CN217611040U - Mattress type flexible sensor for dynamic continuous blood pressure monitoring - Google Patents

Abstract

The utility model belongs to the technical field of physiological index monitoring, specifically be a mattress formula flexible transducer for dynamic continuous blood pressure monitoring. The utility model is a multilayer structure, which comprises an isolation layer, a flexible fabric sensing electrode layer and a buffer layer; the flexible fabric sensing electrode is used for sensing and collecting ECG and BCG signals of a user; the bottom layer of the mattress is an isolation layer for isolating signals between the electrode layers; the buffer layer keeps the body and the electrode in close contact under different postures; the mattress type flexible sensor designed by the utility model has reliable structure, smooth surface, high comfort level and convenient and fast use; the device can be used for sensing and collecting ECG and BCG signals of different heights and body types and different sleeping postures so as to facilitate subsequent continuous blood pressure monitoring.

Description

Mattress type flexible sensor for dynamic continuous blood pressure monitoring

Technical Field

The utility model belongs to the technical field of the physiological index monitoring, concretely relates to mattress formula flexible sensor for dynamic continuous blood pressure monitoring.

Background

The prevalence rate of cardiovascular diseases and the mortality caused by cardiovascular diseases in China are increasing year by year. According to the Chinese cardiovascular health and disease report 2019 issued by the national cardiovascular center of China, the cardiovascular disease death is the first cause of the total death of urban and rural residents in China, 45.91% in rural areas and 43.56% in cities ^[1] . Blood pressure abnormality is one of important risk factors causing cardiovascular diseases, and abnormal blood pressure is controllable through timely discovery and treatment, so blood pressure monitoring is an extremely important health monitoring means in clinic.

The measurement method of blood pressure includes a direct measurement method and an indirect measurement method. The direct measurement method is to insert a catheter with a pressure sensor in the vicinity of the heart or in an arterial blood vessel for measurement, has the most direct and accurate measurement result, has limited application scenes, has high risk, needs professional medical personnel for operation, and is not suitable for being used as a means for monitoring blood pressure for a long time in daily life. Indirect measurement method with Korotkoff sound ^[2] Oscillography, etc ^[3] The method measures the blood pressure by monitoring the vibration condition of the blood, and the specific method for measuring the blood pressure comprises the steps of inflating the cuff by external force to prevent the blood in the arterial blood vessel from passing through, slowly withdrawing the external force to deflate the cuff, immediately dredging the arterial blood vessel, determining the blood pressure value by the vibration generated by the collision of the blood and the blood vessel wall in the whole process, and acquiring the systolic pressure and the diastolic pressure in a fixed time interval. In addition, the user feels the limb tingling due to pressure after long-time use, the wearing comfort is low, and continuous long-time measurement is difficult to realize.

Currently, most of the continuous non-invasive blood pressure measurement is to measure the ECG and PPG to determine the measured Pulse Wave Velocity (PWV) or PulsePulse Wave transit Time (PTT), and then indirectly calculates the blood pressure value ^[4] . In such methods, the corresponding electrodes need to be stuck to the skin and the corresponding measuring device needs to be worn, so that the wearing comfort is still low.

Compared with the blood pressure monitoring system, the electrocardio ECG signal and the ballistocardiogram BCG signal have a correlation with the blood pressure value, and the electrocardiogram and ballistocardiogram acquisition channel can be embedded into the mattress device by combining a novel flexible sensing technology, so that the discomfort of a user can be greatly reduced, and the accuracy of continuous monitoring of the blood pressure can be greatly improved by combining the existing deep learning method.

In summary, compared with the existing blood pressure monitoring products and technologies in the market, the system which is comfortable to collect and simultaneously realizes accurate continuous blood pressure monitoring needs to sense and collect the ECG signals and the BCG signals so as to realize high-accuracy blood pressure monitoring and health assessment, thereby really realizing comfortable and high-accuracy intelligent continuous blood pressure monitoring.

