JP2007209374A - Biological information measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems associated with a prior biological information measuring instrument, for example, a photoelectric plethysmogram signal is not detected properly depending on the position of a living body where a sensor section is pressed. <P>SOLUTION: The biological information measuring instrument has a sensor section comprising a substrate, a light emitting means, a light receiving means, a pressure detecting means and a pressure transmitter. When measuring blood pressure, the sensor section is pressed to a part of a living body and light is emitted from the light emitting means to the living body. The instrument then measures the blood pressure using reflected light from the living body detected by the light receiving means and pressure detected by the pressure detecting means. The sensor section has the pressure transmitter having a predetermined shape between the substrate and the light emitting means or the light receiving means and also has a pressure sensor having a pressure receiving face that comes into contact with the pressure transmitter. With such a configuration, the sensor section adheres closely to the skin and measures biological information easily and accurately. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a biological information measuring apparatus, and more particularly to an apparatus for measuring blood pressure using vibrations that appear in a part of a living body. In particular, the present invention relates to a small apparatus that can be easily used while improving measurement accuracy.

  Among biological information measuring devices that measure biological information, in particular, devices that measure blood pressure using biological vibration caused by blood vessel expansion and contraction are widely known. Such a device is called a sphygmomanometer and is widely used not only in medical institutions but also in general households. In recent years, electronic sphygmomanometers that perform measurement electrically are widely known.

  In a conventional electronic blood pressure monitor, a cuff-oscillometric method or a volume vibration method is used. In the cuff-oscillometric method, the cuff (arm band) wound around the upper arm or wrist is pressurized to press the blood vessel, and the maximum blood pressure (contraction) from the behavior of the cuff pressure fluctuation reflecting the vibration of the blood vessel wall depending on the arterial pressure. Blood pressure (SBP) and diastolic blood pressure (diastolic blood pressure: DBP).

In the slow decompression process of the cuff, this vibration waveform increases near the systolic blood pressure and becomes maximum at the mean blood pressure, and then becomes a substantially constant amplitude around the diastolic blood pressure. Generally, the algorithm for determining the maximum blood pressure and the minimum blood pressure is a threshold value K1 (for example, 0.5) on the high cuff pressure side with respect to the maximum amplitude of the minute fluctuation waveform of the cuff pressure obtained in the slow depressurization process of the cuff. On the low cuff pressure side, the threshold value K2 (for example, 0.7) is set, and the values of the pressure sensor corresponding thereto are the maximum blood pressure and the minimum blood pressure.
The threshold values K1 and K2 are determined so as to coincide with values of a direct method of inserting a pressure sensor into an artery and an auscultation method of listening to Korotkoff sounds, but are not based on a clear and strict principle.

  Furthermore, even if the artery is crushed with a pressure corresponding to the maximum blood pressure, the artery is not completely occluded at both ends of the cuff in principle, so the pressure pulse wave of the artery propagating there is transmitted to the cuff, and the cuff pressure In the algorithm for determining the maximum and minimum blood pressure with the threshold values K1 and K2 as a minute fluctuation, it appears in the signal of the pressure sensor, and accurate blood pressure cannot be determined due to the remaining pressure pulse wave component.

  In addition, because the entire upper arm or wrist is pressurized, the arteries such as bones and tendons are affected by anatomical structures, and even if excessive pressure is applied, the artery cannot be completely tightened, which is an obstacle to accurate blood pressure measurement. There were many things.

  On the other hand, the volume vibration method using a photoelectric volume pulse wave sensor, for example, emits a minute blood vessel volume change caused by blood pressure when the pressure of a cuff wound around a living body of a subject is increased or decreased. The light receiving element that receives the light irradiated from the element and reflected and scattered by the living body is detected as a change in transmittance, and the amplitude change of the volume pulse wave signal that is an alternating current component of the light receiving signal output from the light receiving element with respect to the cuff pressure The blood pressure value is measured from the behavior.

  Among such conventional blood pressure measurement devices, there is also known a blood pressure measurement device that measures a blood pressure value by using a volume vibration method by locally pressing a part of a subject's living body without using a cuff. (For example, refer to Patent Document 1).

The configuration of the prior art shown in Patent Document 1 is as shown in FIG. FIG. 9 is a configuration diagram rewritten without departing from the gist of the invention disclosed in Patent Document 1. In FIG. 9, 101 is a pressure body, and 101a is a gripping part. A light emitting element 102a and a light receiving element 102b constitute a photoelectric volume pulse wave sensor 102. 103 is a pressure bag, 103a is an opening, 104 is a pressure sensor, 105 is a tube, 106 and 107 are amplifiers, 108 is a light emitting element driver, 109 is a control unit, 110 is a display unit, 111 is a living body, and 112 is a blood vessel It is.

