Flexible ultrasonic sensor, manufacturing method thereof and blood pressure waveform and heart rate real-time monitoring system and method
By using a flexible ultrasound sensor and an arterial monitoring system, the problem of existing blood pressure monitoring devices being unable to achieve non-invasive, continuous, and accurate monitoring has been solved. It enables continuous blood pressure monitoring without the need for inflation, improving the comfort and accuracy of monitoring and making it suitable for long-term dynamic monitoring at home.
Patent Information
- Application Number
- CN202511669641.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-14
- Publication Date
- 2026-02-10
AI Technical Summary
Existing blood pressure monitoring devices cannot achieve seamless, continuous, and accurate monitoring. Traditional mercury sphygmomanometers require professional operation, while electronic sphygmomanometers suffer from drift and sleep interference, failing to meet the long-term dynamic monitoring needs of families.
A flexible ultrasound sensor is designed, comprising a flexible composite backing layer, a conductive adhesive layer, independent electrodes, a piezoelectric layer, a flexible matching layer, and an adhesive layer. It employs an array of piezoelectric elements and a serpentine interconnect structure, combined with an arterial monitoring system and real-time algorithm processing, to achieve continuous blood pressure monitoring without the need for inflation.
It achieves unobtrusive, continuous, and accurate blood pressure monitoring, avoiding the operational complexity of traditional devices and the sleep interference of electronic devices, thus improving the comfort and accuracy of monitoring. It is suitable for cardiovascular disease monitoring and prevention in both healthy and sick individuals.
Smart Images
Figure CN121489533A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of blood pressure detection equipment, and particularly relates to a flexible ultrasonic sensor, a manufacturing method thereof, and a blood pressure waveform and heart rate real-time monitoring system and method based on the flexible ultrasonic sensor. BACKGROUND
[0002] Cardiovascular diseases have the characteristics of high morbidity, high disability rate and high mortality, and have the trend of youth. It is the leading cause of death worldwide. The monitoring of blood pressure waveform is of great significance for the prevention of cardiovascular diseases. At present, the detection of blood pressure mainly has the following two ways: The mercury column sphygmomanometer is a traditional and classic blood pressure measuring tool, which is considered as the "gold standard" for blood pressure measurement. The mercury column sphygmomanometer is a blood pressure meter that needs to be manually and auscultated by a professional doctor. By manually squeezing the air bag to inflate the cuff, the arterial blood flow is blocked, and then the doctor listens to the Korotkoff sound with a stethoscope to determine the systolic and diastolic pressures. However, this blood pressure measurement method requires a doctor with professional training to master the correct measurement method, and ordinary people cannot use it by themselves. Moreover, mercury is a highly toxic heavy metal, and once broken, it will cause environmental pollution and health risks. Currently, it is mainly used in medical institutions and operated by professional medical staff as a reference standard for diagnosis and calibration, and is not suitable for daily use at home, nor can it realize long-term dynamic monitoring.
[0003] Electronic sphygmomanometer is the mainstream product in the market for self-measurement at home, which can be divided into upper arm type and wrist type according to the wearing position. The electronic sphygmomanometer automatically inflates and deflates the skin by the built-in motor to apply pressure, and the pressure sensor detects the vibration wave of the blood vessel wall to calculate the blood pressure value through the algorithm. Electronic sphygmomanometer can realize one-key operation and automatically display the results, which is very suitable for home users, especially the elderly. However, the electronic components and sensors may have drift phenomenon, and usually need to be returned to the factory or calibrated at a professional institution once every 1-2 years. In the application scenario of 24-hour dynamic blood pressure monitoring, the electronic sphygmomanometer will automatically inflate and measure according to the preset program (e.g. every 30 minutes during the day and every 1 hour at night). This strong bondage and pressure can easily wake people up from sleep, especially for people with light sleep. This will cause sleep fragmentation and reduce effective sleep time, resulting in fatigue, drowsiness and lack of concentration the next day. Therefore, although the electronic sphygmomanometer is suitable for daily use at home, it is still not suitable for long-term dynamic monitoring.
[0004] With the continuous improvement of people's material living standards in China, people have higher pursuit of cardiovascular health, but the above blood pressure monitoring equipment cannot meet the requirements of non-invasive, continuous and accurate blood pressure monitoring. SUMMARY
[0005] The present application aims at the deficiencies of the prior art, and provides a flexible ultrasonic sensor, a manufacturing method thereof, and a blood pressure waveform and heart rate real-time monitoring system and method, which can realize non-inductive, continuous and accurate blood pressure monitoring.
