A wearable wave feedback-based monitoring device for internal arteriovenous fistula tremor

Abstract

The present application relates to a kind of wearable arteriovenous fistula tremor monitoring device based on wave feedback, the device includes front-end test module (1) and rear-end processing module (2), wherein front-end test module (1) includes the multilayer composite film formed by wave transceiver layer (11), microstructure flexible layer (12), plane reflection plating layer (13), plane flexible layer (14) sequentially arranged, and wave transmission and reception device (15) is arranged on the composite film, the front-end test module (1) and rear-end processing module (2) are connected by connecting line (16). Compared with prior art, the present application solves the problems that patients have difficulty in judging the existence of tremor accurately, traditional vibration sensor is not suitable for human body, etc., avoids the delay in treatment caused by not timely finding that the flow of internal fistula is reduced due to the inconvenience of repeated appointment for examination in medical institutions, and significantly reduces the risk of fistula blockage for hemodialysis patients.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of medical biosensors, and particularly relates to a wearable arteriovenous fistula tremor monitoring device based on wave feedback. BACKGROUND

[0002] An arteriovenous fistula is mainly used for maintenance hemodialysis treatment of patients with renal failure. Specifically, the operation is to anastomose the artery near the wrist or elbow of the patient and the adjacent vein, and make the anastomosed vein arterialized. The shaped arteriovenous fistula is not only convenient for repeated puncture, but also can provide sufficient blood flow for several times of hemodialysis treatment per week.

[0003] Stenosis and thrombosis of an arteriovenous fistula are the most common complications after arteriovenous fistula plasty. A part of high-risk patients have poor blood vessel conditions, and there is a high probability of fistula occlusion after new construction or repair of the fistula. If the repair is not timely, the patient may lose valuable blood vessel resources and have to bear the pain of repeated surgery. Therefore, it is necessary to monitor the blood flow velocity of the arteriovenous fistula of patients with maintenance hemodialysis for renal failure, especially high-risk patients, on a daily basis. If the blood flow velocity is too slow, it indicates that the arteriovenous fistula is at risk of blockage, and measures should be taken to dilate the blood vessels or eliminate thrombus to restore patency.

[0004] There is a characteristic clinical manifestation on the skin of patients with arteriovenous fistula: fistula tremor. The arterial blood in the fistula is folded back through the venous valve to cause turbulent flow, which is transmitted to the body surface in the form of tremor. Further, the strength of the tremor at the arteriovenous fistula can be used to judge whether the blood vessel is patent. Obvious tremor indicates that the blood flow in the fistula is sufficient; weakened or disappeared tremor indicates that the blood flow in the fistula is not smooth, and at this time, only the pulse of the fistula can be felt during physical examination, but not the tremor. Compared with blood flow imaging, tremor is an indirect but easier to measure indicator of fistula blood flow. However, in current clinical practice, in addition to physical examination by medical staff, there is no special device for palpating fistula tremor.

[0005] Among the existing tremor monitoring technologies, the traditional monitoring methods are mainly laser Doppler vibrometry and electronic stethoscope technology. Laser Doppler vibrometry determines the skin vibration frequency and amplitude on the body surface by laser, reflects the tremor intensity, and infers whether the internal fistula is unobstructed. Patent No. CN111870252A discloses a superficial blood vessel tremor measurement method and device based on laser sensing. The patent uses a laser sensor to non-contact collect superficial blood vessel tremor signals, and then uses the method of median filtering and adaptive filtering to restore the pure tremor signal. However, due to the problems of large device size and inconvenience of use, it is rarely actually applied in clinical practice at present, and it is also impossible to realize full-time monitoring. The electronic stethoscope picks up the noise (high-frequency mechanical vibration signal) emitted by the turbulent blood flow in the internal fistula, compares the picked-up noise with the noise of the normal internal fistula, and thus judges the state of the internal fistula. Patent No. CN215227600U discloses an arteriovenous fistula blood flow detector, which analyzes the noise signal picked up by the electronic stethoscope through artificial intelligence to judge the state of the fistula. However, there is a significant risk of misdiagnosis through artificial intelligence methods, so artificial intelligence cannot be simply relied on to judge the state of the internal fistula.

