WO2016092681A1 - Blood flow sensor - Google Patents

Blood flow sensor Download PDF

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Publication number
WO2016092681A1
WO2016092681A1 PCT/JP2014/082889 JP2014082889W WO2016092681A1 WO 2016092681 A1 WO2016092681 A1 WO 2016092681A1 JP 2014082889 W JP2014082889 W JP 2014082889W WO 2016092681 A1 WO2016092681 A1 WO 2016092681A1
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WO
WIPO (PCT)
Prior art keywords
light
tube
blood
emitting element
light emitting
Prior art date
Application number
PCT/JP2014/082889
Other languages
French (fr)
Japanese (ja)
Inventor
智夫 五明
英路 平
直人 友安
Original Assignee
愛知時計電機株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 愛知時計電機株式会社 filed Critical 愛知時計電機株式会社
Priority to PCT/JP2014/082889 priority Critical patent/WO2016092681A1/en
Priority to JP2016563364A priority patent/JP6426199B2/en
Publication of WO2016092681A1 publication Critical patent/WO2016092681A1/en

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/026—Measuring blood flow
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
    • G01P5/26—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring the direct influence of the streaming fluid on the properties of a detecting optical wave

Definitions

  • Patent Document 1 discloses a blood flow sensor that measures the flow velocity of blood flowing through a blood vessel in the body.
  • This blood flow sensor includes a light emitting element, a light receiving element, and a control unit, and is used by being placed near a human body.
  • the light emitting element emits laser light toward the body surface. Part of the laser light emitted from the light emitting element is reflected by the body surface, and the other part is reflected by red blood cells that enter the body and flow through the blood vessels.
  • the light receiving element receives reflected light from the body surface and reflected light from red blood cells.
  • the former is reference light that is not subjected to the Doppler effect due to the blood flow velocity, and the latter is measurement light that is subject to the Doppler effect due to the blood flow velocity.
  • the control unit calculates the flow rate of red blood cells by heterodyne technology based on the light received by the light receiving element and superimposed on the reflected light from the body surface (reference light) and the reflected light from red blood cells (measurement light).
  • This type of blood flow sensor is called a laser Doppler blood flow sensor.
  • extracorporeal circulation is performed in which blood flowing through the body is sent out of the body and the blood sent out of the body is returned to the body again.
  • a tube for extracorporeal circulation is connected to a blood vessel inside the body, blood flowing through the blood vessel inside the body flows into the tube outside the body, and blood flowing through the tube outside the body returns to the blood vessel inside the body.
  • a technique capable of measuring a flow velocity close to the average flow velocity is disclosed. If a flow velocity close to the average flow velocity can be measured, the measured flow velocity can be treated as an approximate value of the average flow velocity. Alternatively, it can be corrected to an average flow velocity that closely approximates the actual average flow velocity.
  • the blood flow sensor disclosed in this specification is capable of measuring the blood flow velocity, and includes a tube that defines a flow path through which blood flows, a light emitting element that emits laser light, and a light receiving element.
  • the light emitting element emits laser light toward the blood flowing through the flow path of the tube.
  • the light receiving element receives light that is not subjected to the Doppler effect that is emitted from the light emitting element and reflected by the tube, and light that is subjected to the Doppler effect that is emitted from the light emitting element and reflected by the blood component flowing through the tube.
  • the flow path is flat, and when the two directions orthogonal to the cross section orthogonal to the blood flow direction are defined as the first direction and the second direction, the width in the first direction is narrower than the width in the second direction.
  • the light emitting element and the light receiving element are disposed on the outer surface of the tube wall that defines the width in the first direction.
  • the width of the flow path in the first direction is narrow, the distance from the central portion of the flow path to the tube wall defining the width in the first direction is shortened, and the flow rate of blood flowing through the central portion And the difference in the flow velocity of blood flowing in the vicinity of the tube wall becomes small.
  • the light emitting element and the light receiving element are arranged on the outer surface of the tube wall that defines the width in the first direction, it is possible to measure a flow velocity close to the flow velocity flowing through the center, and measure a flow velocity close to the average flow velocity. it can.
  • a tube with a circular cross section is used for extracorporeal circulation.
  • the cross-sectional area is the same as the above-described flat cross section, the distance from the center of the flow path to the tube wall is from the center of the flat flow path to the tube wall defining the width in the first direction. And the difference between the flow velocity of the blood flowing in the center and the flow velocity of the blood flowing in the vicinity of the tube wall becomes large.
  • a flow velocity close to the average flow velocity can be measured by using a tube having a flat cross section.
  • FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1 (a cross-sectional view orthogonal to the blood flow direction).
  • It is a block diagram of a blood flow sensor. It is sectional drawing orthogonal to the blood flow direction of the blood flow sensor which concerns on another Example. It is sectional drawing orthogonal to the flow direction of the blood of the blood flow sensor which concerns on another Example. It is sectional drawing orthogonal to the flow direction of the blood of the blood flow sensor which concerns on another Example.
  • a recess is formed on the outer surface of the tube wall.
