Blood flow pulse wave detector

Abstract

To measure a blood flow pulse wave by adjustable pressing force in a living body such as a fingertip.SOLUTION: A blood flow pulse wave detector includes: a sensor probe provided with a sensor for pulse wave detection having a light emitter and a light receiver; a cover member 01 opened with the lower portion as a living body abutment portion, having a through-hole vertically penetrating at least in the central portion, a through-hole side surface being formed with an indication surface 04 having a relatively large width in the vertical direction; and a sensor probe housing member 02 which is a recessed portion capable of housing a surface other than a sensor forming surface of the sensor probe in a lower opening surface of the cover member and having a height smaller than a thickness of the sensor probe, and has a shape capable of vertically moving in the through-hole. The cover member and the sensor probe housing member include a sensor adaptor 00 in which the through-hole of the cover member and the recessed portion of the sensor probe housing member are joined to each other in a state of moving vertically via an elastic member.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pulse wave detector. [Background technology]

[0002] When measuring peripheral blood flow in areas such as the fingertips or earlobes, pulse wave sensors commonly used have a pressure-applying attachment like a clothespin, which is attached with just enough clamping force to prevent the sensor from coming off. JP 2007-244600 A discloses a pulse wave detector equipped with a pressing member that presses the area including the sensor surface against which the fingertip is pressed toward the fingertip, and a stabilizing means for stabilizing the contact state of the fingertip.

[0003] Japanese Patent Application Laid-Open No. 2009-66042 discloses a finger insertion section equipped with an LED and a pulse wave sensor inside, which is rotatable about a shaft and a main body section. The document describes a configuration in which, when pressing a fingertip against the sensor portion of the main body, the finger insertion portion rotates depending on the position of the finger, making it easier to press.

[0004] In Japanese Patent Application Laid-Open No. 2009-201895, a load sensor is formed in a sensor section that presses the finger, and the pressing force of the fingertip can be adjusted according to the output value of the load sensor. There are two types of fingertip pulse wave sensors: one that is pressed against the fingertip and one that is worn on the fingertip. The type that is used depends on the purpose of use. However, when measuring blood flow pulse waves over a long period of time, such as in hemodialysis, the fingertip-worn type is preferred because it places less strain on the patient.

[0005] Japanese Patent Application Laid-Open Publication No. 2013-31534 describes a pulse wave sensor that is worn around the wrist, with an indicator formed at the end of the sensor whose color range changes depending on the force with which it is wrapped around the wrist.The colored area of ​​the indicator makes it possible to determine whether the sensor is in uniform contact with the surface of the wrist when it is placed against the wrist.

[0006] JP 2013-31534 A discloses a wristwatch-type pulse wave measuring device, which, when worn on the arm to detect pulse waves by pressing the wrist flat, has a can member interposed between the part where the band and main body are attached, which moves in a restorable manner, revealing the can member that was hidden by the main body, and the amount of can member that is visible determines whether the sensor at the bottom center of the main body is attached in a vertically pressed state. However, because indicators are displayed on both sides of the main body, it is cumbersome as it is necessary to tighten the device evenly to balance the colored areas on both sides. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-244600 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-66042 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-201895 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-31534 [Non-patent literature]

[0008] [Non-Patent Document 1] Hinatsu S. et al., Fingertip Contact Force Estimation Using Pulse Wave Measurement at the Proximal Joint, Biomedical Engineering, 55(3):115-124, 2017 Summary of the Invention [Problem to be solved by the invention]

[0009] The main purpose of detecting blood flow pulse waves is to measure heart rate by detecting pulse waves, as described above. However, blood flow pulse waves also contain information on peripheral vascular resistance and other factors that are useful for determining blood pressure, such as the pulse wave rise time (upstroke time) and the end point (the point at which the pulse wave rises) of the pulse wave transit time (PTT), and contain useful parts for determining blood pressure information. However, a pulse wave detector that obtains this information requires wearing specifications that allow it to accurately detect pulse waves. In particular, as described in Hinatsu Shun et al., Estimation of fingertip contact force using pulse wave measurement at the proximal joint, Biomedical Engineering, 55(3):115-124, 2017, the fingertips are areas that are sensitive to external pressure, as the arteries are elastic and contractile, and pressure on them can prevent the immediate outflow of blood. Therefore, since blood flow information such as upstroke time can be affected by the force pushing on the blood vessels to the extent that it can be mistaken for a state of arteriosclerosis, there is a need for a configuration that allows for easy adjustment of the pressure when the sensor is attached. [Means for solving the problem]