A photoelectric volume pulse wave sensor 102 is provided at the end of the pressurizing body 101, and a pressurizing bag 103 is provided at the tip thereof. The pressurizing body 101 has a gripping portion 101a, which is gripped and pressed against the subject. By doing so, pressure is generated in the pressure bag 103. This pressure is detected by the pressure sensor 104 through the tube 105. The pressure signal output from the pressure sensor 104 is amplified by the amplifier 106 and input to the control unit 109.
The control unit 109 controls the light emitting element driver 108 to cause the light emitting element 102a to emit light. The light receiving element 102b receives light transmitted through the blood vessel 112 in the living body 111 of the subject. This transmitted light includes a pulse wave signal that appears in the blood vessel 112. The pulse wave signal is amplified by the amplifier 107. To the control unit 109.
The blood pressure is measured by the control unit 109 using the pulse wave signal (output signal of the amplifier 107) output from the photoelectric volume pulse wave sensor 102 and the pressure signal (output signal of the amplifier 106) output from the pressure sensor 104. The result is displayed on the display unit 110.

  By adopting such a configuration, it is possible to measure a blood pressure value by pressing an arbitrary part of the living body, and the measurement work becomes extremely easy, and the subject can be painful without being restricted to the measurement part as in the measurement with the cuff. There is a feature that can be measured without the burden of congestion or blood congestion.

JP-A-6-311972 (page 2-3, FIG. 1)

In the prior art disclosed in Patent Document 1, a photoelectric volume pulse wave sensor 102 is provided at the end of the pressurizing body 101, and a pressurizing bag 103 is provided at the tip thereof. That is, the pressure bag 103 is between the photoelectric volume pulse wave sensor 102 and the living body 111.
In such a configuration, when the pressurizing body 101 is pressed against the living body 111, the pulsation of the blood vessel is transmitted to the pressurizing body 101 through the liquid or gas enclosed in the pressurizing bag 103, and the pressurizing body 101. Will go up and down depending on the pulsation. As a result, the distance between the photoelectric volume pulse wave sensor 102 and the skin of the living body 111 changes, and the light intensity detected by the light receiving element 102b through the blood vessel 112 has a distance between the photoelectric volume pulse wave sensor 102 and the skin. The signal component accompanying this change is detected by being superimposed on the original photoelectric volume pulse wave that depends on the volume change of the blood vessel 112.

  Furthermore, since the positional relationship between the photoelectric volume pulse wave sensor 102 and the skin changes due to pressurization, the position fluctuation is also superimposed on the volume pulse wave signal as a low frequency component, causing deformation of the volume pulse wave waveform. .

  In the volume vibration method, the minimum blood pressure is calculated from the maximum blood pressure, the average blood pressure, and the volume pulse waveform, but the correct minimum blood pressure cannot be determined from superposition of extra signal components or deformation of the volume pulse waveform. There was a big problem.

Further, even if the pressure body 101 is pressed and a pressure higher than the maximum blood pressure is applied, the pressure is applied to the outer peripheral portion under the pressure body 101 according to the general elasticity theory because it is a local pressure. The region is lower than the center of the pressurizing body 101, and a blood vessel that is not necessarily closed is left. The blood vessels pulsate due to pressure (blood pressure) transmitted from the heart side. Since the pressurizing body 101 moves up and down also by this pulsation, the light receiving element 102b detects the vertical motion of the pressurizing body 101 as a pulsation.
That is, even when the blood pressure in the detection optical path region of the photoelectric volume pulse wave sensor 102 near the center of the pressurizing body 101 is closed by the externally applied pressure and the blood flow is stopped, There is a problem that the photoelectric volume pulse wave is detected as a signal, and the disappearance of the true volume pulse wave is not observed.

Furthermore, an optical signal in which reflected light from the skin surface is modulated depending on the displacement of the skin is also detected, and a signal as a surface displacement of the skin accompanying pulsation is also detected.
For this reason, depending on the relationship between the original photoelectric volume pulse wave and the phase and intensity of the reflected light from the skin surface due to the vertical displacement of the skin, the photoelectric volume pulse signal detected by the light receiving element 102b is not originally detected. Even if it was not possible, loss of signal or reversal of the signal waveform occurred.

  Therefore, depending on the position where the pressurizing body 101 is pressed against the living body 111, there is a problem that the photoelectric volume pulse wave signal cannot be detected normally.

