Wearable patch based on flexible ultrasonic sensing and use method

Abstract

The invention provides a wearable patch based on flexible ultrasonic sensing and a use method, and relates to the field of medical monitoring equipment. The sensor comprises a sensing module, a self-adaptive signal processing module and a wireless data transmission module which are packaged by a flexible material and form an integrated flexible packaging layer, the sensing module comprises an ultrasonic transducer array, and the ultrasonic transducer array comprises a plurality of ultrasonic transducers; an ultrasonic transducer; the adaptive signal processing module comprises a microprocessor, an analog front end and a digital signal processor. Through fusion of a flexible electronic technology and ultrasonic sensing, the technical limitation of traditional rigid equipment is broken through, wearable, continuous and non-invasive blood pressure and blood flow synchronous monitoring is achieved, and an important technical scheme is provided for cardiovascular health management, disease early diagnosis and personalized medical treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of medical monitoring devices, in particular to a wearable patch based on flexible ultrasonic sensing and a use method. BACKGROUND

[0002] The prevention and treatment of cardiovascular diseases require continuous monitoring of hemodynamic parameters, but existing clinical monitoring techniques have significant limitations. Traditional cuff blood pressure meters can only provide intermittent single-point measurement data and cannot reflect the dynamic change of blood pressure. The periodic inflation and deflation process not only affects the measurement comfort, but also makes it difficult to meet the standardization requirements of long-term monitoring of hypertensive patients. In terms of blood flow monitoring, although clinical ultrasound devices have the ability to accurately obtain hemodynamic parameters, they are limited by the rigid probe structure and large system volume, and are only suitable for short-term detection in medical institutions, and cannot realize continuous monitoring in daily scenarios.

[0003] With the development of flexible electronic technology, some wearable health monitoring devices have achieved preliminary application, but most of them are limited to single parameter detection function, and lack integrated solutions that can simultaneously monitor blood pressure and hemodynamic parameters. In particular, in dynamic physiological scenarios such as exercise state and body position change, existing technologies are difficult to balance measurement accuracy and wearing comfort, which limits the comprehensive evaluation of cardiovascular function.

[0004] Therefore, developing a new type of ultrasonic sensing system that integrates flexible wearable characteristics, multi-parameter synchronous monitoring capability and continuous measurement accuracy has important clinical value and practical significance for promoting early warning, accurate diagnosis and long-term management of cardiovascular diseases. SUMMARY

[0005] In order to solve the above problems, the present application provides a wearable patch based on flexible ultrasonic sensing, which can break through the technical limitations of traditional monitoring devices and provide a new solution for the long-term management and early warning of cardiovascular diseases.

[0006] The application provides a wearable patch based on flexible ultrasonic sensing, which comprises a sensing module, an adaptive signal processing module and a wireless data transmission module which are encapsulated by a flexible material and form an integrated flexible encapsulation layer; the sensing module comprises a driving circuit and an ultrasonic transducer array, the ultrasonic transducer array comprises a plurality of ultrasonic transducers; the ultrasonic transducers are used for emitting ultrasonic beams and receiving echo signals reflected from the blood vessel wall and blood; the driving circuit is used for exciting the ultrasonic transducers and initially receiving original echo signals; the adaptive signal processing module comprises a microprocessor, an analog front end and a digital signal processor; the microprocessor is used for calculating and processing various signals, the analog front end is used for filtering and amplifying signals, and the digital signal processor is used for processing digital signals; the wireless data transmission module is used for transmitting the results fed back by the adaptive signal processing module to a terminal in a wireless manner and receiving instruction signals from the terminal; and the power supply module is used for supplying power to the sensing module, the adaptive signal processing module and the wireless data transmission module.

[0007] In an implementation manner, the ultrasonic transducer is selected from any one of piezoelectric ceramic, piezoelectric single crystal, piezoelectric composite material, PVDF piezoelectric polymer, piezoelectric micromechanical ultrasonic transducer or capacitive micromechanical ultrasonic transducer.

[0008] In an implementation manner, the frequency of the ultrasonic transducer is 3-15 MHz.