  • the light emitting element and the light receiving element are arranged to face the recess. Thereby, it can suppress that a light emitting element and a light receiving element are damaged by a pipe
  • the bottom surface of the concave portion has a curved surface that is curved in a convex shape toward the light emitting element and the light receiving element. Thereby, a laser beam can be guide
  • the reflected light reflected by the red blood cells can be guided to the light receiving element.
  • a light guide is provided between the tube and the light emitting element and between the tube and the light receiving element.
  • An element-side recess is formed on the element-side surface of the light guide. The light emitting element and the light receiving element are arranged to face the element side recess. Thereby, the laser beam and the reference beam reflected on the bottom surface of the element-side recess can be obtained. Further, the light emitting element and the light receiving element can be suppressed from being damaged by the tube and the light guide, and the light guide can be suppressed from being damaged by the light emitting element and the light receiving element. (Feature 5) The light guide is replaceable.
  • a tube side recess is formed on the tube side surface of the light guide.
  • the bottom surface of the tube-side recess has a curved surface that curves in a convex shape toward the tube.
  • a laser beam can be guide
  • the reflected light reflected by the red blood cells can be guided to the light receiving element.
  • the width of the flow path in the second direction is 10 times or more the width of the first direction.
  • a blood flow sensor 1 according to a first embodiment will be described with reference to FIGS. 1 and 2.
  • the blood flow sensor 1 includes a tube 40, a light emitting element 10, a light receiving element 20, and a cover 70.
  • the blood flow sensor 1 includes a control unit 90 connected to the light emitting element 10 and the light receiving element 20.
  • the tube 40 is for extracorporeal circulation, and is preferably transparent so that blood passing through the tube 40 is visible.
  • the tube 40 includes a tube wall 41 that defines a flow path 42.
  • a recess 30 is formed in a part of the outer surface of the tube wall 40.
  • the tube 40 is connected to a blood vessel (not shown) in the patient's body, and blood B flows into the flow path 42 of the tube 40 from the patient's blood vessel.
  • the blood B flowing through the flow path 42 of the tube 40 is sent back to the patient's blood vessel again.
  • the patient's blood B is once taken out of the patient's blood vessel and sent back to the patient's blood vessel, whereby blood B is extracorporeally circulated.
  • Blood B contains various components.
  • blood B contains components such as red blood cells, white blood cells, platelets, plasma, and lymphocytes.
  • the tube wall 41 is made of, for example, transparent resin or glass.
  • the tube wall 41 is light transmissive and can transmit the laser light L and visible light. Since the tube wall 41 is formed transparently, the inside of the tube wall 41 can be visually recognized through the tube wall 41, and the blood B flowing through the flow path 42 inside the tube wall 41 can be visually recognized.
  • the flow path 42 extends along the central axis 40 a of the tube 40, and the blood B flows through the flow path 42 along the central axis 40 a of the tube 40.
  • the flow path 42 has a rectangular shape in a cross section (cross section orthogonal to the central axis 40 a of the tube 40) perpendicular to the blood B flow direction (x direction in this embodiment).
  • the shape of the flow path 42 is a flat shape.
  • the width w1 in one direction (z direction) is narrower than the width w2 in the second direction (y direction) of the flow path 42.
  • the width w2 of the flow path 42 in the second direction is preferably 10 times or more the width w1 of the flow path 42 in the first direction. That is, w2> 10 ⁇ w1 is preferable.
  • the recess 30 is formed on the outer surface 43 of the tube wall 41.
  • the recess 30 has a shape that is recessed from the outer surface 43 of the tube wall 41 toward the flow path 42.
  • the recess 30 and the channel 42 are formed side by side along the first direction.
  • the width w30 of the recess 30 in the second direction is narrower than the width w2 of the flow path.
  • the recess 30 has a bottom surface 32.
  • the bottom surface 32 is formed flat.
  • the light emitting element 10 and the light receiving element 20 are arranged side by side along the flow direction of the blood B.
  • the light emitting element 10 is disposed on the upstream side in the blood B flow direction
  • the light receiving element 20 is disposed on the downstream side in the blood B flow direction.
  • the light emitting element 10 and the light receiving element 20 are fixed to the cover 70.
  • the light emitting element 10 emits laser light L.
  • a laser diode (LD) can be used.
  • the frequency of the laser beam L emitted from the light emitting element 10 is not particularly limited.
  • the light emitting element 10 is disposed to face the tube 40. Further, the light emitting element 10 is disposed to face the recess 30.
  • the light emitting element 10 is disposed on the outer surface of the tube wall 41 that defines the width in the first direction (z direction).
  • the light emitting element 10 emits laser light L toward the transparent tube 40 and blood B flowing through the tube 40.
  • the light emitting element 10 emits laser light L from the outside of the tube 40 toward the inside of the tube 40.
  • the light emitting element 10 emits laser light L toward the recess 30.
  • the laser light L emitted from the light emitting element 10 travels in the first direction when viewed in a cross section perpendicular to the blood B flow direction.