[0006] Among the existing tremor monitoring technologies, the emerging monitoring method is to use flexible wearable pressure sensors. This category of monitoring devices places pressure sensors on the body surface or implants near blood vessels. When the blood vessels pulsate or tremble, they exert force on the sensor. By analyzing the size and trend of this force, the tremor intensity can be inferred, reflecting the fistula state. Flexible wearable pressure sensors include capacitive, piezoelectric, and resistive types. Luo Kan's Measurement of Tremor on Arteriovenous Fistulas with a Flexible Capacitive Sensor, published in the Annual International Conference of the IEEE Engineering in Medicine and Biology Society (2021, pp. 7324-7327), introduces a skin-type capacitive pressure sensor that can be used to measure the tremor of dialysis patients' internal fistulas. Geun Yeol Bae's Linearly and Highly Pressure-Sensitive Electronic Skin Based on a Bioinspired Hierarchical Structural Array, published in Advanced Materials (2016, 28, 5300-5306), introduces a resistive pressure sensor with a conductive coating. A semispherical microstructure with wrinkles is formed on the surface of the film, and a graphene coating is grown on the surface of the microstructure, achieving the measurement of wrist pulse. However, the existing flexible wearable pressure sensors have some defects: capacitive sensors need to have a built-in power signal source, which affects the miniaturization and commercialization of capacitive sensors; resistive pressure sensors with conductive coatings generally use materials such as graphene or carbon nanotubes as conductive coatings, which are affected by the properties of the materials themselves. The service life of such sensors is relatively low, and after receiving a small number of cyclic loads, they will experience performance degradation such as zero drift and sensitivity decline. Due to these defects, this type of device is currently in the laboratory stage.

[0007] According to the research results of existing patent technologies, the special medical equipment is large in size, which limits the promotion of traditional tremor monitoring technology; the emerging wearable blood flow monitoring technology has low test accuracy and fatigue limit, and is large in size and inconvenient to wear, which is not widely recognized. SUMMARY

[0008] The purpose of the present application is to overcome the defects of the prior art and provide a wearable arteriovenous fistula tremor monitoring device based on wave feedback, which is flexible and wearable, uses wave (including mechanical wave and electromagnetic wave) transmitting and receiving devices, realizes quantitative monitoring of body surface vibration caused by arteriovenous fistula tremor of kidney dialysis patients, and indirectly realizes real-time non-invasive monitoring of fistula patency, so as to timely alert doctors and patients when the fistula flow decreases and thrombosis is suspected, and to take thrombectomy measures and blood vessel expansion measures as soon as possible to ensure the normality of the fistula and the health of the patient.

[0009] The purpose of the present application can be achieved by the following technical solutions: a wearable arteriovenous fistula tremor monitoring device based on wave feedback, which is a wearable flexible biosensor for quantitatively measuring the mechanical vibration waveform of the arteriovenous fistula tremor of kidney dialysis patients and detecting the patency of the internal fistula line.

[0010] Further, the wave transceiving layer, the micro-structure flexible layer and the planar flexible layer are thin films made of flexible polymer materials, including polydimethylsiloxane, polyimide, etc.; the planar reflective plating layer is made of a metal material with strong bonding force and large wave reflection coefficient, including gold, silver, copper, etc., and the plating layer has a thickness of 10-100 nanometers.

[0011] Further, the front-end test module contains four kinds of thin films, each with one layer, wherein the two surfaces of the wave transceiving layer, the planar reflective plating layer and the planar flexible layer are planar, one surface of the micro-structure flexible layer has a micro-structure, and the surface with the micro-structure is tightly bonded to the planar reflective plating layer, the other surface of the planar reflective plating layer is bonded to the planar flexible layer, and the wave transmitting and receiving device is installed on the surface of the wave transceiving layer.

