CN110301907A - A kind of wearable pulse wave detection device and blood pressure detecting method - Google Patents

Abstract

The invention discloses a wearable pulse wave detection device and a blood pressure detection method, comprising a wearable annular body; a first flexible piezoelectric sensor, the first flexible piezoelectric sensor is arranged on the inner surface of the annular body, and is used for communicating with a user contact with the first detection part of the user; the second flexible piezoelectric sensor, the second flexible piezoelectric sensor is arranged on the outer surface of the annular body for contact with the second detection part of the user; the main control circuit module, the main control circuit module is arranged in the The ring-shaped body is connected to the first flexible piezoelectric sensor and the second flexible piezoelectric sensor, and the main control circuit module receives the piezoelectric signals output by the first flexible piezoelectric sensor and the second flexible piezoelectric sensor. Obtain two pulse waves under the same time axis, and obtain pulse parameters according to the two pulse waves. The invention adopts dual-channel pulse wave measurement, has high accuracy, and the detection device is easy to carry, can measure at any time, and can detect the blood pressure condition at the same time.

Description

Wearable pulse wave detection device and blood pressure detection method

technical field

The application belongs to the field of human health detection, and in particular relates to a wearable pulse wave detection device and a blood pressure detection method.

Background technique

In the medical system, pulse and blood pressure are two very important physiological health parameters. The state of the heartbeat can be detected intuitively, and the basic condition of the patient's body can be known through the detected heartbeat state. With the development of the medical level and the improvement of the quality of life, the traditional mercury-column pulse sphygmomanometer in pulse measurement is more and more unable to meet the needs of the public, the operation is complicated and it is easy to hear and distinguish errors. And usually need to use two kinds of instruments to measure the pulse and blood pressure.

With the continuous improvement of the demand for instruments, the commonly used pulse detectors in the prior art are usually pulse detectors that use photoelectric methods to extract fingertip pulse information. Physiological signals are easily disturbed by environmental noise and limb movements, and cannot be monitored in real time; 2. Single-channel pulse wave measurement is used, and the error is large; 3. The equipment is relatively large and not portable. The existing commonly used blood pressure pulse wave measuring instrument usually measures the pulse wave by wearing a cuff and sitting still. Road pulse wave measurement, the error is large; 3. The equipment is relatively large and not portable.

SUMMARY OF THE INVENTION

The wearable pulse wave detection device and blood pressure detection method provided by the present application adopts dual-channel pulse wave measurement, with high accuracy, and the detection device is easy to carry, can measure at any time, and can simultaneously detect blood pressure conditions.

In order to achieve the above-mentioned purpose, the technical scheme adopted in this application is:

A wearable pulse wave detection device, the wearable pulse wave detection device comprises:

an annular body for wearing;

a first flexible piezoelectric sensor, the first flexible piezoelectric sensor is disposed on the inner surface of the annular body, and is used for contacting with the first detection part of the user;

A second flexible piezoelectric sensor, the second flexible piezoelectric sensor is disposed on the outer surface of the annular body and is used for contacting the second detection part of the user, and the position of the second flexible piezoelectric sensor is the same as that of the first flexible piezoelectric sensor. The position of the flexible piezoelectric sensor corresponds to;

a main control circuit module, the main control circuit module is arranged on the annular body and connected with the first flexible piezoelectric sensor and the second flexible piezoelectric sensor, and the main control circuit module receives the first flexible piezoelectric sensor and the piezoelectric signal output by the second flexible piezoelectric sensor, obtain two pulse waves under the same time axis according to the two piezoelectric signals, and obtain pulse parameters according to the two pulse waves.

Preferably, the main control circuit module includes: a processing module, and a piezoelectric module, a somatosensory interaction module and a power supply module connected to the processing module;

The processing module includes a microcontroller, and a Bluetooth radio frequency circuit connected to the microcontroller, the Bluetooth radio frequency circuit is used for receiving signals from the microcontroller and sending two pulse waves and/or pulse parameters;

The piezoelectric module includes a signal processing circuit connected with the first flexible piezoelectric sensor and the second flexible piezoelectric sensor, and the signal processing circuit is used to connect the first flexible piezoelectric sensor and the second flexible piezoelectric sensor The piezoelectric signal output by the sensor is amplified and filtered, and after processing, two pulse electrical signals are obtained and transmitted to the microcontroller;

The somatosensory interaction module includes a linear motor, which is connected with the microcontroller and is used for receiving signals from the microcontroller to generate vibration;

The power supply module is used for supplying power to the processing module, the piezoelectric module and the somatosensory interaction module;

The microcontroller receives two pulse electrical signals output by the piezoelectric module, and performs the following operations:

Obtain two pulse waves under the same time axis according to the two pulse electrical signals, and calculate the time difference T _PTT between the peaks of the two pulse waves as the wave propagation time;

