KR102391685B1 - Earphone for monitoring blood pressure and method for monitoring blood pressure using the same - Google Patents

Abstract

The present invention relates to an earphone for blood pressure monitoring and a blood pressure monitoring method using the same. The earphone for monitoring blood pressure according to an embodiment of the present invention includes a body part, a force sensor, a sensor part including a photodiode and a light emitting diode, a communication part for wired/wireless communication with an external device, and a couple with the body part, the sensor part and the communication part and a control unit for estimating the user's blood pressure by processing a photoplethysmography (PPG) signal detected through the sensor unit.

Description

Earphone for blood pressure monitoring and blood pressure monitoring method using the same

The present invention relates to an earphone for blood pressure monitoring and a blood pressure monitoring method using the same. More particularly, it relates to a system capable of monitoring a user's blood pressure in real time through an earphone capable of measuring blood pressure using the user's photoplethysmography (PPG).

With the recent rapid development of science and technology, the quality of life for the entire human race is improving, and many changes have occurred in the medical environment. In the past, after taking medical images such as X-ray, CT, and fMRI at a hospital, you had to wait several hours or days to read the image.

However, since about 10 years ago, a picture archive communication system (PACS) has been introduced, in which medical images are taken and then the images are transmitted to the monitor screen of the radiologist and can be read immediately. In addition, ubiquitous health care-related medical devices that allow you to check your blood sugar and blood pressure anytime and anywhere without going to a hospital are widely available, and blood sugar patients or hypertensive patients are using them at their homes or offices.

In particular, in relation to hypertension, which is a major cause of various diseases and whose prevalence is increasing, there has been a need for a system that continuously measures blood pressure and informs it in real time, and various types of studies related thereto have been attempted.

As an example of a blood pressure measurement method, a blood pressure sensor is inserted into the pulmonary artery of chronic heart disease patients to measure blood pressure in real time, and then transmits it to the attending physician using wireless communication. Ubiquitous Healthcare (u-Health, ubiquitous Healthcare), which monitors changes and delivers prescriptions to patients, has been introduced, and this technology has the advantage of dramatically reducing the number of times patients visit the hospital. However, while this technique can measure blood pressure continuously and accurately, it has disadvantages such as difficulty in operation and risks of arterial damage and infection because it involves an invasive blood pressure measurement method.

Therefore, research on a system capable of measuring blood pressure in real time in a non-invasive manner without inserting a blood pressure measurement sensor into an arterial blood vessel has been continuously conducted. In addition, a study was conducted to monitor blood pressure in a ubiquitous environment and then biofeedback the measured blood pressure to the user so that the user can control the blood pressure.

On the other hand, there has also been a technique that applies a method of measuring blood pressure by attaching a cuff to an arm. There was a problem that was difficult to measure.

In particular, in order to notify the risk of high blood pressure in a short time so that the patient can receive emergency treatment in a short time, the patient can prevent and manage hypertension by continuously measuring blood pressure as well as notifying the blood pressure measurement result in real time. The introduction of technology to make it possible was requested.

Photoplethysmography (PPG) refers to a pulse wave signal measured in a peripheral blood vessel when ejected blood is delivered to the peripheral blood vessel during ventricular systole. A photoplethysmographic wave (PPG) signal may be measured using optical properties of a living tissue. For example, after attaching a PPG sensor module (optical sensor module) that can measure a pulse wave signal to a location where peripheral blood vessels are distributed, such as a fingertip or toe, the change in blood flow, which is a change in the volume of peripheral blood vessels, is converted into a change in light volume and measured. can

The photoplethysmography (PPG) signal can be measured by irradiating red light generated from the light emitting part of the PPG sensor module to the human body, and then observing the change in the amount of light reflected from the human body and received by the light receiving part. The photoplethysmography (PPG) signal does not use only the photoplethysmographic wave (PPG) signal alone, but analyzes the correlation between the photoplethysmogram (PPG) signal and the electrocardiogram (ECG) signal to determine the pulse wave transit time (PTT, Pulse Transit Time) or pulse wave. Information such as transmission speed (PWV, Pulse Wave Velocity) can be extracted and used for cardiovascular disease diagnosis.

On the other hand, the technique of measuring an electrocardiogram (ECG), which is one of biosignals, using an earphone according to the prior art does not collect biosignals simply by wearing an earphone for measuring biosignals, but a separate device is used to measure the biosignals. There was a problem in that it was inconvenient because it had to be attached to a place (the upper arm of the earphone wearer).

In order to solve the above problems, an embodiment of the present invention

An object of the present invention is to provide an earphone having a sensor unit for monitoring blood pressure without a separate device for collecting bio-signals.

Another object of the present invention is to provide an earphone for blood pressure monitoring capable of more accurately estimating blood pressure based on data detected from a force sensor and data detected from a photodiode.