[0009] In an implementation manner, the material of the flexible substrate is selected from any one of polydimethylsiloxane, Ecoflex silicone, thermoplastic polyurethane or polyimide.

[0010] In an implementation manner, the thickness of the flexible encapsulation layer is ≤2 mm.

[0011] In an implementation manner, the wireless transmission module adopts Bluetooth or near field communication wireless transmission.

[0012] In an implementation manner, the ultrasonic transducers form an MxN ultrasonic transducer array; wherein 2≤N≤15, 2≤M≤15.

[0013] The application further provides a use method of the wearable patch based on flexible ultrasonic sensing, which adopts the wearable patch based on flexible ultrasonic sensing as described above and further comprises the following steps:

[0014] Step S1) wearing the wearable patch on a measurement site, such as a carotid artery or radial artery;

[0015] Step S2) the ultrasonic transducer array emits ultrasonic waves and receives echo signals;

[0016] Step S3) The echo signal is filtered and amplified by the analog front end, and the digital signal processor converts the echo signal into a digital signal and performs preliminary processing; wherein, for blood flow data, the adaptive signal processing module obtains the Doppler shift by calculating the digital signal, and calculates the blood flow velocity in real time to monitor the blood flow; for blood pressure data, the adaptive signal processing module calculates to obtain the pulse wave waveform feature and pulse wave transmission time, and then generates a non-invasive continuous blood pressure value through the built-in machine learning model to monitor the blood pressure;

[0017] Step S4) The wireless data transmission module uploads the blood flow data and blood pressure data to the terminal in real time, and receives the signal of the instruction transmitted by the terminal.

[0018] In a feasible real-time manner, in step 2), the resolution of the blood flow velocity is greater than or equal to 0.1 cm / s.

[0019] In a feasible real-time manner, in step 2), the error of the blood pressure measurement is less than or equal to 5 mmHg.

[0020] The wearable patch based on the flexible ultrasonic sensing provided by the present application has the following beneficial effects: the present application breaks through the technical limitations of traditional rigid devices by the fusion of flexible electronic technology and ultrasonic sensing, realizes the wearable, continuous and non-invasive synchronous monitoring of blood pressure and blood flow, and provides an important technical scheme for cardiovascular health management, early disease diagnosis and personalized medical treatment. Specifically, the present application integrates the flexible wearable characteristics, the multi-parameter synchronous monitoring capability and the continuous measurement accuracy, and has important clinical value and practical significance for promoting the early warning, accurate diagnosis and treatment and long-term management of cardiovascular diseases. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the wearable patch in the embodiment of the present application.

[0022] Figure 2 It is a flowchart of the synchronous detection method of blood pressure and blood flow of the wearable patch in the embodiment of the present application.

[0023] Figure 3 It is a flowchart of the synchronous monitoring of carotid artery blood flow and blood pressure by the wearable patch in the first embodiment of the present application.

[0024] Figure 4 It is a flowchart of the synchronous monitoring of radial artery blood flow and blood pressure by the wearable patch in the second embodiment of the present application.

[0025] Figure 5 It is a serpentine interconnected PZT (lead zirconate titanate) piezoelectric array in the wearable patch in the second embodiment of the present application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described in the description of the embodiments of the present application in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present application. In the description of the present application, it should be noted that the terms "left side", "right side", "upper side", "lower side", "upper", "lower" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0027] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0028] In addition, in the description of the present application, unless otherwise specified, the meaning of "multiple" is two or more.