  As described above, in the prior art disclosed in Patent Document 1, when performing blood pressure determination based on the volume vibration method, accurate processing is performed even though processing is performed with a complicated algorithm according to the acquisition situation of the photoelectric volume pulse wave. Blood pressure could not be determined.

  An object of the present invention is to provide a biological information measuring device capable of improving blood pressure measurement accuracy in order to eliminate the above-described problems caused by the prior art. According to the present invention, it is also possible to provide an electronic sphygmomanometer that can easily measure blood pressure without causing discomfort.

  In order to achieve the above object, the biological information measuring apparatus of the present invention employs the following configuration.

A living body that includes a sensor unit having a substrate, a light emitting unit, a light receiving unit, a pressure detecting unit, and a pressure transmission body, presses the sensor unit against a part of the living body, irradiates the living body with light from the light emitting unit, and is detected by the light receiving unit In the biological information measuring device for measuring biological information using the reflected and scattered light from and the pressure applied to the pressure transmitting body detected by the pressure detecting means,
The pressure transmission body has a predetermined shape and is in contact with the substrate,
The pressure detection means is provided so that its pressure receiving surface is in contact with the pressure transmission body,
The light emitting means and the light receiving means are provided so as to be spaced apart from each other, and are arranged so that the pressure transmission body is sandwiched between the surface opposite to the light emitting surface of the light emitting means or the surface opposite to the light receiving surface of the light receiving means and the substrate. It is characterized by.

  The pressure transmission body is characterized by being an elastic body having a uniform elastic force or a structure made up of an elastic body and a covering body covering a part thereof.

  The light emitting means or the light receiving means is fixed to the substrate with a flexible mounting member.

  The light emitting means or the light receiving means is in contact with the pressure transmission body via a connecting means.

  The connecting means is a film-like thin film or an adhesive.

  The connecting means is not provided in the light emitting optical path of the light emitting surface of the light emitting means or the light receiving optical path of the light receiving surface of the light receiving means.

According to the present invention, since the sensor part for detecting the photoelectric volume pulse wave is in close contact with the skin and only the movement of the arterial blood vessel in the vicinity of the sensor part can be detected, the inversion phenomenon of the photoelectric volume pulse signal is eliminated, In addition, the vanishing point of the photoelectric volume pulse wave for determining the systolic blood pressure becomes clear, and the correct systolic blood pressure is obtained.
Moreover, since only the photoelectric volume pulse wave can be detected, detection instability due to position is eliminated, and determination of the pressurization position is facilitated.
Furthermore, since the low frequency component of the detection optical signal due to the change in applied pressure is eliminated, the photoelectric volume pulse waveform is not deformed, and the minimum blood pressure can be calculated correctly.
In general, a complicated algorithm corresponding to the acquisition situation of the photoelectric volumetric pulse wave is not required.
The present invention has an effect that anyone can easily and accurately measure blood pressure.

  Exemplary embodiments of a biological information measuring device according to the present invention will be described below in detail with reference to the accompanying drawings. In the following description of the embodiments and the accompanying drawings, the same reference numerals are given to the same components.

FIG. 1 is a cross-sectional view schematically showing the structure of the sensor unit 18 showing the first embodiment of the biological information measuring apparatus of the present invention. Reference numeral 13 denotes a substrate, 10 denotes a light emitting element as light emitting means, 12 denotes a light receiving element as light receiving means, 11 denotes a pressure sensor as pressure detecting means, 15 denotes a pressure transmission body, and 50 denotes a connector. The board 13 has not only the arrangement of the connector 50 but also a role of a base for fixing the pressure transmission body 15, the pressure sensor 11, the light emitting element 10, and the light receiving element 12.
The connector 50 is connected to a control system (not shown). The electrical signal from each sensor is connected to other elements (such as the board 13 and the connector 50) via known wiring connection means such as FPC (Flexible Printed Circuit) and electrical wiring. In FIG. 1, they are omitted.

  The living body information measuring device of the present invention presses the sensor unit 18 shown in FIG. 1 against the living body, detects the photoelectric volume pulse wave and the pressure, and measures the blood pressure of the living body.

