Flexible wearable blood flow velocity and pulse detection device and method

Abstract

The flexible wearable blood flow velocity and pulse detection device and method are low in cost, high in universality, high in integration level and convenient to use. The detection device comprises an annular flexible substrate (1) which can be wrapped and worn, wherein a plurality of laser diodes (2), a plurality of piezoelectric transducers (3), a light intensity detector (4) and a signal processing PCB (5) are arranged on the flexible substrate; the method comprises the following steps: step a, the detection device is started to work, laser emitted by the laser diode is conducted to tissue, and the laser is scattered in the tissue; b, the piezoelectric transducer detects ultrasonic waves scattered by particles in the blood vessel and transmits the ultrasonic waves into the signal processing PCB, and the flowing speed of the blood is calculated; c, the light intensity detector detects the light reflected by the tissue, the light intensity change is converted into an electric signal, an AC signal is output, and therefore the heart rate is calculated according to the number of wave crests. The method is applied to the technical field of human health monitoring.

Description

Technical Field

[0001] The present invention relates to the technical field of human health monitoring, and in particular to a flexible wearable blood flow velocity and pulse detection device and method. Background Art

[0002] At present, most of the blood flow rate monitoring based on the principle of ultrasonic detection has the following defects: 1. During the detection, a rigid probe is required to be applied with a coupling agent and a large pressure is applied to the skin surface, which will cause harm to the patient, especially for patients who have undergone surgery such as implanting artificial blood vessels or fistulas. This method is not conducive to postoperative recovery; 2. The probe needs to be manually operated and detected at a certain angle, which has the problem of low efficiency; 3. It is not suitable for long-term monitoring and cannot monitor the blood flow rate indicators of blood vessels in real time, especially when the patient is sleeping or undergoing routine surgery; 4. The integration is poor, and it can only detect the blood flow rate, and cannot provide other health indicators such as blood oxygen saturation and pulse at the same time; 5. It has certain requirements for the use scenario and users, and requires a cumbersome professional training process; 6. The detection equipment is large in size and high in cost. Patients need to go to the hospital for appointments regularly. Patients cannot carry real-time monitoring with them, which is not conducive to emergency treatment of sudden physical conditions of patients. These problems need to be solved urgently. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a low-cost, highly universal, highly integrated and easy-to-use flexible wearable blood flow velocity and pulse detection device and method.

[0004] The technical solution adopted by the flexible wearable blood flow velocity and pulse detection device of the present invention is a flexible wearable blood flow velocity and pulse detection device, which includes a ring-shaped and wearable flexible substrate, on which a plurality of laser diodes, a plurality of piezoelectric transducers, a light intensity detector and a signal processing PCB are installed, the laser diodes, the piezoelectric transducers, and the light intensity detector are all electrically connected to the signal processing PCB, and the plurality of laser diodes and the plurality of piezoelectric transducers are arranged on the flexible substrate in an array structure, and the light of all the laser diodes is incident at different inclination angles to the bottom of the flexible substrate.

[0005] The flexible substrate is composed of a silicone elastomer.

[0006] A signal connection pin and a power supply electrode are arranged on the flexible substrate. The signal connection pin is respectively connected to the laser diode, the piezoelectric transducer and the light intensity detector signals. The signal connection pin is externally connected to the signal processing PCB signal. The power supply electrode supplies power to the laser diode, the piezoelectric transducer and the light intensity detector. The power supply electrode is connected to the power output interface on the signal processing PCB.

[0007] The number of the laser diodes is 3, the number of the light intensity detectors is set to 2, the number of the piezoelectric transducers is 9, and the laser diodes, the light intensity detectors and the piezoelectric transducers are arranged in the flexible substrate in a display structure.

[0008] The signal processing PCB transmits signals to a peripheral receiving display device by wireless communication, and the wireless communication method includes Bluetooth or Wi-Fi communication.