[0006] One of the above-mentioned purposes of the present application is achieved by the following technical solutions: A flexible ultrasonic sensor comprises a flexible composite backing layer, an upper conductive adhesive layer, a lower conductive adhesive layer, a plurality of top independent electrodes, a bottom common electrode, a piezoelectric layer, a 1 / 4 lambda-thickness flexible matching layer and a flexible adhesive layer. The upper conductive adhesive layer, the lower conductive adhesive layer, one end of the top independent electrode, one end of the bottom common electrode and the piezoelectric layer are all encapsulated in the flexible composite backing layer and the 1 / 4 lambda-thickness flexible matching layer, and the flexible composite backing layer and the 1 / 4 lambda-thickness flexible matching layer are arranged in an up-down manner. The piezoelectric layer is composed of a plurality of isolated piezoelectric elements, the upper end of each piezoelectric element is electrically connected to one end of a top independent electrode through a respective upper conductive adhesive layer, and the lower end of each piezoelectric element is electrically connected to one end of a bottom common electrode through a respective lower conductive adhesive layer; the flexible adhesive layer is located below the 1 / 4 lambda-thickness flexible matching layer and is used to realize adhesive contact with the skin.
[0007] Moreover, the piezoelectric elements of the piezoelectric layer are arranged in a 3*3 array, and the piezoelectric elements are filled with the material of the flexible composite backing layer.
[0008] Moreover, the top independent electrode and the bottom common electrode both adopt a "island-bridge" type serpentine interconnection structure; the top independent electrode and the bottom common electrode both can adopt a three-layer structure, in which the upper and lower layers are polyimide film PI layers and the middle layer is a metal layer.
[0009] Moreover, the upper conductive adhesive layer and the lower conductive adhesive layer adopt low-temperature cured epoxy resin conductive adhesive.
[0010] Moreover, the 1 / 4 lambda-thickness flexible matching layer is prepared by using silicone ECOFLEX 00-30 component A and component B, the silicone component A and the component B are configured in a mass ratio of 1:1, stirred and mixed uniformly, then vacuumed for 3 minutes by using a vacuum pump to discharge the air bubbles in the solution, coated on the bottom common electrode and below the flexible composite backing layer by using a spin coating method, and placed in a 60 DEG C oven for heating for 15 minutes for curing.
[0011] Moreover, the flexible adhesive layer is prepared by using polydimethylsiloxane (PDMS) and a curing agent; the polydimethylsiloxane and the curing agent are mixed in a mass ratio of 40:1, and after being stirred and mixed uniformly, the mixture is subjected to vacuum pumping for 3 minutes to discharge air bubbles in the solution, and then the solution is spin-coated on the 1 / 4λ flexible matching layer of the flexible ultrasonic sensor, and then the solution is placed in a 60℃ oven for heating and curing for 50 minutes.
[0012] Moreover, the base material of the flexible composite backing layer is two-component liquid silicone rubber ECOFLEX 00-30, and component A and component B are mixed in a mass ratio of 1:1; then functional fillers with sound absorption performance are added to the mixed solution, and the fillers are uniformly dispersed in the silica gel matrix by mechanical stirring; and the slurry is subjected to vacuum degassing treatment; finally, the slurry after the degassing treatment is placed in a 60℃ constant-temperature oven for heating and curing for 15 minutes to form the flexible composite backing layer with predetermined acoustic characteristics.
[0013] The second purpose of the present application is achieved by the following technical solutions. A preparation method of a flexible ultrasonic sensor, comprising the following steps: Step 1: arranging piezoelectric elements at a set interval; then electrically connecting the upper end of each piezoelectric element to one end of a top independent electrode through an upper conductive bonding layer, and electrically connecting the lower end of all piezoelectric elements to one end of a common bottom common electrode through a lower conductive bonding layer; Step 2: placing the combined structure of step 1 in a pouring mold, pouring flexible composite backing layer material into the mold, and performing low-temperature heating and curing in a set constant-temperature environment to realize packaging of the combined structure of step 1; Step 3: after the flexible composite backing layer is completely cured, spin-coating a 1 / 4λ-thickness flexible matching layer below the semi-finished product prepared in step 2, and performing low-temperature heating and curing in a set constant-temperature environment to realize complete packaging of the combined structure of step 1; Step 4: after the 1 / 4λ-thickness flexible matching layer is completely cured, spin-coating a flexible adhesive layer material below the 1 / 4λ-thickness flexible matching layer, and performing low-temperature heating and curing in a set constant-temperature environment to complete preparation of the flexible ultrasonic sensor.