The problems of the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above object, an embodiment of the present invention is a body portion; a sensor unit including a force sensor, a photodiode, and a light emitting diode; a communication unit for wired/wireless communication with an external device; and a control unit coupled to the body unit, the sensor unit, and the communication unit, and estimating the user's blood pressure by processing a photoplethysmography (PPG) signal detected through the sensor unit.

In addition, in an embodiment of the present invention, the control unit is characterized in that the PPG signal is detected in the anti-tragus region of the user's ear through the photodiode.

In addition, in an embodiment of the present invention, the light emitting diode is characterized in that it is composed of at least two or more light emitting diodes that emit light of different wavelengths.

In addition, in an embodiment of the present invention, the control unit detects a DC component signal corresponding to the force data through the force sensor, detects an AC component signal corresponding to the PPG signal through the photodiode, and the detected It is characterized in that the blood pressure is estimated based on the DC component signal and the detected AC component signal.

In addition, in an embodiment of the present invention, the sensor unit is characterized in that it is provided at a predetermined angle with respect to the center line of the body unit.

In addition, in an embodiment of the present invention, the body portion, the force sensor, the light emitting diode and the photodiode is mounted further comprises a wing portion and a close contact adjustment unit, the control unit, by controlling the close contact adjustment unit, the wing It is characterized in that the degree of protrusion from the body portion is adjusted.

In addition, in an embodiment of the present invention, the body portion further includes an angle adjusting unit, and the control unit controls the angle adjusting unit, characterized in that the wing portion adjusts the angle formed with respect to the body portion.

In addition, in an embodiment of the present invention, the distance between the photodiode and the light emitting diode is characterized in that it forms a 3mm to 6mm.

In addition, in an embodiment of the present invention, the control unit sets a predetermined threshold value for the force data, and processes the PPG signal in response to the force data falling below the set threshold value. .

In addition, in an embodiment of the present invention, the control unit is characterized in that the blood pressure monitoring is started in any one of the user aware mode and the user non-aware mode.

According to an embodiment of the present invention, there are one or more of the following effects.

First, unlike the conventional cuff-type blood pressure diagnosis device for diagnosing hypertension, there is an effect that the user can measure the blood pressure without realizing any discomfort by using the no-pressure method through the earphone.

Second, it is possible to measure blood pressure while on the move because it uses a small size in-ear mounting type that is built into the body of the earphone, and it is possible to measure blood pressure while performing daily life in parallel.

Third, it is possible to provide various medical services due to sudden fluctuations because blood pressure, which can be measured one-time in the prior art, can be continuously measured. Furthermore, it is possible to predict the risk of cardiovascular disease due to blood pressure variability (BPV).

1 is a view for explaining a portion where a user's blood pressure is monitored through an earphone for blood pressure monitoring according to an embodiment of the present invention.
2 is a block diagram of an earphone for blood pressure monitoring according to an embodiment of the present invention.
3 is a cross-sectional view of a sensor unit of an earphone for blood pressure monitoring according to an embodiment of the present invention.
4 is a cross-sectional view of a sensor unit of an earphone for blood pressure monitoring according to an embodiment of the present invention.
5 is a diagram illustrating a method of detecting a PPG signal by a sensor unit of an earphone for blood pressure monitoring according to an embodiment of the present invention.
6 is a diagram illustrating a structure in which a sensor unit of an earphone for blood pressure monitoring is provided in a body portion according to an embodiment of the present invention.
7 is a diagram illustrating a structure in which a sensor unit of an earphone for blood pressure monitoring is provided in a body portion according to an embodiment of the present invention.
8 is a diagram illustrating a structure in which a sensor unit of an earphone for blood pressure monitoring is provided in a body portion according to an embodiment of the present invention.
9 is a diagram illustrating a signal quality index according to a distance between a photodiode and a light emitting diode of an earphone for blood pressure monitoring.
10 is a diagram illustrating a PPG signal for each wavelength according to a change in pressure detected by a force sensor of an earphone for blood pressure monitoring according to an embodiment of the present invention.
11 is a diagram illustrating a blood pressure value estimated by an earphone for blood pressure monitoring through a force sensor according to an embodiment of the present invention.
12 shows a time domain graph of a PPG signal.
13 is a flowchart illustrating a blood pressure monitoring method of an earphone according to an embodiment of the present invention.

Hereinafter, the embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings, but the same or similar components are assigned the same reference numbers regardless of reference numerals, and redundant description thereof will be omitted. The suffixes "module" and "part" for components used in the following description are given or mixed in consideration of only the ease of writing the specification, and do not have distinct meanings or roles by themselves. In addition, in describing the embodiments disclosed in the present specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in this specification, the detailed description thereof will be omitted. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and the technical idea disclosed herein is not limited by the accompanying drawings, and all changes included in the spirit and scope of the present invention , should be understood to include equivalents or substitutes.