  • Part of the laser light L emitted from the light emitting element 10 is reflected by the bottom surface 32 of the recess 30 and enters the light receiving element 20.
  • the laser light L reflected by the bottom surface 32 of the recess 30 becomes reference light that has not been subjected to the Doppler effect.
  • another part of the laser light L emitted from the light emitting element 10 passes through the recess 30 and the tube wall 41 of the tube 40.
  • Part of the laser light L that has passed through the tube wall 41 is reflected at the boundary between the tube wall 41 and the flow path 42 (the inner surface of the tube wall 41).
  • a part of the laser light L is reflected by stationary red blood cells contained in the blood B in the part in contact with the inner surface of the tube wall 41.
  • the laser light L reflected at the boundary between the tube wall 41 and the flow path 42 travels toward the light receiving element 20.
  • the laser light L reflected at the boundary between the tube wall 41 and the flow path 42 is reference light that has not been subjected to the Doppler effect.
  • the laser light L traveling toward the light receiving element 20 enters the light receiving element 20 after passing through the tube wall 41 and the recess 30.
  • the laser light L incident on the flow path 42 from the boundary between the tube wall 41 and the flow path 42 travels in the blood B.
  • the laser light L incident on the flow path 42 is refracted at the boundary between the tube wall 41 and the flow path 42.
  • the laser light L traveling in the blood B strikes and reflects the components contained in the blood B.
  • the laser light L strikes and reflects the red blood cells R contained in the blood B, and the reflected light S is generated.
  • the frequency of light changes before and after the reflection. Therefore, the frequency of the laser light L and the frequency of the reflected light S are different.
  • the reflected light S reflected by the red blood cells R is measurement light that has been subjected to the Doppler effect.
  • the reflected light S travels toward the light receiving element 20.
  • the reflected light S enters the tube wall 41 from the boundary between the flow path 42 and the tube wall 41, passes through the tube wall 41 and the recess 30, and then enters the light receiving element 20.
  • the reflected light S emitted to the tube wall 41 is refracted at the boundary between the flow path 42 and the tube wall 41.
  • the light receiving element 20 receives light incident on the light receiving element 20 and outputs an electrical signal corresponding to the received light quantity.
  • a photodiode (PD) can be used for the light receiving element 20.
  • the light receiving element 20 is disposed to face the tube 40.
  • the light receiving element 20 is disposed to face the recess 30.
  • the light receiving element 20 is disposed on the outer surface of the tube wall 41 that defines the width in the first direction (z direction).
  • the light receiving element 20 receives light reflected by the tube 40 (reference light not receiving the Doppler effect) and light reflected by the red blood cells R (measurement light receiving the Doppler effect).
  • the light receiving element 20 receives light that has passed through the tube wall 41 and the recess 30.
  • the light received by the light receiving element 20 (the light reflected by the tube 40 and the light reflected by the red blood cell R) is used to calculate the flow velocity of the blood B flowing through the tube 40.
  • the cover 70 covers the light emitting element 10 and the light receiving element 20.
  • the light emitting element 10 and the light receiving element 20 are fixed to the cover 70.
  • the cover 70 is opaque and has a light shielding property.
  • the color of the cover 70 is preferably black.
  • the cover 70 is preferably matte.
  • the cover 70 blocks light so that unnecessary light does not enter the light emitting element 10 and the light receiving element 20.
  • the cover 70 has a contact surface 71.
  • the contact surface 71 contacts the outer surface 43 of the tube 40.
  • the contact surface 71 is formed to have a shape that matches the shape of the outer surface 43 of the tube 40.
  • the cover 70 covers a part of the outer surface 43 of the tube 40.
  • the controller 90 can calculate the flow rate of the blood B flowing through the tube 40 based on the light received by the light receiving element 20. Further, the control unit 90 can calculate the flow rate of blood B.
  • the control unit 90 performs calculation using a heterodyne technique.
  • the heterodyne technique is a method in which two waves (lights) having different frequencies are superimposed to generate a beat (beat), and calculation is performed using this beat.
  • the heterodyne technique is a direction in which calculation is performed using the difference between the frequencies of two waves (light), that is, Doppler shift.
  • the control unit 90 calculates the frequency difference between the reference light and the measurement light using the heterodyne technique, and calculates the blood B flow velocity from the calculation result. Since the heterodyne technique is known, a detailed description is omitted.
  • the control unit 90 outputs the calculated blood B flow velocity and flow rate to a monitor (not shown).
  • the blood flow sensor 1 includes a tube 40 that defines a flow path 42 through which blood B flows, a light emitting element 10 that emits laser light L, and a light receiving element 20.
  • the light emitting element 10 emits laser light L toward the blood B flowing through the flow path 42 of the tube 40.
  • the light receiving element 20 is reflected by reflected light (light not subjected to the Doppler effect) that is emitted from the light emitting element 10 and reflected within the tube 40 and blood components that are emitted from the light emitting element 10 and flow through the tube 40. The reflected light (light subjected to the Doppler effect) is received.