Reference documents:

[1] summary of cardiovascular health and disease report 2019 in china [ J ] cardiovascular and cerebrovascular disease prevention, 2020, 20 (05): 437-450.

[2]Mcghee B H,Bridges E J.Monitoring arterial blood pressure:what you may not know.[J].Critical Care Nurse,2002,22(2):60-4,66-70,73passim.

[3]Peter L,Noury N,Cerny M.A review of methods for non-invasive and continuous blood pressure monitoring:Pulse transit time method is promising [J].IRBM, 2014.

[4]Sola J,Proenca M,Ferrafio D,et a1.Noninvasive and nonocclusive blood pressure estimation via a chest sensor[J].IEEE Trans on Bio Eng,2013,60(12)： 3505—3513。

Disclosure of Invention

An object of the utility model is to provide a mattress formula flexible transducer for dynamic continuous blood pressure monitoring for correctly, continuously, comfortably perceive, gather Electrocardio (ECG) and Ballistocardiogram (BCG) signal.

The utility model discloses a mattress formula flexible sensor for dynamic continuous blood pressure monitoring, for multilayer structure, whole shape can be rectangle, oval or circular etc. and wherein evenly distributed has flexible fabric sensing electrode for carry out multichannel signal acquisition to the user, and can satisfy signal perception and the collection under arbitrary prone position (lie on the back, the side lies, lie prostrate).

The flexible fabric sensing electrodes are mainly and uniformly distributed on the trunk of a human body, such as the chest and the abdomen, and the flexible fabric sensing electrodes are also uniformly distributed on the head, the neck, the legs and the like, and the number of the flexible fabric sensing electrodes can be smaller. The number of the flexible fabric sensing electrodes is designed in a redundancy mode, so that high-quality ECG and BCG signals of not less than one channel can be obtained, the number of effective characteristic values can be increased when the high-quality signals of more channels are helpful for later-stage calculation, and the accuracy of blood pressure calculation is improved.

The mattress type flexible sensor is of a multilayer structure and comprises an isolation layer, a flexible fabric sensing electrode layer, a buffer layer and the like; specifically, the bottom layer of the mattress is an isolation layer, and a first flexible fabric sensing electrode layer with the same size as the isolation layer is arranged on the isolation layer; the second flexible fabric sensing electrode layer is discretely distributed on the first flexible fabric sensing electrode layer; the shape of the discretely distributed second flexible fabric sensing electrode layer can be a plurality of transversely arranged flexible fabric sensing electrode strips (shown in fig. 1) or a dot-shaped flexible fabric sensing electrode array (shown in fig. 2); an isolation layer and a buffer layer which are correspondingly discrete and correspondingly shaped are arranged between the discretely distributed second flexible fabric sensing electrode layer and the first flexible fabric sensing electrode layer; the discrete second flexible fabric sensing electrode layers can be arranged at key measurement positions corresponding to the human body according to requirements.

The utility model discloses in, flexible fabric sensing electrode, soft, close skin can direct contact skin surface.

The isolating layer is made of non-conductive fabric, can isolate signals between the electrode layers, avoids crosstalk, can shield external signals and attenuate noise, and improves the sensing capability of the sensor on physiological signals.

The buffer layer adopts a sponge and foam structure, has flexibility and certain support property, can ensure that the body and the electrode are in close contact under different postures, reduces the instability of signal acquisition caused by the shaking of the body, and ensures that a high-quality physiological signal is sensed.

The mattress type flexible sensor designed by the utility model has the advantages of reliable structure, smooth surface, high comfort level and convenient and quick use; the device can be used for sensing and collecting ECG and BCG signals of different heights and body types and different sleeping postures so as to facilitate subsequent continuous blood pressure monitoring.

Drawings

FIG. 1 is a diagram of a flexible sensor structure (the second electrode layer is in a shape of a transverse strip); the front view (a) and the side view (b) are shown.

FIG. 2 is a schematic diagram of a flexible sensor structure (the second electrode layer is in the shape of a dot array, and (a) is a front view and (b) is a side view.