Terms including an ordinal number such as 1st, 2nd, etc. may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

When an element is referred to as being “connected” or “connected” to another element, it is understood that it may be directly connected or connected to the other element, but other elements may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle.

The singular expression includes the plural expression unless the context clearly dictates otherwise.

In the present application, terms such as “comprises” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

[anti-tragus region and PPG signal]

1 is a view for explaining a portion where a user's blood pressure is monitored through an earphone for blood pressure monitoring according to an embodiment of the present invention.

Blood pressure can be measured in various parts of the body, such as the brachial arteries in the ears, wrists, and elbows, the carotid arteries in the fingers, neck, and plantar arteries in the heels. However, since the signal quality of the blood pressure measured in each body part is different from each other, the method of estimating the blood pressure from the measured signal may be different. The earphone for blood pressure monitoring according to an embodiment of the present invention provides a method for monitoring blood pressure in a user's ear.

First, with reference to FIG. 1 , a region where the earphone for monitoring blood pressure monitors the user's blood pressure will be described. The human (user) ear is largely divided into an outer ear, a middle ear, and an inner ear. 1 shows the outer ear, the outer ear is a triangular fossa, crus of helix, ear beads (tragus), intertragic notch (intertragic notch), daeju (anti-tragus), Daeryun (anti-tragus) -helix) and the auricle (helix).

In particular, the anti-tragus of the ear has more blood vessels than other regions. Accordingly, the earphone according to the embodiment of the present invention is designed to detect a photoplethysmography (PPG) signal for blood pressure estimation from the great migration region through the sensor unit.

A photoplethysmography (PPG) signal refers to a pulse wave signal measured in a peripheral blood vessel when ejected blood is delivered to the peripheral blood vessel during ventricular systole. A photoplethysmographic wave (PPG) signal is measured using the optical properties of a living tissue.

2 is a block diagram of an earphone for blood pressure monitoring according to an embodiment of the present invention. The earphone 200 for blood pressure monitoring according to an embodiment of the present invention includes a body 210 , a sensor 220 , a communication unit 230 , and a control unit 240 .

The body part 210 forms the body of the earphone 200 according to an embodiment of the present invention, and may have various shapes. The body portion 210 may include additional components in order to attach the earphone 200 to the large migration region of the ear. In this regard, it will be described later in detail with reference to FIGS. 7 to 8 .

The sensor unit 220 includes a force sensor 221 , a photodiode 223 and a light emitting diode 222 , and is provided in the body unit. The sensor unit 220 detects the PPG signal from the large migration region of the user's ear. Meanwhile, the sensor unit 220 may further include a printed circuit board 224 .

The communication unit 230 may include one or more modules that enable communication between the earphone 200 and the external device 300 according to an embodiment of the present invention. In addition, the communication unit 230 may include one or more modules for connecting the earphone 200 to one or more networks.

The control unit 240 is coupled to the body portion 210 , the sensor unit 220 and the communication unit 230 of the earphone 200 according to an embodiment of the present invention, and controls the sensor unit 220 and the communication unit 230 . Thus, the PPG signal detected from the large migration region of the user's ear is processed.

The external device 300 is a mobile phone, a smart phone, a laptop computer, a digital broadcasting terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation system, a slate PC, a tablet A tablet PC (PC), an ultrabook, a wearable device, for example, a watch-type terminal (smartwatch), a glass-type terminal (smart glass), a head mounted display (HMD), etc. may be included.

Meanwhile, the earphone for blood pressure monitoring according to an embodiment of the present invention may be linked with a service system (not shown) through the communication unit 230 . The service system may provide a warning message and feedback to the user by comparing the blood pressure data of another user with the user's blood pressure data.

[Sensor part of GENERAL TYPE]

3 is a cross-sectional view of a sensor unit of an earphone for blood pressure monitoring according to an embodiment of the present invention. More specifically, FIG. 3 is a diagram illustrating the structure of a sensor unit of an earphone capable of sensing a PPG signal in a body part other than the ear.

Referring to FIG. 3A , the sensor unit 220 of the earphone for blood pressure monitoring according to an embodiment of the present invention includes a force sensor 221 , a light emitting diode 222 and a photo diode. (Photo diode, 223). The force sensor 221 , the light emitting diode 222 , and the photo diode 223 are coupled to a printed circuit board 224 to receive power required for driving.

The control unit 240 determines whether the earphone is in close contact with the user's ear (more specifically, large migration) with an appropriate pressure through the force data sensed by the force sensor 221 . When the earphone according to an embodiment of the present invention is in close contact with the large migration area with a pressure within a predetermined range, it is possible to obtain an optimal PPG signal for blood pressure monitoring. The correlation between the force data and the PPG signal will be described later in detail with reference to FIGS. 10 to 11 .

The light emitting diode 222 is a device that converts electrical energy into light energy, and the sensor unit 200 according to an embodiment of the present invention includes at least one light emitting diode 222 .