[0014] The third purpose of the present application is achieved by the following technical solutions. An arterial monitoring system based on the flexible ultrasonic sensor, comprising the flexible ultrasonic sensor, a pulse generation receiver, a high-speed signal acquisition card, and a PC end. The flexible ultrasonic sensor is connected with the pulse generation receiver through the FPC to realize transmission of ultrasonic excitation signals and ultrasonic pulse echo signals; the pulse generation receiver is connected with the high-speed signal acquisition card to realize acquisition of the ultrasonic pulse echo signals; and the high-speed signal acquisition card is connected with the PC end to realize online transmission and real-time algorithm processing of the ultrasonic pulse echo signals on the PC end. The flexible ultrasonic sensor is used for emission and reception of ultrasonic waves. The pulse generation receiver comprises a high-frequency pulse excitation module, an echo gain amplification module and a band-pass filtering module; the high-frequency pulse excitation module is used for controlling excitation pulse voltage size, excitation pulse width and excitation pulse repetition frequency of an excitation signal of a piezoelectric element according to a subcutaneous position depth of an artery blood vessel to be detected and detection resolution; the echo gain amplification module is used for amplifying weak ultrasonic echo signals without distortion so as to be accurately acquired by the high-speed signal acquisition card; and the band-pass filtering module is used for filtering various low-frequency and high-frequency noises and extracting reliable ultrasonic echo signals. The high-speed signal acquisition card is used for realizing high-speed acquisition and storage of pulse echo signals processed by the pulse generation receiver. The PC end realizes signal recognition and detection through a data processing algorithm.
[0015] The fourth purpose of the present application is achieved by the following technical scheme. A monitoring method based on the above-mentioned artery monitoring system comprises the following steps: Step 1: attaching the flexible ultrasonic sensor to the surface of the human body skin, the flexible ultrasonic sensor generates high-frequency ultrasonic waves under the excitation of the pulse generation receiver, the high-frequency ultrasonic waves propagate in the human body and return, the returned ultrasonic echo signals in the human body are received by the flexible ultrasonic sensor, and echo gain amplification and band-pass filtering processing are performed by the pulse generation receiver; Step 2: acquiring the echo signals in the human body by the high-speed data acquisition card, the echo signals in the human body include pulse echo signals of the front wall and the back wall of the artery blood vessel; Step 3: the PC end extracts the echo signals in the human body of the acquisition card to identify and extract time of the pulse echo signals of the front wall boundary and the back wall boundary of the artery blood vessel, processes the depth of the front wall boundary and the back wall boundary of the artery blood vessel in the human body based on the time of flight method, and performs difference processing to obtain the curve of the diameter of the blood vessel in the human body changing with time; Step 4: determining the relationship between the artery blood pressure and the cross-sectional diameter of the human body, and obtaining the artery pressure waveform of the human body by the PC end algorithm processing; the blood pressure waveform is directly related to the heart beat cycle, each complete blood pressure waveform cycle corresponds to one heartbeat, and the real-time heart rate of the human body can be obtained by identifying the peak value of the blood pressure waveform.
[0016] The present application has the advantages and positive effects that: 1、The present application realizes the miniaturization of the flexible ultrasonic sensor and has good skin adhesion and extensibility, meanwhile, a preparation method of a flexible composite backing layer and a 1 / 4 lambda thickness flexible matching layer are proposed to improve the performance of the flexible ultrasonic sensor, which is expected to be widely applied in the field of human wearable electronics, the present application can obtain the images of the changes of the vascular wall tissue movement over time with different time resolutions by changing the pulse repetition frequency of the pulse generator receiver, and the change curve of the arterial vessel diameter is obtained.
[0017] 2、The sensor of the present application is prepared with an adhesive layer with adhesion, without the use of coupling agent, good impedance matching and stable adhesion can be realized, so that better ultrasonic wave transmission efficiency is achieved, the artifact phenomenon caused by the instability of the traditional rigid ultrasonic probe when held is avoided, at the same time, the pressure deformation of the human body caused by the rigid ultrasonic probe and the discomfort of the human body are avoided, and the accuracy and comfort of blood pressure detection are increased.
[0018] 3、The present application proposes a flexible ultrasonic sensor that can be attached to the skin, without the need for inflation and deflation, completely eliminating physical compression, and an arterial blood pressure detection system and method are proposed, which upgrades the blood pressure monitoring from a "discrete, indirect, and interfering" monitoring mode to a "continuous, direct, and non-intrusive" real-time dynamic monitoring mode, which is of great benefit to the monitoring, prevention and treatment of cardiovascular diseases of healthy people and sick people. BRIEF DESCRIPTION OF DRAWINGS
[0019] Figure 1 is a schematic view of the cross-sectional structure of the flexible ultrasonic sensor of the present application; Figure 2 is a schematic view of the "island-bridge" type serpentine electrode structure, 2a is a schematic view of the top independent electrode structure, and 2b is a schematic view of the bottom common electrode structure; Figure 3 is a schematic view of the implementation principle of the arterial blood pressure detection system; Figure 4 is a pulse echo signal waveform diagram of the anterior and posterior walls of the carotid artery; Figure 5 is a curve of the change of human blood pressure over time and a heart rate identification schematic view. DETAILED DESCRIPTION
[0020] The structure of the present application will be further described below in combination with the drawings and through examples. It should be noted that the present examples are descriptive rather than limiting.