Fig. 3 is a block diagram of a dynamic continuous blood pressure monitoring system.

FIG. 4 is a block diagram of a data acquisition module.

Fig. 5 is a flow chart of the system for monitoring blood pressure.

Fig. 6 is an ECG and BCG illustration.

Fig. 7 is a specific operation flow of the present apparatus.

FIG. 8 shows waveforms of cardiac signals.

Fig. 9 is a ballistocardiogram signal.

Fig. 10 shows the calculation results of the diastolic and systolic pressures.

Reference numbers in the figures: the sensor electrode layer is characterized in that 1 is a flexible fabric sensing electrode layer, 2 is a buffer layer, and 3 is an isolation layer.

Detailed Description

The flexible sensor designed by the utility model is particularly used for synchronously sensing multichannel Electrocardiosignals (ECG) and ballistocardiogram signals (BCG) in real time in a dynamic continuous blood pressure monitoring system; the dynamic continuous blood pressure monitoring system also comprises a subsequent data acquisition module, an embedded main control module, a wireless communication module, a power consumption management module, a signal identification algorithm module and monitoring terminal equipment; wherein:

the data acquisition module is used for synchronously acquiring multichannel Electrocardiosignals (ECG) and ballistocardiogram signals (BCG) from the flexible sensor module in real time;

the data acquisition module adopts a high-precision crystal oscillator module, a plurality of high-precision and high-sampling-frequency ADCs and high-precision crystal oscillator modules to obtain better signal quality and time sequence precision; a plurality of synchronous ADCs (analog to digital converters) are used for data acquisition through a high-precision crystal oscillator, BCG (BCG-positive tone) and ECG (ECG) signals can be synchronously acquired, and the influence of signal delay on blood pressure calculation and monitoring is reduced.

The method comprises the following steps that an original analog signal mixed with noise is obtained by a flexible sensor module, and enters a data acquisition module to acquire data: the method comprises the steps of firstly performing impedance matching through a buffer circuit, then performing a series of physiological electric signal processing steps such as power frequency filtering, low-pass filtering, power amplification and the like through a filter circuit, performing analog-to-digital conversion through an ADC (analog-to-digital converter) conversion module to obtain an Electrocardiosignal (ECG) and a ballistocardiogram signal (BCG) which are in a digital signal form after primary processing, and then connecting the Electrocardiosignal (ECG) and the BCG with an embedded main control module in an SPI (serial peripheral interface) communication mode to perform data transmission.

Specifically, the data acquisition module comprises: the device comprises a buffer circuit, a filter circuit, a MUX circuit, a gain amplification circuit, a high-precision ADC circuit, a high-precision crystal oscillator module, a high-precision reference voltage reference source module and a temperature measurement circuit; wherein:

the buffer circuit is connected with the data acquisition module and is used for increasing the anti-interference capability and the load carrying capability when signals are acquired and improving the input impedance of the data acquisition module; the device is composed of an operational amplifier;

the filter circuit is connected with the buffer circuit and is used for carrying out power frequency filtering, low-pass filtering and electromagnetic interference suppression on the acquired signals;

the MUX circuit is connected with the filter circuit and is used for multiplexing physiological signals and other signals (such as temperature signals and electrode falling monitoring signals);

the temperature measuring module is connected with the MUX circuit and used for monitoring whether the PCB runs over-temperature and over-heat or not and ensuring the accuracy and reliability of signal acquisition. Specifically, two internal diodes are adopted, wherein the current of one diode is 16 times that of the other diode, and the difference of the current of the diodes can generate voltage difference which is proportional to the actual temperature;

the gain amplifying circuit is a programmable low-noise PGA gain amplifying circuit and is used for amplifying the amplitude of the acquired signal.

The high-precision ADC circuit is a 24-bit delta-sigma analog-to-digital converter for multi-channel synchronous sampling and is used for converting sampled analog signals into digital signals; the data rate is 8kSPS.