[0010] In view of the above, the present invention provides a sensor probe equipped with a pulse wave detection sensor having a light emitter and a light receiver; a cover member having an open lower portion facing the living body contact portion and having a through-hole penetrating vertically at least in the center, with relatively wide indicating surfaces formed on the sides of the through-hole; a sensor probe housing member having a shape that allows the sensor probe to move vertically within the through-hole, and in which the surfaces of the sensor probe other than the sensor-forming surface can be housed in the open lower surface of the cover member; The cover member and the sensor probe accommodating member are combined with a sensor adapter in which the bottom surface of the recess in the sensor probe accommodating member is connected to the through hole in the cover member via an elastic member so that it can move up and down.This configuration allows the pressure applied when the sensor probe is accommodated in the sensor adapter and brought into contact with and fixed to the skin to be adjusted, making it possible to detect blood flow pulse waves without deforming the state of the blood vessels.

[0011] The sensor probe is formed in a state that it can be used alone, so it can be used handheld when the measurement time is short, but by using the adapter shown in this invention and adjusting the force with which the sensor probe is pressed while looking at the indication surface, it can be used by abutting it with the optimal pressing force. The cover member in the present invention is formed from a hard material such as plastic, resin, or metal, and when the direction in which the sensor part abuts against the skin surface is defined as the lower side, the thickness of the side of the through hole in the upward direction can be increased to display in detail the amount of movement of the sensor probe accommodating member when it moves up and down.

[0012] The sensor probe accommodating member of the present invention is formed of the same hard material as the cover member, and the sensor probe accommodating section is a recess having a shape capable of accommodating the bottom and side surfaces of the sensor probe when the sensor surface of the sensor probe is positioned at the top, The depth of the recess is preferably such that, after the sensor probe is housed in the sensor adapter, when the sensor surface is placed against the skin and attached, the cushioning member formed on the skin-contacting surface of the sensor adapter is contracted and sufficient contact with the skin is achieved.

[0013] The buffer material in the present invention may be any porous, stretchable, and reproducible material such as Eptsealer (registered trademark) or urethane, and it is preferable that the height when contracted is approximately the same as the contact surface of the sensor probe and that it has light-blocking properties. The amount of pressure the sensor probe applies to the skin can be indicated by moving the underside of the bottom surface of the recess of the sensor probe housing up and down on the indicating surface of the cover member. The cover member and the sensor probe accommodating member are joined via an elastic member such as a plate-shaped or coil-shaped spring, resin, etc., and the sensor probe accommodating member is joined in a manner that allows it to move vertically while retaining its elasticity. [Effects of the Invention]

[0014] When the sensor probe is used in contact with a living body, the present invention makes it possible to adjust the pressure at the time of contact, thereby enabling blood flow pulse waves to be detected without obstructing blood flow even in peripheral areas such as fingertips that have blood vessels that react sensitively to external forces, thereby enabling accurate detection of blood flow pulse waves. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram illustrating an embodiment of the present invention. [Figure 2] 1A and 1B are diagrams for explaining an embodiment of the present invention. [Figure 3] 1A and 1B are diagrams for explaining an embodiment of the present invention. [Figure 4] 1A and 1B are diagrams for explaining an embodiment of the present invention. [Figure 5] 1A and 1B are diagrams for explaining an embodiment of the present invention. [Figure 6] 1A and 1B are diagrams for explaining an embodiment of the present invention. [Figure 7] 10A and 10B are diagrams illustrating experimental results for explaining the operation of an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention can detect blood flow pulse waves from a living body with an appropriate pressure, and is therefore applicable to non-invasive blood pressure measurement and devices that measure blood flow information from a living body based on blood pressure information such as PTT (Pulse Wave Transit Time) and PWS (Pulse Wave Velocity) obtained from the blood flow pulse waves, as well as blood flow information such as blood flow velocity and blood volume. [Example]

[0017] An embodiment of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 shows the sensor adapter 00. Fig. 1(a) shows the side (underside) where the sensor probe is attached to the sensor adapter 00. Fig. 1(b) shows the state where Fig. 1(a) is turned upside down, showing the state when the sensor probe is brought into contact with the fingertip.

