CN115633947B - Wearable blood pressure monitoring device and blood pressure monitoring method - Google Patents
Wearable blood pressure monitoring device and blood pressure monitoring method Download PDFInfo
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Abstract
The invention relates to the technical field of blood pressure monitoring, and particularly discloses a wearable blood pressure monitoring device and a blood pressure monitoring method, wherein the wearable blood pressure monitoring device comprises wearable equipment; the wearable device is provided with an angular artery sensor, a superficial temporal artery sensor and a posterior auricular artery sensor which are used for respectively detecting pulse waves at the angular artery, the superficial temporal artery and the posterior auricular artery of the user; the wearable device is also provided with an inertial sensor for monitoring the head motion state of the user; the wearable device is integrated with the blood pressure monitor, and the controller is integrated on the wearable device and used for processing the acquired pulse wave signals and calculating the blood pressure of the user. The invention can continuously collect pulse waves all day long to calculate the blood pressure, thereby realizing all-weather continuous monitoring of the blood pressure in the wearing process.
Description
Technical Field
The invention relates to the technical field of blood pressure monitoring, in particular to a wearable blood pressure monitoring device and a method for monitoring blood pressure by using the same.
Background
At present, the blood pressure monitoring in daily use mainly depends on a cuff type oscillation measuring device. The existing equipment is cheap and simple to use. However, the cuff is used to detect blood pressure, which takes at least several minutes and takes a long time. More importantly, such devices require the inflatable cuff to be worn correctly and are therefore unsuitable for use outside the home. Moreover, the recommended instruments are used for measuring the blood pressure at the same time every day, once or twice a day, namely, the blood pressure can only be detected at intervals, and the continuous tracking measurement of the blood pressure of the user is inconvenient.
On the other hand, the increasing popularity of ubiquitous computing platforms such as smart phones and wearable devices opens up a new platform for integrating blood pressure measurements that are readily available. This is achieved by using the pulse transit time as a basis for measuring blood pressure, without the need for mechanical hardware like cuffs and pumps. Due to the characteristics of portability, wearability, unobtrusiveness and the like, the intelligent glasses are becoming an attractive item in wearable electronic products. Currently, existing smart glasses products can integrate signal acquisition units such as cameras, microphones, GPS, accelerometers, gyroscopes, magnetometers, and optical sensors, and are used for virtual reality and augmented reality, or for eye movement tracking, but are used for less biological signal acquisition in the medical field.
Disclosure of Invention
The present invention aims to provide a wearable blood pressure monitoring device and a blood pressure monitoring method, which partially alleviate or solve the above problems, and calculate the blood pressure by collecting the pulse waves of three different parts of the head of a user and the time difference of pulse wave pulse transmission time.
In order to solve the above mentioned technical problem, the present invention specifically provides a wearable blood pressure monitoring device, including a wearable device, wherein the wearable device is provided with an arteriolar sensor, a superficial temporal artery sensor, and a posterior auricular artery sensor for respectively detecting pulse waves at the arteriolar, superficial temporal artery, and posterior auricular artery of a user; the wearable equipment is also provided with an inertial sensor for monitoring the head motion state of the user; the wearable device further comprises a controller which is integrated on the wearable device and used for processing the acquired pulse wave signals and calculating the blood pressure of the user.
As an improvement, the wearable device is a pair of spectacles, and the angular artery sensor is arranged on a nose pad of the spectacles; the superficial temporal artery sensor is arranged on the glasses legs of the glasses; the posterior ear artery sensor is arranged on an ear hook of the glasses.
As an improvement, the nose pad is connected with the spectacle frame by an elastic support.
As a refinement, the superficial temporal artery sensor is a pressure sensor; the angular artery sensor and the posterior auricular artery sensor are PPG sensors.
As an improvement, the PPG sensor comprises a photodiode and an LED light source; the photodiode and the LED light source are encapsulated by glue pouring, and the glue surface is flush with the top surfaces of the photodiode and the LED light source.
The invention also provides a blood pressure monitoring method applied to the wearable blood pressure monitoring device, which comprises the following steps:
converting the pulse signals of the pulse waves at the corner artery, the superficial temporal artery and the posterior auricular artery into corresponding signal curves and main frequencies, and verifying whether the main frequencies of the corner artery, the superficial temporal artery and the posterior auricular artery are the same;
segmenting the signal profile of the pulse signal through a time window; detecting a target peak of any signal curve in each section of signals, finding out a peak of other two signals closest to the target peak, and finding out a trough of the other two signals closest to the target peak before the target peak; the time corresponding to the wave trough is the starting time stamp of the pulse wave in the time window, and the time corresponding to the three wave crests is the pulse arrival time of the three pulse waves in the time window;
eliminating the pulse signals interfered by noise;
obtaining a time difference between the arrival time of any pulse wave of the angular artery, the superficial temporal artery and the posterior auricular artery and the reference arrival time by taking the arrival time of the pulse wave of any one of the angular artery, the superficial temporal artery and the posterior auricular artery as the reference arrival time;
establishing a blood pressure model by utilizing the two time differences;
calibrating the blood pressure model by using the real blood pressure value;
and inputting the acquired time difference into a blood pressure model so as to obtain a blood pressure value.