[0021] A flexible ultrasonic sensor, please see Figure 1 and Figure 2The application point of the sensor is that the sensor comprises a flexible composite backing layer, an upper conductive adhesive layer, a lower conductive adhesive layer, a plurality of top independent electrodes, a bottom common electrode, a piezoelectric layer, a 1 / 4λ-thickness flexible matching layer, and a flexible adhesive layer.
[0022] The upper conductive adhesive layer, the lower conductive adhesive layer, the top independent electrodes, the bottom common electrode, and the piezoelectric layer are encapsulated by the flexible composite backing layer and the 1 / 4λ-thickness flexible matching layer; the piezoelectric layer is composed of a plurality of isolated piezoelectric elements, and the top independent electrodes and the bottom common electrode are respectively arranged in parallel at the upper end and the lower end of the piezoelectric elements. The upper end of each piezoelectric element is electrically connected to a top independent electrode through the upper conductive adhesive layer, and the lower end of each piezoelectric element is electrically connected to the bottom common electrode through the lower conductive adhesive layer. The flexible adhesive layer is located below the 1 / 4λ-thickness flexible matching layer.
[0023] Preferably, the piezoelectric elements of the piezoelectric layer are arranged in a 3*3 array, and the piezoelectric elements are filled with the material of the flexible composite backing layer. Wherein, * represents multiplication.
[0024] The piezoelectric layer adopts arrayed piezoelectric elements, which can be piezoelectric ceramic sheets, and the shape of the piezoelectric elements can be a positive direction, a circle, a rectangle, or other polygons. The number of rows and columns n and the spacing p of the two-dimensional rectangular piezoelectric element array, as well as the size of a single piezoelectric element (such as its thickness d and side length l), can be optimized by finite element simulation technology to simulate the sound field, thereby matching the target to be detected by ultrasound. A laser-drilled steel mesh mold can be designed for positioning the array spacing of the piezoelectric elements.
[0025] The piezoelectric material can be selected from lead zirconate titanate (PZT-5, PZT-4 series), lead titanate (PT), and piezoelectric composite material (1-3 composite). A certain thickness of sheet-shaped piezoelectric ceramic is cut into piezoelectric ceramic sheets of the required size using a grinding wheel slicing machine. The piezoelectric composite material (1-3 composite) can be prepared by embedding a PZT-5H piezoelectric ceramic column array into an epoxy resin matrix. The acoustic impedance of PZT-5H piezoelectric ceramic is usually between 30-35 MRayl. The acoustic impedance of the epoxy resin matrix is about 2.5 MRayl~3.5 MRayl, which is closer to the acoustic impedance of human tissue (the average acoustic impedance of human soft tissue is about 1.63 MRayl). According to the transmission coefficient ( ) and the reflection coefficient ( ) formulas of the distribution of ultrasonic energy when ultrasonic waves are vertically incident: wherein, is the acoustic impedance of the piezoelectric material, is the acoustic impedance of the human tissue. Due to the addition of the epoxy matrix, the acoustic impedance of the piezoelectric composite is reduced. The reflection loss between the low acoustic impedance piezoelectric composite (1-3 composite) and the interface of the human tissue is reduced, and the transmission rate of the ultrasonic energy is improved. In the piezoelectric composite (1-3 composite), the epoxy resin also improves the piezoelectric, dielectric and mechanical properties of the composite through mechanical coupling and electrical isolation mechanism, so that it has higher thickness vibration coupling coefficient.
[0026] According to Figure 2 As shown in the figure, the top independent electrode and the bottom common electrode both adopt the "island-bridge" type serpentine interconnection structure, and the island element spacing and the number correspond to the structural parameters between the piezoelectric array (the number of piezoelectric elements in rows and columns can be designed according to actual detection requirements). The independent control of each piezoelectric element is realized. The serpentine structure in the middle converts the macroscopic tensile strain applied on the whole structure into local and small bending strain, thereby protecting the fragile metal conductive material itself from being pulled apart and providing flexibility and stretchability for the sensor device. The top independent electrode and the bottom common electrode can both adopt a three-layer structure, that is, two layers of polyimide film PI and a middle metal layer. The middle metal layer can be made of copper, gold, silver, etc. Among them, the round island element is single-sidedly hollowed out to expose the metal layer, realizing electrical conduction of the electrode and the piezoelectric element. The single-sidedly hollowed-out metal layer of the rectangular pad can realize electrical conduction of the ultrasonic sensor and the arterial monitoring system through the FPC connecting line. The polyimide film has good flexibility, improves the mechanical stability of the metal thin layer, and can effectively avoid short circuit of the top independent electrode and the bottom common electrode. The metal layer can be deposited on the surface of the PI substrate by magnetron sputtering, electron beam evaporation or resistance type thermal evaporation. The required island-bridge pattern and single-sided hollowing of the island element and the pad can be obtained by femtosecond laser processing.