[0009] A detection method for the above-mentioned flexible wearable blood flow velocity and pulse detection device, the method comprising the following steps: Step a, the detection device starts working, the laser light emitted by the laser diode is transmitted into the blood vessel, the laser light is scattered in the blood vessel, and part of the scattered light is absorbed; Step b, the piezoelectric transducer detects the ultrasonic signal scattered by the particles in the blood vessel and transmits it to the signal processing PCB, the signal processing PCB performs denoising and filtering on the signal, and calculates the frequency shift between the receiving frequency and the reference frequency, thereby calculating the flow velocity of the blood; Step c: The light intensity detector detects the light (532nm wavelength) reflected in the blood vessel, converts the light intensity change into an electrical signal, outputs an AC signal, and calculates the heart rate based on the number of peaks.

[0010] The detection method of the flexible wearable blood flow rate and pulse detection device also includes a step of blood oxygen detection: the laser diode emits two groups of specific lights with different wavelengths (665nm and 940nm wavelengths) into the blood vessel, and utilizes the spectral absorption characteristics of oxygenated hemoglobin and deoxygenated hemoglobin in the blood vessel to different wavelengths. The unabsorbed lights of the two different wavelengths are reflected and detected by the light intensity detector, and the light intensity detector sends the signals of the reflected lights of the two different wavelengths to the signal processing PCB. The signal processing PCB compares the concentrations of oxygenated hemoglobin and deoxygenated hemoglobin in the blood vessel according to the light intensity information of the two groups of lights of different wavelengths at the time of incidence and reflection.

[0011] In step b, when the laser diode emits laser, the laser penetrates the skin and is transmitted in the tissue, and is absorbed by the red blood cells flowing in the blood vessels. After absorbing the energy of the laser, the red blood cells heat up and expand, and then quickly contract. The mechanical vibration generated thereby generates sound waves. The sound waves carry the speed information of the red blood cells and propagate upward, and are detected, absorbed and converted into electrical signals by the piezoelectric transducer. The electrical signals are output to the signal processing PCB, and the difference between the sound wave frequency and the laser sample frequency emitted by the laser diode is detected, so that the movement speed of the red blood cells is calculated.

[0012] The specific steps of step c are:

[0013] The light intensity detector detects the light that passes through the skin and enters the blood vessels and then reflects, and modulates the output electrical signal according to the light intensity. Since the absorption of light by arteries changes while the absorption of light by other tissues remains basically unchanged, the obtained signal can be divided into a direct current (DC) signal and an alternating current (AC) signal. By extracting the AC signal, the characteristics of blood flow can be reflected. By detecting and calculating the number of peaks of the AC signal per unit time, the heart rate data can be obtained.

[0014] Beneficial effects of the present invention: In the present invention, its structure includes a flexible substrate, a laser diode, a piezoelectric transducer, a light intensity detector, and a signal processing PCB. The laser diode is arranged in an array structure and incident at different angles, which solves the angle adjustment required in traditional inspections; the ultrasonic wave scattered by particles such as hemoglobin in the blood vessels is detected by a piezoelectric transducer, and after the signal is transmitted to the signal processing PCB for denoising and filtering, the frequency shift of the receiving frequency and the reference frequency is calculated, thereby calculating the flow rate of the blood; the light reflected by the human tissue is detected by the light intensity detector, and converted into an electrical signal through the change of light intensity, and an AC signal is output, thereby calculating the heart rate according to the number of peaks; by injecting two different wavelengths of light into the blood vessel, the absorption characteristics of oxygenated hemoglobin and deoxygenated hemoglobin for light of different wavelengths are used, and the reflectivity of the two lights is detected by the signal processing PCB, thereby detecting the concentration of the sun; on the other hand, compared with the traditional rigid probe, the flexible substrate is lighter in weight, has less pressure on the skin, and is still accurate in recording under long-term monitoring. The present invention can realize long-term wear monitoring for patients with fragile skin or patients after blood and vascular surgery. The present invention has low cost, can be used in most scenarios, and can perform two or more tests at the same time, with high universality and high integration; in addition, the flexible substrate can be easily attached to the skin, and through multiple laser diodes set at different incident angles, there is no need for manual operation of the probe to perform detection at different angles, which improves its ease of use and also improves work efficiency.