Let the propagation velocity of waves in an ideal fluid in an elastic tube be:

In formula (1), V is the propagation velocity of the wave in the elastic tube, Δx is the propagation distance of the wave in the elastic tube, T _PTT is the propagation time of the wave in the elastic tube, E is the elastic modulus, h is the wall degree of the elastic tube, ρ is the ideal fluid density, r is the inner radius of the elastic tube in equilibrium;

Let the relationship between vascular elastic modulus and blood pressure be:

In the formula (2), E represents the elastic modulus of the blood vessel under the pressure P, that is, the elastic modulus in the formula (1), E ₀ represents the initial elastic modulus, and α is the proportional parameter;

According to formula (1) and formula (2), the relationship between blood pressure and the propagation time of the wave in the elastic tube is obtained as:

According to formula (3), the relationship model between blood pressure and pulse wave propagation time is obtained as follows:

P=a ₁ lnT _PTT +a ₂ (4)

In formula (4), a ₁ and a ₂ are fitting parameters that need to be calibrated, so that the blood pressure value can be obtained by formula (4) according to the propagation time of the pulse wave.

Preferably, the annular main body is provided with a device slot with an opening facing the outside of the annular main body, the device slot and the annular main body have an integral structure, the device slot is connected with a slot cover, and the main control circuit module is located in the device slot.

Preferably, the main control circuit module further includes a display module, the display module includes a display screen embedded on the slot cover, the display screen is connected to the microcontroller, and is used for displaying two pulse waves and / or pulse parameters.

Preferably, the main control circuit module further includes a motion module, the motion module includes an acceleration sensor connected to the microcontroller, the acceleration sensor transmits the detected acceleration electrical signal to the microcontroller, the acceleration sensor The electrical signal is used by the microcontroller to correct the pulse electrical signal.

Preferably, the signal processing circuit includes an amplification filter circuit and a bias amplifier circuit; the amplification filter circuit includes an OPA2314 operational amplifier, and the bias amplifier circuit includes a TLV6001 operational amplifier;

The piezoelectric signal output by the first flexible piezoelectric sensor or the second flexible piezoelectric sensor is used as the non-inverting input of the OPA2314 operational amplifier, the output signal of the TLV6001 operational amplifier is used as the inverting input of the OPA2314 operational amplifier, and the OPA2314 operational amplifier The output is sent to the microcontroller as a pulse electrical signal after passing through the RC low-pass filter circuit.

The present application also provides a blood pressure detection method based on a wearable pulse wave detection device, the blood pressure detection method comprising:

The wearable pulse wave detection device is used to obtain two pulse waves under the same time axis, and the time difference T _PTT between the peaks of the two pulse waves is calculated as the wave propagation time;

Let the propagation velocity of waves in an ideal fluid in an elastic tube be:

In formula (1), V is the propagation velocity of the wave in the elastic tube, Δx is the propagation distance of the wave in the elastic tube, T _PTT is the propagation time of the wave in the elastic tube, E is the elastic modulus, h is the wall degree of the elastic tube, ρ is the ideal fluid density, r is the inner radius of the elastic tube in equilibrium;

Let the relationship between vascular elastic modulus and blood pressure be:

In the formula (2), E represents the elastic modulus of the blood vessel under the pressure P, that is, the elastic modulus in the formula (1), E ₀ represents the initial elastic modulus, and α is the proportional parameter;

According to formula (1) and formula (2), the relationship between blood pressure and the propagation time of the wave in the elastic tube is obtained as:

According to formula (3), the relationship model between blood pressure and pulse wave propagation time is obtained as follows:

P=a ₁ lnT _PTT +a ₂ (4)

In formula (4), a ₁ and a ₂ are fitting parameters that need to be calibrated, so that the blood pressure value can be obtained by formula (4) according to the propagation time of the pulse wave.

In the wearable pulse wave detection device and blood pressure detection method provided by the present application, flexible piezoelectric sensors are arranged on the inner and outer surfaces of the annular body to simultaneously collect the pulse conditions of two detection parts of the human body to obtain dual-channel pulse waves. The pulse wave is processed to obtain pulse parameters with high accuracy; the wearable annular body enables the detection device of the present application to be conveniently carried on the user, which is not only easy to carry, but also avoids picking and placing steps to realize detection at any time; the present application also The blood pressure parameters can be obtained through dual-channel pulse wave calculation, so as to realize the simultaneous measurement of pulse and blood pressure, which further simplifies the user's use steps and improves the convenience.