[0012] Further, the microstructure flexible layer is a double-layer polymer film with one or more basic microstructures shaped as cylinders, triangular pyramids, quadrangular pyramids, hemispheres, or semi-elliptical spheres, with a characteristic size of 10-90 microns.

[0013] Further, the basic microstructures on the microstructure flexible layer are arranged in an array, which can be a circumferential array, a linear array, or a random array.

[0014] Further, the surface of the basic microstructures on the microstructure flexible layer is a porous structure, which can be prepared by a foaming method using a filling material during molding.

[0015] Further, the wave transmitting and receiving layer is extended to an outer electrode at the edge. A metal wire is etched from the wave transmitting and receiving device to the outer electrode, and connected to the back-end processing module through a connecting line.

[0016] Further, the back-end processing module includes a top PDMS package, a back-end processing module circuit board, and a bottom PDMS package. The back-end processing module circuit board includes a circuit substrate, and a signal conditioning circuit composed of a Wheatstone bridge, a low-pass filter, an operational amplifier, and an analog-to-digital converter, a microprocessor chip, a battery, and a wireless communication module arranged on the circuit substrate.

[0017] Further, the circuit substrate is made of a hard insulating material or a flexible insulating material. The Wheatstone bridge and the low-pass filter in the signal conditioning circuit are made of a resistor-capacitor network. The operational amplifier and the analog-to-digital converter are made of a small commercial module with a surface mount package. The microprocessor chip and the wireless communication module are made of a small commercial module with a surface mount package. The battery is a button cell.

[0018] Further, the front-end test module is connected to the signal conditioning circuit of the back-end processing module through a connecting line, realizing the electrical connection of the two modules, and the two modules adopt a tiled layout, that is, the front-end test module is located at the fistula tremor part, and the back-end processing module is adjacent to the front-end test module but does not overlap or is spaced apart by a certain distance and is tiled on the patient's skin at the same time, or the back-end processing module is tiled on a table and chair through a lengthened entity connecting line.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] (1) The present application is based on a wave feedback pressure sensor, wherein the thickness of the microstructure flexible layer in the front-end test module changes with the internal fistula tremor, causing the wave transmission and receiving device to measure signal changes, thereby representing the measured internal fistula tremor signal, and comparing it with the normal internal fistula tremor signal to determine the internal fistula blockage. The pyramid-shaped and hemispherical microstructures in the microstructure flexible layer have strong deformation ability under the condition of small pressure changes such as pulse and blood vessel tremor, so they can achieve higher sensitivity than traditional pressure sensors, and realize real-time quantitative monitoring of the internal fistula tremor of dialysis patients. The planar reflective coating in the front-end test module is more easily reflected by the wave signal than the surface of the human skin, so the signal measured by the wave receiving device is stronger, facilitating data processing; the planar flexible layer is soft in texture, which can reduce the discomfort when attached to the surface of the human skin.

[0021] (2) The device of the present application is a flexible wearable biosensor that quantitatively measures the mechanical vibration waveform of the arteriovenous fistula tremor of patients with maintenance hemodialysis for renal failure, and detects whether the internal fistula blood vessel is unobstructed. The present application solves the problems that patients cannot accurately determine the existence of tremor on their own, and traditional vibration sensors are not suitable for use on the human body, etc. It can achieve the technical effect of real-time monitoring of the internal fistula blockage state, meet the needs of timely warning to medical staff and kidney dialysis patients when the internal fistula gradually narrows, and avoid the delay in treatment caused by the fact that the internal fistula flow is not reduced in time due to the inconvenience of repeated visits to medical institutions for examination, thereby significantly reducing the risk of fistula blockage for hemodialysis patients.