  • the flow path 42 of the tube 40 has a width w1 in the first direction narrower than a width w2 in the second direction in a cross section orthogonal to the blood B flow direction.
  • the light emitting element 10 emits laser light L in the first direction in the cross section of FIG.
  • the width w1 in the first direction of the flow path 42 is narrow, the distance between the center portion and the peripheral edge portion of the flow path 42 in the first direction can be shortened.
  • the distance between the central portion and the peripheral portion of the flow path 42 becomes short, the difference between the flow velocity of the blood B flowing through the central portion and the flow velocity of the blood B flowing through the peripheral portion becomes small.
  • the flow rate of blood B flowing through the peripheral edge of the flow path 42 approaches the average flow rate.
  • the blood flow rate of the blood B is measured by the blood flow sensor 1
  • a flow rate close to the average flow rate of the blood B can be measured.
  • the correction coefficient can be reduced, and the error from the actual flow rate can be reduced.
  • the light emitting element 10 and the light receiving element 20 are arranged to face the recess 30, the light emitting element 10 and the light receiving element 20 do not contact the tube wall 41 of the tube 40. Thereby, it is possible to suppress the light emitting element 10 and the light receiving element 20 from being damaged by the tube wall 41.
  • the width w2 of the flow path 42 in the second direction is 10 times or more than the width w1 of the flow path 42 in the first direction
  • the central portion of the flow path 42 and the tube wall defining the width in the first direction The flow rate of the blood B flowing in the vicinity can be made substantially the same.
  • the bottom surface 32 of the recess 30 is formed flat, but the present invention is not limited to this configuration.
  • the bottom surface 32 of the recess 30 has a curved surface 33 as shown in FIG.
  • the curved surface 33 is curved in a convex shape toward the light emitting element 10 and the light receiving element 20.
  • the curved surface 33 protrudes on the side opposite to the flow path 42.
  • the curved surface 33 is curved in a cross section orthogonal to the flow direction of the blood B.
  • a convex lens is formed on the tube wall 41 by the curved surface 33.
  • the convex lens formed by the curved surface 33 is formed so that the central portion of the flow path 42 is a focal point.
  • the light emitting element 10 and the light receiving element 20 are arranged to face the curved surface 33.
  • the light emitting element 10 emits laser light L toward the curved surface 33.
  • the laser light L emitted from the light emitting element 10 is refracted by the curved surface 33 and enters the tube wall 41, passes through the tube wall 41, and enters the flow path 42.
  • the laser light L travels toward the center of the flow path 42 by being refracted by the curved surface 33.
  • the laser light L incident on the flow path 42 is reflected by the red blood cells R contained in the blood B flowing through the flow path 42.
  • the reflected light S reflected by the red blood cells R passes through the flow path 42 and the tube wall 41 and exits from the curved surface 33.
  • the reflected light S is refracted by the curved surface 33 and travels toward the light receiving element 20.
  • the light receiving element 20 receives light that has passed through the curved surface 33.
  • the laser light L emitted from the light emitting element 10 is refracted by the curved surface 33 and the flow path 42. Go towards the center of the city.
  • the width w2 in the second direction of the flow path 42 becomes wider than the width w1 in the first direction, and from the center of the flow path 42 to the tube wall 41 that defines the width in the second direction. The distance becomes longer.
  • the difference between the flow rate of the blood B flowing through the central portion of the flow path 42 and the flow rate of the blood B flowing through the peripheral portion becomes large.
  • the laser beam L can be guide
  • the blood flow sensor 1 As shown in FIG. 5, the blood flow sensor 1 according to the third embodiment includes a transparent light guide 50 disposed between the tube 40, the light emitting element 10, and the light receiving element 20.
  • the light guide 50 is made of, for example, transparent resin or glass.
  • the light guide 50 is light transmissive and can transmit the laser light L and visible light.
  • the refractive index of the light guide 50 and the refractive index of the tube 40 are preferably the same refractive index. In addition, both refractive indexes may differ.
  • Grease (not shown) is applied between the light guide 50 and the tube 40. The light guide 50 is in close contact with the tube 40 via grease. The grease is light transmissive and can transmit the laser light L and visible light.
  • the light guide 50 includes a first contact surface 51 and a second contact surface 52.
  • the first contact surface 51 contacts the contact surface 71 of the cover 70.
  • the first contact surface 51 is formed to have a shape that matches the shape of the contact surface 71 of the cover 70.
  • the second contact surface 52 contacts the outer surface 43 of the tube 40.
  • the second contact surface 52 is formed to have a shape that matches the shape of the outer surface 43 of the tube 40.
  • the light guide 50 includes an element-side recess 60 and a tube-side recess 80.
  • the element-side recess 60 is formed on the surface of the light guide 50 on the light-emitting element 10 and light-receiving element 20 side.
  • the element-side recess 60 has a shape that is recessed from the surface of the light guide 50 on the elements 10 and 20 side toward the flow path 42.
  • the element-side recess 60 and the flow path 42 are arranged along the first direction.