Description of drawings

Fig. 1 is the schematic diagram of human artery;

2 is a schematic structural diagram of the wearable pulse wave detection device of the present application;

3 is a schematic diagram of the use of the wearable pulse wave detection device of the present application;

4 is a schematic structural diagram of a main control circuit module of the application;

Fig. 5 is the circuit schematic diagram of the processing module of the application;

Fig. 6 is the circuit schematic diagram of the amplification filter circuit of the present application;

Fig. 7 is the simulation schematic diagram of the cut-off frequency of the amplification filter circuit of the present application;

Fig. 8 is the circuit schematic diagram of the bias amplifier circuit of the present application;

FIG. 9 is a circuit schematic diagram of the first part of the power supply module of the application;

FIG. 10 is a circuit schematic diagram of the second part of the power module of the application;

Fig. 11 is the circuit schematic diagram of the third part of the power supply module of the application;

FIG. 12 is a circuit schematic diagram of the fourth part of the power module of the application;

Fig. 13 is the circuit schematic diagram of the fifth part of the power supply module of the application;

Fig. 14 is the circuit schematic diagram of the power supply part on the microcontroller of the application;

15 is a schematic diagram of the circuit connection of the acceleration sensor of the application;

16 is a schematic diagram of a single-channel initial pulse wave in Example 1;

FIG. 17 is a waveform diagram obtained after performing fast Fourier transform and inverse fast Fourier transform on FIG. 16;

Fig. 18 is a waveform diagram obtained after EMD algorithm filtering is performed on Fig. 16;

FIG. 19 is a schematic diagram of a dual-channel pulse wave obtained after filtering the dual-channel initial pulse wave in Embodiment 1. FIG.

In the figure: 1. Second flexible piezoelectric sensor; 2. First flexible piezoelectric sensor; 3. Somatosensory interaction module; 4. Power module; 5. Display screen; 6. Processing module; 7. Motion module.

Detailed ways

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

It should be noted that when a component is referred to as being "connected" to another component, it can be directly connected to the other component or an intervening component may also exist. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used herein in the specification of the present application are for the purpose of describing specific embodiments only, and are not intended to limit the present application.

A wearable pulse wave detection device of the present application is used to detect the pulse wave conditions of two detection parts of a user at the same time, so as to obtain pulse parameters with high accuracy.

As shown in FIG. 1 , in this embodiment, the pulse waves of the user’s carotid artery (the position shown at A is the carotid artery) and the radial artery (the position shown at B is the carotid artery) are simultaneously detected as follows: example for further explanation.

As shown in FIG. 2, in one embodiment, a wearable pulse wave detection device is provided, and the wearable pulse wave detection device includes:

an annular body for wearing;

a first flexible piezoelectric sensor 2, the first flexible piezoelectric sensor 2 is arranged on the inner surface of the annular body, and is used for contacting the first detection part of the user;

A second flexible piezoelectric sensor 1, the second flexible piezoelectric sensor 1 is disposed on the outer surface of the annular body for contact with the second detection part of the user, and the position of the second flexible piezoelectric sensor is the same as that of the second flexible piezoelectric sensor the position of the first flexible piezoelectric sensor corresponds to;

The main control circuit module, the main control circuit module is arranged on the annular body and connected with the first flexible piezoelectric sensor 2 and the second flexible piezoelectric sensor 1, and the main control circuit module receives the first flexible piezoelectric sensor. For the piezoelectric signals output by the electrical sensor 2 and the second flexible piezoelectric sensor 1, two pulse waves on the same time axis are obtained according to the two piezoelectric signals, and pulse parameters are obtained according to the two pulse waves.

In this embodiment, the skin at the radial artery is used as the first detection site, and the skin at the carotid artery is used as the second detection site. Therefore, the overall shape of the wearable pulse wave detection device of this embodiment is set as a wristband structure. The wristband structure can be worn on the user's arm in real time. When the user needs to perform pulse detection, the detection method shown in Figure 3 is used for detection. C in Figure 3 represents the wearable pulse of this embodiment of the wristband structure. The wave detection device, when detecting, wears the bracelet on the wrist and presses the corresponding part of the neck at the same time to realize the detection of dual-path pulse waves.

Due to the user's pressing operation, the flexible piezoelectric sensor in the device can be tightly attached to the skin surface, so as to collect a better pulse wave signal and obtain a more accurate measurement result.

In order to ensure the simultaneous detection of two pulse waves, the position of the second flexible piezoelectric sensor 1 is set to correspond to the position of the first flexible piezoelectric sensor 2, that is, the first flexible piezoelectric sensor 2 and the second flexible piezoelectric sensor 1 are located in The same area of the bracelet, and on the inner and outer surfaces of the area, to ensure that the first and second flexible piezoelectric sensors can work at the same time during the pressing operation.

Further, the main control circuit modules may be scattered and buried inside the annular body, or may be centrally arranged in one place of the annular body. In one embodiment, the annular main body is provided with a device slot with an opening facing the outside of the annular main body, the device slot and the annular main body have an integral structure, the device slot is connected with a slot cover, and the main control circuit module is located in the device slot. .