[0022] (3) The device of the present application uses a flexible microstructure sensor, which reflects the internal fistula tremor signal based on the principle that the deformation of the flexible microstructure caused by tremor changes the propagation path of light waves and ultrasonic waves in it, resulting in a synchronous change in the received wave feedback signal. The device of the present application adopts a split configuration, consisting of a flexible front-end test module and a rigid back-end processing module, and uses a flexible microstructure sensor to replace a rigid MEMS accelerometer, reducing the weight of the measurement part to less than 1 gram. The weight of the device reduces the impact of internal fistula tremor measurement, because the energy of the internal fistula tremor of the human body is small, so the reduction of the weight of the device can reduce its own impact on the internal fistula tremor, and improve the correct identification rate of the tremor signal.

[0023] (4) The present application improves the comfort of the user, uses a flexible sensor instead of a rigid sensor, is more easily pasted with the human skin, can reduce the discomfort of the user, uses a thin film patch type configuration instead of a wrist sleeve type configuration, is not easy to compress the internal fistula, has a lower force on the internal fistula, and is beneficial to protect the internal fistula. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a schematic diagram of the overall structure of the present application.

[0025] Figure 2 is an exploded view of Figure 1 .

[0026] Figure 3 is a schematic diagram of the overall structure of the present application.

[0027] Figure 4 is a schematic diagram of the overall structure of the present application.

[0028] Figure 5 is a schematic diagram of the overall structure of the present application.

[0029] Figure 6 is a schematic diagram of the overall structure of the present application.

[0030] Figure 7 is a schematic diagram of the overall structure of the present application.

[0031] Figure 8 is a schematic diagram of the overall structure of the present application.

[0032] Figure 9 is a schematic diagram of the overall structure of the present application. Figure 8 .

[0033] Figure 10 is a schematic diagram of the overall structure of the present application.

[0034] Figure 11 is a schematic diagram of the overall structure of the present application.

[0035] In the above drawings, each figure number mark represents:

[0036] 1-front end test module, 11-wave transceiver layer, 12-microstructure flexible layer, 13-flat reflective coating, 14-flat flexible layer, 15-wave transmitting and receiving device, 16-connection line, 2-back end processing module, 21-top PDMS package, 22-back end processing module circuit board, 221-signal conditioning circuit, 222-micro processing chip, 223-battery, 224-wireless communication module, 225-circuit substrate, 23-bottom PDMS package. DETAILED DESCRIPTION

[0037] The purposes, technical solutions and advantages of the embodiments of the present application will be further described in detail below with reference to the drawings of the embodiments of the present application. It should be understood that the specific embodiments described herein are only a part of the embodiments of the present application, and not all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0038] The various components and raw materials used in the present application are all commonly used commercially available products in the art, for example:

[0039] The wave transceiver layer 11 and the flat flexible layer 14 both use commercially available flexible polymer materials, for example: commercially available PDMS; the microstructure flexible layer 12 uses commercially available PDMS as the material, and a pre-prepared microstructure nickel mold is imprinted thereon, and a PDMS film containing microstructures is prepared after thermal curing.

[0040] The flat reflective coating 13 is prepared by a magnetron sputtering process, that is, the incident ions generated by low-pressure inert gas glow discharge are used to bombard the surface of the plating target material, so that the target atoms are sputtered and deposited on the plated substrate to form a coating. A layer of high reflectivity material is plated on the opposite side surfaces of the flat flexible layer 14 and the microstructure flexible layer 12, including but not limited to gold, silver, copper, etc.

[0041] The wave transmitting and receiving device 15 uses commercially available light emitting diodes and photoresistors.

[0042] The top PDMS package 21 and the bottom PDMS package 23 use SYLGARD184 polydimethylsiloxane film produced by Dow Corning Corporation of the United States; in the signal conditioning circuit 221, the amplifier uses OPA2277UA precision operational amplifier produced by Texas Instruments Corporation of the United States; the analog-to-digital converter uses ADS1148 sixteen-bit analog-to-digital converter produced by Texas Instruments Corporation of the United States; the Wheatstone bridge and the low-pass filter use conventional components in the art; the micro processing chip 222 uses STM32F103C8T6 series chip produced by STMicroelectronics Corporation of Italy.