[0015] In addition, the present invention not only solves the problem of large device size, but also avoids the impact of problems such as probe angle on users. It also uses flexible materials to solve the problems of long-term wearing, real-time monitoring, and blood flow detection in patients with fragile skin after surgery. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of a simple explosion structure of a detection device; Figure 2 This is a schematic diagram of the measurement principle inside the skin; Figure 3 is a simplified layout diagram of the flexible substrate; Figure 4 is a schematic cross-sectional view of a measuring end of the flexible substrate; Figure 5 is a simplified cross-sectional schematic diagram of the specific configuration structure of the flexible substrate; Figure 6 It is a simple flow chart of the present invention in measuring blood flow velocity; Figure 7 It is a simple flow chart of the present invention in measuring heart rate; Figure 8 It is a simple flow chart of the present invention in measuring blood oxygen. DETAILED DESCRIPTION

[0017] like Figures 1 to 8 As shown, a flexible wearable blood flow rate and pulse detection device includes a ring-shaped and wearable flexible substrate 1, on which are installed a plurality of laser diodes 2, a plurality of piezoelectric transducers 3, a light intensity detector 4 and a signal processing PCB 5. The laser diodes 2, the piezoelectric transducers 3, the light intensity detector 4 are all electrically connected to the signal processing PCB 5, and the plurality of laser diodes 2 and the plurality of piezoelectric transducers 3 are arranged on the flexible substrate 1 in an array structure. Figure 2 The figure shows the principle diagram of measurement inside the skin, where A is the skin layer, B is the muscle layer, C is the blood vessel, and D is the hemoglobin in the blood vessel. When measuring blood flow, the incident signal is a light signal and the reflected signal is an ultrasonic signal; when measuring heart rate and blood oxygen, the incident signal is a light signal and the reflected signal is also a light signal. Figure 4 As shown, the light beams of all the laser diodes 2 are emitted at different inclination angles ( Figure 4 The angles a, b and c shown in FIG. 1 are incident on the bottom of the flexible substrate 1. Similarly, Figure 5As shown, the piezoelectric transducer 3 and the light intensity detector 4 are also arranged at different inclination angles. The flexible substrate 1 is made of silicone elastomer. A signal connection pin 6 and a power supply electrode 7 are arranged on the flexible substrate 1. The signal connection pin 6 is respectively connected to the laser diode 2, the piezoelectric transducer 3 and the light intensity detector 4. The signal connection pin 6 is externally connected to the signal processing PCB5. The power supply electrode 7 supplies power to the laser diode 2, the piezoelectric transducer 3 and the light intensity detector 4. The power supply electrode 7 is connected to the power output interface on the signal processing PCB5. In the present invention, a power supply battery 8 is provided on the signal processing PCB5, and a battery fixing plate 9 is provided between the power supply battery 8 and the signal processing PCB5. The detection device is provided with a housing 10 on the outside, and a bottom plate 11 is provided at the bottom. The flexible substrate 1 is provided on the lower side of the bottom plate 11, and a via 12 for the active power line and the signal line to pass through is provided on the bottom plate 11. The number of laser diodes 2 arranged on the flexible substrate 1 is 3, the number of light intensity detectors 4 is set to 2, the number of piezoelectric transducers 3 is 9, and the laser diodes 2, the light intensity detectors 4 and the piezoelectric transducers 3 are arranged in the flexible substrate 1 in a display structure. The signal processing PCB 5 transmits signals with the peripheral receiving display device through wireless communication, and the wireless communication method includes Bluetooth or Wi-Fi communication. Here, the receiving display device is a computer equipped with image display software, wherein the image display software and the computer are existing technologies and are currently commonly used equipment in medical institutions.

[0018] The detection method of the above-mentioned flexible wearable blood flow velocity and pulse detection device comprises the following steps: Step a, the detection device starts working, the laser light emitted by the laser diode 2 is transmitted into the blood vessel, the laser light is scattered in the blood vessel, and part of the scattered light is absorbed; Step b, the piezoelectric transducer 3 detects the ultrasonic signal scattered by the particles in the blood vessel and transmits it to the signal processing PCB 5. After the signal processing PCB 5 performs denoising and filtering on the signal, it calculates the frequency shift between the receiving frequency and the reference frequency, thereby calculating the flow velocity of the blood; Step c: the light intensity detector 4 detects the light (light with a wavelength of 532 nm) reflected in the blood vessel, converts the light intensity change into an electrical signal, and outputs an AC signal, thereby calculating the heart rate based on the number of peaks.