The temperature measuring module adopts two internal diodes, wherein the current of one diode is 16 times that of the other diode, and the difference of the current of the diodes can generate voltage difference proportional to the actual temperature; the monitoring device is used for monitoring whether the PCB runs over-temperature and over-heat, and ensuring the accuracy and reliability of signal acquisition.

The high-precision crystal oscillator module adopts an internal and external double-crystal oscillator clock design. Wherein, use the internal clock when low-power consumption, battery power are not enough, use external active clock crystal oscillator under the high accuracy requirement. The internal clock is provided with a time reference by an internal oscillator of the ADC module, and high clock precision can be guaranteed to be kept at room temperature. The external clock adopts a 2.048Mhz active crystal oscillator, the precision is 5ppm, the clock selection is controlled by a chip pin corresponding to the control unit and a corresponding register bit, and the internal or external clock is selected by a main control program;

the high-precision reference voltage reference source module is a precision series voltage reference source with 3 mu Vpp/V noise and 3 ppm/DEG C temperature drift. And the reference voltage source connected in series with the high-precision voltage reference circuit provides a high-precision reference voltage for the high-precision ADC circuit. The temperature coefficient, the line adjustment rate, the load adjustment rate, or the long-term drift may cause the output accuracy of the reference voltage source to vary. The high-precision reference voltage reference source can provide better performance in the parameters, and high-precision ADC sampling is guaranteed.

So that the system can acquire high-precision physiological signals to facilitate subsequent blood pressure monitoring.

The embedded main control module is used for configuring the data acquisition and processing module at a high speed in real time, performing instruction control and time sequence control on the data acquisition and processing module, reading an Electrocardiosignal (ECG) and a ballistocardiogram signal (BCG) from the data acquisition module, preprocessing the signals, primarily calculating a blood pressure value, and transmitting original data and results to the wireless communication module;

the preprocessing comprises operations such as amplification, filtering, noise reduction, wavelet transformation and the like to obtain electrocardiosignals with complete waveforms and clear characteristic waves;

the device is consistent with the electrocardiographic waveforms collected by the gold standard. The device senses electrocardiosignals from the surface of a human body, obtains the electrocardiosignals with complete waveforms and clear characteristic waves through operations such as amplification, filtering, noise reduction, wavelet transformation and the like, and can be used for diagnosing and monitoring the electrical activity of the heart;

the wireless communication module is used for transmitting the acquired Electrocardiosignal (ECG) and ballistocardiogram signal (BCG) data into the monitoring terminal equipment to realize real-time processing and analysis of the data, and the baud rate of the serial port is set as: 115200, and even check is matched to prevent error of transmitted data;

the power consumption management module is used for supplying power to the data acquisition module, the wireless communication module, the embedded main control module and the like and reasonably configuring the power consumption of the power;

the monitoring terminal equipment is used for receiving and displaying the electrocardio and the electrocardio shock data, storing the data, analyzing the data, finishing the interaction with the user and providing a long-time precise blood pressure analysis report of the user;

the signal identification algorithm module comprises the steps of preprocessing the collected original electrocardio and electrocardio impact signals, extracting and calculating characteristics and primarily screening and calculating blood pressure values. The signal identification algorithm module is deployed in the embedded main control module.

The specific process of the system for monitoring blood pressure (see fig. 5) is as follows:

(1) Data acquisition: the power consumption management module is started, the system is powered on, and the flexible sensing module and the data acquisition module automatically acquire the electrocardio and the electrocardio impact signals;

(2) Signal preprocessing: the embedded main control module carries out operations such as signal preprocessing, filtering, noise reduction and the like on the acquired original electrocardio and electrocardio impact signals;

(3) Feature extraction: the embedded main control module automatically divides the heart beat and extracts the signal characteristics: identifying characteristic waves of P, Q, R, S and T of electrocardio and characteristic waves of H, I, J, K, L, M and N of a ballistocardiogram in a concentric jump cycle, automatically extracting electrocardio signal characteristics and ballistocardiogram characteristics from the characteristic waves, wherein the characteristic waves include but are not limited to RR interval, PR interval, R wave amplitude, QT interval, P wave amplitude, T wave amplitude, HI peak amplitude difference, KL peak amplitude difference, IJ peak slope, heart rate, RJ interval, pulse wave transmission time PTT and other parameters, and physiological indexes such as respiratory rate, heart rate and the like;