As an improvement, the method for verifying the co-frequency of the main frequencies of the angular artery, the superficial temporal artery and the posterior auricular artery comprises the following steps:
respectively acquiring absolute values of differences between the main frequencies of the other two arteries and a reference value by taking the main frequency of one of the angular artery, the superficial temporal artery and the posterior auricular artery as a reference value, comparing the two absolute values with a preset same-frequency threshold value, and judging the same frequency of the angular artery, the superficial temporal artery and the posterior auricular artery if the two absolute values are smaller than the same-frequency threshold value; wherein the common frequency threshold is in the order of 10 -1 The empirical value of (2).
As an improvement, the pulse signal which is excluded from being interfered by noise comprises a motion interference exclusion and a non-motion interference exclusion;
the motion disturbance rejection comprises:
segmenting a pulse signal curve by taking n seconds before and after one pulse wave fluctuation as a time window, judging whether inertia measurement in the time window exceeds a preset inertia threshold value, and if so, excluding the pulse signal in the time window;
the non-motion interference exclusion comprises:
performing phase correlation on the pulse signal curves of the angular artery, the superficial temporal artery and the posterior auricular artery to obtain maximum amplitude and evaluate the best matching phase deviation; and if the maximum amplitude is lower than a preset amplitude threshold value or the phase value distribution exceeds a preset distribution threshold value, excluding the pulse signals in the time window corresponding to the timestamp where the maximum amplitude is located.
As an improvement, the blood pressure model is:
wherein BP is the blood pressure value, PTT is the time difference, K 1 Is the slope, K 2 Is the intercept.
As an improvement, the method for calibrating the blood pressure model by using the real blood pressure value comprises the following steps:
wearing the wearable blood pressure monitoring device, and acquiring a time difference by using the wearable blood pressure monitoring device;
simultaneously acquiring a current real blood pressure value;
the time difference and the real blood pressure value are brought into a model to calculate the slope K 1 And intercept K 2 。
The invention has the advantages that: the invention can continuously collect pulse waves all day long to calculate the blood pressure, thereby realizing all-weather continuous monitoring of the blood pressure in the wearing process. After the intelligent glasses (namely the wearable blood pressure monitoring device) provided by the invention are worn, the whole blood pressure detection process does not need manual intervention, and all collection and calculation work is automatically completed; the user has no uncomfortable feeling, and the feeling is not different from the feeling of wearing ordinary glasses; the device is not required to be worn on four limbs, and the action of the user is not limited.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. Throughout the drawings, like elements or portions are generally identified by like reference numerals. In the drawings, elements or portions are not necessarily drawn to scale. It is obvious that the drawings in the following description are some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive exercise.
Fig. 1 is a schematic structural diagram of a wearable blood pressure monitoring device according to an exemplary embodiment of the present invention;
FIG. 2 is a flow chart of a blood pressure monitoring method according to an exemplary embodiment of the present invention;
FIG. 3 is a waveform diagram of a time window;
fig. 4 is a flowchart of a blood pressure monitoring method according to another exemplary embodiment of the present invention.
The reference numbers are 11-spectacle frame, 12-spectacle leg, 13-ear hook, 14-nasal cushion, 21-angular artery sensor, 22-superficial temporal artery sensor and 23-posterior auricular artery sensor.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Herein, suffixes such as "module", "part", or "unit" used to indicate elements are used only for facilitating the description of the present invention, and have no particular meaning in itself. Thus, "module", "component" or "unit" may be used mixedly.
Herein, the terms "upper", "lower", "inner", "outer", "front", "rear", "one end", "the other end", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience in describing and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
As used herein, unless otherwise expressly specified or limited, the terms "mounted," "disposed," "connected," and the like are to be construed broadly, such that the terms "connected," or "connected," as used herein, may be fixedly connected, detachably connected, or integrally connected; they may be mechanically coupled, directly coupled, indirectly coupled through intervening media, or may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in a specific case to those of ordinary skill in the art.
Herein "and/or" includes any and all combinations of one or more of the associated listed items.
By "plurality" herein is meant two or more, i.e. it includes two, three, four, five, etc.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising a … …" does not exclude the presence of another identical element in a process, method, article, or apparatus that comprises the element.