The main control circuit module is centrally arranged in the equipment slot, which is convenient for circuit arrangement and heat dissipation, and the equipment slot and the slot cover can be an integral structure to improve the protection of the main control circuit module, or a detachable connection structure for later maintenance.

As shown in FIG. 4 , in one embodiment, the main control circuit module includes: a processing module 6 , and a piezoelectric module, a somatosensory interaction module 3 and a power supply module 4 connected to the processing module 6 .

The processing module 6 of the main control circuit module includes a microcontroller, and a Bluetooth radio frequency circuit connected to the microcontroller, and the Bluetooth radio frequency circuit is used to receive signals from the microcontroller to perform two pulse waves and/or pulse parameters. send.

In one embodiment, a device terminal is externally connected to the Bluetooth radio frequency circuit, and data transmission is performed between the two through the Bluetooth protocol. The device terminal receives two pulse waves and/or pulse parameters sent by the Bluetooth radio frequency circuit, and is used to compare the two pulse waves. and/or pulse parameters for further analysis or display. And the device terminal may be a smart phone or a computer or the like.

Specifically, the circuit schematic diagram of the processing module 6 is shown in FIG. 5 . In this embodiment, the microcontroller adopts an MCU (microcontroller) integrating BLE function and analog-to-digital conversion function, and the model of the microcontroller is CC2640R2FRSM .

The bluetooth radio frequency circuit connected to the microcontroller includes a bluetooth chip. In this embodiment, the model of the bluetooth chip is balun/LFB182G45BG5D920, the RF_N pin of the microcontroller is connected to the BP1 pin of the bluetooth chip, and the RF_P pin of the microcontroller It is connected to the BP2 pin of the Bluetooth chip to control the Bluetooth chip to upload pulse waves and/or pulse parameters to the device terminal.

The piezoelectric module of the main control circuit module includes a signal processing circuit connected with the first flexible piezoelectric sensor and the second flexible piezoelectric sensor, and the signal processing circuit is used for connecting the first flexible piezoelectric sensor and the second flexible piezoelectric sensor. The piezoelectric signal output by the electrical sensor is amplified and filtered, and after processing, two pulse electrical signals are obtained and transmitted to the microcontroller.

In order to obtain pulse data with high accuracy, in an embodiment, the signal processing circuit includes an amplification filter circuit and a bias amplifier circuit; the amplification filter circuit includes an OPA2314 operational amplifier, and the bias amplifier circuit includes a TLV6001 operational amplifier.

In the signal conversion process, the piezoelectric signal output by the first flexible piezoelectric sensor or the second flexible piezoelectric sensor is used as the non-inverting input of the OPA2314 operational amplifier, and the output signal of the TLV6001 operational amplifier is used as the inverting input of the OPA2314 operational amplifier, The output of the OPA2314 operational amplifier is sent to the microcontroller as a pulse electrical signal after passing through the RC low-pass filter circuit.

Specifically, as shown in Figure 6, the amplification filter circuit uses an OPA2314 operational amplifier, which mainly amplifies the collected piezoelectric signal. A resistor R25 is connected between the output terminal of the OPA2314 operational amplifier and the inverting input terminal, and a resistor R24 is connected to the inverting input terminal. The other end of the resistor R24 is connected to the TLV6001 operational amplifier. The output of a flexible piezoelectric sensor or a second flexible piezoelectric sensor is input to the non-inverting input terminal through the No. 2 pin, and the non-inverting input terminal is grounded through the resistor R23. The No. 1 pin of the pin header J2 is connected to the ground terminal of the resistor R23. The OPA2314 calculates The output end of the amplifier is connected to the resistor R26, the other end of the resistor R24 is connected to the microcontroller, and the other end of the resistor R24 is grounded through the capacitor C23 at the same time.

The magnification of the amplifying filter circuit is determined by the ratio of R25 and R24, and the magnification=R25/R24=10. According to the experiment, the magnification of 10 times meets the requirements. The function of C24 connected to the power input end of the OPA2314 operational amplifier is to filter the high frequency to stabilize the power supply. R26 and C23 together form an RC low-pass filter circuit. The frequency of human pulse is generally lower than 30Hz, so the RC frequency should be set at about 40Hz.

As shown in Figure 7, the cut-off frequency of the low-pass filter circuit using a 39kΩ resistor and a 100nF capacitor is obtained through simulation and its actual cut-off frequency is: 40.65Hz. Therefore, in this embodiment, the resistance value of R26 is 39KΩ, and the capacitance value of C23 is 100nF.

As shown in Figure 8, the bias amplifier circuit uses the TLV6001 operational amplifier. The non-inverting input terminal of the TLV6001 operational amplifier is connected to the slider of the adjustable resistor RJ1, one terminal of the adjustable resistor RJ1 is connected to 3V through the resistor R22, and the other terminal of the adjustable resistor RJ1 is connected to -3V through the resistor R21; the inverting input terminal and the output terminal are connected to the resistor R7 in the amplifying filter circuit. C21 and C22 connected to the positive and negative poles of the TLV6001 operational amplifier are 100nF respectively, which can regulate and filter the power supply and filter out high-frequency noise.

