KR20180004611A - Apparatus for measuring pulse wave - Google Patents

Abstract

The present invention relates to a device capable of detecting a pulse wave. More specifically, the present invention relates to a pulse wave detecting device which comprises a cylindrical rigid case which has one surface opened and a storage space therein, a structure in which a piezoelectric sensor, an ethyl cyanoacrylate, an acrylic plate and a silicon bar are sequentially laminated from the rigid case, and a composition filling silicon around the laminated structure.

Description

[0001] APPARATUS FOR MEASURING PULSE WAVE [0002]

The present invention relates to an apparatus for detecting a radial pulse wave using an acupressure.

Modern medicine has a very big problem in quantification and objectification. Accordingly, simple pulse machines for quantifying oriental medicine are being developed. However, the problem of oriental medicine goes beyond simple quantification problem. As a simple example, in the definition of a pulse, a pulse is a feeling of the pulse of the patient in contact with a specific part of the patient, and the blood flow of the human body is determined based on the pulse of the pulse. At this time, the subjective part of the oriental doctor has already contributed to the feeling of the patient's pulse. In other words, the problem of quantification in Oriental medicine is to quantify the experiences and feelings about the Mac, which the oriental doctor holds now, beyond the interpretation based on the simple quantification of pulse pressure. An essential element here is synchronization. The oriental doctor needs to be able to read the Mac and feel the Mac and simultaneously quantify it as a pulse pressure graph or number. This method has the advantage of being able to achieve the numerical value at the same time without departing from the existing oriental medicine framework. In other words, intuitive objectification can be achieved with a one-to-one correspondence between subjective experience and objective figures. To this end, the present invention designs a sensor having a structure capable of measuring pulse pressure using acupressure and a circuit therefor. After calibration, we show the result of signal processing and analysis based on the actual measurement result. We perform Brand-Altman test with reference to the existing pulse generator (DMP-1000 +) for reliability of the instrument.

The present invention is directed to solving the above-mentioned problems and other problems. Another object of the present invention is to provide a sensor which can be used as a starting point.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, unless further departing from the spirit and scope of the invention as defined by the appended claims. It will be possible.

According to an aspect of the present invention, there is provided a cylindrical rigid-body case having one side opened and a receiving space therein, a piezoelectric sensor from the rigid case, ethyl cyanoacrylate, And a structure for filling silicon around the laminated structure are provided.

The effect of the radial pulse wave detecting apparatus according to the present invention will be described as follows.

According to at least one of the embodiments of the present invention, there is an advantage that a medical expert such as a Chinese medicine doctor can sense a pulse wave so that a pulse can be performed.

Further scope of applicability of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and specific examples, such as the preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art.

FIGS. 1A and 1B are views showing a structure and a bottom surface of a sensor according to an embodiment of the present invention.
2A is a diagram showing a path through which the pressure of the radial artery is transmitted.
2B is a diagram illustrating pressure transfer dynamics modeling in the radial artery, in accordance with an embodiment of the present invention.
Figure 3A is a filter and amplifier portion of the system during circuit configuration.
FIG. 3B is a graph showing a voltage (red line: measured value, blue line: straight line obtained by least square error method) according to the weight of the sensor.
4A is a diagram illustrating signals measured through an apparatus according to an embodiment of the present invention.
FIG. 4B is a diagram for calculating blood pressure of a subject using Equation 5 and FIG. 4A. FIG.
4C is a diagram showing a Bland-Altman Plot.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals are used to designate identical or similar elements, and redundant description thereof will be omitted. The suffix "module" and " part "for the components used in the following description are given or mixed in consideration of ease of specification, and do not have their own meaning or role. In the following description of the embodiments of the present invention, a detailed description of related arts will be omitted when it is determined that the gist of the embodiments disclosed herein may be blurred. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. , ≪ / RTI > equivalents, and alternatives.

Terms including ordinals, such as first, second, etc., may be used to describe various elements, but the elements are not limited to these terms. The terms are used only for the purpose of distinguishing one component from another.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The singular expressions include plural expressions unless the context clearly dictates otherwise.

In the present application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

1. Structure of sensor

FIGS. 1A and 1B are views showing a structure and a bottom surface of a sensor according to an embodiment of the present invention.

1A is a view showing a structure of a sensor. A case is fabricated using a rigid body that has little deformation with respect to stress. In order to prevent silicon from entering between the acrylic plate and the piezoelectric sensor inside the silicon, ethyl cyanoacrylate was treated to firmly fix the two, and the silicon was poured and hardened. The acrylic plate was used to uniformly transfer the pressure from the silicon to the sensing area. 1B is a bottom view of the sensor. The inside diameter circle of 0.8 cm means the diameter of the silicon bar, and the outside circle diameter of 1 cm means the sensing area. The body is 1.6 cm in diameter. The silicone bar here refers to the pressure range from the radial artery.

2. Modeling of pressure sensor and radial artery

2A is a diagram showing a path through which the pressure of the radial artery is transmitted.

2B is a diagram illustrating pressure transfer dynamics modeling in the radial artery, in accordance with an embodiment of the present invention.

The parts in FIG. 2B are as follows.

k1: Tissue of doctor, k2: Rigid Case, k3: Silicon, k4: Transducer, k5: Acrylic, k6: Silicon Bar, k7: Tissue, k8: Artery, k9: Radius, Tendon,

The silicon bar of the sensor applies pressure to the radial artery to make it flat. The tension in the flattened radial artery is then only converted to a horizontal force, which does not affect the force in the vertical direction. Therefore, the pressure transmitted from the blood vessel to the sensor in the vertical direction is only the blood pressure. At this time, the product of the blood pressure to be delivered and the cross-sectional area of the silicon which is in contact with the blood vessel becomes Fa in Fig.