The term is to be interpreted:
PAT: the pulse arrival time;
ECG: an electrocardiogram;
PPG: photoplethysmography;
PTT (pulse transit time, pulse transmission time);
BCG for ballistic cardiogram;
SCG: and (4) a cardiac seismogram.
The existing blood pressure calculation modes through pulse waves include two modes: firstly, the blood pressure is reversely deduced by measuring the Pulse Arrival Time (PAT); the second is to measure the blood pressure by measuring the Pulse Transmission Time (PTT).
Pulse Arrival Time (PAT) is the time required for a blood pressure wave generated by the beating heart to reach a certain point of the body along the arterial tree, and is inversely proportional to blood pressure. In order to measure PAT, two events must be measured, when the heart beats and when the pulse wave reaches a certain location on the body. A typical method is to measure the Electrocardiogram (ECG) of the subject using electrodes and monitor their heartbeat by recording r-waves. At the same time, the patient's finger is usually fitted with a light pulse sensor for measuring the photoplethysmogram (PPG) of the fingertip. An electrocardiographic sensor observes when the heart is beating and a PPG sensor measures when the pulse wave reaches a remote location.
PAT is inversely correlated with blood pressure and requires calibration to directly estimate the absolute blood pressure value. This is because the propagation time of the pressure wave depends on the propagation distance and the stiffness of the artery. Since the PPG is always measured at the same location, the propagation distance remains unchanged, while the arterial stiffness changes. For example, as humans age, arterial stiffness tends to increase, which is often a slow process, and thus calibration lasts at least several months. However, the use of PAT, even if calibrated, has not proven to be a very reliable method of absolute blood pressure measurement. The challenge in monitoring PAT using ECG and PPG is that the ECG recording does not capture the precise moment blood is actually ejected from the heart, but depolarizes when the heart begins to contract. The period from depolarization to aortic valve opening (i.e., cardiac ejection) is called the pre-ejection period (PEP) and is not constant from beat to beat. Thus, the ECG-to-PPG measurement of PAT is inherently noisy, as this pre-ejection variable may be independent of blood pressure (i.e., vasoconstriction, stress, or neurohormonal factors).
By converting the measurements to Pulse Transit Time (PTT), the variability of the pre-firing period can be offset. The pulse transit time is the time delay after the heart beat for the pressure wave to propagate between the two arterial sites. Thus, PTT is also negatively correlated with human blood pressure. One such method, known as Ballistic Cardiography (BCG), measures the slight vibrations that the reaction force caused by the cardiac ejection propagates to other parts of the body. Another approach is to measure the response of the vibrations around the heart to the mechanical activity of the heart, known as the cardiac Seismogram (SCG). Both measurements are directly caused by the physical contraction of the heart, avoiding the pre-ejection uncertainty in the electrocardiogram measurement and showing a useful correlation with the absolute blood pressure measurement.
Another method to counteract the problem of non-constant pre-ejection period is to measure the PPG at two parts of the body, ideally along the same artery, at a known distance from each other. Because the blood that the pressure wave propels to two sites in the body comes from the same source, the difference in the arrival times of the pulse waves at the two sites can be used to measure PTT. This is usually done on the wrist and fingers or on the fingers and toes of the same hand. The invention adopts the blood pressure measuring method to come from the principle, but the part for collecting the pulse wave is the head of the user.
In order to facilitate the wearing of the wearable blood pressure monitoring device and the collection of pulse waves of several parts of the head of a user, as shown in fig. 1, the invention provides a wearable blood pressure monitoring device which can continuously track and measure the blood pressure of the user and comprises wearable equipment; the wearable equipment is provided with an angular artery sensor 21, a superficial temporal artery sensor 22 and a posterior auricular artery sensor 23 which are used for respectively detecting pulse waves at the angular artery, the superficial temporal artery and the posterior auricular artery of the user; the wearable device is also provided with an inertial sensor (not shown in the figure) for monitoring the head motion state of the user; and a controller (therefore, also called a smart wearable device) integrated on the wearable device for processing the acquired pulse wave signals to calculate the blood pressure of the user. Of course, a battery for power supply is also integrated on the wearable device. In order to conveniently transmit data to the outside, a wireless transmission module such as a Bluetooth module is integrated on the wearable device.
In the present invention, the wearable device is preferably glasses, which are similar to ordinary glasses and include a frame 11, temples 12, ear hooks 13, a nose pad 14, and the like.
Specifically, the angular artery sensor 21 is provided on the nose pad 14 of the eyeglasses; the superficial temporal artery sensor 22 is arranged on the temple 12 of the spectacles; the posterior ear artery sensor 23 is provided on the earhook 13 of the eyeglasses. In order to make the sensor at the nose pad 14 more fit to the human body, the nose pad 14 is connected to the frame 11 by an elastic support.