(4) Preliminary screening and calculating of blood pressure values: the Moens-Korteweg equation based on biomechanics carries out real-time calculation of blood pressure in a short time period according to characteristics such as RJ inter-period value and heart rate, and the calculation formula is as follows:

the equation simulates the relationship between the pulse wave velocity and the elastic modulus and distensibility of the artery wall; in the formula, PWV is pulse wave velocity, L is blood vessel length, PTT is pulse transmission time, E is blood vessel wall elastic modulus, h is blood vessel wall thickness, r is blood vessel inner radius, and rho is blood density;

wherein the elastic modulus parameter E of the blood vessel wall is closely related to the blood pressure and is the basis of the relation between PTT and the blood pressure; the relationship between the elastic modulus E and the blood pressure BP is expressed as:

E＝E ₀ ·e ^α·BP

wherein E is ₀ α is a constant relating to blood vessels, and is obtained by substituting:

obtaining the blood pressure value after approximation:

wherein, the calculation of PTT is completed in the embedded main control module;

the embedded main control module takes the R wave peak time of the ECG as reference time, calculates and determines the J wave peak of the BCG in a specific time t range, calculates RJ interval time and calculates the pulse wave transmission time PTT, and thus preliminarily calculates the blood pressure value; when the blood pressure value of the user is abnormal due to complex reasons, the blood pressure value preliminary screening mode can calculate real-time blood pressure in time and judge a threshold value, and informs the user and family members when risks exist, so that the user and family members pay attention to the health state of the user in time, and the risk of occurrence of cardiovascular and cerebrovascular diseases is reduced;

(5) Precisely calculating the blood pressure value: all the characteristics extracted in the steps, namely electrocardiosignal characteristics, heart impact signal characteristics (including RR interval, PR interval, R wave amplitude, QT interval, P wave amplitude, T wave amplitude, HI peak amplitude difference, KL peak amplitude difference, IJ peak slope, heart rate, RJ interval, pulse wave transmission time PTT and the like), important physiological indexes such as respiratory rate, heart rate and the like are sent into a multi-layer neural network designed in a monitoring terminal, blood pressure monitoring is carried out for a long time period and more precisely, a blood pressure curve is drawn, the blood pressure trend is predicted, and a related health report is generated so as to assist doctors and provide reference suggestions.

The specific operation flow of the device (see fig. 7):

(1) Before use, in order to make the blood pressure test result more accurate, personalized calibration is needed: recording information such as age, sex, height, body Mass Index (BMI) and the like of a user in the system, measuring a standard blood pressure value of the user by using standard blood pressure testing equipment, and starting the equipment for calibration; then, inputting blood pressure value information measured by standard blood pressure testing equipment into the system, automatically acquiring electrocardio and cardioshock signals, performing signal processing, feature extraction and the like to obtain n electrocardio characteristic parameters and cardioshock characteristic parameters, sending the electrocardio characteristic parameters and the cardioshock characteristic parameters into a primary blood pressure resolving equation and a deep learning regression model based on a Moens-Korteweg equation, calculating model parameters, and screening to obtain an optimal algorithm model;

(2) When the device is normally used, the device is started, the electrocardio and cardiac shock signals are automatically recorded by the device, the electrocardio characteristics and the cardiac shock characteristics are obtained, the electrocardio characteristics and the cardiac shock characteristics are sent to a blood pressure resolving equation based on a Moens-Korteweg equation for preliminary real-time blood pressure calculation, the blood pressure value is monitored, short-time abnormal blood pressure values are subjected to early warning in time, family members or medical personnel are called to take care of the blood pressure values, the blood pressure values are controlled in a normal range, and potential risks are reduced; and at the monitoring terminal, the obtained characteristics are sent into a neural network, the systolic pressure and the diastolic pressure which are accurate for a long time are calculated, and a more accurate and reliable health report is further generated by combining a historical blood pressure report.