[0029] The present application provides a wearable patch based on flexible ultrasonic sensing, referring to Figure 1 , including a sensing module, an adaptive signal processing module and a wireless data transmission module encapsulated by a flexible material and forming an integrated flexible encapsulation layer. Among them, the flexible encapsulation layer can closely adhere to the surface of human skin, adapt to the morphological changes of different parts, and realize comfortable and stable long-term wearing. The sensing module includes an ultrasonic transducer array, the ultrasonic transducer array includes a plurality of ultrasonic transducers; the ultrasonic transducer is used for emitting ultrasonic beams and receiving echo signals reflected from the blood vessel wall and blood, usually adopting a transceiving version, which can realize mutual conversion between acoustic energy and electric energy in the ultrasonic frequency range. Continue to refer to Figure 1The adaptive signal processing module includes a microprocessor, an analog front end, and a digital signal processor. Specifically, the analog front end is used for filtering and amplifying the echo signal, and the model of the analog front end can be TI AFE5801, AD9671, AD927x, THS3201, etc. The digital signal processor is used for converting the echo signal into a digital signal and performing preliminary processing on the digital signal, and the model of the digital signal processor can be TMS320C674x, Zynq-7000, ZU48DR, etc. The microprocessor is used for processing the digital signal and obtaining data, and the microprocessor is usually a low-power and high-performance microprocessor, such as AM62x, i.MX8M Plus, or TI C6678, etc. The wireless data transmission module is used for transmitting the data processed by the adaptive signal processing module to the terminal in a wireless manner, and receiving the instruction signal from the terminal. The wireless data transmission module usually includes a low-power Bluetooth (BLE) system-on-chip (SoC) and a matched antenna design, and is responsible for packaging the final results calculated by the adaptive signal processing module, including real-time blood pressure, blood flow velocity, waveform data, and system status information, and stably transmitting the final results to the user terminal device such as a smart phone, a tablet computer, or a remote medical cloud platform in a wireless manner. The matching application program on the terminal can visually display the data, analyze the historical trend, and issue an abnormal alarm, so as to realize real-time interaction and remote management of the monitoring data. The power supply module is used for supplying power to the sensing module, the adaptive signal processing module, and the wireless data transmission module. The power supply module usually uses a flexible battery, and the flexible battery uses near field wireless (NFC) charging technology to supply energy, which not only maintains the overall flexibility of the device, but also avoids the discomfort caused by the traditional rigid battery, and eliminates the need for frequent battery replacement, thereby providing reliable energy support for long-term continuous work of the device.

[0030] Further, the adaptive signal processing module further comprises a plurality of memories for storing embedded algorithms, which can typically be machine learning models. The analog front end filters and amplifies the raw echo signals from the ultrasonic transducer. Then, the digital signal processor converts the echo signals into digital signals and processes them. After that, the microprocessor extracts features and recognizes patterns from the digital signals, and calculates blood flow velocity, pulse wave waveform, and pulse wave transit time in real time. The machine learning models embedded in the memories are called to convert the pulse wave transit time and other parameters into continuous and accurate non-invasive blood pressure values based on individual physiological characteristics, which can effectively compensate for signal interference caused by movement or slight displacement of the patch. For details, please refer to the following documents: 1) A review of machine learning in hypertension detection and blood pressure estimation based on clinical and physiological data, https: / / doi.org / 10.1016 / j.bspc.2021.102813; 2) Using machine learning to predict hypertension from a clinical dataset, DOI: 10.1109 / SSCI.2016.7849886.

[0031] In a specific embodiment, the ultrasonic transducer is selected from any one of piezoelectric ceramic, piezoelectric single crystal, PVDF piezoelectric polymer, piezoelectric micromechanical ultrasonic transducer, or capacitive micromechanical ultrasonic transducer. Preferably, the ultrasonic transducer is selected from piezoelectric micromechanical ultrasonic transducer (PMUT) or capacitive micromechanical ultrasonic transducer (CMUT). The frequency of the ultrasonic transducer is 3-15 MHz.

[0032] In a specific embodiment, the material of the flexible substrate is selected from any one of polydimethylsiloxane (PDMS), Ecoflex silicone, thermoplastic polyurethane (TPU), or polyimide (PI).

[0033] In a specific embodiment, the material of the flexible encapsulation layer is biocompatible silicone. Preferably, the biocompatible silicone is Ecoflex silicone.

[0034] In a specific embodiment, the thickness of the flexible encapsulation layer is ≤2 mm.

[0035] In a specific embodiment, the wireless transmission module uses Bluetooth or near field communication wireless transmission.

[0036] In a specific embodiment, the ultrasound transducers form an MxN ultrasound transducer array; wherein 2≤N≤15, 2≤M≤15.