[0019] The above detection method also includes the step of blood oxygen detection: the laser diode 2 emits two groups of specific lights with different wavelengths (lights with wavelengths of 665nm and 940nm) into the blood vessel, and utilizes the spectral absorption characteristics of oxygenated hemoglobin (light with a wavelength of 665nm) and deoxygenated hemoglobin (light with a wavelength of 940nm) in the blood vessel to different wavelengths. The unabsorbed lights of the two different wavelengths are reflected and detected by the light intensity detector 4, and the light intensity detector 4 sends the signals of the reflected lights of the two different wavelengths to the signal processing PCB 5. The signal processing PCB 5 compares the concentrations of oxygenated hemoglobin and deoxygenated hemoglobin in the blood vessel according to the light intensity information of the two groups of lights with different wavelengths at the time of incidence and reflection.

[0020] In step b, when the laser diode 2 emits a laser, the laser penetrates the skin and is transmitted in the tissue, and is absorbed by the red blood cells flowing in the blood vessels. After absorbing the energy of the laser, the red blood cells heat up and expand, and then quickly contract. The mechanical vibration generated thereby generates a sound wave. The sound wave carries the speed information of the red blood cells and propagates upward, is detected and absorbed by the piezoelectric transducer 3, and is converted into an electrical signal. The electrical signal is output to the signal processing PCB, and the difference between the sound wave frequency and the laser sample frequency emitted by the laser diode 2 is detected, so that the movement speed of the red blood cells is calculated.

[0021] The specific steps of step c are:

[0022] The laser emitted by the laser diode will be absorbed by tissues, including arterial blood, venous blood, human bones and other tissues. Among these parts, venous blood, human bones and other tissues can be considered to be relatively static, and only the blood flow in the arteries can be considered to be relatively moving. As the heart contracts and relaxes, the flow rate of blood in the arteries will also change, thereby affecting the absorption rate of light. The light intensity detector 4 detects the light that passes through the skin and enters the blood vessels and then reflects, and modulates the output of the electrical signal according to the light intensity. Since the absorption of light by the artery changes while the absorption of light by other tissues remains basically unchanged, the obtained signal can be divided into a direct current (DC) signal and an alternating current (AC) signal. Extracting the AC signal can reflect the characteristics of blood flow, and by detecting and calculating the number of peaks of the AC signal per unit time, the heart rate data can be obtained.

[0023] In the present invention, the principle of photoacoustic Doppler velocimetry is as follows: photoacoustic refers to the absorption of continuous light waves or pulsed light waves with intensity modulation by blood protein particles, which leads to periodic changes in temperature, and the protein particles periodically shrink and expand, thereby generating ultrasonic waves. When the particles move, the ultrasonic frequency received by the ultrasonic detection end is not equal to the modulation frequency of the light, resulting in a frequency shift, which is the photoacoustic Doppler frequency shift.

[0024] The laser is scattered in the tissue, and some of the scattered light is absorbed. After hitting the blood cells flowing in the capillaries, the wavelength of the laser changes, resulting in a Doppler effect, also known as Doppler frequency shift, which produces a slight red shift or blue shift. The red-shifted or blue-shifted laser is then received by the receiver, while the wavelength of the laser hitting the stationary tissue does not change. The intensity and frequency distribution of these wavelength changes are directly related to the number and movement speed of blood cells in the monitoring volume.

[0025] The light emitted by the photodetector is absorbed by the particles, generating sound waves which are detected by the ultrasound transducer. The motion of the particles (velocity V) causes a Doppler shift in the frequency of the sound waves.

[0026] The photoacoustic Doppler shift (fPAD) can be expressed as: , in: f0 is the modulation frequency of the laser, V is the velocity of the particles (blood velocity), ·c A is the speed of sound in the medium, θ is the angle between the particle movement direction and the ultrasonic detection direction (Doppler angle).

[0027] This formula shows that the frequency shift is proportional to the velocity of the particle, inversely proportional to the speed of sound, and depends on the cosine of the angle between the direction of particle motion and the direction of ultrasonic detection.