[Description of First Embodiment of Sensor Unit 18: FIG. 1]
As shown in FIG. 1, in the sensor unit 18 of the biological information measuring device of the present invention, the pressure transmission body 15 is in contact with the substrate 13 having a predetermined shape (for example, a dome shape). Further, the pressure transmission body 15 is sandwiched between the light emitting element 10 and the light receiving element 12 and the substrate 13. The pressure sensor 11 is provided inside the pressure transmission body 15.
In FIG. 1, since the lower side of the drawing, that is, the side on which the light emitting element 10 and the light receiving element 12 are disposed is the side in contact with the living body, there is no extra space between these and the living body. When pressed, the light emitting element 10 and the light receiving element 12 can be in close contact with the skin of the living body.

  Although the pressure transmission body 15 may be sandwiched between the light emitting element 10, the light receiving element 12, and the living body, it is preferable that the amount (film thickness) is small. In this case, the pressure transmission body 15 is preferably composed of a transparent or translucent pressure guiding medium that does not interfere with the light emitted from the light emitting element 10 (light incident on the light receiving element 12). A detailed description of the pressure transmission body 15 will be described later.

  The pressure sensor 11 converts an applied pressure into an electrical signal, and is not particularly limited, but a piezo bridge resistance type semiconductor sensor or a capacitance change detection type pressure sensor can be used.

  The light-emitting element 10 may be an infrared LED (Light Emitting Diode) that emits light in the near-infrared region that has good biological permeability and absorbs hemoglobin. The emission wavelength is preferably about 800 to 950 nm.

  The light receiving element 12 receives light that is incident on the living body from the light emitting element 10, is scattered and absorbed in the living body, and is reflected, and converts it into an electrical signal. The light receiving wavelength preferably has a sensitivity of approximately 800 to 950 nm according to the light emitting wavelength of the light emitting element 10. For example, a silicon photodiode having a maximum light receiving sensitivity in this wavelength region is suitable.

The light emitting element 10 and the light receiving element 12 are provided apart from each other. The light-emitting element 10 or the light-receiving element 12 is provided on the surface side of the pressure transmitting body 15 that comes into contact with the living body in order to adhere to the skin. Further, the light emitting element 10 and the light receiving element 12 are arranged so as to be substantially perpendicular to the blood vessel direction.
The diameter of the radial artery of the human body depends on physique factors such as height, weight, and body surface area, but is generally 2.5 to 3.5 mm for Japanese men and 2.2 to 3.0 mm for women. Therefore, in order for the optical path from the light emitting element 10 to traverse the radial artery, the distance between the light emitting element 10 and the light receiving element 12 is preferably 8 mm or more and 16 mm or less. This arrangement can be freely set so that the optical path passes through the vascular pressure closure part.
The light emitting element 10 and the light receiving element 12 preferably have a diameter of 3 mm or less so as to be in close contact with the skin and move freely.

Although the pressure transmission body 15 is not specifically limited, It is comprised with the gel-like pressure guiding medium. When the sensor unit 18 of the biological information measuring device of the present invention is pressed against the living body, it easily deforms according to the shape of the living tissue, and the contact pressure (pressing force) is accurately transmitted to the pressure sensor 11. ing. Since the pressure transmitted to the pressure sensor 11 must not be biased, the pressure transmission body 15 is formed of an elastic body having a uniform elastic force.
It is desirable for the pressure transmission body 15 to absorb visible light in order to reduce optical background noise such as outside light. Further, in order to reduce stray light in the pressure transmission body 15, it is desirable that the light emitting element 10 also absorbs the emission wavelength.

  The pressure transmission body 15 may be different from the gel pressure medium, but the gel pressure medium is a preferable medium with good durability. For example, a gel-like pressure guiding medium having a rubber hardness of 0.5 or less according to JIS standards may be used.

The pressure sensor 11 is covered with the pressure transmission body 15, and the pressure receiving surface of the pressure sensor 11 is in contact with the pressure transmission body 15. In the example shown in FIG. 1, this pressure receiving surface is the lower side (biological side) of the drawing.
The pressure transmission body 15 is easily deformed according to the shape of the living tissue, and the contact pressure (pressing force) is accurately transmitted to the pressure sensor 11. In order to achieve this object, the entire pressure sensor 11 may be provided inside the pressure transmission body 15. For this reason, in the example shown in FIG. 1, the pressure sensor 11 is provided in the pressure transmission body 15, and the pressure transmission body 15 covers the periphery of the pressure sensor 11. In the following description, this configuration will be described as an example.

[Description of Second Embodiment of Sensor Unit 18: FIG. 2]
Next, the structure of the sensor part 18 which shows 2nd Embodiment of the biometric information measuring apparatus of this invention is demonstrated. FIG. 2 is a cross-sectional view schematically illustrating the sensor unit 18. Reference numeral 14 denotes a covering.
The difference from the first embodiment of the biological information measuring device of the present invention is that the pressure transmitting body 15 which is a gel-like pressure guiding medium is covered with a covering body 14.