[0043] Example 1

[0044] AsFigure 1 and Figure 2 A wearable arteriovenous fistula tremor monitoring device shown in the figure comprises a front-end test module 1 and a back-end processing module 2. The front-end test module 1 comprises a wave transceiver layer 11, a microstructure flexible layer 12, a planar reflective plating layer 13, a planar flexible layer 14, a photodiode and a photosensitive resistor 15, and a connecting line 16. The back-end processing module 2 comprises a top PDMS package 21, a back-end processing module circuit board 22, and a bottom PDMS package 23. The back-end processing module circuit board 22 is the core of the module and comprises a signal conditioning circuit 221, a microprocessor chip 222, a battery 223, a wireless communication module 224, and a circuit substrate 225. The wave transceiver layer 11, the microstructure flexible layer 12, and the planar flexible layer 14 are all in the form of a sheet. The microstructure flexible layer 12 has a microstructure on one side of a large plane, and a layer of high reflectivity material, including but not limited to gold, silver, and copper, is plated on the large plane to form the planar reflective plating layer 13. The photodiode and the photosensitive resistor 15 are welded at the center position of the wave transceiver layer 11. An interface is extended at the edge of the wave transceiver layer 11, and the connecting line 16 is welded on the interface and vertically extends to the outside to be connected to the signal conditioning circuit 221 of the back-end processing module 2, thereby realizing the electrical connection of the two modules.

[0045] In the embodiment, as shown in the figure, Figure 2 The wave transceiver layer 11, the microstructure flexible layer 12, and the planar flexible layer 14 of the front-end test module 1 are made of a flexible insulating polymeric material PDMS. After the surface is activated by plasma bombardment, silver is plated on the opposite plane of the microstructure flexible layer 12 by a magnetron sputtering process to form the planar reflective plating layer 13. The connecting line 16 is made of a copper wire and is welded on the external electrode of the wave transceiver layer 11 by a reflow soldering process.

[0046] In the embodiment, as shown in the figure, Figure 5 The microstructure flexible layer 12 of the front-end test module 1 is shaped with a columnar microstructure array with a height of 45 microns, and one side of the columnar array directly contacts the planar reflective plating layer 13.

[0047] In the embodiment, the circuit substrate 225 of the back-end processing module 2 is made of a flexible insulating material. In the embodiment, a SYLGARD184 polydimethylsiloxane film produced by Dow Corning Corporation of the United States is selected. The signal conditioning circuit 221 comprises a Wheatstone bridge, a low-pass filter, an amplifier, and an analog-to-digital converter. The Wheatstone bridge and the low-pass filter are made of a resistance-capacitance network. The amplifier is a precision operational amplifier. The analog-to-digital converter is a 12-bit analog-to-digital converter. The microprocessor chip 222 is an STM32F103C8T6 chip. The battery 223 is a button cell. The wireless communication module 224 is an HC05 Bluetooth module.

[0048] In the present embodiment, the wave transmitting and receiving layer 11 of the front-end testing module 1 is connected to the measured arm of the Wheatstone bridge of the signal conditioning circuit 221 in the back-end processing module 2 through the connecting line 16, the Wheatstone bridge is connected to the low-pass filter, the low-pass filter is connected to the operational amplifier, the operational amplifier is connected to the analog-to-digital converter, the analog-to-digital converter is connected to the microprocessor chip 222, the microprocessor chip 222 is connected to the wireless communication module 224, and the battery 223 provides power for all IC components.

[0049] In the present embodiment, as shown in Figure 3 , during use of the device, the device is placed on the body surface of the patient's arm, the front-end testing module 1 is placed on the arteriovenous interface of the arteriovenous fistula, and one side of the planar flexible layer 14 is in contact with the skin. The back-end processing module 2 naturally overlaps the skin in other parts, and both modules are adhered to the skin or applied with a coupling agent before being adhered to the skin.