[0028] Assuming cA = 1500 m / s, fO = 2.4550 MHz, measured fPAD = 100 Hz, and θ = 0° (i.e. the particle moves directly toward the transducer), we can calculate , In the actual situation of the current system, it is assumed that two beams 1 and 2 with different incident angles θ1 and θ2 are emitted from the laser transmitting end. Snell's law describes the relationship between the incident angle and the refraction angle: ,

[0029] where n1 and n2 are the refractive indices of the two media.

[0030] In addition, according to the Doppler effect and geometric conditions, We obtain the following equation: , in is the refractive index, c is the speed of sound in the blood, θ1 and θ2 are also the angles between the piezoelectric detector and the skin, 1 and 2 is the Doppler angle, f0 is the modulation frequency of the laser, and f D1 、f D2 are the photoacoustic Doppler frequency shifts obtained from the two measurements, and v is the blood flow velocity;

[0031] From these equations, the Doppler angle can be derived 1 and 2. The unique solution for flow velocity v.

[0032] By using two beams at different angles of incidence, we can obtain two different Doppler shifts. This has two main advantages:

[0033] 1. Improved accuracy: By comparing two frequency shifts (on the device, one direction is 3 angles, and the 3×3 arrangement can be counted 9 times, which is equivalent to measuring a surface), we can determine the blood flow rate more accurately. This is similar to using two different measurement angles to eliminate the influence of other factors, thereby determining the speed more accurately.

[0034] 2. Determine direction: The two frequency shifts can also help determine the direction of blood flow. Different Doppler shifts can indicate whether the blood is moving toward or away from the detector, providing information about the direction of flow.

[0035] Each received echo has a Doppler frequency shift relative to the emitted laser frequency, which is related to the velocity of the scatterer. There are many moving scatterers in the blood flow, which will produce mixed signals of Doppler frequency shifts. These frequency shifts will change in time and space within the blood vessel lumen. After signal demodulation and power spectral density (PSD) analysis by the measuring instrument, a Doppler spectrum containing absolute frequency shift and blood flow velocity can be obtained.

[0036] To this end, in the present invention, all piezoelectric transducers are used as ultrasonic receivers and are placed on the skin at different positions of the human body. Each piezoelectric transducer corresponds to a different part of the blood vessel and adopts a different detection angle. The piezoelectric transducer detects the blood pulsation conducted through the skin tissue to the skin surface. By using piezoelectric transducer arrays with different inclination angles, the influence of the Doppler angle on the velocity measurement can be overcome, and the blood flow velocity can be quantitatively measured.

[0037] The present invention provides a flexible wearable blood flow rate and pulse life monitoring device. It specifically solves the defects of existing devices: 1. It adopts a flexible substrate and polyester fiber to form a ring-shaped wrappable wearable device; 2. It adopts an array structure to detect health parameters such as heart rate, blood flow rate, blood oxygen concentration, pulse, etc. in blood vessels from multiple angles; 3. It effectively performs real-time monitoring under micro-pressure and realizes simple operation; 4. The product is small in size and low in cost, which is conducive to long-term monitoring of the patient's health status.

[0038] In addition, through different combinations, the photoacoustic effect can measure the blood flow rate, and light intensity detection can provide feedback on blood oxygen content, pulse beats, heart rate measurement, etc. These are existing technologies and will not be elaborated here.

[0039] Finally, it should be emphasized that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A flexible wearable blood flow rate and pulse detection device, characterized in that: The invention comprises a flexible substrate (1) which is in the shape of a ring and can be wrapped and worn. A plurality of laser diodes (2), a plurality of piezoelectric transducers (3), a light intensity detector (4) and a signal processing PCB (5) are arranged on the flexible substrate (1). The laser diodes (2), the piezoelectric transducers (3) and the light intensity detector (4) are all electrically connected to the signal processing PCB (5). The plurality of laser diodes (2) and the plurality of piezoelectric transducers (3) are arranged on the flexible substrate (1) in an array structure. Light rays of all the laser diodes (2) are incident at different inclination angles toward the bottom of the flexible substrate (1).

2. A flexible wearable blood flow velocity and pulse detection device according to claim 1, characterized in that: The flexible substrate (1) is made of silicone elastomer.