In the example shown in FIG. 2, the pressure transmission body 15 has a diameter of 20 to 25 mm and a thickness of 6 to 10 mm, and the surface is covered with the covering body 14 except for the surface in contact with the substrate 13.
The covering 14 is preferably polyurethane, but polyethylene, polypropylene, polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) may be used. Further, polyimide (PI), polyolefin (PO) or the like may be used. The thickness of the covering 14 is not particularly limited, but is preferably 30 to 60 μm.

  The hardness and material of the gel-like pressure guiding medium constituting the pressure transmitting body 15 can be freely selected. By adopting such a configuration, even if a pressure guiding medium that is so soft that the pressure transmission body 15 cannot maintain its shape is used, the pressure transmission body 15 is covered with the covering body 14, and therefore has a predetermined shape as shown in FIG. 2. (For example, a dome shape). In this case, the shape of the covering 14 may be set to a predetermined shape in advance.

  Moreover, when the user handles the biological information measuring device of the present invention by covering the surfaces of the light emitting element 10 and the light receiving element 12 with each other, the light emitting element 10 and the light receiving element 12 provided in the sensor unit 18 are provided. There is also an effect that the surface (element surface) is touched unnecessarily and accidental damage is reduced.

[Description of Third Embodiment of Sensor Unit 18: FIG. 3]
Next, the structure of the sensor part 18 which shows 3rd Embodiment of the biometric information measuring apparatus of this invention is demonstrated. FIG. 3 is a cross-sectional view schematically illustrating the sensor unit 18. Reference numeral 16 denotes an attachment member made of a flexible member.
The difference from the first embodiment of the biological information measuring device of the present invention is that the light emitting element 10 and the light receiving element 12 are fixed to the substrate 13 using the attachment member 16.

In the example shown in FIG. 3, one end of a flexible mounting member 16 having a shape along the pressure transmission body 15 is connected to the substrate 13, and the light emitting element 10 and the light receiving element 12 are connected to the other end.
As the flexible member constituting the attachment member 16, a resin member or FPC can be used. It can also be made of a shape memory material. In particular, when a normal memory material is used, even when an unexpected force is applied to the sensor unit 18 and the mounting member 16 is deformed when the biological information measuring device of the present invention is used, a predetermined temperature is applied. , It can be returned to a predetermined shape.

With such a configuration, the light emitting element 10 and the light receiving element 12 can be disposed at predetermined positions with respect to the pressure transmission body 15. For example, the distance between the light emitting element 10 and the light receiving element 12 can be determined more accurately.
Since the attachment member 16 has flexibility, it can be easily deformed, and even if the sensor unit 18 is pressed against the living body, the shape change of the pressure transmitting body 15 is not hindered.

[Description of connecting means: FIG. 4]
Next, the form which fixes the light emitting element 10 and the light receiving element 12 of the sensor part 18 of the biological information measuring device of this invention shown in FIGS. 1-3 to the pressure transmission body 15 etc. is demonstrated. FIG. 4 is a diagram showing a part of the sensor unit 18, and FIG. 4 (a) uses a gel pressure guiding medium as the pressure transmission body 15, and the light emitting element 10, the light receiving element 12, and the pressure guiding medium are used. Is connected through the connecting means 17. FIG. 4B shows an example in which only a part of the light emitting element 10 and the light receiving element 12 are connected via the connecting means 17.

By using the connecting means 17, the light emitting element 10 and the light receiving element 12 are fixed to the pressure transmission body 15, and therefore the positional relationship with each other and the substrate 13 can be arbitrarily determined.
The connecting means 17 can be a sticky light-transmitting sheet or a similar adhesive.

The path of light emitted from the light emitting surface of the light emitting element 10 is referred to as a light emitting optical path, and similarly the path of light incident on the light receiving surface of the light receiving means is referred to as a light receiving optical path. In FIG. 4A, although not shown, the light emitting optical path and the light receiving optical path pass through the connecting means 17. Therefore, although there is some light absorption and attenuation, there is no problem because the connection means 17 has light transparency in the first place.
On the other hand, in FIG. 4B, the light emission path of the surface (light emitting surface) of the light emitting portion of the infrared LED chip 10a of the light emitting element 10 and the surface (light receiving surface) of the light receiving portion of the silicon photodiode 12a of the light receiving element 12 are shown. The connecting means 17 is not provided in the light receiving optical path. That is, the connecting means 17 is not provided on the optical path. That is, the connection means 17 does not hinder the transmission and reception of light between the light emitting element 10 and the light receiving element 12.