Referring to FIG. 3B , the light emitting diode 222 according to the embodiment of the present invention may be composed of at least two light emitting diodes emitting light of different wavelengths.

For example, the light emitting diode 222 is a first light emitting diode 222-1 and a second light emitting diode 222-2 emitting light having a wavelength of 400-700 nm corresponding to visible light, and infrared rays (IR). A third light emitting diode 222 - 3 emitting light of a corresponding wavelength of 700 nm or more may be included.

Since optical properties of living tissue, such as absorption and reflection of light, vary according to wavelength, the present invention provides a method for monitoring blood pressure based on multi-wavelength. In this regard, it will be described later in detail with reference to FIG. 5 .

The photodiode 223 is a device that converts light energy into electrical energy, and detects light to generate an electrical signal. Light generated from the light emitting diode 222 is absorbed and reflected by a living tissue (eg, large migration), and is detected by the photodiode 223 .

Meanwhile, the distance between the light emitting diode 222 and the photodiode 223 of the sensor unit 220 according to an embodiment of the present invention affects the quality of the PPG signal sensed by the photodiode 223 . Accordingly, it is necessary to maintain an optimal distance between the light emitting diode 222 and the photodiode 223 . In this regard, it will be described later in detail with reference to FIG. 4 below.

[Sensor part of EAR TYPE]

4 is a cross-sectional view of a sensor unit of an earphone for blood pressure monitoring according to an embodiment of the present invention. More specifically, FIG. 4 is a diagram illustrating the structure of a sensor unit of an earphone capable of sensing a PPG signal in an ear (eg, large migration).

Referring to FIG. 4A , the sensor unit 220 of the earphone for blood pressure monitoring according to an embodiment of the present invention is provided at a predetermined angle with respect to the vertical center line 211 of the body (not shown). can be This is for the sensor unit 220 of the earphone 200 to be in close contact with the large migration region of the ear, and the predetermined angle is, for example, about 15 to 75°.

As described above, since more blood vessels are distributed in the large migration region of the ear than in other regions, the earphone according to the embodiment of the present invention detects the PPG signal from the large migration region of the ear through the photodiode 223 .

4 (b), the photodiode 223 of the sensor unit 220 of the earphone according to the embodiment of the present invention is located in the first area corresponding to about 15 to 75 ° in the great migration direction, the sensor The force sensor 221 of the unit 220 is located in the second area except for the first area.

Meanwhile, the distance between the light emitting diode 222 and the photodiode 223 of the sensor unit 220 according to an embodiment of the present invention affects the quality of the PPG signal sensed by the photodiode 223 . Accordingly, it is necessary to maintain an optimal distance between the light emitting diode 222 and the photodiode 223 .

Accordingly, the photodiode 223 and the light emitting diode 222 according to an embodiment of the present invention may be disposed with an interval of 3.2mm to 5.6mm. In addition, the force sensor 221 is disposed as close to the photodiode 223 as possible. The quality of the PPG signal according to the distance between the light emitting diode 222 and the photodiode 223 will be described later in detail with reference to FIG. 9 .

[Multi-wavelength-based feature extraction]

5 is a diagram illustrating a method of detecting a PPG signal by a sensor unit of an earphone for blood pressure monitoring according to an embodiment of the present invention. A method of detecting a PPG signal by the sensor unit in FIG. 5 will be described with reference to FIGS. 3 to 4 together.

3 to 4, the sensor unit 220 of the earphone according to the embodiment of the present invention includes at least one light emitting diode (222-1 to 222-3). Since optical properties of living tissues such as absorption and reflection of light vary according to wavelength, the earphone according to an embodiment of the present invention provides a multi-wavelength-based blood pressure monitoring method to detect at a single wavelength. Blood pressure can be estimated by detecting difficult hemodynamic information.

FIG. 5A is a view showing the penetration depth of the light emitted by the light emitting diode 222 to the skin tissue for each wavelength. Referring to Figure 5 (a), blue wavelength light penetrates to the epidermis, green wavelength light penetrates to a part of the dermis, yellow wavelength light penetrates to the arterioles of the dermis, red wavelength of infrared It can be seen that the light penetrates to the harpy. That is, it can be seen that the light of a long wavelength is transmitted to a deeper region of the skin tissue.

FIG. 5B is a diagram comparing the penetration depth of light of a red wavelength and a green wavelength through the skin tissue. Referring to FIG. 5B , it can be seen that light (λ1) of green wavelength penetrates to capillaries, and light (λ2) of red wavelength penetrates into arterioles and arteries. The sensor unit of the earphone according to an embodiment of the present invention includes a plurality of light emitting diodes and emits light of a plurality of wavelengths, so that blood pressure can be estimated by detecting hemodynamic information that is difficult to detect at a single wavelength.