 The following conditions are assumed in FIG. 2B.

1. The stiffness of the acrylic plate, rigid case and frame support is infinite.

2. The frame support is firmly supported on the radial and tendon around the blood vessels.

3. During the measurement, the contact area between the silicon bar and the blood vessel is kept constant.

4. k ₁ means the stiffness of the finger tissue of the measurer, which is very small.

2b is modeled by the above assumption as shown in the following equations (1) and (2).

조건을 더하여 정리하면 다음 수학식3과 같다.In Equation (2), k ₈ , as mentioned in FIG. 2A, makes the blood vessel flat with the silicon bar and exists in the horizontal direction. Therefore,

The condition is summarized as follows.

Where k ₆ is the elasticity of the silicon bar and x ₄ is the height at which the silicon bar is raised by the blood pressure. The F _a is then transferred back to the acrylic plate, which is then transferred to the pressure sensor.

3. Circuit configuration

Figure 3A is a filter and amplifier portion of the system during circuit configuration. The piezoelectric sensor used in the present invention is a Flexiforce 201-a1 model in which the pressure received is linearly proportional to the conductance of the sensor. The circuit shown in Fig. 3b is implemented as shown in Fig.

FIG. 3B is a graph showing a voltage (red line: measured value, blue line: straight line obtained by least square error method) according to the weight of the sensor. Table 1 below is a table of voltage values per weight in FIG. 3B.

Weight (g) Voltage (mV) 0 4 13.5 23.5 20.1 32.5 120 90 176.0 172 180 194 202.1 252 278.8 432 341.8 562

As a result of checking the sensor, it was possible to identify a relatively nonlinear section between 100 and 150 g. In order to linearize the above graph, it was linearized as least square error method. The equation of the linearized line is as shown in the following equation (4).

In this case, the linearity was evaluated with full scale, and it was found that there was a nonlinearity of 13.7%. We assume that the nonlinearity is increased due to the viscoelastic characteristics of silicon during the construction of the sensor. The f _c of the high-pass filter above is 0.32 Hz, taking into account that 99% of the frequency band of the Radial Artery Pulse Wave is in the region of 1 to 10 Hz. The f _c of the low pass filter is 200 Hz, which is twice the frequency of 100 Hz, which is 10 times the frequency of 10 Hz, with most frequencies interlocked with the microcomputer.

3C is a graph of the pressure according to the measured voltage. In the course of the experiment, you should know how much blood pressure the measured voltage represents. To do this, the blood pressure corresponding to the voltage measured using the mmHg for 35.84 times the gain through the circuit, the equation 4, and 1gf / mm can be obtained directly. This can be summarized as follows. When the gain through the circuit is multiplied by Equation 3 and the inverse of it is found, a graph of gf according to V _o can be obtained. At this time, since the sensing area is 78.54 mm ² and ¹ gf / (mm) ² is 73.56 mmHg, the following equation can be obtained by summarizing the above equation.

This graph is shown in FIG. 3C.

4. Signal analysis and system evaluation

4A is a diagram illustrating signals measured through an apparatus according to an embodiment of the present invention. FIG. 4B is a diagram for calculating blood pressure of a subject using Equation 5 and FIG. 4A. FIG. 4C is a diagram showing a Bland-Altman Plot.

Figures 4a and 4b show the results of a conventional 25-year-old man with a heart rate of 82 beats per minute, a systolic pressure peak of 118, and a reflective pulse return time of 0.1 s. 4A, the characteristics of the radial artery pulse wave can be confirmed. First, when the experiment was performed with ECG for 1 minute, the sensitivity of the P wave was 100% and could be detected every time. On the other hand, the sensitivity of T wave was 52.3%, which was quite low. The sensitivity of both C. notch and D wave was 94%, which was quite high. At the heart rate of 75 times / min, it had an error of about 8% with the reference device. However, this was not measured at the same time, and the heart rate was 100% sensitive when compared to ECG, so this value is not significant. The return time of the reflective pulse can be seen in the first waveform of FIG. 4A. The measurement result was 0.1 s, which was the same as the reference instrument. FIG. 4B is a drawing of FIG. 4A using equation (5). Here, a considerable problem was found, and the pulse pressure was about 35 mmHg, which was about 70 mmHg from the conventional reference device. Bland-Altman Plot was performed to confirm this.

4c is a Bland-Altman Plot between the reference pulse generator and the designed pulse generator for 5 seconds. What mean means mean the difference between the values measured in the two systems, and SD means the standard deviation of the mean. As shown in FIG. 4c, the bias value 77 exists between the two systems. Adding this bias value to the pulse pressure measured from Equation (5), the measured value has a confidence of 95%.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, The scope of the present invention is not limited by the description with reference to the drawings or the drawings. It will also be appreciated by those skilled in the art that the concepts and embodiments of the invention set forth herein may be used as a basis for modifying or designing other structures for carrying out the same purposes of the present invention It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims and their equivalents. And various changes, substitutions, and alterations can be made without departing from the scope of the invention.

Claims (1)

A cylindrical rigid case with one side opened and a housing space inside, a structure in which a piezoelectric sensor, an ethyl cyanoacrylate, an acrylic plate and a silicon bar are stacked in this order from a rigid case and a structure in which silicon is filled around the laminated structure ≪ / RTI >
Pulse wave detection device.

Images