3. A flexible wearable blood flow velocity and pulse detection device according to claim 1, characterized in that: A signal connection pin (6) and a power supply electrode (7) are provided on the flexible substrate (1); the signal connection pin (6) is respectively connected to the laser diode (2), the piezoelectric transducer (3) and the light intensity detector (4) for signals; the signal connection pin (6) is externally connected to the signal processing PCB (5) for signals; the power supply electrode (7) supplies power to the laser diode (2), the piezoelectric transducer (3) and the light intensity detector (4); and the power supply electrode (7) is connected to a power output interface on the signal processing PCB (5).

4. A flexible wearable blood flow velocity and pulse detection device according to any one of claims 1 to 3, characterized in that: The number of the laser diodes (2) is 3, the number of the light intensity detectors (4) is set to 2, the number of the piezoelectric transducers (3) is 9, and the laser diodes (2), the light intensity detectors (4) and the piezoelectric transducers (3) are arranged in a display structure within the flexible substrate (1).

5. A flexible wearable blood flow velocity and pulse detection device according to any one of claims 1 to 3, characterized in that: The signal processing PCB (5) transmits signals to a peripheral receiving display device by means of wireless communication, wherein the wireless communication method includes Bluetooth or Wi-Fi communication.

6. A detection method for the flexible wearable blood flow velocity and pulse detection device as claimed in claim 1, characterized in that: The method comprises the following steps: Step a, the detection device starts working, the laser light emitted by the laser diode (2) is transmitted into the blood vessel, the laser light is scattered in the blood vessel, and part of the scattered light is absorbed; Step b, the piezoelectric transducer (3) detects the ultrasonic signal scattered by the particles in the blood vessel and transmits it to the signal processing PCB (5), the signal processing PCB (5) performs denoising and filtering on the signal, and then calculates the frequency shift between the receiving frequency and the reference frequency, thereby calculating the flow velocity of the blood; Step c: The light intensity detector (4) detects the light reflected in the blood vessel, converts the light intensity change into an electrical signal, and outputs an alternating current (AC) signal, thereby calculating the heart rate based on the number of wave peaks.

7. The detection method of the flexible wearable blood flow velocity and pulse detection device according to claim 6 is characterized in that: The detection method also includes a blood oxygen detection step: the laser diode (2) emits two groups of specific lights with different wavelengths into the blood vessel, and utilizes the spectral absorption characteristics of oxygenated hemoglobin and deoxygenated hemoglobin in the blood vessel to different wavelengths. The two lights of different wavelengths that are not absorbed are reflected and detected by the light intensity detector (4), and the light intensity detector (4) sends the signals of the reflected lights of the two different wavelengths to the signal processing PCB (5). The signal processing PCB (5) compares the concentrations of oxygenated hemoglobin and deoxygenated hemoglobin in the blood vessel based on the light intensity information of the two groups of lights of different wavelengths at the time of incidence and at the time of reflection.

8. The detection method of the flexible wearable blood flow velocity and pulse detection device according to claim 6 is characterized in that: In step b, when the laser diode (2) emits laser light, the laser light penetrates the skin and is transmitted in the tissue, and is absorbed by the red blood cells flowing in the blood vessels. After absorbing the energy of the laser light, the red blood cells heat up and expand, and then quickly contract. The mechanical vibration generated thereby generates sound waves. The sound waves carry the speed information of the red blood cells and propagate upwards. They are detected and absorbed by the piezoelectric transducer (3) and converted into electrical signals. The electrical signals are output to the signal processing PCB, and the difference between the frequency of the sound waves and the frequency of the laser sample emitted by the laser diode (2) is detected, so that the movement speed of the red blood cells is calculated.

9. The detection method of the flexible wearable blood flow velocity and pulse detection device according to claim 6, characterized in that: The specific steps of step c are: The light intensity detector (4) detects the light that passes through the skin and enters the blood vessels and then reflects, and modulates the output of an electrical signal according to the light intensity. Since the absorption of light by arteries changes while the absorption of light by other tissues remains basically unchanged, the obtained signal can be divided into a direct current (DC) signal and an alternating current (AC) signal. By extracting the AC signal, the characteristics of blood flow can be reflected. By detecting and calculating the number of peaks of the AC signal per unit time, heart rate data can be obtained.

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