  • the width w60 of the element-side recess 60 in the second direction is narrower than the width w2 of the flow path.
  • the element side recess 60 has a bottom surface 62.
  • the bottom surface 62 is formed flat.
  • the tube side recess 80 is formed on the surface of the light guide 50 on the tube 40 side.
  • the tube-side recess 80 faces the tube 40.
  • the tube side recess 80 has a shape that is recessed from the surface of the light guide 50 on the tube 40 side toward the element side recess 60.
  • the tube side recessed part 80, the element side recessed part 60, and the flow path 42 are located in a line along the first direction.
  • the width w80 of the tube-side recess 80 in the second direction is narrower than the width w2 of the flow path 42.
  • the tube-side recess 80 has a bottom surface 82.
  • the bottom surface 82 of the tube-side recess 80 has a curved surface 83.
  • the curved surface 83 is curved in a convex shape toward the tube 40.
  • the curved surface 83 protrudes toward the tube 40 side.
  • the curved surface 83 is curved in a cross section orthogonal to the blood B flow direction.
  • a convex lens is formed on the light guide 50 by the curved surface 83.
  • the light emitting element 10 and the light receiving element 20 are disposed so as to face the element side recess 60.
  • the light emitting element 10 emits laser light L toward the element side recess 60.
  • a part of the laser light L emitted from the light emitting element 10 is reflected by the bottom surface 62 of the element side recess 60 and enters the light receiving element 20.
  • the other part of the laser light L passes toward the tube 40 through the element-side recess 60, the inside of the light guide 50, and the tube-side recess 80.
  • the laser light L is refracted by the curved surface 83 when it exits from the curved surface 83. Thereafter, the laser light L passes through the tube wall 41 of the tube 40 and enters the flow path 42.
  • the laser light L incident on the flow path 42 is reflected by the red blood cells R contained in the blood B flowing through the flow path 42.
  • the reflected light S reflected by the red blood cells R travels toward the light guide 50 through the flow path 42 and the tube wall 41. Further, the reflected light S travels toward the light receiving element 20 through the tube side recess 80, the inside of the light guide 50, and the element side recess 60. The reflected light S is refracted by the curved surface 83 when entering the light guide 50 from the curved surface 83.
  • the light receiving element 20 receives the laser light L that has passed through the element-side recess 60.
  • the light guide 50 is disposed between the tube 40 and the light emitting element 10 and the light receiving element 20, and the light emitting element 10 and the light receiving element 20 face the element side recess 60. Therefore, the light emitting element 10 and the light receiving element 20 do not contact the tube 40 and the light guide 50. Thereby, it can suppress that the light emitting element 10 and the light receiving element 20 are damaged by the pipe
  • FIG. The light guide 50 is replaceable. Further, the light reflected by the bottom surface 62 of the element-side recess 60 can be received as the reference light.
  • the laser light L emitted from the light emitting element 10 is refracted by the curved surface 83 toward the center of the flow path 42. Go ahead.
  • the laser light L can be guided to the center of the flow path 42, and the flow rate of the blood B flowing through the center of the flow path 42 can be measured.
  • the reflected light S reflected by the red blood cells R contained in the blood B is refracted by the curved surface 83 and travels toward the light receiving element 20. Thereby, the reflected light S can be guided to the light receiving element 20.
  • the bottom surface 62 of the element-side recess 60 of the light guide 50 is formed flat.
  • the present invention is not limited to this configuration.
  • the bottom surface 62 of the element-side recess 60 may have a curved surface.
  • the flow path 42 has a rectangular shape in a cross section perpendicular to the flow direction of the blood B, but is not limited to this configuration.
  • the channel 42 may have an oval shape or an oval shape in a cross section orthogonal to the flow direction of the blood B.
  • the width w1 of the flow path 42 in the first direction is narrower than the width w2 of the flow path 42 in the second direction orthogonal to the first direction. Even with such a configuration, the distance between the peripheral edge portion and the central portion of the flow path 42 in the first direction can be reduced.
  • the configuration of the light emitting element 10 is not limited to the above embodiment.
  • a lens (not shown) may be attached to a portion of the light emitting element 10 where the laser light L is emitted.
  • the lens is fixed to the tip of the light emitting element 10.
  • the laser light L emitted from the light emitting element 10 is diffused by the lens, and the diffused laser light L travels toward the tube 40 and the blood B.
  • a part of the laser light L is reflected at the boundary between the tube wall 41 and the flow path 42 (the inner surface of the tube wall 41), and another part is incident on the blood B flowing through the flow path 42 and is included in the blood B. Reflected by the moving red blood cell R.
  • Even with such a configuration it is possible to receive the reference light not subjected to the Doppler effect and the measurement light subjected to the Doppler effect.
  • the recess 30 is formed on the outer surface 43 of the tube 40.
  • the present invention is not limited to this configuration, and the recess 30 can be omitted.