[0050] In the present embodiment, as shown in Figures 6-7 , the wave transmitting and receiving device 15 is a light-emitting diode and a photoresistor. The light-emitting diode emits light stably after being powered on, the light passes through the microstructure flexible layer 12 and is reflected by the planar reflective coating layer 13, and is received by the photoresistor to obtain an initial resistance value. When no external force is applied to the front-end testing module 1 and the arteriovenous fistula is not pulsating or trembling, the thickness of the microstructure flexible layer 12 remains constant, and the value of the photoresistor also remains constant, and the resistance between the two connecting lines 16 at this time is recorded as R0 (as shown in Figure 6 ). When the arteriovenous fistula starts to pulsate or tremble, the skin on the body surface vibrates with the fistula, at this time the planar reflective coating layer 13 starts to move up and down, causing the thickness of the microstructure flexible layer 12 to increase or decrease, and then the light intensity received by the photoresistor decreases or increases, thereby causing the value of the photoresistor to increase or decrease, and the resistance between the two connecting lines 16 at this time is recorded as R1 (as shown in Figure 7 ). It can be seen that R1 fluctuates above and below R0, that is, the front-end testing module 1 converts the skin vibration signal into a resistance signal.

[0051] In the present embodiment, as shown in Figure 1 and Figure 4 , the front-end testing module 1 and the back-end processing module 2 together realize three functions, including signal conversion, signal processing, and signal transmission. The resistance change of the front-end testing module 1 causes the Wheatstone bridge in the signal conditioning circuit 221 of the back-end processing module 2 to be unbalanced, outputting a voltage signal carrying an amplitude signal, then filtering out high-frequency noise through the low-pass filter, amplifying the signal voltage value through the operational amplifier, converting it into a digital signal through the analog-to-digital converter, and transmitting the digital signal to the microprocessor chip 222 for transmission; the microprocessor chip 222 delivers the amplitude information to the patient's communication device through the wireless communication module 224.

[0052] Example 2

[0053] A wearable arteriovenous fistula tremor monitoring device as shown in Figure 1 and Figure 2 includes a front-end test module 1 and a back-end processing module 2. The front-end test module 1 includes a wave transceiver layer 11, a microstructure flexible layer 12, a planar reflective plating layer 13, a planar flexible layer 14, a MEMS ultrasonic probe 15, and a connecting line 16. The back-end processing module 2 includes a top PDMS package 21, a back-end processing module circuit board 22, and a bottom PDMS package 23. The back-end processing module circuit board 22 is the core of the module, including a signal conditioning circuit 221, a microprocessor chip 222, a battery 223, a wireless communication module 224, and a circuit substrate 225. The wave transceiver layer 11, the microstructure flexible layer 12, and the planar flexible layer 14 are all in sheet form. The microstructure flexible layer 12 has a microstructure on one side of the large plane, which is plated with a layer of high reflectivity material, including but not limited to gold, silver, and copper, forming the planar reflective plating layer 13. The MEMS ultrasonic probe 15 is welded at the center of the wave transceiver layer 11. An interface is extended at the edge of the wave transceiver layer 11, and the connecting line 16 is welded on the interface, vertically extending to the outside and connected to the signal conditioning circuit 221 of the back-end processing module 2, realizing the electrical connection of the two modules.

[0054] In this embodiment, as shown in Figure 2 , the wave transceiver layer 11, the microstructure flexible layer 12, and the planar flexible layer 14 of the front-end test module 1 are made of flexible insulating polymeric material PDMS. After plasma bombardment surface activation, copper is plated on the opposite plane of the microstructure flexible layer 12 using a magnetron sputtering process, forming the planar reflective plating layer 13. The connecting line 16 is made of copper wire and is welded on the external electrode of the wave transceiver layer 11 by reflow soldering process.