The bias amplifier circuit performs bias processing on the piezoelectric signal, converts the bipolar piezoelectric signal into a unipolar piezoelectric signal, and ensures that the piezoelectric signal is in a position suitable for analysis. R22, R21 and RJ1 in the bias amplifier circuit together form an adjustable voltage divider circuit to adjust the non-inverting input of the amplifier.

In one embodiment, the resistance values of the resistors R22 and R21 are selected as 100KΩ. In order to limit the input current of the amplifier, the voltage division adjustment range is:

In this embodiment, the first flexible piezoelectric sensor and the second flexible piezoelectric sensor are respectively connected with independent signal processing circuits, and after amplifying, filtering and biasing the two piezoelectric signals, two pulse electrical signals are obtained. (One way is represented by PIEZO, one way is represented by INTB), one way is input to the DIO_7 pin of the microcontroller, and the other way is input to the DIO_8 pin of the microcontroller.

And in order to facilitate the display and upload processing of the electrical pulse signal, the microcontroller adopts the ADC module to collect the two input pulse electrical signals, obtains two sets of discrete waveform data corresponding to the electrical pulse signal, and connects the discrete waveform data according to the time axis. The pulse wave is obtained, and the pulse parameters are calculated at the same time.

In one embodiment, when the microcontroller calculates the pulse parameters, it receives two pulse electrical signals output by the piezoelectric module, and performs the following operations:

Obtain two pulse waves under the same time axis according to the two pulse electrical signals, and calculate the time difference T _PTT between the peaks of the two pulse waves as the wave propagation time;

Let the propagation velocity of waves in an ideal fluid in an elastic tube be:

In formula (1), V is the propagation velocity of the wave in the elastic tube, Δx is the propagation distance of the wave in the elastic tube, T _PTT is the propagation time of the wave in the elastic tube, E is the elastic modulus, h is the wall degree of the elastic tube, ρ is the ideal fluid density, r is the inner radius of the elastic tube in equilibrium;

Let the relationship between vascular elastic modulus and blood pressure be:

In formula (2), E represents the elastic modulus of the blood vessel under pressure P, that is, the elastic modulus in formula (1), E ₀ represents the initial elastic modulus, and α is a proportional parameter.

According to formula (1) and formula (2), the relationship between blood pressure and the propagation time of the wave in the elastic tube is obtained as:

According to formula (3), the relationship model between blood pressure and pulse wave propagation time is obtained as follows:

P=a ₁ lnT _PTT +a ₂ (4)

In formula (4), a ₁ and a ₂ are fitting parameters that need to be calibrated, so that the blood pressure value can be obtained by formula (4) according to the propagation time of the pulse wave.

It should be noted that the pulse parameters are not limited to wave propagation time and blood pressure, but can also be required parameters such as heart rate, so the microcontroller can also calculate other parameters according to the two sets of pulse waves. For example, when calculating the heart rate, the number of peaks or troughs in a certain period of time can be obtained according to the two groups of pulse waves, thereby converting the heart rate value.

The somatosensory interaction module 3 of the main control circuit module includes a linear motor, and the linear motor is connected to the microcontroller for receiving signals from the microcontroller to generate vibration.

After receiving the electrical pulse signal, the microcontroller judges whether the collected signal is normal. If it is normal, it drives the linear motor to vibrate for a preset time (for example, 30s) to remind the user that the collection is completed; if the collected signal is abnormal, it will continue to Collect until enough data is collected. In this embodiment, the linear motor adopts ELV1411A X-direction vibration linear motor. The ELV1411A X-direction vibration linear motor has its own driver chip, which communicates with the MCU through the I ² C bus.

The power supply module 4 of the main control circuit module is used to supply power to the microcontroller. It should be noted that the power module mainly supplies power to the microcontroller, and can also supply power to the peripherals of the microcontroller, such as a Bluetooth radio frequency circuit and a piezoelectric module. The power module includes a battery and a power circuit, where the battery may be a rechargeable battery.

Figures 9 to 13 show the circuit schematics of the power module. Three pieces of TPS78230DDCR are used to output voltages of 3.3V, 3V, and 1.8V, respectively, and provide appropriate power supply voltages to each component according to component requirements.

The MOS tube at the output end of a TPS78230DDCR connected to the operational amplifier is connected to the DIO_4 pin of the microcontroller, so as to control whether to supply power to the operational amplifier, and stop the power supply for power consumption control when it is not working. When it needs to be turned off, the MOSG pin (DIO_4 pin) of the microcontroller outputs a high level, and the MOS tube is not turned on, that is, the power supply to the operational amplifier is stopped; when it needs to be turned on, the MOSG pin outputs a low level, and the MOS The tube is turned on to supply power to the operational amplifier. The R02 resistor is a pull-up resistor, and its resistance value is based on the comprehensive consideration of ensuring its switching speed and pull-up, so that the MOS tube is usually at a high level and is turned off.