Meanwhile, referring to [Table 1] below, it can be seen that the average blood pressure is different for each type of blood vessel. More specifically, it can be seen through [Table 1] below that the mean blood pressure decreases as the diameter of the blood vessel decreases. As such, since the average blood pressure differs according to the type of blood vessel as well as the wavelength, different pulse wave morphology is shown during pressurization/decompression depending on the body part where the blood pressure is measured.

blood vessel Mean blood pressure (mmHg) aorta 100 artery 100 to 40 capillaries 60 to 40 pulmonary artery 18 to 15 pulmonary vein 10 to 8 vein 10 to 2 vena cava 2 to 5

In consideration of the various factors described above, the earphone for blood pressure monitoring according to an embodiment of the present invention is a method of estimating a user's blood pressure from a PPG signal measured in a large ear migration region through multi-wavelength-based monitoring provides

[ sensor unit Adhesion structure]

6 is a diagram illustrating a structure in which a sensor unit of an earphone for blood pressure monitoring is provided in a body portion according to an embodiment of the present invention. More specifically, FIG. 6 is a view showing the body of the earphone as viewed from the side.

The body part 210 of the earphone according to the embodiment of the present invention includes a wing part 212 . A force sensor 221 , a light emitting diode 222 , and a photodiode 223 which are components of the sensor unit 220 are mounted on the wing unit 212 . As described above in FIG. 4 , the photodiode 223 and the light emitting diode 222 according to an embodiment of the present invention are disposed with an interval of 3.2mm to 5.6mm, and the force sensor 221 is the photodiode 223 . placed as close as possible to

As described above in FIG. 3 , when the earphone according to an embodiment of the present invention is in close contact with the large migration area with a pressure within a predetermined range, it is possible to obtain an optimal PPG signal for blood pressure monitoring.

The wing portion 212 according to the embodiment of the present invention may be provided inclined by 10° with respect to the horizontal center line 213 of the body portion 210 . In addition, the wing portion 212 transmits a force to the surface in contact with the inner surface of the wing portion 212 when the user wears the earphone on the ear. The force sensor 221 according to an embodiment of the present invention is provided on the bonding surface. That is, the wing portion 212 has an ergonomic structure that automatically transmits a force to the force sensor 221 according to whether the user wears it or not.

Meanwhile, the wing unit 212 according to the embodiment of the present invention may include a flexible type printed circuit board 224 therein. In addition, the wing portion 212 guarantees an optimal signal to noise ratio when the distance between the light emitting diode 222 and the photodiode 223 is 5 mm or less.

The distance (a) between the wing portion 212 and the user's skin contact surface, for example, the major migration according to an embodiment of the present invention is preferably maintained in a range of 1.5mm to 3.0mm. In this case, if the distance between the light emitting diode 222 and the photodiode 223 is b, the length of the light path may be calculated as shown in Equation 1 below.

7 is a diagram illustrating a structure in which a sensor unit of an earphone for blood pressure monitoring is provided in a body portion according to an embodiment of the present invention. More specifically, FIG. 7 is a view showing that the sensor unit is in close contact with an appropriate pressure in the large migration area using the adhesion adjustment unit provided in the body unit. 7 (a) to (b) are views showing the body portion 210 of the earphone as viewed from the side.

The control unit 240 may control the adhesion adjustment unit 270 to adjust the degree of adhesion of the wing portion 212 to the large ear migration region. More specifically, the degree to which the wing part 212 protrudes from the body part 210 may be adjusted by the close contact adjustment part 270 . Comparing (a) and (b) of FIG. 7 , the distance d at which the wing part 212 protrudes from the body part 210 may be variably adjusted.

For example, it can be seen that the degree of protrusion of the wing part 212 is set higher in (b) of FIG. 7 than that of (a) of FIG. Although it is illustrated that the degree of adhesion of the adhesion adjusting unit 270 is four steps in (a) to (b) of FIG. 7 , it may be designed to be adjusted in more steps or continuously.

The earphone according to an embodiment of the present invention may obtain a PPG signal having an optimal signal quality index by adjusting the degree of contact with the sensor unit 220 . When the sensor unit 220 according to the embodiment of the present invention is in close contact with the large migration area, the closer the pressure is to 0, the more ideal. In this regard, it will be described later in detail with reference to FIG. 10 .

In a state in which the sensor unit 220 is ideally in close contact with the large migration area, the control unit 240 of the earphone according to the embodiment of the present invention detects a DC component signal through the force sensor 221 , and a photodiode 223 . Detects the AC component signal through Also, the controller 240 may more accurately estimate the user's blood pressure value based on the detected DC component signal and AC component signal.