  • Blood flow sensor 10 Light emitting element 20: Light receiving element 30: Recess 32: Bottom surface 33: Curved surface 40: Tube 40a: Center axis 41: Tube wall 42: Channel 43: Outer surface 50: Light guide 51: First Contact surface 52: Second contact surface 60: Element side recess 62: Bottom surface 70: Cover 71: Contact surface 80: Tube side recess 82: Bottom surface 83: Curved surface 90: Control unit B: Blood L: Laser light R: Red blood cell S :reflected light

Abstract

This blood flow sensor 1 can measure the flow speed of blood B, and is provided with a tube 40 which defines a flow path 42 through which the blood B flows, a light-emitting element 10 which emits a laser beam L, and a light-receiving element 20. The light-emitting element 10 emits a laser beam L towards the blood B flowing through the tube 40. The light-receiving element 20 receives non-Doppler-shifted light which is emitted by the light-emitting element 10 and reflected by the tube 4, and Doppler-shifted light which is emitted by light-emitting element 10 and reflected by a blood component flowing through the tube 40. Defining a first direction and a second direction as two orthogonal directions in a cross-section perpendicular to the flow direction of the blood B, the width w1 of the flow path in a first direction is less than the width w2 in the second direction. The light-emitting element 10 and the light-receiving element 20 are arranged on the outer surface of the tube wall that defines the width w1 in the first direction.

Description

血流センサBlood flow sensor
　本明細書では、血流センサに関する技術を開示する。 In this specification, a technique relating to a blood flow sensor is disclosed.
　特許文献１に、体内にある血管を流れる血液の流速を計測する血流センサが開示されている。この血流センサは、発光素子と受光素子と制御部を備えており、人体の近くに置いて用いられる。発光素子が、体表面に向けてレーザー光を発光する。発光素子が発光したレーザー光は、その一部が体表面で反射し、他の一部は体内に侵入して血管を流れる赤血球によって反射される。受光素子は、体表面からの反射光と、赤血球からの反射光を受光する。前者は、血液の流速によるドップラー効果を受けていない参照光となり、後者は血液の流速によるドップラー効果を受けている計測光となる。制御部は、受光素子が受光した、体表面からの反射光（参照光）と赤血球からの反射光（計測光）を重ね合わせた光に基づいて、ヘテロダイン技術によって赤血球の流速を計算する。この種の血流センサは、レーザードップラー式の血流センサと呼ばれている。 Patent Document 1 discloses a blood flow sensor that measures the flow velocity of blood flowing through a blood vessel in the body. This blood flow sensor includes a light emitting element, a light receiving element, and a control unit, and is used by being placed near a human body. The light emitting element emits laser light toward the body surface. Part of the laser light emitted from the light emitting element is reflected by the body surface, and the other part is reflected by red blood cells that enter the body and flow through the blood vessels. The light receiving element receives reflected light from the body surface and reflected light from red blood cells. The former is reference light that is not subjected to the Doppler effect due to the blood flow velocity, and the latter is measurement light that is subject to the Doppler effect due to the blood flow velocity. The control unit calculates the flow rate of red blood cells by heterodyne technology based on the light received by the light receiving element and superimposed on the reflected light from the body surface (reference light) and the reflected light from red blood cells (measurement light). This type of blood flow sensor is called a laser Doppler blood flow sensor.
　医療現場では、体内を流れる血液を体外に送り出し、体外に送り出した血液を再び体内に戻す体外循環が行われている。体外循環用の管が体内の血管に接続され、体内の血管を流れる血液が体外の管に流入し、体外の管を流れた血液が体内の血管に戻る。 In the medical field, extracorporeal circulation is performed in which blood flowing through the body is sent out of the body and the blood sent out of the body is returned to the body again. A tube for extracorporeal circulation is connected to a blood vessel inside the body, blood flowing through the blood vessel inside the body flows into the tube outside the body, and blood flowing through the tube outside the body returns to the blood vessel inside the body.
特開２００８－２７２０８５号公報JP 2008-272085 A
　体外循環に用いる管を流れる血液の流速を計測するために、特許文献１の血流センサを利用することが考えられる。この場合、発光素子から発光されたレーザー光の一部が管で反射して参照光となり、レーザー光の他の一部が管を流れる血液に入射し、血液中の赤血球で反射して計測光となる現象を利用することになる。 In order to measure the flow velocity of blood flowing through a tube used for extracorporeal circulation, it is conceivable to use the blood flow sensor of Patent Document 1. In this case, a part of the laser light emitted from the light emitting element is reflected by the tube to become reference light, and another part of the laser light is incident on the blood flowing through the tube and reflected by the red blood cells in the blood. Will be used.
　体外循環に用いる管を血液が流れるとき、流路の中心部では管壁の影響が小さいので流速が速くなるのに対し、管壁に近い周縁部では管壁の影響が大きいので流速が遅くなる。また、血液は透明度が低いので、レーザー光は血液の中を進みにくい。計測光の大部分は管壁に近い周縁部を流れる赤血球からの反射光となる。 When blood flows through a tube used for extracorporeal circulation, the flow velocity increases because the influence of the tube wall is small at the center of the flow path, whereas the flow velocity slows because the influence of the tube wall is large at the peripheral portion near the tube wall. . Moreover, since blood has low transparency, it is difficult for laser light to travel through the blood. Most of the measurement light is reflected light from red blood cells flowing in the peripheral edge near the tube wall.