In the present invention, the superficial temporal artery sensor 22 is a pressure sensor; the angular artery sensor 21 and the posterior ear artery sensor 23 are PPG sensors. The pressure sensor is higher than the PPG sensor in the aspect of sensitivity, but the horn artery and the posterior auricular artery are far away from the epidermis, and measurement is inconvenient through the pressure sensor, so the PPG sensor is selected. The superficial temporal artery is closer to the epidermis, and the pulse waves are collected by a pressure sensor.
The sensors are connected to the main board (built in the glasses frame) through flexible PCB cables to communicate with the controller. The main components of the mainboard of the invention are a PSoC microcontroller (Cypress CY8C5888LTI-LP 097) based on ARM Cortex m3 and a controller of the invention, an external real-time clock (Maxim Integrated DS1344D-33+ T &R), a 3-axis 12-bit digital accelerometer (NXP 8652FCR 1) and an inertial sensor of the invention, a micro USB connector for charging and transmitting data, a micro SD card slot for inserting SD card to store data, a switch and a synchronous battery for supplying power to the external real-time clock. The present invention uses microchip technology charger IC (MCP 73832-2 ACI/MC). A305 mAmp-hour lithium polymer battery powered device, which can run for about 15 hours.
The PPG sensor of the present invention includes a photodiode (Broadcom APDS-9008), a corresponding spectrally matched green LED light source, a small opamp IC (Microchip Technology MCP 6001T-I/OT) and amplification and filtering circuitry. The filter circuit is designed to adapt the gain to changes in brightness intensity and to eliminate reflected dc offset and to mask frequencies above 50 Hz in the original signal. The photodiode on the sensor board is connected directly to the controller through a flexible PCB cable, where a PSoC (programmable system on a chip) integrated 12-bit ADC samples the reflected signal in a synchronized manner.
To obtain an optimal signal, the sensor needs to be as close to the skin as possible. Also, the LED light source needs to be attached to the skin to prevent cross-lights from leaking directly into the sensor. Covering both components in a cloud of clear glue can result in internal reflections, and surface covering can result in internal reflections, both of which can reduce the signal-to-noise ratio. At the same time, the sensor needs to resist water damage to prevent sweat erosion; and the surface is smooth enough not to cause itching or scratching of the skin.
In order to alleviate or solve the problems to a certain extent, in the invention, the photodiode and the LED light source are encapsulated by potting adhesive, and the adhesive surface is flush with the top surfaces of the photodiode and the LED light source. This allows for smooth sealing of all components against direct exposure while keeping the distance between the LED light source and the user's skin or the photodiode and the user's skin at zero.
In operation, the device continuously samples data from inertial sensors (which may be integrated with the motherboard) to record user actions, and measures the amount of reflected light from pressure sensors or photodiodes to obtain pulse signals. The controller samples the reflections at 5000 hertz and the inertial measurements at 200 hertz.
The controller buffers all measurement streams as long as possible (about 1.5 seconds) and then dumps them into the SD card for additional offline analysis along with time stamps obtained from a separate real time clock on board. To achieve approximately 15 hours of operation, the sensing needs to be cycled on a duty cycle such that the device senses 4 minutes every 5 minutes throughout the life cycle of the battery. In the remaining minute, the LED light source is turned off, the ADC does not sample the reflected level, and the controller enters a soft sleep state.
As shown in fig. 2, the present invention further provides a blood pressure monitoring method, which can continuously measure the blood pressure of a user, and is applied to the wearable blood pressure monitoring device capable of continuously tracking and measuring the blood pressure of the user, including:
s1, converting pulse signals of pulse waves at the collected angular artery, superficial temporal artery and posterior auricular artery into corresponding signal curves and main frequencies, and verifying whether the main frequencies of the angular artery, the superficial temporal artery and the posterior auricular artery are the same frequency or not.
In some embodiments, after the pulse signal of the pulse wave is acquired, filtering is required. According to the invention, a 5-order 8 Hz Butterworth low-pass filter and a 2-order 0.4 Hz Butterworth high-pass filter are adopted to filter all three signals (the three signals are acquired from the corner artery, the superficial temporal artery and the posterior auricular artery). The filtering makes the signal smoother, eliminates dc offset that may be present temporarily, and produces identifiable pulse reflections.
The three filtered signals are subjected to fast Fourier transform to extract a signal curve S of the pulse signal at the angular artery ang Signal curve S of pulse signal at superficial temporal artery sta Signal curve S of pulse signal at posterior auricular artery occ And the dominant frequency f of the pulse signal at the angular artery ang Dominant frequency f of pulse signal at superficial temporal artery sta Dominant frequency f of pulse signal at posterior auricular artery occ . In order to ensure that the three signals are homologous, i.e. from the same user, co-frequency verification is required. The method for verifying the main frequency co-frequency of the angular artery, the superficial temporal artery and the posterior auricular artery comprises the following steps:
using dominant frequency of any of the angular artery, superficial temporal artery and posterior auricular artery as reference value, e.g. using dominant frequency f of angular artery ang Is a reference value.