8 is a diagram illustrating a structure in which a sensor unit of an earphone for blood pressure monitoring is provided in a body portion according to an embodiment of the present invention. More specifically, FIG. 8 is a view showing that the sensor unit is accurately positioned in the large migration area by using the angle adjusting unit provided in the body unit. FIG. 8(a) is a view showing the body part 210 of the earphone as viewed from the side, and FIGS. 8(b) to (d) are views showing the body part 210 of the earphone as viewed from above.

In general, earphones are designed using an anatomical structure so that they can be used for ears of various shapes. However, due to differences in ear anatomy, the inclination of the great migration may be different for each individual. Accordingly, the sensor unit 220 according to the embodiment of the present invention may include an angle adjustment unit 280 .

The control unit 240 according to the embodiment of the present invention may control the angle adjusting unit 280 to rotate the wing unit 212 to optimize the angle of the sensor unit 220 according to the anatomical structure.

For example, in (a) of FIG. 8 , the body 210 of the earphone further includes an angle adjustment unit 280 as well as the close contact adjustment unit 270 . The control unit 240 of the earphone according to the embodiment of the present invention controls the angle adjusting unit 280 so that the angle formed by the wing unit 212 with respect to the body unit 210 as shown in FIGS. They can be adjusted differently.

Furthermore, the earphone according to an embodiment of the present invention can monitor whether the wing unit 212 is properly adhered to the large migration area through an external device (eg, a smart phone) connected through the communication unit 230 . there is.

[Experimental data]

9 is a diagram illustrating a signal quality index according to a distance between a photodiode and a light emitting diode of an earphone for blood pressure monitoring.

As described above in FIG. 4 , in the sensor unit 220 of the earphone for monitoring blood pressure according to an embodiment of the present invention, the distance between the light emitting diode 222 and the photodiode 223 is sensed by the photodiode 223 . Affects the quality of the PPG signal. Accordingly, it is necessary to maintain an optimal distance between the light emitting diode 222 and the photodiode 223 .

9 , the horizontal axis represents the distance between the photodiode 223 and the light emitting diode 222 , and the vertical axis represents the signal quality index indicating the quality of the PPG signal. As shown in FIG. 9 , when the distance between the photodiode 223 and the light emitting diode 222 is 3.2 mm to 5.6 mm, the signal quality index indicates 0.8 or more.

More specifically, when the distance between the photodiode 223 and the light emitting diode 222 is 3.2 mm or less, the photodiode 223 receives more light directly through the subcutaneous tissue than the light reflected from the blood vessel, so the signal quality index is falling On the other hand, when the distance between the photodiode 223 and the light emitting diode 222 is 5.6 mm or more, as the photodiode 223 is further away from the light emitting diode 222, the amount of light reflected from the blood vessel decreases. index goes down.

In conclusion, in the sensor unit 220 of the earphone according to the embodiment of the present invention, the distance between the photodiode 223 and the light emitting diode 222 may be designed such that 3.2mm ~ 5.6mm is maintained. Through this, the earphone for blood pressure monitoring according to an embodiment of the present invention may acquire a PPG signal having a signal quality index of 0.8 or more.

10 is a diagram illustrating a PPG signal for each wavelength according to a change in pressure detected by a force sensor of an earphone for blood pressure monitoring according to an embodiment of the present invention. 10 , the horizontal axis represents time and the vertical axis represents pressure sensed by the force sensor 221 .

Referring to FIG. 10 , it can be seen that the pressure sensed by the force sensor 221 is 0.55N or more in the 0 to 12 second interval. When the pressure sensed by the force sensor 221 is large, it means that the pressure of the skin (great migration) in contact with the force sensor 221 is large. Because the large pressure on the capillaries of the great migration impedes the blood flow in the blood vessels, the PPG signal is not well detected. Therefore, it can be seen that the quality of the PPG signal using the green, red, and infrared light emitting diodes is deteriorated in the 0 to 12 second section of FIG. 10 .

On the other hand, it can be seen that the PPG signal using the green, red, and infrared light emitting diodes is detected in the 12 to 45 second period when the pressure sensed by the force sensor 221 is 0.55N or less. Also, as shown in FIG. 10 , it can be confirmed that the quality of the PPG signal using the green light emitting diode and the infrared light emitting diode is higher than the quality of the PPG signal using the red light emitting diode in the period of 12 to 45 seconds.

Accordingly, the threshold value of the force data detected by the force sensor 221 of the earphone for blood pressure monitoring according to the embodiment of the present invention may be set to 0.55N. That is, the controller 240 may be designed to set a predetermined threshold value (eg, 0.55N) for the force data and process the PPG signal in response to the force data falling below the set threshold value.

On the other hand, the reason that the PPG signal is not well detected even though the pressure sensed by the force sensor 221 is 0.55N or less is because the force sensor 221 is not in close contact with the large migration area and the SNR is lowered by ambient light. . It can be seen that the PPG signal is not detected in the section after 45 seconds of FIG. 10 .

11 is a diagram illustrating a blood pressure value estimated by an earphone for blood pressure monitoring through a force sensor according to an embodiment of the present invention.