[0027] The upper and lower conductive adhesive layers can be made of low-temperature curing epoxy conductive adhesive, which has the functions of adhesion and conductivity. The upper conductive adhesive layer is between the top independent electrode and the piezoelectric element, and the lower conductive adhesive layer is between the bottom common electrode and the piezoelectric element, which plays a role in conducting and fixing. The ideal solder paste should be able to ensure firm electrical and mechanical connection, while not damaging the performance of the piezoelectric material. The Curie temperature of PZT-5H is about 190-200℃, and too high curing temperature will exceed the Curie temperature of the piezoelectric element, which will have a negative impact on the reliability of the piezoelectric performance. The epoxy conductive adhesive used in the conductive adhesive layer has a certain fluidity, which is printed on the surface of each piezoelectric element by laser-holed steel mesh mold squeegee, and is placed in a 60℃ oven for 2h for curing.
[0028] The silicone (ECOFLEX 00-30) is used as the flexible matching layer material of the ultrasonic sensor, which endows the ultrasonic sensor with flexible performance, and can realize sealing and waterproof performance, and improve the working reliability and service life of the ultrasonic sensor. The 1 / 4λ-thickness flexible matching layer is prepared by using silicone ECOFLEX 00-30 component A and component B, the silicone component A and component B are configured in a mass ratio of 1:1, stirred and mixed uniformly, then the bubbles in the solution are discharged by using a vacuum pump for 3 minutes, and the 1 / 4λ-thickness flexible matching layer is prepared by using a spin coating technology, and is placed in a 60°C oven for heating for 15 minutes for curing.
[0029] The spin coating technology is used to prepare the flexible matching layer with a certain thickness, and the thickness of the flexible packaging layer is controlled by controlling the spin coating speed and spin coating time; the thickness of the flexible matching layer is determined according to the propagation speed of the ultrasonic wave in the matching layer, wherein the propagation speed of the ultrasonic wave in the matching layer ( ) can be obtained by the pulse echo method: wherein d is the thickness of the matching layer material test piece, is the time difference of the echoes on both sides of the matching layer; Based on the interference principle, when the thickness of the matching layer is an odd multiple of 1 / 4 of the wavelength of the ultrasonic wave in the matching layer ( ), the reflected ultrasonic waves of the upper and lower interfaces of the matching layer interfere and cancel each other out, and the tailing phenomenon of the ultrasonic pulse is optimized. The wavelength of the ultrasonic wave ( ) is calculated as follows: wherein is the frequency of the ultrasonic wave, and c is the wave speed of the ultrasonic wave. At the same time, in order to reduce the attenuation of the ultrasonic wave in the matching layer, when the thickness of the matching layer is 1 / 4 , the ultrasonic wave energy transmitted into the human body is stronger.
[0030] The flexible adhesive layer is prepared by using polydimethylsiloxane (PDMS) and a curing agent, the polydimethylsiloxane and the curing agent are configured in a mass ratio of 40:1, stirred and mixed uniformly, then the bubbles in the solution are discharged by using a vacuum pump for 3 minutes, and the flexible matching layer of the flexible ultrasonic sensor is spin coated by using a spin coating technology, and is placed in a 60°C oven for heating for 50 minutes for curing. The cured PDMS and ECOFLEX 00-30 are stably bonded, and have good adhesive performance. In addition, the PDMS has good biocompatibility and can be directly contacted with the human skin.
[0031] The preparation process of the flexible composite backing layer is as follows: taking two-component liquid silicone rubber ECOFLEX 00-30 as the base material, component A and component B are accurately weighed and mixed according to the mass ratio of 1:1; then, functional fillers with sound absorption performance, such as hollow glass microbeads (selected 60 mesh hollow glass microbeads), tungsten powder (selected 500 nm-2000 nm tungsten powder) and other sound absorption materials are added to the mixed solution, and they are uniformly dispersed in the silicone base by mechanical stirring; in order to exclude the gas involved in the mixing process, the slurry is subjected to vacuum degassing treatment, and the vacuum time is 3 min; finally, the mixed system is placed in a constant temperature oven at 60°C and heated and cured for 15 min to form a flexible composite backing layer with predetermined acoustic characteristics.