Obtaining the dominant frequency f of the other two arteries sta 、f occ And a reference value f ang The absolute value of the difference between them, and compare it with a preset same-frequency threshold, i.e. | f ang − f sta | <ε and | f ang − f occ | <Epsilon; if the two absolute values are smaller than the same-frequency threshold epsilon, determining the same frequency of the angular artery, the superficial temporal artery and the posterior auricular artery; wherein the same frequency threshold epsilon is in the order of magnitude of 10 -1 Is a number of experience ofThe value is obtained.
In addition, in this step, the signal is segmented and fast fourier transformed, and the time window for segmentation is 15 seconds in this embodiment.
S2, segmenting the pulse signal curve through a time window; detecting a peak of any one signal curve in each section of signal (namely, using the detected any peak as a target peak), and finding out a peak of the other two signal curves which is closest to the peak, and a trough which is in front of the peak and is closest to the peak in the three signal curves; the time corresponding to the wave trough is the starting time stamp of the pulse wave in the time window, and the time corresponding to the three wave crests is the pulse arrival time of the three pulse waves in the time window.
The step is also a segmentation processing mode, and the time window for segmentation processing is 0.2 seconds. FIG. 3 is an example of signal curves for a time window, wherein the three signal curves are the angular artery signal curve S ang Temporal superficial artery signal curve S sta Posterior auricular artery signal curve S occ . First, a peak of a signal curve is found, in this embodiment, the same angular artery signal curve S is used ang For example, any peak of the signal curve, such as the first peak, is sought, such as the peak with the symbol in the figure. Then, the peaks of the other two signals and a valley closest to the signal are found, wherein the closest means the shortest distance in the x-axis direction. As shown, with S ang Superficial temporal artery signal curve S with nearest wave peak sta Posterior auricular artery signal curve S occ Shown in dashed lines. The time corresponding to the three wave crests is the pulse signal arrival angle arterial time t ang Time t of pulse signal reaching superficial temporal artery sta Time t of pulse signal arriving at posterior ear artery occ . It is also necessary to find the trough closest to the star-numbered peak that precedes it, i.e., the trough shown in the figure. The time corresponding to the trough is the starting timestamp of the time window and is used for marking the time window.
S3, eliminating the pulse signals interfered by the noise.
The impulse signal disturbed by the noise affects the accuracy of the subsequent calculation, and therefore needs to be eliminated. In the invention, the pulse signals which are eliminated from noise interference comprise movement interference elimination and non-movement interference elimination;
s31 motion disturbance rejection:
and segmenting the pulse signal curve by taking n seconds before and after the fluctuation of the pulse wave of one time as a time window, judging whether the inertia measurement in the time window exceeds a preset inertia threshold value, and if so, excluding the pulse signal in the time window.
During movement, the contact between the sensor interface and the human body is unstable, so the acquired data needs to be eliminated. The step also needs to be segmented, and n seconds before and after one pulse wave fluctuation, such as 1 second, is taken as a time window. Thus, if the inertial measurement in any direction of xyz within the time window exceeds the threshold, the user is considered to be in large motion or not wearing smart glasses at all, and therefore the pulse signal within the time window needs to be excluded.
S32 non-motion interference rejection:
performing phase correlation on pulse signal curves of an angular artery, a superficial temporal artery and a posterior auricular artery to obtain maximum amplitude and evaluate the best matching phase deviation; and if the maximum amplitude is lower than the amplitude threshold value or the phase value distribution exceeds the distribution threshold value, excluding the pulse signals in the time window corresponding to the timestamp with the maximum amplitude.
Even without motion noise interference, the signal may be interfered with by other factors. Therefore, other noise interference judgment is needed. The waveform after noise interference is less similar to the pulse wave, so in this step, the signal curve can be phase-correlated. The phase correlation means that one curve is static, and the other curve is moved from left to right in the coordinate system, when the two curves are completely matched, the correlation is the highest, and the distance of the curve movement is the best matching phase offset. For example, curve S of angular artery signal ang Temporal superficial artery signal curve S sta Performing phase correlation, and then obtaining an angular artery signal curve S ang Curve S of signal of posterior ear artery occ Phase correlation is performed. The phase correlation may determine a maximum amplitude and evaluate a best match phase offset, and then determine whether the maximum amplitude is below an amplitude threshold or a phase value distribution exceeds a distribution threshold, and then exclude the pulse signal within a time window corresponding to a timestamp where the maximum amplitude is located.