The PPG signal is a relative number without units because the intensity of reflected light varies depending on the distribution of blood vessels, skin color, ambient light noise, the degree of contact with the skin of the photodiode, and the light intensity of the light emitting diode. Therefore, since the blood pressure monitoring method according to the prior art needs to estimate the blood pressure only with the PPG signal, which is a relative value, a method of estimating the change in blood pressure by calibrating the measured PPG signal after receiving the reference blood pressure value is used.

On the other hand, the earphone for blood pressure monitoring according to the embodiment of the present invention may measure the absolute value of the pressure applied to the large migration region by the sensor unit 220 through the force sensor 221 .

Referring to FIG. 11A , the DC component signal 1110 is measured by the force sensor 221 in a state in which the sensor unit 220 is ideally in close contact with the large migration region. In addition, the controller 240 may analyze the AC component signal 1120 measured by the photodiode 223 together with the DC component signal 1110 to more accurately estimate the blood pressure value.

FIG. 11B shows that the DC component signal 1110 and the AC component signal 1120 of FIG. 11A are corrected for phase and amplitude through an ensemble average method. According to an embodiment of the present invention, a blood pressure value corresponding to one cycle may be estimated every 20 seconds.

[ PPG How to estimate blood pressure from signals]

Factors for estimating blood pressure are divided into pulse wave signal factors and physiological factors. Physiological factors include factors such as age, gender, height and weight. The pulse wave signal factor is again divided into a morphological factor, a frequency factor, and a time-frequency factor. The morphological factor is classified into a time domain analysis, an amplitude domain analysis, and a time-frequency domain analysis.

12 shows a time domain graph of a PPG signal. More specifically, the morphological factors of the PPG signal, particularly the time domain analysis, will be described in detail with reference to FIG. 12 .

The controller 240 pre-processes the PPG signal obtained through the photodiode 223 . 12 illustrates a preprocessed PPG signal 1210 corresponding to one cycle of a pulse wave. Next, the control unit 240 first differentiates the preprocessed PPG signal 1210 . Next, the controller 240 second-differentiates the first-differentiated PPG signal 1220 . Finally, the controller 240 detects a fiducial point from the second-differentiated PPG signal 1230 .

Meanwhile, the controller 240 of the earphone for blood pressure monitoring according to an embodiment of the present invention may use a Windkessel model to estimate the user's blood pressure from the detected PPG signal. The Wind Kessel model models the change in the PPG signal according to the blood vessel shape and pressure change according to the inflow of blood. The preprocessed PPG signal 1210 of FIG. 12 is a signal in which the forward wave and the reflected wave are superimposed, and the PPG signal of the blood pressure within the normal range and the PPG signal of the blood pressure outside the normal range are morphologically different.

The control unit 240 of the earphone for blood pressure monitoring according to an embodiment of the present invention detects a reference point a to a reference point g from the second differentiated PPG signal 1230 shown in FIG. 12 .

The control unit 240 of the earphone for blood pressure monitoring according to an embodiment of the present invention models the user's blood pressure through time domain or amplitude domain analysis of the reference points a to g shown in FIG. Compare.

[FLOW CHART]

13 is a flowchart illustrating a blood pressure monitoring method of an earphone according to an embodiment of the present invention. More specifically, with reference to FIG. 13 , a monitoring method when the user is in an conscious state and in an unaware state with respect to blood pressure monitoring will be described.

The control unit 240 of the earphone for blood pressure monitoring according to an embodiment of the present invention starts blood pressure monitoring in any one of the user aware mode and the user non-aware mode.

In the user awareness mode, the controller 240 determines whether to start monitoring blood pressure according to step 1310 . For example, in response to an input to a predetermined button provided in the earphone according to an embodiment of the present invention, the controller 240 may start monitoring blood pressure.

When there is no input for monitoring blood pressure, the controller 240 controls the sleep mode in which the sensor unit 220 does not operate according to step 1311 to be maintained. When there is an input for monitoring blood pressure, the controller 240 initializes the sensor unit 220 according to step 1312 .

Meanwhile, in the user unaware mode, the controller 240 initializes the sensor unit 220 immediately according to step 1320 without determining whether to start monitoring blood pressure as in step 1310 .

When the sensor unit 220 is initialized to obtain a PPG signal according to step 1312 or 1320, the controller 240 determines whether the quality of the obtained PPG signal is equal to or greater than a preset value in step 1330. In this case, the signal quality index described above in FIG. 9 may be used. For example, when the signal quality index is 0.8 or more, the controller 240 may determine that the quality of the PPG signal is equal to or greater than a preset value.

If the quality of the acquired PPG signal is less than or equal to a preset value, the controller 240 outputs a message requesting to wear the earphone again according to step 1331. The message may be output as a voice message or a vibration message.