[0018] FIG. 2 shows an exploded view of the combination of the cover member 01, the sensor probe housing member 02, and the buffer member 03 that constitute the sensor adapter 00 shown in FIG. FIG. 3(a) shows the sensor adapter 00 in a state before the sensor probe 20 is accommodated in the recess 02A, and FIG. 3(b) shows the sensor adapter 00 in a state after the sensor probe 20 has been accommodated in the recess 02A.

[0019] In Figures 1 and 2, 01 is a cover member, which is shown to have a triangular shape resembling a fingertip, and is made of a hard material such as PC (polycarbonate) resin, POM (polyoxymethylene) resin, ABS (acrylonitrile butadiene styrene) resin, acrylic resin, FRP (fiber reinforced plastic), aluminum alloy, magnesium alloy, etc. The cover member 01 is open downwards, with the surface to which the sensor probe accommodating member 02 is joined being the underside, and has a through hole 01A formed on the upper surface with a thickness sufficient to form the indicating surface 04, and a gap 01B is formed from the through hole 01A to allow an accommodating passage 02B to be fitted in for accommodating a portion of the connecting cord 24 for electrically connecting the sensor probe 20 to an external measuring device.

[0020] The cover member 01 has three screw holes 01C formed deep enough that the head of the screw portion 51 does not protrude from the top surface of the cover member 01 even when it moves up and down. In this embodiment, the screw holes are formed in three locations, but they are not limited to these locations and can be adjusted appropriately depending on the size and shape of the cover member 01. 01C1 indicates the side surface of the screw hole 01C, and is molded when the cover member 01 is formed so as to have a predetermined thickness. Reference numeral 51 denotes a threaded portion, which is formed by, for example, a cylindrical pan head screw as shown in FIG. The screw portion 51 is intended to support at least the elastic member 52 shown in Figure 5, but it does not have to be screw-shaped; it may be rivet-shaped, penetrating the cover member 01 and forming a fixed state with the sensor probe accommodating member 02.

[0021] 02 is a sensor probe housing member, which is made of the same material as the cover member 01. The sensor probe accommodating member 02 has a recess 02A formed in a shape that fits the side and bottom surfaces of the sensor probe 20 other than the sensor surface 21 shown in Figure 3, and a concave accommodating path 02B that accommodates the connection cord extending from the sensor probe 20.

[0022] 02C is a screw hole for fixing, which is a portion that fits onto the tip of the screw portion 51 inserted from the side of the cover member 01 to form a fixed state. 02D is the bottom surface of the recess 02A, and has a small through-hole 05 formed in the center, which contacts the unit bottom surface 25 of the housing 22 shown in FIG.

[0023] 03 is a cushioning material, which is made of a porous, flexible, and elastic material such as urethane foam or other sponge material, and its volume shrinks and deforms when pressed, but it is preferable that it returns to its original shape after it is released from contact with the skin. 04 is a support surface, which is formed by, for example, the side surface of a through hole 01A provided in the cover member 01.

[0024] The indicator surface 04 is preferably colored or the like, and the area appears to change as the outer bottom surface of the recess 02A of the sensor probe accommodating member 02, which cooperates with the unit bottom surface 25 of the sensor probe 20, slides up and down.As the area of ​​the indicator surface 04 increases, the pressing force on the sensor surface 21 decreases, and as the area of ​​the indicator surface 04 decreases, the pressing force on the sensor surface 21 increases. By pressing the sensor adapter 00 toward the living body so that the outer bottom surface of the recess 02A is always at a predetermined position on this indication surface 04, the force with which the sensor surface 21 presses against the skin surface of the living body can be made constant.

[0025] Reference numeral 51 shown in FIG. 1 denotes a screw portion, for example, a pan head screw (51a denotes a pan head screw) in which a Phillips head screw is threaded on a cylindrical body. In FIG. 3, reference numeral 20 denotes a sensor probe, which has a sensor surface 21, which is a combination of a light emitting section and a light receiving section, disposed on the top of a cylindrical housing 22 that can be held by hand. The shape of the sensor probe 20 is merely an example, and any shape that allows the sensor to be operated by hand is sufficient. In this case, it is preferable that the shape of the recess 02A of the sensor probe housing member 02 is also adjusted to match the shape (side surface, bottom surface, etc.) of the housing 22 of the sensor probe 20.

