2O5 / PVDF energy harvesting sports insole. The flexible BaTi2O5 / PVDF piezoelectric composite material is placed at the pressure point when the foot steps down. The thickness of the piezoelectric composite material BaTi2O5 / PVDF is 50μm. All BaTi2O5 / PVDF in the insole are connected in parallel, with the positive electrode at the top and the negative electrode at the bottom. The insole has a specially designed structure.

[0030] Figure 4The insole features a structure inlaid with BaTi2O5 / PVDF piezoelectric composite material. The insole comprises three layers: upper, middle, and lower. The middle layer is a layered BaTi2O5 / PVDF piezoelectric composite film 14, as shown in Figure 4. The lower surface of the upper layer has a serrated structure, and the upper surface of the lower layer also has a serrated structure. The lower serrated structure 11 serves as a base, and the upper serrated structure 13 serves as a load-bearing element. The serrations of the upper and lower layers are matched in an interlocking position or state, allowing the BaTi2O5 / PVDF to deform significantly under pressure, generating a large potential difference. Elastic support bow-shaped springs 12 are provided between the upper and lower layers and at both ends of the BaTi2O5 / PVDF (the bow-shaped springs are fixed to the load-bearing element or base at points to prevent movement while maintaining elasticity). The upper surface of the lower layer is concave overall, with protruding baffles at both ends, and the upper layer is fitted into the concave shape of the lower layer.

[0031] Figure 5 This is a structural diagram of a varicose vein sensing array containing BaTi2O5 / PVDF piezoelectric composite material. The array is a rectangular array of 4 rows and 4 columns, and each unit of the array has an electrode line.

[0032] This energy harvester converts the mechanical energy of the human foot into electrical energy to power a varicose vein monitoring sensor in the ankle. This lower limb varicose vein acoustic monitoring system can accurately and in real-time monitor the condition of the veins in the lower limbs. This device achieves efficient mechanical-to-electrical energy conversion and highly sensitive varicose vein monitoring, significantly advancing the fields of self-powered devices, sensors, and wearable piezoelectric technologies.

Claims

1. A flexible thin-film foot energy harvesting and lower limb varicose vein monitoring device, characterized in that, The invention includes a flexible plantar energy harvester (1) located on the sole of the shoe, an energy storage device (2), and a flexible PVDF piezoelectric material array varicose vein monitoring strap (3) for lower limb binding; the flexible plantar energy harvester is electrically connected to the energy storage device, and the energy storage device is electrically connected to the monitoring strap. The flexible PVDF piezoelectric material array varicose vein monitoring band is a sensing device designed based on BaTiO3 / PVDF piezoelectric composite material, which can receive and display the varicose vein condition of the lower limbs; the energy of the flexible PVDF piezoelectric material array varicose vein monitoring band is collected by a flexible plantar energy harvester and stored in a storage device.

2. The flexible thin-film plantar energy harvesting and lower limb varicose vein monitoring device according to claim 1, characterized in that, The flexible foot energy harvester of the sole (1) has two layers, the upper and lower layers. The lower surface of the upper layer and the upper surface of the lower layer are both serrated. The BaTi2O5 / PVDF piezoelectric composite material is located between the upper and lower serrations. There is a protrusion and a depression between the upper and lower serrations to increase the deformation of the BaTi2O5 / PVDF piezoelectric composite material and collect more energy. The thickness of the flexible BaTi2O5 / PVDF composite piezoelectric film material is 50µm.

3. The flexible thin-film foot energy harvesting and lower limb varicose vein monitoring device according to claim 2, characterized in that, Multiple flexible BaTi2O5 / PVDF composite piezoelectric film materials are spliced ​​or layered, and all BaTi2O5 / PVDF in the insole are connected in parallel.

4. A flexible thin-film foot energy harvesting and lower limb varicose vein monitoring device according to claim 2, characterized in that, The lower layer is the base (11), and the upper layer is the load-bearing element (13). Bow-shaped springs (12) are provided between the two ends or around the upper and lower layers. BaTi2O5 / PVDF composite piezoelectric film material (14) is placed between the base and the load-bearing element. The upper surface of the base is provided with a groove. The load-bearing element, bow-shaped springs, and BaTi2O5 / PVDF composite piezoelectric film material are all located in the groove. At the same time, the groove also serves to limit the load-bearing element, bow-shaped springs, and BaTi2O5 / PVDF composite piezoelectric film material. The load-bearing element can only move up and down relative to the base to form an encapsulated energy harvester component. The lower end face of the load-bearing element and the upper end face of the inner cavity of the base are both sawtooth structures. The sharp protrusion of the load-bearing element faces the depression of the base, so that the base and the load-bearing element are staggered.

5. A flexible thin-film foot energy harvesting and lower limb varicose vein monitoring device according to claim 1, characterized in that, The flexible PVDF piezoelectric material array varicose vein monitoring strap (3) for lower limb binding is composed of a signal acquisition module, an information processing module and an information transmission module; the signal acquisition module is electrically connected to the information processing module, and the information processing module is electrically connected to the information transmission module; the information transmission module is composed of a Bluetooth module and a mobile terminal, and transmits the data processed by the signal processing module to the mobile terminal via Bluetooth, and presents the data on the mobile terminal.

6. A flexible thin-film foot energy harvesting and lower limb varicose vein monitoring device according to claim 5, characterized in that, The signal acquisition module includes a BaTiO3 / PVDF piezoelectric composite material sensing module and a preamplifier; the BaTi2O5 / PVDF piezoelectric composite material sensing module includes a rectangular array (31) composed of 4 rows and 4 columns of BaTi2O5 / PVDF piezoelectric composite materials, and each unit of the array has an electrode line.

7. A flexible thin-film foot energy harvesting and lower limb varicose vein monitoring device according to claim 5, characterized in that, The information processing module includes a filter and an analog-to-digital converter component, which converts the signals collected by the sensor into digital signals and accurately extracts the collected information.

8. A flexible thin-film foot energy harvesting and lower limb varicose vein monitoring device according to claim 5, characterized in that, The information processing module uses big data and artificial intelligence algorithms to convert the data into information about varicose veins in the lower limbs.

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