[0055] In this embodiment, as shown in Figures 8-9 , the microstructure flexible layer 12 of the front-end test module 1 is shaped with a porous gold pyramid four-prism microstructure array with a height of 45 microns. The vertex of the four-prism array is in direct contact with the planar reflective plating layer 13.

[0056] In this embodiment, the circuit substrate 225 of the back-end processing module 2 is made of flexible insulating material. In this embodiment, SYLGARD184 polydimethylsiloxane film produced by Dow Corning Company of the United States is selected. The signal conditioning circuit 221 includes a low-pass filter, an amplifier, and an analog-to-digital converter. The low-pass filter uses a resistor-capacitor network, the amplifier uses a precision operational amplifier, and the analog-to-digital converter uses a 12-bit analog-to-digital converter. The microprocessor chip 222 uses an STM32F103C8T6 chip, the battery 223 uses a button cell, and the wireless communication module 224 uses an HC05 Bluetooth module.

[0057] In the present embodiment, the wave transmitting and receiving layer 11 of the front-end testing module 1 is connected to the low-pass filter of the signal conditioning circuit 221 in the back-end processing module 2 through the connecting line 16, the low-pass filter is connected to the operational amplifier, the operational amplifier is connected to the analog-to-digital converter, the analog-to-digital converter is connected to the microprocessor chip 222, the microprocessor chip 222 is connected to the wireless communication module 224, and the battery 223 provides power for all IC components.

[0058] In the present embodiment, as shown in Figure 3 , during use of the device, the device is placed on the body surface of the patient's arm, the front-end testing module 1 is placed on the arterial-venous interface of the arteriovenous fistula, and one side of the planar flexible layer 14 is in contact with the skin. The back-end processing module 2 naturally overlaps the skin in other parts, and both modules are adhered to the skin or adhered to the skin after applying a coupling agent.

[0059] In the present embodiment, as shown in Figures 10-11 , the wave transmitting and receiving device 15 is a MEMS ultrasonic probe. After the ultrasonic probe is powered on, it stably emits ultrasonic waves. The ultrasonic waves are reflected by the planar reflective coating layer 13 after passing through the microstructure flexible layer 12, and are received by the ultrasonic probe to obtain an initial sound pressure value. When no external force is applied to the front-end testing module 1 and the arteriovenous fistula is not pulsating or trembling, the thickness of the microstructure flexible layer 12 remains constant, and the initial sound pressure value also remains constant. When the arteriovenous fistula starts to pulsate or tremble, the skin on the body surface vibrates with the fistula, at which time the planar reflective coating layer 13 starts to move up and down, causing the thickness of the microstructure flexible layer 12 to increase or decrease, and then the sound pressure received by the ultrasonic probe decreases or increases, and fluctuates around the initial sound pressure value, that is, the front-end testing module 1 converts the skin vibration signal into a sound pressure signal.

[0060] In the present embodiment, as shown in Figure 1 and Figure 4 , the front-end testing module 1 and the back-end processing module 2 together realize three functions, including signal conversion, signal processing, and signal transmission. The front-end testing module 1 outputs a sound pressure signal, which is then filtered by a low-pass filter to remove high-frequency noise, amplified by an operational amplifier, converted into a digital signal by an analog-to-digital converter, and transmitted to the microprocessor chip 222 for transmission; the microprocessor chip 222 delivers amplitude information to the patient's communication device through the wireless communication module 224.

[0061] The preferred embodiments of the present application are described in detail above. It should be understood that those of ordinary skill in the art can make modifications and changes to the present application without creative labor based on the concept of the present application. Therefore, any technical solutions obtained by logical analysis, reasoning or limited experiments based on the prior art within the concept of the present application shall be within the protection scope determined by the claims.