[0037] The application also provides a use method of the wearable patch based on flexible ultrasonic sensing, referring to Figure 2 The wearable patch based on flexible ultrasonic sensing also includes the following steps:

[0038] Step S1) wearing the wearable patch on the measurement site, such as the carotid artery or radial artery;

[0039] Step S2) the ultrasound transducer array emits ultrasonic waves and receives echo signals;

[0040] Step S3) the analog front end filters and amplifies the echo signals, and the digital signal processor converts the echo signals into digital signals and performs preliminary processing; for blood flow data, the adaptive signal processing module obtains the Doppler shift by calculating the digital signals, and calculates the blood flow velocity in real time to monitor the blood flow; for blood pressure data, the adaptive signal processing module calculates to obtain the pulse wave waveform features and pulse wave transit time, and then generates non-invasive continuous blood pressure values through the built-in machine learning model to monitor the blood pressure;

[0041] Step S4) the wireless data transmission module uploads the blood flow data and blood pressure data to the terminal in real time, and receives the signal of the instructions transmitted by the terminal.

[0042] For blood flow collection, the resolution of blood flow velocity can be ≥0.1 cm / s. For blood pressure collection, the error of blood pressure measurement can be ≤5 mmHg.

[0043] Example one: carotid artery monitoring application

[0044] In this embodiment, the wearable patch provided by the application is attached to the carotid artery to monitor the blood flow and blood pressure of the carotid artery.

[0045] In this embodiment, the ultrasound transducer array uses a 10x10 array of capacitive micromachined ultrasonic transducers (CMUT), and the center frequency of a single CMUT is 5 MHz with a bandwidth ≥50%. The ultrasound transducer array is integrated on a 100μm thick polyimide (PI) flexible substrate through an Au / Sn eutectic bonding process, which is a commonly used eutectic bonding process. The overall thickness of the wearable patch is ≤1.5mm, and the area size is 2cmx3cm.

[0046] The wearable patch is entirely encapsulated with Ecoflex silicone, which not only ensures excellent biocompatibility and long-term wearing comfort of the device, but also effectively blocks environmental factors such as sweat and dust from eroding the internal precision components, significantly improving the durability and reliability of the device. In addition, a surface of the wearable patch that contacts the human skin is coated with an acoustic impedance matching layer (acoustic impedance value 3.0 MRayl) to optimize the efficiency of ultrasonic wave conduction. The power supply module uses a 3.7V flexible lithium polymer battery (capacity 25mAh) in combination with near-field wireless charging, which can work continuously for 18 hours in a dynamic fitting state.

[0047] For blood flow measurement of the carotid artery, refer to Figure 3 The wearable patch in this embodiment is attached to the carotid artery pulse of the user's neck. The ultrasonic transducer array is configured to alternately emit and receive ultrasonic waves at a sampling rate of 500Hz, then the analog front end filters and amplifies the echo signal, and then the digital signal processor converts it into a digital signal and performs preprocessing, and then the microprocessor performs 192-point FFT spectral analysis on the digital signal, obtains the Doppler frequency shift by accurate calculation, and calculates the blood flow velocity in real time, which can achieve a wide range of ±100cm / s, while maintaining a high speed resolution of 0.08cm / s, which is sufficient to accurately capture the complete dynamic changes of the carotid artery blood flow from diastole to systole. The method of using 192-point FFT spectral analysis to obtain Doppler frequency and real-time inversion to calculate blood flow velocity is a general method in the industry, which will not be described in detail here.

[0048] Simultaneously, for non-invasive continuous blood pressure monitoring of the carotid artery, refer to Figure 3 : The adaptive signal processing module continuously acquires and processes the carotid artery pulse waveform obtained by the same ultrasonic transducer, and then extracts the feature parameters from the waveform with high precision, including waveform rise time (RT, accuracy up to ±1ms) and pulse wave transmission time (PWTT, typical value in 30-100ms), taking the optimal solution. Specifically, the analog front end filters and amplifies the echo signal, the digital signal processor converts the analog signal into a digital signal and performs preprocessing, and the microprocessor extracts the feature parameters from the waveform of the digital signal with high precision, including waveform rise time and pulse wave transmission time, taking the optimal solution; then, these feature parameters are input into a pre-trained deep neural network model for calculation, thereby obtaining an accurate estimate of the individual blood pressure value, and the deep neural network can directly use the existing trained model. Specifically, the deep neural network is usually trained based on more than 1000 clinical data, and its network structure contains three layers of long short-term memory (LSTM) units, which can effectively learn and model the complex nonlinear spatiotemporal relationship between blood pressure and multi-modal physiological parameters (PWTT, RT, etc.), thereby achieving accurate estimation of individual blood pressure values.