  In general, the detection sensitivity is improved so that there is no factor that obstructs the passage of light in the optical path. However, in the case where the connection means 17 is not provided on the optical path and there is an air layer in the light receiving optical path, the light is scattered by the air layer. In some cases, the light receiving sensitivity is lowered. However, the detection sensitivity may be improved depending on the material of the pressure transmission body 15 and the connection means 17.

  The infrared LED chip 10a is of course driven at a constant current value in a safe range, but even if an overcurrent flows and heats up abnormally due to an unexpected situation, as shown in FIG. Since the skin and the infrared LED chip 10a are separated from each other by the connecting means 17 and an air layer is included between them, the heat is not directly transferred to the skin, and an unexpected feeling such as an unpleasant feeling or a burn is caused. It will not cause a situation.

  Of course, since the light emission wavelength of the infrared LED chip 10a and the light receiving sensitivity of the silicon photodiode 12a can be freely selected, the connecting means 17 can freely select the film thickness between the infrared LED chip 10a side and the silicon photodiode 12a side. be able to. Although not shown in view of the emission wavelength and light transmittance, for example, a configuration in which the connection means 17 is not provided only on the silicon photodiode 12a side may be employed.

[Brief description of manufacturing method]
Although not particularly limited, a part of the manufacturing method of the sensor unit 18 will be described by taking the second embodiment of the biological information measuring apparatus of the present invention shown in FIG. 2 as an example.
The covering body 14 is processed into a predetermined shape, for example, a dome shape. Of course, the shape of the covering 14 may be determined according to the desired shape of the pressure transmission body 15. The light-emitting element 10 and the light-receiving element 12 are bonded to the cover 14 with, for example, a light-transmitting adhesive. After an appropriate curing step, a thermosetting gel is poured into the inside of the covering 14. After wiring with the board | substrate 13 and these, it heats on predetermined | prescribed heat conditions and solidifies a gel. The gel becomes the pressure transmission body 15.

  By the way, the shape of the sensor part 18 of embodiment already demonstrated is not limited to it. The covering 14 shown in FIG. 2 may be used in the configuration shown in FIG. That is, the covering body 14 may be provided so as to cover the surface of the mounting member 16. With such a configuration, it is possible to achieve both the positioning of the light emitting element 10 and the light receiving element 12 provided on the element surface of the sensor unit 18 and the protection of these element surfaces.

Further, the overall shape of the pressure transmitting body 15 is such that the surface in contact with the living body becomes a flat surface as shown in FIGS. 1 to 3 when there is no load when the sensor unit 18 is not pressed against the skin of the living body. However, the present invention is not limited to this.
It is desirable that the edge where the skin contact surface and the outer peripheral side surface of the pressure transmitting body 15 intersect each other has a gently curved shape without extreme corners. The edge portion may have a radius of curvature of 2 to 3 mm. Further, the shape of the skin contact surface of the pressure transmission body 15 may be a dome shape having a curvature radius of 30 to 40 mm as shown in FIG.

In the example shown in the embodiment described above, the light emitting element 10 and the light receiving element 12 are arranged at the lowermost part (biological side) of the pressure transmitting body 15 and arranged so that the distance from the living body is the same distance. However, as shown in FIG. 5, the portion where the sensor unit 18 and the living body are in contact with each other may be arcuate.
In the example shown in FIG. 5, the first point in contact with the living body is a P point, and the distance L1 between the P point and the light emitting element 10 is the same as the distance L2 between the P point and the light receiving element 12. Of course, these distances L1 and L2 can be freely selected according to the shape of the living body.
When the distance L1 and the distance L2 are the same, when the sensor unit 18 is pressed against a living body, particularly a portion having an arc-shaped cross section opposite to the arc shape of the sensor unit 18 such as an arm, the pressure transmission body 15 is pressed. Due to the deformation in the direction toward the pressure sensor 11 due to the pressing force, the light emitting element 10 and the light receiving element 12 can be positioned flat with respect to the blood vessel inside the living body.
In either example, what is important is that the light emitting element 10 and the light receiving element 12 are in close contact with the skin.