The -3V in the power module is converted by the negative voltage converter LTC1983-3 to form a dual power supply to supply power to the operational amplifier. The SHDN pin on the LTC1983-3 controls the shutdown of the LTC1983-3 for power control. The capacitors connected to the power supply are used for voltage stabilization and filtering.

J01 in the power module is an external battery pin, which is the initial source of power supply for the entire detection device. Q1 is a P-type MOS tube to prevent reverse connection. When it is connected, the gate of the MOS tube is low, and the MOS tube is turned on. When the positive and negative electrodes of the battery are reversely connected, the gate is at a high level, the MOS tube is not turned on, and the system is not energized.

As shown in Figure 14, it is the circuit of the power supply part of the microcontroller. Among them, DCDCSW is the DC voltage step-down module inside the chip, its inductance is 10Uh, the filter capacitor is 10uF, 100nF, 100nF, and the pre-stage filter capacitor is 10uF. In order to filter low frequency, reduce output pulsation and low frequency interference, the 100nF capacitor is used to reduce the high frequency interference caused by the instantaneous change of load current, and can also play a role in voltage regulation.

3.3V is the output voltage of the power supply module. VDDS is connected to the VDDS, VDDS2, VDDS_DCDC pins of the microcontroller. The magnetic beads are used to suppress noise. The selection of magnetic beads should be based on the actual effect. In this embodiment, 1k magnetic beads are used; filter capacitors are used. 100nF, 1000nF, 10μF, 100nF respectively.

In one embodiment, in order to improve the human-computer interaction performance of the detection device, the main control circuit module further includes a display module, the display module includes a display screen 5 embedded in the slot cover, the display screen is connected to the Microcontroller connection for displaying two pulse waves and/or pulse parameters. The display can be OLED or LED etc.

Since the pulse wave detection device in this embodiment is a wristband structure, the measurement result may be inaccurate due to the user's shaking or displacement during the inspection process. In order to avoid the above situation, in an embodiment, the main control circuit module further includes: Motion module 7, the motion module 7 includes an acceleration sensor connected to the microcontroller, the acceleration sensor transmits the detected acceleration electrical signal to the microcontroller, and the acceleration electrical signal is used for the microcontroller to The electrical pulse signal is corrected.

Due to human movement, the flexible piezoelectric sensor will deform, and at the same time, a sudden change in the pulse electrical signal will appear, and the acceleration electrical signal measured by the acceleration sensor can compensate for the sudden change to correct the sudden change of the pulse electrical signal.

Specifically, as shown in FIG. 15 , the model of the acceleration sensor is BMA250E.

The INT1 pin of the chip BMA250E is connected to the DIO_3 pin of the microcontroller, the SDA pin of the chip BMA250E is connected to the DIO_6 pin of the microcontroller, and the SCL pin of the chip BMA250E is connected to the DIO_5 pin of the microcontroller to realize the microcontroller. Control the acceleration sensor and obtain the acceleration electrical signal.

In order to improve the accuracy of the detection results, after the microcontroller receives the electrical pulse signal from the signal processing circuit, it will further perform algorithmic filtering on the waveform discrete data. The following examples will further illustrate the processing of the present application for performing algorithmic filtering on the waveform discrete data. process.

It should be noted that the model or value of the components in each module is listed in this example, which is only used as a reference for an implementation, not as a restriction on each module. Components in the module can be replaced.

Example 1

As shown in Figure 16, in order to connect the initial pulse wave obtained after the discrete data of the single-channel waveform, perform fast Fourier transform on the initial pulse wave, determine the power frequency noise as 50Hz, and perform frequency domain zeroing and noise reduction processing. Since the pulse frequency is between 0.4Hz and 8Hz, frequency domain filtering is performed, the frequency domain range of 0~0.4Hz and greater than 8Hz is reduced to zero, and the inverse fast Fourier transform is performed to obtain the filtered signal, as shown in Figure 17 shown.

It should be noted that the filtering algorithm is not limited to the above-mentioned method, and the filtering algorithm can also be performed using the wavelet transform method or the EMD algorithm. As shown in FIG. 18 , the signal obtained after filtering the initial pulse wave in FIG. 11 by using the EMD algorithm.

Based on the above filtering operation of the single-channel initial pulse wave, the filtering of the dual-channel initial pulse wave is realized. The dual-channel pulse wave obtained after filtering is shown in Figure 19. The dual-channel pulse wave can be used to obtain the relevant pulse parameters, such as Figure 19 The time difference PTT (ie, T _PTT ) between the two peaks of the dual-path pulse wave can be used as the propagation time of the pulse wave.