[0049] The adaptive signal processing module outputs continuous systolic and diastolic blood pressure estimates at an update rate of 1 Hz. The results are based on a 30-second time window sliding average calculation, effectively smoothing out transient fluctuations and providing stable and reliable monitoring readings.

[0050] All processed data, including continuous blood flow velocity waveforms, blood pressure values, and raw echo signal quality indicators, are transmitted in real-time to a smartphone App or cloud server through the low-power Bluetooth module of the wireless data output layer, completing display, recording, and further analysis and diagnosis.

[0051] Clinical tests show that compared with invasive arterial pressure measurement, the average deviation of systolic / diastolic blood pressure is 2.8±1.5mmHg and 3.1±1.7mmHg(n=50) respectively, meeting the American Medical Instrument Promotion Association(AAMI) standard.

[0052] Embodiment Two: Motion Health Monitoring Scheme

[0053] In this embodiment, the wearable patch provided by the present application is attached to the wrist to monitor the blood flow and blood pressure of the wrist.

[0054] In this embodiment, the ultrasonic transducer array adopts a 5x5 ultrasonic transducer array, a total of 25 units forming a serpentine interconnected PZT (Lead Zirconate Titanate) piezoelectric array. As an illustration, the serpentine interconnection can refer to Figure 5 , the serpentine interconnection is that the wires between the ultrasonic transducers adopt a serpentine wire, so that the wire has a certain amount of stretching, which can cope with slight deformation during movement. Among them, the center frequency of each PZT piezoelectric unit is 7.5MHz. The ultrasonic transducer array is embedded in a 30% stretchable Ecoflex flexible substrate, and the overall modulus matches the skin of the human body (elastic modulus 0.5-2MPa).

[0055] Refer to Figure 4To cope with the inevitable motion interference brought by daily activities, a high-performance three-axis MEMS accelerometer is integrated inside the wearable patch in this embodiment, which can be LIS2DW12, ADXL362, ICM-42688-P, FXLS8964AF, etc., with a wide range of ±16g and a low noise density of 200μg / Hz, which can sensitively and accurately capture the acceleration artifacts generated by the wearer's limb movement. The monitoring of blood flow and blood pressure adopts the same method as in Embodiment One, that is, to obtain ultrasonic Doppler signals and pulse wave signals. These data are sent into the adaptive signal processing layer in real time, and the microprocessor uses the adaptive Kalman filter algorithm to calculate and process the data. The adaptive Kalman filter algorithm is a filter algorithm that dynamically adjusts the filter parameters by real-time estimation of the statistical characteristics of the system model and noise on the basis of traditional Kalman filtering, which is a relatively common filtering algorithm in the field. Specifically, the signals of the three-axis MEMS accelerometer are used as external inputs, which are deeply fused and processed with the original ultrasonic Doppler signals and pulse wave signals, so as to dynamically establish a motion interference model and effectively separate and subtract the motion component from the mixed physiological signals, thereby correcting the blood flow velocity waveform and the measured value of PWTT in real time, and significantly improving the monitoring accuracy and signal reliability in the motion state of walking, slight shaking, etc.

[0056] In the treadmill motion test, the wearable patch provided by this embodiment collects radial artery signals at a sampling rate of 1 kHz, analyzes the blood flow spectrum under the motion state through short-time Fourier transform (256-point Hamming window), and calculates the pulse wave attenuation coefficient (0.5-5.0 dB / cm range) as an auxiliary parameter for blood pressure estimation.