And S4, obtaining the time difference between the other two arrival times and the reference arrival time by taking the arrival time of the pulse wave at any one of the angular artery, the superficial temporal artery and the posterior auricular artery as the reference arrival time.
Still using the time of arrival angle of pulse wave to artery as the reference arrival time, using the formula
Calculating two time differences, wherein
The time difference between the arrival angle of the pulse wave and the arrival time of the pulse wave at the superficial temporal artery,
the time difference between the pulse wave arrival angle artery and the pulse wave arrival behind the ear artery.
And S5, establishing a blood pressure model by using the two time differences.
After two time differences are calculated, a blood pressure model of the user can be established by the principle that a straight line is determined by two points:
(ii) a Wherein BP is blood pressure value, PTT is time difference, K 1 Is the slope, K 2 Is the intercept.
In some embodiments, the angle artery is selected for modeling as a reference, and accordingly, the pulse wave arrival angle can be selected for PTT hereinTime difference PTT of arrival of artery and pulse wave at superficial temporal artery AA-STA Of course, the time difference PTT between the arrival angle of the pulse wave and the arrival time of the pulse wave at the posterior auricular artery can also be selected AA-OA . A large number of experiments show that the PTT is selected AA-STA The obtained blood pressure value is more accurate; and if the superficial temporal artery has noise or sensor has a problem, the PTT can be selected AA-OA . Specifically, whether noise occurs at the superficial temporal artery position (for example, if it is detected that the main frequency at the superficial temporal artery is different from the main frequency at the angular artery and the active frequency at the posterior auricular artery, it is indicated that noise occurs) or a sensor has a problem can be determined through the common-frequency detection in step S1 and the noise interference elimination in step S3.
And S6, calibrating the blood pressure model by using the real blood pressure value.
The specific method for calibrating comprises the following steps:
wearing the intelligent glasses capable of continuously tracking and measuring the blood pressure of the user, and acquiring the time difference by using the intelligent glasses capable of continuously tracking and measuring the blood pressure of the user;
simultaneously acquiring a current real blood pressure value;
the time difference and the real blood pressure value are brought into a model to calculate the slope K 1 And intercept K 2 . Because the unknown number is two, several groups of data can be added to establish an equation set, thereby solving the slope K 1 And intercept K 2 The value of (c). Then the slope K is measured 1 And intercept K 2 And carrying the model into a model to finish the calibration of the model.
In some embodiments, the slope K of the line is determined by the slope of each person's corresponding line 1 And intercept K 2 Almost certainly, therefore, calibration may be performed before a formal blood pressure measurement is performed. For example, before the user uses the wearable device for measuring blood pressure for the first time, the calibration is performed according to the steps (i.e. the slope K is determined first) 1 And intercept K 2 And then blood pressure is measured). Of course, calibration may be performed before each use of the measured blood pressure.
In some embodiments, the real blood pressure value can be obtained by various existing standard blood pressure measurement methods, for example, when a user uses the wearable device for the first time to perform calibration, the wearable device of the present invention and the conventional cuff-type blood pressure monitoring device are worn to obtain two blood pressure values respectively, and then the two blood pressure values are respectively substituted into the blood pressure model to calculate the slope and the intercept. Of course, in other embodiments, multiple measurements may be made and then averaged over multiple slopes and intercepts.
And S7, inputting the acquired time difference into a blood pressure model so as to obtain a blood pressure value.
The time difference acquired by wearing the intelligent glasses provided by the invention is input into a blood pressure model of the user, and then the blood pressure value of the user can be obtained. Because the acquisition of the pulse wave is continuously carried out, the calculation of the subsequent blood pressure is also continuous, thereby realizing the continuous monitoring of the blood pressure of the user.
In some embodiments, it is preferable that the blood pressure value is calculated by substituting a time difference between the reference arrival time and the arrival time of the pulse wave at the first priority into the above blood pressure model. For example, taking the angular artery as a reference, the blood pressure value of the user is calculated by substituting the time difference between the reference arrival time and the pulse wave arrival time at the superficial temporal artery into the blood pressure model.
In other embodiments, the two time differences are respectively substituted into the blood pressure model, and an average value of the two calculated blood pressure values is used as the blood pressure value of the user.
For convenience of description, the previous and subsequent steps are consistent, in this embodiment, the angular artery is taken as an example, and the angular artery is taken as a reference, for example, the same frequency comparison in step S1, the acquisition of the start time stamp in step S2, the elimination of the non-motion interference in step S3, the acquisition of the time difference in step S4, the establishment of the blood pressure model in step S5, and the like are performed, but the superficial temporal artery or the posterior auricular artery is not taken as a reference.