It should be noted that this embodiment focuses on showing the flow and effect of algorithm filtering, and the specific data of the waves in the drawings are not limited, so the relevant coordinate axes in the waveform diagram are omitted.

In an embodiment, a blood pressure detection method is also provided, and the detection method is based on the wearable pulse wave detection device of the present application. Specifically, the blood pressure detection method includes:

The wearable pulse wave detection device is used to obtain two pulse waves under the same time axis, and the time difference T _PTT between the peaks of the two pulse waves is calculated as the wave propagation time;

Let the propagation velocity of waves in an ideal fluid in an elastic tube be:

In formula (1), V is the propagation velocity of the wave in the elastic tube, Δx is the propagation distance of the wave in the elastic tube, T _PTT is the propagation time of the wave in the elastic tube, E is the elastic modulus, h is the wall degree of the elastic tube, ρ is the ideal fluid density, r is the inner radius of the elastic tube in equilibrium;

Let the relationship between vascular elastic modulus and blood pressure be:

In formula (2), E represents the elastic modulus of the blood vessel under pressure P, that is, the elastic modulus in formula (1), E ₀ represents the initial elastic modulus, and α is a proportional parameter.

According to formula (1) and formula (2), the relationship between blood pressure and the propagation time of the wave in the elastic tube is obtained as:

Assuming that the arterial vessel wall is an ideal elastic tube, blood is an ideal fluid, and the influence of unmeasurable parameter changes such as blood viscosity and density is ignored, the relationship model between blood pressure and pulse wave propagation time is obtained according to formula (3) as follows:

P=a ₁ lnT _PTT +a ₂ (4)

In formula (4), a ₁ and a ₂ are fitting parameters that need to be calibrated, so that the blood pressure value can be obtained by formula (4) according to the propagation time of the pulse wave.

In another embodiment, the method for obtaining the blood pressure according to the dual-channel pulse wave may also be, using a neural network, taking the filtered pulse wave acquisition feature points as the input of the neural network, and using the measured blood pressure data as the output label, through a large number of The labeled data trains the neural network to obtain a nonlinear regression blood pressure numerical algorithm.

In the wearable pulse wave detection device and blood pressure detection method provided in this embodiment, flexible piezoelectric sensors are arranged on the inner and outer surfaces of the annular body to collect the pulse conditions of two detection parts of the human body at the same time to obtain dual-path pulse waves. The pulse wave is processed to obtain pulse parameters with high accuracy; the wearable ring-shaped body makes the detection device of the present application easy to carry on the user's body, which is not only easy to carry, but also avoids picking and placing steps to realize detection at any time; the present application The blood pressure parameter can also be obtained by calculating the dual-channel pulse wave, so as to realize the simultaneous measurement of the pulse and blood pressure, further simplify the user's use steps and improve the convenience.

The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity, all possible combinations of the technical features in the above-described embodiments are not described. However, as long as there is no contradiction between the combinations of these technical features, All should be regarded as the scope described in this specification.

The above-mentioned embodiments only represent several embodiments of the present application, and the descriptions thereof are specific and detailed, but should not be construed as a limitation on the scope of the invention patent. It should be pointed out that for those skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the scope of protection of the patent of the present application shall be subject to the appended claims.

Claims (7)