[0032] By adjusting the mass fraction of hollow glass microbeads and tungsten powder in the silicone base, the acoustic impedance and acoustic attenuation coefficient of the backing layer can be controlled; the composite backing layer can satisfy the impedance matching and improve the acoustic attenuation coefficient; this control mechanism can inhibit the pulse tailing phenomenon of the ultrasonic transducer, thereby improving the axial resolution of the sensor. The density of the flexible composite backing layer can be obtained by Archimedes drainage method: wherein, is the mass of the flexible composite backing layer sample in air (g), is the mass obtained on the balance when the flexible composite backing layer sample is in liquid (g), is the density of distilled water (1 g / cm³).
[0033] The pulse echo method can measure the acoustic impedance (Z) and acoustic attenuation coefficient (α): wherein is the density of the flexible composite backing layer sample, is the wave speed of ultrasonic wave in the flexible composite backing layer sample.
[0034] wherein is the thickness of the flexible composite backing layer sample, is the first echo voltage amplitude of the pulse echo, is the second echo voltage amplitude of the pulse echo.
[0035] The preparation method of the flexible ultrasonic sensor comprises the following steps: Step 1, arranging piezoelectric elements according to the set pitch; then electrically connecting the upper end of each piezoelectric element to one end of a top independent electrode through an upper conductive bonding layer, and electrically connecting the lower end of all piezoelectric elements to one end of a common bottom common electrode through a lower conductive bonding layer; Step 2, place the combined structure of step 1 in a pouring mold, inject flexible composite backing layer material into the mold, and perform low-temperature heating and curing in a set constant temperature environment to encapsulate the combined structure of step 1; Step 3, after the flexible composite backing layer is completely cured, spin-coat a 1 / 4λ-thickness flexible matching layer under the semi-finished product prepared in step 2, and perform low-temperature heating and curing in a set constant temperature environment to completely encapsulate the combined structure of step 1; Step 4, after the 1 / 4λ-thickness flexible matching layer is completely cured, spin-coat a flexible adhesive layer material under the 1 / 4λ-thickness flexible matching layer, and perform low-temperature heating and curing in a set constant temperature environment to complete the preparation of the flexible ultrasonic sensor.
[0036] The flexible ultrasonic sensor prepared in this example is a patch with a thickness of about 1 millimeter, which enables the flexible ultrasonic patch to better conform to the skin and have better wearing comfort.
[0037] According to Figure 3 As shown in FIG. 1, the present application provides an arterial monitoring system based on a flexible ultrasonic sensor, which includes a flexible ultrasonic sensor, a pulse generation receiver, a high-speed signal acquisition card, and a PC end. In the arterial monitoring system, the flexible ultrasonic sensor is connected to the pulse generation receiver through an FPC to realize transmission of ultrasonic excitation signals and ultrasonic pulse echo signals; the pulse generation receiver is connected to the high-speed signal acquisition card to realize acquisition of ultrasonic pulse echo signals; and the high-speed signal acquisition card is connected to the PC end to realize online transmission and real-time algorithm processing of ultrasonic pulse echo signals at the PC end.
[0038] The flexible ultrasonic sensor is used for transmission and reception of ultrasonic waves.
[0039] The pulse generation receiver includes a high-frequency pulse excitation module, an echo gain amplification module, and a band-pass filtering module. The high-frequency pulse excitation module is used to control the excitation pulse voltage size, excitation pulse width, and excitation pulse repetition frequency of the excitation signal of the piezoelectric element according to the subcutaneous position depth and detection resolution of the detected arterial blood vessel; the echo gain amplification module is used to amplify the weak ultrasonic echo signal without distortion so as to be accurately acquired by the high-speed signal acquisition card; The band-pass filtering module is used to filter out various low-frequency and high-frequency noises and extract reliable ultrasonic echo signals; and the high-speed signal acquisition card realizes high-speed acquisition and storage of the pulse echo signals processed by the pulse generation receiver. The PC end realizes signal recognition and detection through a data processing algorithm.