It should be noted that, for example, after the peak of the superficial temporal artery is selected as the marker in step S2 to find the time difference, the acquisition of the timestamp in step S4 and the establishment of the blood pressure model in step S5 both need to use the superficial temporal artery as a reference. Especially in step S5, with different arteriesModel built for benchmarking K 1 And K 2 The values of (a) are different, so that the time difference measured at the time of subsequent use also needs to be referenced to the same artery as the one at the time of modeling.
Referring to fig. 4, the present invention further provides another blood pressure monitoring method, which is based on the wearable blood pressure monitoring device, and before blood pressure monitoring is performed each time or before a user uses the wearable blood pressure monitoring device for the first time, a monitoring mode is configured in advance, that is, a reference signal or a reference position is set, and then a blood pressure model of the user is obtained by using steps S1 to S6 in the above embodiment, that is, device initialization is performed. After the device is initialized, the blood pressure monitoring is performed, i.e. the above steps S1-S4 are performed.
In contrast, in step S4, only the time difference between the pulse wave arrival time at the first priority and the reference arrival time among the two non-reference sites is calculated (for example, when the angular artery is used as a reference, only the time difference between the pulse wave arrival time at the superficial temporal artery belonging to the first priority and the reference arrival time is calculated).
And then substituting the time difference into a pre-constructed blood pressure model to calculate the blood pressure of the user.
In some embodiments, the user configures, i.e. sets a reference position (e.g. referenced at the angular artery) or a reference signal (i.e. pulse wave signal at the reference position), through a user interface of the client on the mobile terminal, e.g. a mobile phone, in data communication with the wearable device.
Of course, in some embodiments, if the pulse signal at the first priority is noisy or the sensor is in trouble, the time difference between the reference arrival time and the pulse wave arrival time at the second priority is calculated and then substituted into the blood pressure model to calculate the blood pressure value of the user. For example, when a pulse signal of a pulse wave in a superficial temporal artery of a first priority level has noise or a sensor in the superficial temporal artery has a problem with reference to a corner artery, a time difference between a reference arrival time and a pulse wave arrival time in a posterior auricular artery is calculated and substituted into the blood pressure model to calculate a blood pressure value.
Specifically, as described above, it can be determined whether the signal at the first priority is noisy (for example, if different frequencies are different, it is said that there is noise) or a problem occurs in the sensor (for example, the sensor is damaged, or the sensor is not stably contacted with the corresponding portion, etc.) through the common-frequency detection in step S1 and the noise interference elimination in step S3.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising a … …" does not exclude the presence of another identical element in a process, method, article, or apparatus that comprises the element.
While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (10)
1. A wearable blood pressure monitoring device which characterized in that: the wearable device is provided with an angular artery sensor, a superficial temporal artery sensor and a posterior auricular artery sensor which are used for respectively collecting pulse waves at the angular artery, the superficial temporal artery and the posterior auricular artery of a user; the wearable device is also provided with an inertial sensor for monitoring the head motion state of the user; further comprising a controller integrated on the wearable device for processing the acquired pulse wave signals to calculate a blood pressure value of the user; the controller is used for processing the pulse wave signal that gathers, specifically includes:
converting the pulse signals of the pulse waves at the angular artery, the superficial temporal artery and the posterior auricular artery into corresponding signal curves and main frequencies, and verifying whether the main frequencies of the angular artery, the superficial temporal artery and the posterior auricular artery have the same frequency or not;
segmenting the signal profile of the pulse signal through a time window; detecting a target peak of any signal curve in each section of signal, and finding out a peak of the other two signal curves which is closest to the target peak of any signal curve and a trough which is closest to the target peak before the target peak; the time corresponding to the wave trough is the starting timestamp of the pulse wave, and the time corresponding to the three wave crests is the pulse arrival time of the three pulse waves in the time window;
eliminating the pulse signals interfered by noise;
obtaining the time difference between the pulse wave arrival time of the rest two parts and the reference arrival time by taking the pulse wave arrival time of any one of the angular artery, the superficial temporal artery and the posterior auricular artery as the reference arrival time;
establishing a blood pressure model by utilizing the two time differences;
calibrating the blood pressure model by using the real blood pressure value of the user;
inputting the obtained time difference into the calibrated blood pressure model, thereby obtaining the blood pressure value of the user.
2. A wearable blood pressure monitoring device according to claim 1, wherein: the wearable device is glasses, and the angular artery sensor is arranged on a nose pad of the glasses; the superficial temporal artery sensor is arranged on a temple of the glasses; the posterior ear artery sensor is arranged on an ear hook of the glasses.
3. A wearable blood pressure monitoring device according to claim 2, wherein: the nose pad is connected with the glasses frame by an elastic support.