On the other hand, if the quality of the acquired PPG signal is equal to or greater than a preset value, the controller 240 monitors the user's operation according to steps 1340 and 1341 and outputs a message indicating the blood pressure measurement cycle.

According to step 1350 , the controller 240 determines whether the user is in a stable state. More specifically, since it is difficult to monitor blood pressure through PPG signal measurement in a situation in which the user is moving excessively (for example, during exercise), the control unit 240 of the earphone for monitoring blood pressure according to the embodiment of the present invention provides the user with First, it is determined whether or not is in a stable state.

If it is determined that the user is not in a stable state, the controller 240 monitors the user's operation again according to step 1340 . If it is determined that the user is in a stable state, the controller 240 starts measuring blood pressure in step 1360 . The method described above with reference to FIGS. 11 to 12 may be used for measuring blood pressure.

When blood pressure measurement is started, the control unit 240 detects a surrounding factor according to step 1361 . The ambient factor refers to a factor that may affect blood pressure measurement, such as ambient light noise. Next, according to step 1362, the controller 240 determines whether the detected surrounding factors affect the measured blood pressure.

When it is determined that the detected surrounding factors affect the measured blood pressure, the controller 240 outputs a preset message according to step 1370 . The message may be output as a voice message or a vibration message.

When it is determined that the detected surrounding factors do not affect the measured blood pressure, the controller 240 determines whether there is an abnormal blood pressure change based on the measured blood pressure in operation 1371 .

When it is determined that there is an abnormal blood pressure change, the controller 240 outputs a warning message according to step 1380 . Meanwhile, when it is determined that there is no abnormal blood pressure change, the controller 240 stores the blood pressure data measured in operation 1381 .

The present invention described above can be implemented as computer-readable codes on a medium in which a program is recorded. The computer-readable medium includes all types of recording devices in which data readable by a computer system is stored. Examples of computer-readable media include Hard Disk Drive (HDD), Solid State Disk (SSD), Silicon Disk Drive (SDD), ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc. There is also a carrier wave (eg, transmission over the Internet) that is implemented in the form of. In addition, the computer may include a control unit of the terminal. Accordingly, the above detailed description should not be construed as restrictive in all respects but as exemplary. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the present invention are included in the scope of the present invention.

200: earphone
210: body part
220: sensor unit
230: communication department
240: control unit

Claims (10)

In the earphone for blood pressure monitoring,
body part;
sensor unit;
a communication unit for wired/wireless communication with an external device; and
a control unit coupled to the body unit, the sensor unit, and the communication unit, the control unit estimating a user's blood pressure by processing a photoplethysmography (PPG) signal detected through the sensor unit; including,
The sensor unit,
a photodiode detecting the PPG signal; a light emitting diode detecting the PPG signal; and a force sensor configured to obtain a reference value for detecting the PPG signal of the photodiode and the light emitting diode. including,
The photodiode and the light emitting diode are disposed to be spaced apart by a first distance, the photodiode and the force sensor are disposed to be spaced apart from each other by a second distance, and the first distance is greater than the second distance,
Earphones for blood pressure monitoring. According to claim 1,
The control unit is
The earphone for blood pressure monitoring, characterized in that detecting the PPG signal in the anti-tragus region of the user's ear through the photodiode. According to claim 1,
The light emitting diode is
An earphone for blood pressure monitoring, comprising at least two or more light emitting diodes emitting light of different wavelengths. According to claim 1,
The control unit is
A DC component signal corresponding to the force data is detected through the force sensor, an AC component signal corresponding to the PPG signal is detected through the photodiode, and based on the detected DC component signal and the detected AC component signal An earphone for blood pressure monitoring, characterized in that the blood pressure is estimated. According to claim 1,
The sensor unit,
The earphone for blood pressure monitoring, characterized in that it is inclined at a predetermined angle with respect to the center line of the body part. According to claim 1,
The body part,
The force sensor, the light emitting diode and the photodiode further comprising a wing portion and a close contact adjustment unit,
The control unit is
The earphone for blood pressure monitoring, characterized in that by controlling the close contact control unit to adjust the degree to which the wing portion protrudes from the body portion. 7. The method of claim 6,
The body part,
Further comprising an angle adjustment unit,
The control unit is
The earphone for blood pressure monitoring, characterized in that by controlling the angle adjusting unit, the angle formed by the wing unit with respect to the body unit is adjusted. According to claim 1,
The earphone for blood pressure monitoring, characterized in that the first distance is 3mm to 6mm. 5. The method of claim 4,
The control unit is
The earphone for blood pressure monitoring, characterized in that a predetermined threshold value is set for the force data, and the PPG signal is processed in response to the force data falling below the set threshold value. According to claim 1,
The control unit is
An earphone for blood pressure monitoring, characterized in that the blood pressure monitoring is started in any one of a user aware mode and a user non-aware mode.

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