[0040] The detection method using the above arterial monitoring system based on a flexible ultrasonic sensor includes: Step 1: Attach the flexible ultrasonic sensor to the surface of the human body, and the flexible ultrasonic sensor generates high-frequency ultrasonic waves under the excitation of the pulse generator receiver, the high-frequency ultrasonic waves propagate in the human body and return, the returned ultrasonic echo signal in the human body is received through the flexible ultrasonic sensor, and the echo gain amplification and band pass filtering processing are carried out through the pulse generator receiver; Step 2: Collect the echo signal in the human body through a high-speed data acquisition card, and the echo signal in the human body includes the pulse echo signals of the front wall and the back wall of the arterial blood vessel; Step 3: The PC end extracts the echo signal in the human body collected by the acquisition card to identify and time extract the pulse echo signals of the arterial blood vessel front wall boundary and the arterial blood vessel back wall boundary, and based on the time of flight method, the depth of the arterial blood vessel front wall boundary and the arterial blood vessel back wall boundary changes with time, and difference processing is carried out, and the curve of the diameter of the human blood vessel changes with time is obtained; The flexible ultrasonic sensor introduced in the embodiment can realize the transmission and reception functions of ultrasonic pulse signals. Figure 4 The pulse echo signal waveform diagram of the neck artery front wall and back wall in a certain pulse repetition period of the embodiment.
[0041] Step 4: Determine the relationship between the arterial blood pressure and the cross-sectional diameter of the human body, and the PC end algorithm processing obtains the arterial pressure waveform of the human body; the blood pressure waveform is directly related to the heart beat cycle, and each complete blood pressure waveform cycle corresponds to a heartbeat, and the real-time heart rate of the human body can be obtained by identifying the peak value of the blood pressure waveform, see Figure 5 .
[0042] The relationship between the arterial blood pressure and the cross-sectional diameter of the human body is as follows: Among them, is the diastolic pressure, is the diastolic arterial cross section, is the stiffness coefficient. In the formula, is the diameter waveform of the target artery. Assuming that the artery is rotationally symmetrical, A(t) can be calculated as: In the formula, d(t) is the diameter waveform of the target artery. The stiffness coefficient can be calibrated as follows: Among them, is the systolic arterial cross-sectional area.
[0043] Although the embodiments of the present application and the drawings disclose the present application for illustrative purposes, those skilled in the art can understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present application and the appended claims, and therefore the scope of the present application is not limited to the disclosed embodiments and drawings.
Claims
1. A flexible ultrasonic sensor, characterized in that: It includes a flexible composite backing layer, an upper conductive adhesive layer, a lower conductive adhesive layer, multiple top independent electrodes, a bottom common ground electrode, a piezoelectric layer, a 1 / 4λ thick flexible matching layer, and a flexible adhesive layer. The upper conductive adhesive layer, the lower conductive adhesive layer, one end of the top independent electrode, one end of the bottom common ground electrode, and the piezoelectric layer are all encapsulated within a flexible composite backing layer and a 1 / 4λ thick flexible matching layer, which are arranged vertically. The piezoelectric layer is composed of multiple isolated piezoelectric elements. The upper end of each piezoelectric element is electrically connected to one end of a top independent electrode through its respective upper conductive adhesive layer, and the lower end of each piezoelectric element is electrically connected to one end of a bottom common ground electrode through its respective lower conductive adhesive layer. The flexible adhesive layer is located below the 1 / 4λ thickness flexible matching layer and is used to achieve adhesive contact with the skin.
2. The flexible ultrasonic sensor according to claim 1, characterized in that: The piezoelectric elements of the piezoelectric layer are evenly distributed in a 3*3 array, and the piezoelectric elements are filled with the material of the flexible composite backing layer.
3. The flexible ultrasonic sensor according to claim 1, characterized in that: Both the top independent electrode and the bottom common ground electrode adopt an "island-bridge" type serpentine interconnection structure; both the top independent electrode and the bottom common ground electrode adopt a three-layer structure, wherein the top and bottom layers are polyimide film PI layers and the middle layer is a metal layer.
4. The flexible ultrasonic sensor according to claim 1, characterized in that: Both the upper and lower conductive adhesive layers are made of low-temperature curing epoxy resin conductive adhesive.
5. The flexible ultrasonic sensor according to claim 1, characterized in that: The 1 / 4λ thickness flexible matching layer is prepared using silicone ECOFLEX 00-30 components A and B. Silicone components A and B are configured in a 1:1 mass ratio. After being stirred and mixed evenly, the solution is evacuated for 3 minutes using a vacuum pump to remove air bubbles. The solution is then coated under the bottom common ground electrode and the flexible composite backing layer using a spin coating method and placed in a 60℃ oven for 15 minutes to cure.
6. The flexible ultrasonic sensor according to claim 1, characterized in that: The flexible adhesive layer is prepared using polydimethylsiloxane and a curing agent. The polydimethylsiloxane and curing agent are mixed in a mass ratio of 40:
1. After stirring and mixing evenly, the solution is evacuated for 3 minutes using a vacuum pump to remove air bubbles. The solution is then spin-coated onto the 1 / 4λ flexible matching layer of the flexible ultrasonic sensor using spin coating technology and placed in a 60℃ oven for 50 minutes to cure.