[0026] 21 is the sensor surface, on which a reflective sensor selected from, for example, a combination of an LED and a light-receiving semiconductor, a combination of a laser light source and a light-receiving semiconductor, or a combination of the laser light irradiation surface of an optical fiber and the light-receiving surface of an optical fiber is arranged. Reference numeral 22 denotes a cylindrical housing made of a hard plastic material such as PC (polycarbonate) resin, POM (polyoxymethylene) resin, ABS (acrylonitrile butadiene styrene) resin, acrylic resin, or FRP (fiber reinforced plastic) formed into a cylindrical shape. A combination of electrical lead wires or optical fibers extending from the sensor surface 21 through the inside of the housing 22 passes through a relay section 23 integrally molded with the housing 22 and extends to a measuring device (not shown) in the form of a connecting cord 24 whose surface is covered with resin.

[0027] Reference numeral 23 denotes a relay section, which extends the electrical lead wires and optical fibers integrally molded with the housing 22 to the connection cord 24, and is a reinforcing section to prevent the electrical lead wires and optical fibers from being cut by the shaking of the housing 22 during use. In this embodiment, the relay section 23 is formed in a rectangular shape, but it may be cylindrical or other shapes as long as the electrical lead wires and optical fibers are not cut by external disturbances. Reference numeral 24 denotes a connection cord, which is coated with a soft resin such as PVC (polyvinyl chloride), PE (polyethylene), soft urethane, or FEP (fluorinated ethylene propylene), and connects the measuring device and the sensor probe. The connecting cord for the probe used to detect pulse waves uses a shielded cable protected by a copper and aluminum mesh tube to reduce electromagnetic noise, and the laser probe uses an optical fiber cable coated with aramid fiber and PVC (aramid fiber is suitable as it has tensile strength to ensure tensile strength and prevent breakage).

[0028] Reference numeral 25 denotes the bottom surface of the unit, which is formed as a cylindrical bottom surface and comes into contact with the inner bottom surface of the recess 02A of the sensor probe housing member 02 shown in FIG. In FIG. 4, 52 is an elastic member, which is formed from, for example, a fluid spring, natural rubber, synthetic rubber, silicone rubber, other metals shaped to generate elastic force, non-metallic materials such as resin, or materials that themselves have elasticity (soft resin, porous material). One or more shim rings (trademark) may be inserted to adjust the gap and prevent the springs from overlapping. In this embodiment, a hollow coil-shaped elastic member 52 is used, and the threaded portion 51 passes through the hollow portion of the elastic member 52 to generate elasticity between the cover member 01 and the sensor probe accommodating member 02. However, this is not particularly limited, and any member that generates elasticity between the cover member 01 and the sensor probe accommodating member 02 may be used.

[0029] The cover member 01 and the sensor probe housing member 02 are fixed in a vertically movable state by inserting the screw portion 51 from the bottom to the top (02E) in the figure into the screw holes 01C provided in three places on the cover member 01 shown in Fig. 2, and engaging the screw portion 51 with the fixing screw hole 02C of the sensor probe housing member 02 via an elastic member 52 along the way. Note that, as shown in Figs. 5(a) and 5(b), the amount of vertical movement of the screw head of the screw portion 51 may indicate the amount of pressure that the sensor surface 21 presses against the skin. In this case, the side of the screw hole 01C is used as the indicator surface 01C1, and the pan head of the screw 51a is the indicator that moves on the indicator surface. The buffer member 03 is fixed onto the sensor probe accommodating member 02 with adhesive, double-sided tape, etc., but it may be replaceable without being particularly fixed, or it may be possible to connect a holding member that will hold it in place permanently by interposing an adhesive layer or the like on the surface that comes into contact with the living body.

[0030] Next, the operation of this embodiment will be described in detail with reference to FIGS. Figure 4(a) shows a cross section taken along line A-A' in Figure 3(a), Figure 4(b) shows a cross section taken along line B-B' in Figure 3(b), and Figure 5(a) shows a cross section taken along line C-C' in Figure 3(b). 4(a) and 5(a) show the sensor probe 20 in an uncontained state.

[0031] Next, the sensor probe 20 is accommodated in the recess 02A, and the relay portion 23 and part of the connection cord 24 are accommodated in the accommodation path 02B. Fig. 4(b) shows the sensor probe 20 accommodated. In this state, the buffer member 03 side is brought into contact with the measurement site of the fingertip Y as shown in FIG. Next, when force is applied to the cover member 01, the buffer member 03 is deformed as shown in Figures 4(c) and 5(b), and a force is applied to the sensor probe accommodating member 02 in the opposite direction to the skin via the buffer member 03, pushing it up and compressing the elastic member 52.