[Explanation of Overall Block Diagram: FIG. 6]
FIG. 6 shows an overall block diagram of the biological information measuring apparatus of the present invention. In FIG. 6, 1 is a pressure detection unit, 2 is a volume pulse wave detection unit, 3 is an A / D converter, 4 is a display means, 5 is an MPU (Micro Processing Unit), 6 is a notification means, and 7 An operation unit 61 is a casing.
The display means 4 is a liquid crystal display device, for example, and can display the result measured by the biological information measuring device of the present invention as characters, icons, or images. The notification means 6 is, for example, a piezoelectric buzzer, and can notify information based on the operation of the biological information measuring device of the present invention by sound or voice.
The sensor unit 18 includes a pressure detection unit 1 that receives a pressure signal received from the pressure sensor 11 and a volume pulse wave detection unit 2 that receives a volume pulse wave signal received from the light receiving element 12.
The A / D converter 3 receives the signals from the pressure detection unit 1 and the volume pulse wave detection unit 2, converts them into digital signals, and then outputs them to the MPU 5.
The MPU 5 controls the biological information measuring apparatus of the present invention. Although not shown, the MPU 5 has storage means such as a ROM for storing a program and the like therein, and a RAM for storing data and intermediate processing results, and performs arithmetic processing according to instructions of the program stored in the ROM. It is a general microprocessor that performs.

[Description of Blood Pressure Measurement Method: FIGS. 6 to 8]
Next, a method for measuring blood pressure using the biological information measuring apparatus of the present invention will be described with reference to FIGS. FIG. 7 is a cross-sectional view schematically showing a cross section of a wrist of a human body. 21 is a radial artery, 22 is skin, 23 is a tendon, 24 is an ulnar artery, 25 is an ulna, 26 is a radius, 27 is a vein, and 710 is a flat region. FIG. 8 is a graph for explaining the externally applied pressure and the detection of the volume pulse wave. The horizontal axis indicates the time when the sensor unit 18 is pressed against the living body, the vertical axis indicates the pressure detected by the pressure sensor 11, and the vertical axis indicates the detected volume pulse wave signal. . Reference numeral 800 denotes an externally applied pressure waveform, and reference numeral 801 denotes a volume pulse waveform.

The radial artery 21 is located on the radius 26. The radial artery 21 is usually an artery that is most easily recognized when examining the pulse rate and the like, and its position can be easily confirmed by touching the skin 22 with a finger. Therefore, it is preferable that the sensor unit 18 is pressed against the wrist at this position. This position is at the top of the flat region 710 of the distal radius flat region.

The flat region of the distal end of the radius is a portion where the radius 26 becomes flat when the wrist is viewed in the direction in which the palm can be seen, and FIG. 7 shows a cross section at that portion. The flat region of the distal end of the radius is only about 7 to 8 mm in the blood vessel direction, and the upstream side is deepened immediately. The flat region 710 is a portion where the radial artery 21 is on the upper side (skin 22 side) in the flat region of the distal end of the radius.
For this reason, the diameter is preferably about 20 to 25 mm so that the pressure transmission body 15 of the sensor unit 18 that presses the upper skin 22 of the flat region 710 does not protrude from the flat region 710 to the upstream side. is there.

The relationship between the pressure applied to the arterial tube (internal / external pressure difference) and the internal volume of the blood vessel has a shape in accordance with a generally known tube law. A volume pulse wave is a change in the internal volume of the blood vessel detected by optical means. According to the volume vibration method, the volume pulse wave has the maximum amplitude because the difference between the average blood pressure in the blood vessel and the external blood pressure is zero. The externally applied pressure at this time becomes the average blood pressure. Further, the externally applied pressure is increased, the blood vessel is blocked, the blood flow is stopped, and the externally applied pressure when the volume pulse wave disappears becomes the maximum blood pressure.
In the volume vibration method, the artery is directly pressurized, the volume vibration of the blood vessel wall at the pressurized site is optically detected directly, and the blood pressure is determined from the displacement behavior of the blood vessel, so that the accuracy of blood pressure measurement is improved. Normally, the blood pressure value is detected when either the pressure of the pressurizing bag increases or decreases.

Detection of the externally applied pressure and volume pulse wave is performed using a sensor unit 18 having a pressure sensor 11, a light emitting element 10, and a light receiving element 12. The sensor unit 18 is pushed slowly and uniformly over time over about 20 seconds toward the wrist radial artery 21. By doing so, a good volume pulse wave waveform 801 and a corresponding externally applied pressure waveform 800 as shown in FIG. 8 are obtained.
The time series data of the volume pulse waveform data and the applied pressure waveform data is sequentially A / D converted by the A / D converter 3 and recorded in a storage means (not shown) in the MPU 5. The sampling time interval of the A / D converter 3 is preferably about 10 ms.