[0057] The wireless data transmission module adopts Bluetooth 5.1 protocol, and still maintains stable data transmission of 0.5Mbps under arm-swing motion interference. The specially designed waterproof structure (IP68 level) is realized through laser welding process, which ensures reliable work in sweat environment. The actual measurement shows that when running at a speed of 0-8km / h, the blood pressure tracking delay is less than 2.5 seconds, and the blood flow velocity measurement deviation is less than ±5% (compared with the ultrasonic Doppler reference instrument). In terms of thermal management, the surface temperature rise is not more than 1.2℃ after 4 hours of continuous work, which meets the long-term wearing safety requirements.

[0058] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and replacements without departing from the technical principles of the present application, and these improvements and replacements should also be considered as the protection scope of the present application.

Claims

1. A wearable patch based on flexible ultrasonic sensing, characterized in that: This includes a sensing module, an adaptive signal processing module, and a wireless data transmission module, which are encapsulated in flexible materials to form an integrated flexible encapsulation layer. The sensing module includes an ultrasonic transducer array, which includes multiple ultrasonic transducers; the ultrasonic transducers are used to emit ultrasonic beams and receive echo signals reflected from the blood vessel wall and blood. The adaptive signal processing module includes a microprocessor, an analog front-end, and a digital signal processor; the analog front-end is used for echo signal filtering and amplification, the digital signal processor is used for converting the echo signal into a digital signal and performing preliminary processing, and the microprocessor is used for processing the digital signal and obtaining data; The wireless data transmission module is used to wirelessly transmit the data processed by the adaptive signal processing module to the terminal and to receive instruction signals from the terminal. The power supply module is used to supply power to the sensing module, the adaptive signal processing module, and the wireless data transmission module.

2. The wearable patch based on flexible ultrasonic sensing according to claim 1, characterized in that: The ultrasonic transducer is selected from any one of piezoelectric ceramics, piezoelectric single crystals, piezoelectric composite materials, PVDF piezoelectric polymers, piezoelectric micromechanical ultrasonic transducers, or capacitive micromechanical ultrasonic transducers.

3. The wearable patch based on flexible ultrasonic sensing according to claim 1, characterized in that: The frequency of the ultrasonic transducer is 3 to 15 MHz.

4. The wearable patch based on flexible ultrasonic sensing according to claim 1, characterized in that: The flexible substrate is made of any one of polydimethylsiloxane, Ecoflex silicone, thermoplastic polyurethane, or polyimide.

5. The wearable patch based on flexible ultrasonic sensing according to claim 1, characterized in that: The thickness of the flexible encapsulation layer is ≤2mm.

6. The wearable patch based on flexible ultrasonic sensing according to claim 1, characterized in that: The wireless transmission module uses Bluetooth or near-field communication for wireless transmission.

7. The wearable patch based on flexible ultrasonic sensing according to claim 1, characterized in that: The ultrasonic transducers form an M×N ultrasonic transducer array; wherein, 2≤N≤15, 2≤M≤15.

8. A method of using a wearable patch based on flexible ultrasonic sensing, comprising the wearable patch based on flexible ultrasonic sensing as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Step S1) Wear the wearable patch on the measurement site, such as the carotid artery or radial artery; Step S2) The ultrasonic transducer array emits ultrasonic waves and receives echo signals. Step S3) The simulation front end filters and amplifies the echo signal, and the digital signal processor converts the echo signal into a digital signal and performs preliminary processing. Among them, for blood flow data, the adaptive signal processing module calculates the Doppler frequency shift by calculating the digital signal and calculates the blood flow velocity in real time for blood flow monitoring. For blood pressure data, the adaptive signal processing module calculates the pulse wave waveform characteristics and pulse wave conduction time, and then generates non-invasive continuous blood pressure values ​​through the built-in machine learning model for blood pressure monitoring. Step S4) The wireless data transmission module uploads blood flow data and blood pressure data to the terminal in real time, and at the same time receives the signal of the instruction transmitted by the terminal.

9. The method of using the wearable patch based on flexible ultrasonic sensing according to claim 8, step 2) further includes: The resolution of blood flow velocity is ≥0.1cm / s.

10. The method of using the wearable patch based on flexible ultrasonic sensing according to claim 8, further comprising: The error in blood pressure measurement is ≤5 mmHg.

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