　このために、体外循環に用いる管にレーザードップラー式の血流センサと適用すると、流速の遅い管壁に近い部分を流れる血液の流速を計測することになり、管を流れる血液の平均流速ないし代表流速を計測しないという問題が生じる。計測して得られた流速を補正して平均流速に換算することも考えられるが、計測流速と平均流速の差が大きいと、補正しても実際の平均流速からの誤差が大きくなるという問題があった。 For this reason, when a laser Doppler blood flow sensor is applied to a tube used for extracorporeal circulation, the flow rate of blood flowing through a portion close to the tube wall having a slow flow rate is measured, and the average flow rate or representative flow of blood flowing through the tube is measured. The problem of not measuring the flow velocity occurs. It is conceivable to correct the flow velocity obtained by measurement and convert it to the average flow velocity, but if the difference between the measured flow velocity and the average flow velocity is large, the error from the actual average flow velocity will increase even if it is corrected. there were.
　本明細書では、平均流速に近い流速を計測することができる技術を開示する。平均流速に近い流速が計測できれば、計測流速を平均流速の近似値と扱うことが可能となる。あるいは、実際の平均流速によく近似する平均流速に補正することが可能となる。 In the present specification, a technique capable of measuring a flow velocity close to the average flow velocity is disclosed. If a flow velocity close to the average flow velocity can be measured, the measured flow velocity can be treated as an approximate value of the average flow velocity. Alternatively, it can be corrected to an average flow velocity that closely approximates the actual average flow velocity.
　本明細書に開示する血流センサは、血液の流速を計測可能であり、血液が流れる流路を画定する管と、レーザー光を発光する発光素子と、受光素子を備えている。発光素子は、管の流路を流れる血液に向けてレーザー光を発光する。受光素子は、発光素子が発光して管で反射されたドップラー効果を受けていない光と、発光素子が発光して管を流れる血液成分で反射されたドップラー効果を受けた光を受光する。流路は扁平であり、血液の流れ方向に直交する断面において直交する２方向を第１方向と第２方向とすると、第１方向の幅が第２方向の幅より狭い。発光素子と受光素子は、第１方向の幅を画定する管壁の外面に配置されている。 The blood flow sensor disclosed in this specification is capable of measuring the blood flow velocity, and includes a tube that defines a flow path through which blood flows, a light emitting element that emits laser light, and a light receiving element. The light emitting element emits laser light toward the blood flowing through the flow path of the tube. The light receiving element receives light that is not subjected to the Doppler effect that is emitted from the light emitting element and reflected by the tube, and light that is subjected to the Doppler effect that is emitted from the light emitting element and reflected by the blood component flowing through the tube. The flow path is flat, and when the two directions orthogonal to the cross section orthogonal to the blood flow direction are defined as the first direction and the second direction, the width in the first direction is narrower than the width in the second direction. The light emitting element and the light receiving element are disposed on the outer surface of the tube wall that defines the width in the first direction.
　このような構成によれば、流路の第１方向の幅が狭いので、流路の中心部から第１方向の幅を画定する管壁までの距離が短くなり、中心部を流れる血液の流速と管壁の近傍を流れる血液の流速の差が小さくなる。第１方向の幅を画定する管壁の外面に発光素子と受光素子を配置しておけば、中心部を流れる流速に近い流速を計測することができ、平均流速に近い流速を計測することができる。 According to such a configuration, since the width of the flow path in the first direction is narrow, the distance from the central portion of the flow path to the tube wall defining the width in the first direction is shortened, and the flow rate of blood flowing through the central portion And the difference in the flow velocity of blood flowing in the vicinity of the tube wall becomes small. If the light emitting element and the light receiving element are arranged on the outer surface of the tube wall that defines the width in the first direction, it is possible to measure a flow velocity close to the flow velocity flowing through the center, and measure a flow velocity close to the average flow velocity. it can.
　通常であれば、断面が円形の管を体外循環に用いる。この場合、前記した扁平断面と比較し、断面積が同じであれば、流路の中心部から管壁までの距離が、扁平流路の中心部から第１方向の幅を画定する管壁までの距離よりも長くなり、中心部を流れる血液の流速と管壁の近傍を流れる血液の流速の差が大きくなる。本技術では、扁平断面の管を利用することで、平均流速に近い流速を計測可能とする。 Normally, a tube with a circular cross section is used for extracorporeal circulation. In this case, if the cross-sectional area is the same as the above-described flat cross section, the distance from the center of the flow path to the tube wall is from the center of the flat flow path to the tube wall defining the width in the first direction. And the difference between the flow velocity of the blood flowing in the center and the flow velocity of the blood flowing in the vicinity of the tube wall becomes large. In the present technology, a flow velocity close to the average flow velocity can be measured by using a tube having a flat cross section.