7. The flexible ultrasonic sensor according to claim 1, characterized in that: The matrix material of the flexible composite backing layer is a two-component liquid silicone rubber ECOFLEX 00-30, in which component A and component B are mixed at a mass ratio of 1:
1. Then, a functional filler with sound absorption properties is added to the mixture and mechanically stirred to disperse it evenly in the silicone matrix. The slurry is then subjected to vacuum degassing treatment. Finally, the degassed slurry is placed in a 60°C constant temperature oven for 15 minutes to cure, forming a flexible composite backing layer with predetermined acoustic properties. The functional filler with sound absorption properties is made of 60-mesh hollow glass microspheres or tungsten powder of 500-2000 nanometers.
8. A method for fabricating a flexible ultrasonic sensor as described in any one of claims 1-7, characterized in that: Includes the following steps: Step 1: Arrange piezoelectric elements according to the set spacing; then connect the upper end of each piezoelectric element to one end of a top independent electrode through the upper conductive adhesive layer, and connect the lower end of all piezoelectric elements to one end of a common bottom ground electrode through the lower conductive adhesive layer. Step 2: Place the combined structure from Step 1 into a casting mold, inject flexible composite backing material into the mold, and perform low-temperature heating and curing under a set constant temperature environment to achieve the encapsulation of the combined structure from Step 1. Step 3: After the flexible composite backing layer is fully cured, a flexible matching layer with a thickness of 1 / 4λ is spin-coated under the semi-finished product prepared in step 2, and then cured by low-temperature heating in a set constant temperature environment to achieve complete encapsulation of the combined structure in step 1. Step 4: After the 1 / 4λ thickness flexible matching layer has completely cured, spin-coat a flexible adhesive layer material under the 1 / 4λ thickness flexible matching layer, and perform low-temperature heating and curing in a set constant temperature environment to complete the fabrication of the flexible ultrasonic sensor.
9. An arterial monitoring system employing the flexible ultrasound sensor according to any one of claims 1-7, characterized in that: The system includes a flexible ultrasonic sensor, a pulse generator and receiver, a high-speed signal acquisition card, and a PC. The flexible ultrasonic sensor and the pulse generator and receiver are connected via a flexible printed circuit board (FPC) to transmit ultrasonic excitation signals and ultrasonic pulse echo signals. The pulse generator and receiver are connected to the high-speed signal acquisition card via a signal cable to acquire ultrasonic pulse echo signals. The high-speed signal acquisition card is then connected to the PC to enable online transmission and real-time algorithm processing of the ultrasonic pulse echo signals on the PC. The flexible ultrasonic sensor is used for transmitting and receiving ultrasonic waves; The pulse generator receiver includes a high-frequency pulse excitation module, an echo gain amplification module, and a bandpass filter module. The high-frequency pulse excitation module controls the excitation pulse voltage, pulse width, and repetition frequency of the piezoelectric element's excitation signal based on the subcutaneous depth of the detected artery and the detection resolution. The echo gain module amplifies the weak ultrasound echo signal without distortion, enabling accurate acquisition by the high-speed signal acquisition card. The bandpass filter module filters out various low-frequency and high-frequency noises, extracting reliable ultrasound echo signals. The high-speed signal acquisition card is used to realize the high-speed acquisition and storage of pulse echo signals processed by the pulse generator receiver; The PC terminal uses data processing algorithms to identify and detect signals.
10. A monitoring method based on the arterial monitoring system of claim 9, characterized in that: Includes the following steps: Step 1: Attach the flexible ultrasonic sensor to the surface of human skin. The flexible ultrasonic sensor generates high-frequency ultrasonic waves under the excitation of the pulse generator receiver. The high-frequency ultrasonic waves propagate in the human body and return. The flexible ultrasonic sensor receives the returned ultrasonic echo signal in the human body and performs echo gain amplification and bandpass filtering through the pulse generator receiver. Step 2: Acquire echo signals from within the human body using a high-speed data acquisition card. The echo signals from within the human body include pulse echo signals from the anterior and posterior walls of arteries. Step 3: The PC extracts the echo signals from the human body inside the acquisition card to identify and extract the pulse echo signals of the anterior and posterior boundaries of the arterial vessels. The depth of the anterior and posterior boundaries of the human arterial vessels changes over time based on the time-of-flight method, and the difference is processed to obtain the curve of the human blood vessel diameter changing over time. Step 4: Determine the relationship between human arterial blood pressure and the diameter of the blood vessel cross-section. The PC-side algorithm processes the data to obtain the human arterial pressure waveform. The blood pressure waveform is directly related to the heartbeat cycle. Each complete blood pressure waveform cycle corresponds to one heartbeat. By identifying the peak value of the blood pressure waveform, the real-time heart rate of the human body can be obtained.