  After the pressurization is completed, the systolic blood pressure and the average blood pressure are determined according to the known volume vibration method described above using the volume pulse waveform data and the pressure waveform data recorded in the storage means in the MPU 5. The minimum blood pressure can be estimated from the maximum blood pressure (Pm) and the average blood pressure (Pa) using the fact that the volume pulse waveform and the pressure pulse waveform are similar. The obtained maximum blood pressure, average blood pressure and minimum blood pressure are displayed on the display means 4.

  As described above, according to the biological information measuring apparatus of the present invention, anyone can measure blood pressure easily and accurately. The sensor unit 18, which is a photoelectric volume pulse wave sensor, is in close contact with the skin, and the light emitting element 10 and the light receiving element 12 are fixed at predetermined coordinates of the biological system, and only the movement of the arterial blood vessels in the vicinity of the sensor unit 18 is detected. Since it can be detected, the inversion phenomenon of the photoelectric volume pulse wave signal is eliminated, the vanishing point of the photoelectric volume pulse wave for determining the systolic blood pressure becomes clear, and the correct systolic blood pressure is obtained. Furthermore, since only the photoelectric volume pulse wave can be detected, detection instability due to the position of the living body is eliminated, and the position where the living body is pressed is easily determined. Further, since the low frequency component of the detection optical signal due to the change in applied pressure is eliminated, the photoelectric volume pulse wave waveform is not deformed, and the minimum blood pressure can be calculated correctly.

  Since the biological information measuring device of the present invention can easily measure correct blood pressure, it can be used as an electronic sphygmomanometer in places such as hospitals and care facilities. Since it does not press the body of the subject such as a cuff, it is suitable for use on a subject who cannot place a load on the living body. Of course, since a cuff or the like is unnecessary, the entire apparatus can be reduced in size and weight, which is suitable for general household use.

It is a figure explaining the sensor part of the biological information measuring device of the present invention. It is a figure explaining the different sensor part of the biological information measuring device of this invention. It is a figure explaining the further different sensor part of the biological information measuring device of the present invention. It is a figure explaining the connection of the light emitting element and light receiving element by the connection means in the sensor part of the biological information measuring device of this invention. It is a figure explaining the shape of the sensor part of the biological information measuring device of the present invention. It is a block diagram of the biological information measuring device of the present invention. It is sectional drawing explaining the position of the artery of a wrist. It is a graph explaining the volume pulse wave waveform and pressure waveform which are obtained by the biological information measuring device of the present invention. It is a figure explaining a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pressure detection part 2 Volume pulse wave detection part 3 A / D converter 4 Display means 5 MPU
6 Notification means 7 Operation unit 10 Light emitting element 10a Infrared LED chip 11 Pressure sensor 12 Light receiving element 12a Silicon photodiode 13 Substrate 14 Cover 15 Pressure transmitter 16 Mounting member 17 Connection means 21 Radial artery 22 Skin 23 Tendon 24 Ulna artery 25 Ulna 26 fibula 27 vein 50 connector

Claims (6)

A sensor unit having a substrate, a light emitting unit, a light receiving unit, a pressure detecting unit, and a pressure transmitting body is provided. The sensor unit is pressed against a part of a living body, and the living body is irradiated with light from the light emitting unit and detected by the light receiving unit. In the biological information measuring apparatus for measuring biological information using reflected and scattered light from the living body and the pressure applied to the pressure transmitting body detected by the pressure detecting means,
The pressure transmission body has a predetermined shape and is in contact with the substrate,
The pressure detecting means is provided such that its pressure receiving surface is in contact with the pressure transmitting body,
The light emitting means and the light receiving means are provided apart from each other, and the pressure transmission body is sandwiched between the substrate opposite to the light emitting surface of the light emitting means or the surface opposite to the light receiving surface of the light receiving means. A biological information measuring device characterized by being arranged.   2. The biological information measuring apparatus according to claim 1, wherein the pressure transmission body is an elastic body having a uniform elastic force or a structure body including the elastic body and a covering body covering a part thereof.   The biological information measuring apparatus according to claim 1, wherein the light emitting unit or the light receiving unit is fixed to the substrate with a flexible mounting member.   The biological information measuring apparatus according to claim 1, wherein the light emitting unit or the light receiving unit is in contact with the pressure transmission body via a connection unit.   The biological information measuring apparatus according to claim 4, wherein the connecting means is a film-like thin film or an adhesive.   6. The biological information measuring apparatus according to claim 4, wherein the connecting means is not provided in a light emitting optical path of a light emitting surface of the light emitting means or a light receiving optical path of a light receiving surface of the light receiving means.

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