4. A wearable blood pressure monitoring device according to claim 1, characterized in that: the superficial temporal artery sensor is a pressure sensor; the angle artery sensor and the posterior ear artery sensor are PPG sensors.
5. A wearable blood pressure monitoring device according to claim 4, wherein: the PPG sensor comprises a photodiode and an LED light source; the photodiode and the LED light source are encapsulated by glue pouring, and the glue surface is flush with the top surfaces of the photodiode and the LED light source.
6. The wearable blood pressure monitoring device according to claim 1, wherein the method for verifying whether the main frequencies of the angular artery, the superficial temporal artery and the posterior auricular artery are the same frequency comprises:
respectively acquiring absolute values of differences between the main frequencies of the other two arteries and a reference value by taking the main frequency of any one of the angular artery, the superficial temporal artery and the posterior auricular artery as a reference value, comparing the two absolute values with a preset common-frequency threshold value, and judging the common frequency of the angular artery, the superficial temporal artery and the posterior auricular artery if the two absolute values are smaller than the common-frequency threshold value; the common frequency threshold value is in the order of magnitude of 10 -1 The empirical value of (2).
7. The wearable blood pressure monitoring device of claim 1, wherein the pulse signals excluded from being disturbed by noise include motional disturbance exclusion and non-motional disturbance exclusion;
the motion disturbance rejection comprises:
segmenting a signal curve of the pulse signal by taking n seconds before and after one pulse wave fluctuation as a time window, judging whether inertia measurement in the time window exceeds a preset inertia threshold value, and if so, excluding the pulse signal in the time window;
the non-motion interference exclusion comprises:
performing phase correlation on the signal curves of the pulse signals of the angular artery, the superficial temporal artery and the posterior auricular artery to obtain maximum amplitude and evaluate the best matching phase offset; and if the maximum amplitude is lower than a preset amplitude threshold value or the phase value distribution exceeds a preset distribution threshold value, excluding the pulse signal in the time window corresponding to the timestamp where the maximum amplitude is located.
8. The wearable blood pressure monitoring device of claim 1, wherein the blood pressure model is
Wherein, BP is the blood pressure value, PTT is the time difference, K 1 Is the slope, K 2 Is the intercept.
9. The wearable blood pressure monitoring device of claim 8, wherein the method of calibrating the blood pressure model with the user's true blood pressure value comprises:
the user wears the wearable blood pressure monitoring device and obtains the time difference by using the wearable blood pressure monitoring device;
simultaneously acquiring the current real blood pressure value of the user;
substituting the time difference and the real blood pressure value into the blood pressure model to calculate the slope K 1 And said intercept K 2 To obtain the calibrated blood pressure model.
10. A method for processing pulse wave signals is characterized in that the method for processing the pulse wave signals is based on a wearable blood pressure monitoring device, the wearable blood pressure monitoring device comprises wearable equipment, and the wearable equipment is provided with an angular artery sensor, a superficial temporal artery sensor and a posterior auricular artery sensor which are respectively used for collecting pulse waves at the angular artery, the superficial temporal artery and the posterior auricular artery of a user, and an inertial sensor used for monitoring the head movement state of the user; the wearable device is integrated with the controller for processing the acquired pulse wave signals; the method comprises the following steps:
acquiring pulse signals of pulse waves at the angular artery, the superficial temporal artery and the posterior auricular artery through the angular artery sensor, the superficial temporal artery sensor and the posterior auricular artery sensor;
converting the pulse signals into corresponding signal curves and main guide frequencies through the controller, and verifying whether the main guide frequencies of the angular artery, the superficial temporal artery and the posterior auricular artery are the same in frequency;
the controller carries out segmented processing on the signal curve through a time window to obtain a starting time stamp of the pulse wave and the pulse arrival time of the pulse wave in the time window; the method for obtaining the start time stamp of the pulse wave and the pulse arrival time of the pulse wave in the time window specifically includes: segmenting the signal curves through a time window by the controller, detecting a target peak of any signal curve in each segment of signals, and finding out a peak of the other two signal curves which is closest to the target peak of any signal curve and a trough which is closest to the target peak before the target peak; the time corresponding to the wave trough is the starting timestamp of the pulse wave, and the time corresponding to the three wave crests is the pulse arrival time of the three pulse waves in the time window;
rejecting, by the controller, the pulse signal disturbed by noise;
establishing a blood pressure model of the user through the controller, wherein the specific modeling method comprises the following steps: obtaining the time difference between the pulse wave arrival time of the rest two parts and the reference arrival time by taking the pulse wave arrival time of any one of the angular artery, the superficial temporal artery and the posterior auricular artery as the reference arrival time;
establishing a blood pressure model by utilizing the two time differences;
and calibrating the blood pressure model by using the real blood pressure value to obtain the calibrated blood pressure model.
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