1. A wearable pulse wave detection device is characterized in that, the described wearable pulse wave detection device comprises: an annular body for wearing; a first flexible piezoelectric sensor, the first flexible piezoelectric sensor is disposed on the inner surface of the annular body, and is used for contacting with the first detection part of the user; A second flexible piezoelectric sensor, the second flexible piezoelectric sensor is disposed on the outer surface of the annular body and is used for contacting the second detection part of the user, and the position of the second flexible piezoelectric sensor is the same as that of the first flexible piezoelectric sensor. The position of the flexible piezoelectric sensor corresponds to; a main control circuit module, the main control circuit module is arranged on the annular body and connected with the first flexible piezoelectric sensor and the second flexible piezoelectric sensor, and the main control circuit module receives the first flexible piezoelectric sensor and the piezoelectric signal output by the second flexible piezoelectric sensor, obtain two pulse waves under the same time axis according to the two piezoelectric signals, and obtain pulse parameters according to the two pulse waves. 2. The wearable pulse wave detection device according to claim 1, wherein the main control circuit module comprises: a processing module, and a piezoelectric module, a somatosensory interaction module and a power supply module connected to the processing module; The processing module includes a microcontroller, and a Bluetooth radio frequency circuit connected to the microcontroller, the Bluetooth radio frequency circuit is used for receiving signals from the microcontroller and sending two pulse waves and/or pulse parameters; The piezoelectric module includes a signal processing circuit connected with the first flexible piezoelectric sensor and the second flexible piezoelectric sensor, and the signal processing circuit is used to connect the first flexible piezoelectric sensor and the second flexible piezoelectric sensor The piezoelectric signal output by the sensor is amplified and filtered, and after processing, two pulse electrical signals are obtained and transmitted to the microcontroller; The somatosensory interaction module includes a linear motor, which is connected with the microcontroller and is used for receiving signals from the microcontroller to generate vibration; The power supply module is used for supplying power to the processing module, the piezoelectric module and the somatosensory interaction module; The microcontroller receives two pulse electrical signals output by the piezoelectric module, and performs the following operations: Obtain two pulse waves under the same time axis according to the two pulse electrical signals, and calculate the time difference T _PTT between the peaks of the two pulse waves as the wave propagation time; Let the propagation velocity of waves in an ideal fluid in an elastic tube be: In formula (1), V is the propagation velocity of the wave in the elastic tube, Δx is the propagation distance of the wave in the elastic tube, T _PTT is the propagation time of the wave in the elastic tube, E is the elastic modulus, h is the wall degree of the elastic tube, ρ is the ideal fluid density, r is the inner radius of the elastic tube in equilibrium; Let the relationship between vascular elastic modulus and blood pressure be: E=E ₀ e ^αP (2) In the formula (2), E represents the elastic modulus of the blood vessel under the pressure P, that is, the elastic modulus in the formula (1), E ₀ represents the initial elastic modulus, and α is the proportional parameter; According to formula (1) and formula (2), the relationship between blood pressure and the propagation time of the wave in the elastic tube is obtained as: According to formula (3), the relationship model between blood pressure and pulse wave propagation time is obtained as follows: P=a ₁ lnT _PTT +a ₂ (4) In formula (4), a ₁ and a ₂ are fitting parameters that need to be calibrated, so that the blood pressure value can be obtained by formula (4) according to the propagation time of the pulse wave. 3 . The wearable pulse wave detection device according to claim 2 , wherein the annular main body is provided with a device slot with an opening facing the outside of the annular main body, and the device slot and the annular main body have an integral structure. A slot cover is connected, and the main control circuit module is located in the device slot. 4 . The wearable pulse wave detection device according to claim 3 , wherein the main control circuit module further comprises a display module, and the display module comprises a display screen embedded in the slot cover, and the display module The screen is connected with the microcontroller for displaying two pulse waves and/or pulse parameters. 5. The wearable pulse wave detection device according to claim 2, wherein the main control circuit module further comprises a motion module, the motion module comprises an acceleration sensor connected to the microcontroller, and the acceleration The sensor transmits the detected electrical acceleration signal to the microcontroller, and the electrical acceleration signal is used for the microcontroller to correct the pulse electrical signal. 6 . The wearable pulse wave detection device according to claim 2 , wherein the signal processing circuit comprises an amplification filter circuit and a bias amplification circuit; the amplification filter circuit comprises an OPA2314 operational amplifier, and the bias amplification circuit The circuit includes a TLV6001 operational amplifier; The piezoelectric signal output by the first flexible piezoelectric sensor or the second flexible piezoelectric sensor is used as the non-inverting input of the OPA2314 operational amplifier, the output signal of the TLV6001 operational amplifier is used as the inverting input of the OPA2314 operational amplifier, and the OPA2314 operational amplifier The output is sent to the microcontroller as a pulse electrical signal after passing through the RC low-pass filter circuit. 7. A blood pressure detection method based on the wearable pulse wave detection device according to claim 1, wherein the blood pressure detection method comprises: The wearable pulse wave detection device is used to obtain two pulse waves under the same time axis, and the time difference T _PTT between the peaks of the two pulse waves is calculated as the wave propagation time; Let the propagation velocity of waves in an ideal fluid in an elastic tube be: In formula (1), V is the propagation velocity of the wave in the elastic tube, Δx is the propagation distance of the wave in the elastic tube, T _PTT is the propagation time of the wave in the elastic tube, E is the elastic modulus, h is the wall degree of the elastic tube, ρ is the ideal fluid density, r is the inner radius of the elastic tube in equilibrium; Let the relationship between vascular elastic modulus and blood pressure be: E=E ₀ e ^αP (2) In the formula (2), E represents the elastic modulus of the blood vessel under the pressure P, that is, the elastic modulus in the formula (1), E ₀ represents the initial elastic modulus, and α is the proportional parameter; According to formula (1) and formula (2), the relationship between blood pressure and the propagation time of the wave in the elastic tube is obtained as: According to formula (3), the relationship model between blood pressure and pulse wave propagation time is obtained as follows: P=a ₁ lnT _PTT +a ₂ (4) In formula (4), a ₁ and a ₂ are fitting parameters that need to be calibrated, so that the blood pressure value can be obtained by formula (4) according to the propagation time of the pulse wave.