When the device is used, a user firstly lies on the sensor module and keeps relaxed, then the power supply of the device is turned on, the device automatically collects electrocardio and heart impact signals, and analog signals are converted into digital signals through the ADC module. After the digital signal is obtained, the converted register data is read from the ADC through pins DOUT and SCLK, the data is output on the rising edge of SCLK, and MSB precedes. When CS is high, DOUT enters a high impedance state.

And data is transmitted from the data acquisition module to the embedded main control module in an SPI communication mode, and preprocessing operations such as baseline removal, filtering, denoising and the like of signals are performed.

The waveform of the electrocardiographic signal is shown in fig. 8. The ballistocardiogram signal is shown in figure 9.

The signals after signal preprocessing obtain corresponding signal characteristics, relevant data are sent into a blood pressure resolving equation based on a Moens-Korteweg equation to carry out preliminary real-time blood pressure calculation, the blood pressure value is monitored, short-time abnormal blood pressure values are early warned in time, family members or medical staff are called to nurse, the blood pressure values are controlled within a normal range, and potential risks are reduced.

And then, sending the data and the characteristics to the monitoring terminal through the wireless module. Taking a WiFi transmission mode as an example, the wireless module core processor is ESP8266, a Tensiica L106 ultra-low power consumption 32-bit micro MCU is integrated in a small-size package, a standard IEEE802.11 b/g/n protocol is supported, and a complete TCP/IP protocol stack is provided. The module is used for adding a networking function, and establishes a local area network with the monitoring terminal equipment to transmit signals.

The monitoring terminal sends the obtained characteristics into a neural network, calculates the long-time accurate systolic pressure and diastolic pressure, and further generates a more accurate and reliable health report by combining a historical blood pressure report. The diastolic and systolic pressures are resolved and displayed as shown in fig. 10.

Claims (4)

1. A mattress type flexible sensor for dynamic continuous blood pressure monitoring is characterized in that the sensor is of a multilayer structure, wherein flexible fabric sensing electrodes are uniformly distributed and used for sensing and collecting ECG and BCG signals of a user; the sensor specifically comprises an isolation layer, a flexible fabric sensing electrode layer and a buffer layer; the mattress comprises a mattress body, an isolation layer, a first flexible fabric sensing electrode layer, a second flexible fabric sensing electrode layer and a second flexible fabric sensing electrode layer, wherein the bottom layer of the mattress body is the isolation layer, the isolation layer is used for isolating signals between the electrode layers, avoiding crosstalk and shielding external signals and attenuating noise, and the first flexible fabric sensing electrode layer is the same as the isolation layer in size; the second flexible fabric sensing electrode layer is distributed discretely on the first flexible fabric sensing electrode layer; an isolation layer and a buffer layer which are correspondingly discrete and correspondingly shaped are arranged between the discretely distributed second flexible fabric sensing electrode layer and the first flexible fabric sensing electrode layer; the buffer layer adopts sponge, so that the body and the electrode are kept in close contact under different postures; the discrete second flexible fabric sensing electrode layers are arranged at key measurement positions corresponding to the human body according to requirements.

2. A mattress-style flexibility sensor according to claim 1, wherein said discretely distributed second flexible fabric sensing electrode layer is in the shape of a plurality of transversely arranged flexible fabric sensing electrode strips or an array of flexible fabric sensing electrodes in the shape of dots.

3. A mattress-style flexibility sensor according to claim 1 wherein the overall shape is rectangular, oval or circular.

4. A mattress-based flexible sensor according to claim 1, wherein the flexible fabric sensing electrodes are distributed substantially uniformly about the torso of the person, including the chest and abdomen, and relatively few are distributed uniformly about the head, neck and legs; the number of the flexible fabric sensing electrodes is a redundant design, so that high-quality ECG and BCG signals of not less than one channel can be obtained.

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