[0032] At this time, the recess 02A of the sensor probe accommodating member 02 moves in the direction away from the skin, narrowing the display area of ​​the indicator surface 04 (Figures 4(c) and 5(b)). When the indicator surface 04 reaches a predetermined area, the pressure is stopped and the indicator surface 04 is fixed with a band B or the like as shown in Figure 4(c). In this state, the fingertip is constantly pressed with a constant pressure, which allows accurate measurement of upstroke time and the like without applying excessive force to the blood vessels. After use, when the band B is removed, the restoring force of the elastic member 52 causes the band B to return to the state shown in FIG. 4(b).

[0033] Experimental Example A dummy sensor probe 20-shaped dummy is attached to the sensor probe housing member 02 constituting the sensor adapter 00 shown in FIG. 3, and the sensor adapter 00 is placed on a table with the dummy side facing downward. A tension gauge for displaying pressure is pressed downward against the plate-shaped top surface placed on the top surface of the cover member 01 for measurement purposes until the buffer member 03 is crushed to its limit. The tip of the lever-type dial gauge that measures the amount of deformation is positioned so that the tip touches the top surface of the cover member 01 when the buffer member 03 is crushed to its limit, and so that the tips of both gauges are close to each other. Readjust the tips of both gauges placed on the top surface of the cover member 01 so that they are in the center of the cover member 01. In this state, the amount of deformation was measured when a predetermined force was applied to the top surface of the cover member 01. The results are shown in Figure 7. It was found that when the sensor adapter 00 is attached to a living body, the amount of pressure to be applied can be known and adjusted based on the position and area indicated by the indication surface 04, which corresponds to the amount of deformation. [Industrial Applicability]

[0034] The present invention is an adapter that can be easily used to switch between an LED-based sensor and a laser-based sensor in an optical sensor used to measure blood flow pulse waves. By allowing the sensor to be brought into contact with the living body with an appropriate pressure, the adapter can be used to obtain accurate blood flow information without affecting the state of the blood vessels. This makes it possible to use the adapter as a wearable pulse wave detection device, and since it can measure pulse waves with a specified force even during long-term measurements, it can also be used in the medical device field, such as for hemodialysis treatment. [Explanation of symbols]

[0035] 00 Sensor Adapter 01 Cover material 01A Through hole 01C screw hole 02 Sensor probe housing 02A Recess 02B Enclosure 02C Fixing screw hole 02D bottom 03 Cushioning materials 04 Instruction surface 05 Through hole 51 Threaded part 20 Sensor Unit 21 Sensor surface 22 Case 23 Relay Section 24 Connection cord 25 Unit bottom

Claims

1. a sensor probe equipped with a pulse wave detection sensor having a light emitter and a light receiver; a cover member having an open lower portion facing the living body contact portion, a through-hole penetrating vertically at least in the center, and a relatively wide indicating surface formed on the side of the through-hole; a sensor probe housing member having a shape that can accommodate the surface of the sensor probe other than the sensor-forming surface on the lower open surface of the cover member and can move vertically within the through-hole; A pulse wave detector equipped with a sensor adapter in which the cover member and the sensor probe accommodating member are connected via an elastic member in a state in which the bottom surface of the recess in the sensor probe accommodating member can move up and down relative to the through hole in the cover member.

2. 2. The pulse wave detector of claim 1, wherein the sensor probe has a thickness and an integrated light-emitting unit and a light-receiving unit on one surface, and the component has a shape and size that allows it to fit into the recess of the sensor probe accommodating portion.

3. The pulse wave detector has a shock-absorbing member having elasticity and deformability on the surface of the sensor probe housing that comes into contact with the living body.

4. The pulse wave detector according to claim 2, wherein the combination of the light-emitting unit and the light-receiving unit of the sensor probe is formed by a combination of an LED and an LED light-receiving semiconductor, a combination of a laser light semiconductor and a laser light-receiving semiconductor, or a combination of a laser light irradiating surface and a laser light receiving surface.

5. The pulse wave detector according to claim 1 , wherein the recess has a through hole formed therein.

6. 2. The pulse wave detector according to claim 1, wherein a cylindrical insertion body is formed on the surface of the sensor probe housing that comes into contact with the living body, so that a finger can be inserted and the fingertip can come into contact with the sensor surface of the sensor probe.

7. 2. The pulse wave detector according to claim 1, wherein an edge of the outer bottom surface of the recess of the sensor unit housing member supports a supporting surface of the cover member.

8. The pulse wave detector according to claim 1 , wherein the cover member has a fingertip shape.

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