Claims

1. A wearable arteriovenous fistula thrill monitoring device based on wave feedback, characterized in that, This device is a wearable flexible biosensor that detects the patency or blockage of arteriovenous fistulas by quantifying the mechanical vibration waveform of arteriovenous fistula tremors in renal dialysis patients. It includes a front-end testing module (1) and a back-end processing module (2). The front-end testing module (1) includes a multilayer composite film formed by sequentially arranging a wave transceiver layer (11), a microstructure flexible layer (12), a planar reflective coating (13), and a planar flexible layer (14), as well as a wave transmitting and receiving device (15) arranged on the composite film. The front-end testing module (1) and the back-end processing module (2) are connected by a connecting line (16). The two modules adopt a flat layout, that is, the front-end testing module (1) is located at the fistula tremor site, and the back-end processing module (2) is adjacent to the front-end testing module (1) but does not overlap or is laid flat on the patient's skin at a certain distance. The wave transceiver layer (11) 1) Both sides of the planar reflective coating (13) and the planar flexible layer (14) are planar. One side of the microstructure flexible layer (12) has a microstructure, and the side with the microstructure is tightly bonded to the planar reflective coating (13). The other side of the planar reflective coating (13) is bonded to the planar flexible layer (14). The wave transmitting and receiving device (15) is installed on the surface of the wave transmitting and receiving layer (11). The microstructure flexible layer (12) is a double-layer polymer film with one or more basic microstructures formed on a planar thin film. The shape of the basic microstructure is prism, triangular pyramid, quadrangular pyramid, hemisphere, or semi-ellipsoid, and the characteristic dimension height is 10~90 micrometers. The planar reflective coating (13) is made of a metal material with strong bonding force with the microstructure flexible layer (12) and a large wave reflection coefficient. The coating thickness is 10~100 nanometers. The back-end processing module (2) includes: a top PDMS package (21), a back-end processing module circuit board (22) and a bottom PDMS package (23). The back-end processing module circuit board (22) includes a circuit substrate (225) and a signal conditioning circuit (221) consisting of a Wheatstone bridge, a low-pass filter, an operational amplifier, and an analog-to-digital converter, a microprocessor chip (222), a battery (223) and a wireless communication module (224) disposed thereon.

2. The wearable arteriovenous fistula thrill monitoring device based on wave feedback according to claim 1, characterized in that, The wave transceiver layer (11), the microstructure flexible layer (12) and the planar flexible layer (14) are thin films made of flexible polymer materials, including polydimethylsiloxane (PDMS), polyimide (PI) and the like; the planar reflective coating (13) includes gold, silver or copper.

3. The wearable arteriovenous fistula thrill monitoring device based on wave feedback according to claim 1, characterized in that, The basic microstructures on the microstructure flexible layer (12) are arranged in an array, which can be a circular array, a linear array, or a random array.

4. The wearable arteriovenous fistula thrill monitoring device based on wave feedback according to claim 1, characterized in that, The basic microstructure surface on the microstructure flexible layer (12) is a porous structure, which is prepared by foaming with filling material during molding.

5. A wearable arteriovenous fistula thrill monitoring device based on wave feedback according to claim 1, characterized in that, An external electrode is obtained by extending outward from the edge of the wave transceiver layer (11); a metal wire is etched from the wave transmitting and receiving device (15) to the external electrode, and connected to the back-end processing module (2) through the connecting line (16).

6. The wearable arteriovenous fistula thrill monitoring device based on wave feedback according to claim 1, characterized in that, The circuit substrate (225) is made of rigid insulating material or flexible insulating material. The Wheatstone bridge and low-pass filter in the signal conditioning circuit (221) are made of resistor-capacitor network. The operational amplifier, analog-to-digital converter and microprocessor chip (222) and wireless communication module (224) are made of small commercial modules with surface mount packaging. The battery (223) is made of button cell battery.

7. The wearable arteriovenous fistula thrill monitoring device based on wave feedback according to claim 1, characterized in that, The front-end test module (1) is connected to the signal conditioning circuit (221) of the back-end processing module (2) via a connecting line (16) to realize the electrical connection between the two modules. The back-end processing module (2) is laid flat on the table and chair by extending the physical connecting line between the two modules.

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