血流センサの断面図である。It is sectional drawing of a blood flow sensor. 図１のII－II断面図である（血液の流れ方向に直交する断面図である）。FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1 (a cross-sectional view orthogonal to the blood flow direction). 血流センサのブロック図である。It is a block diagram of a blood flow sensor. 他の実施例に係る血流センサの血液の流れ方向に直交する断面図である。It is sectional drawing orthogonal to the blood flow direction of the blood flow sensor which concerns on another Example. 更に他の実施例に係る血流センサの血液の流れ方向に直交する断面図である。It is sectional drawing orthogonal to the flow direction of the blood of the blood flow sensor which concerns on another Example. 更に他の実施例に係る血流センサの血液の流れ方向に直交する断面図である。It is sectional drawing orthogonal to the flow direction of the blood of the blood flow sensor which concerns on another Example.
　以下に説明する実施形態の主要な特徴を列記する。なお、以下に記載する技術要素は、それぞれ独立した技術要素であって、単独であるいは各種の組合せによって技術的有用性を発揮するものである。
（特徴１）管壁の外面に凹部が形成されている。発光素子と受光素子が凹部に対向して配置されている。これにより、発光素子と受光素子が管によって傷付くことを抑制できる。逆に、管が発光素子と受光素子によって傷付くことを抑制できる。
（特徴２）凹部の底面は、発光素子と受光素子に向かって凸状に湾曲した湾曲面を有している。これにより、レーザー光を流路の中心部に導くことができる。また、赤血球で反射した反射光を受光素子に導くことができる。
（特徴３）管と発光素子の間、ならびに管と受光素子の間に配置された導光体を備えている。
（特徴４）導光体の素子側の面に、素子側凹部が形成されている。発光素子および受光素子は、素子側凹部に対向して配置されている。これにより、素子側凹部の底面で反射したレーザー光と参照光にできる。また、発光素子および受光素子が管および導光体によって導光体が傷付くことを抑制でき、導光体が発光素子および受光素子によって傷付くことを抑制できる。
（特徴５）導光体は交換可能である。
（特徴６）導光体の管側の面には、管側凹部が形成されている。
（特徴７）管側凹部の底面は、管に向かって凸状に湾曲した湾曲面を有している。これにより、レーザー光を流路の中心部に導くことができる。また、赤血球で反射した反射光を受光素子に導くことができる。
（特徴８）流路の第２方向の幅は、第１方向の幅の１０倍以上である。 The main features of the embodiments described below are listed. Note that the technical elements described below are independent technical elements, and exhibit technical usefulness alone or in various combinations.
(Feature 1) A recess is formed on the outer surface of the tube wall. The light emitting element and the light receiving element are arranged to face the recess. Thereby, it can suppress that a light emitting element and a light receiving element are damaged by a pipe | tube. Conversely, the tube can be prevented from being damaged by the light emitting element and the light receiving element.
(Feature 2) The bottom surface of the concave portion has a curved surface that is curved in a convex shape toward the light emitting element and the light receiving element. Thereby, a laser beam can be guide | induced to the center part of a flow path. Further, the reflected light reflected by the red blood cells can be guided to the light receiving element.
(Feature 3) A light guide is provided between the tube and the light emitting element and between the tube and the light receiving element.
(Feature 4) An element-side recess is formed on the element-side surface of the light guide. The light emitting element and the light receiving element are arranged to face the element side recess. Thereby, the laser beam and the reference beam reflected on the bottom surface of the element-side recess can be obtained. Further, the light emitting element and the light receiving element can be suppressed from being damaged by the tube and the light guide, and the light guide can be suppressed from being damaged by the light emitting element and the light receiving element.
(Feature 5) The light guide is replaceable.
(Characteristic 6) A tube side recess is formed on the tube side surface of the light guide.
(Feature 7) The bottom surface of the tube-side recess has a curved surface that curves in a convex shape toward the tube. Thereby, a laser beam can be guide | induced to the center part of a flow path. Further, the reflected light reflected by the red blood cells can be guided to the light receiving element.
(Feature 8) The width of the flow path in the second direction is 10 times or more the width of the first direction.
（第１実施例）
　第１実施例の血流センサ１を、図１と図２を参照して説明する。血流センサ１は、図１と図２に示すように、管４０、発光素子１０、受光素子２０およびカバー７０を備えている。また、図３に示すように、血流センサ１は、発光素子１０と受光素子２０に接続された制御部９０を備えている。管４０は、体外循環用であり、内部を通過する血液が視認可能なように、透明であることが好ましい。 (First embodiment)
A blood flow sensor 1 according to a first embodiment will be described with reference to FIGS. 1 and 2. As shown in FIGS. 1 and 2, the blood flow sensor 1 includes a tube 40, a light emitting element 10, a light receiving element 20, and a cover 70. As shown in FIG. 3, the blood flow sensor 1 includes a control unit 90 connected to the light emitting element 10 and the light receiving element 20. The tube 40 is for extracorporeal circulation, and is preferably transparent so that blood passing through the tube 40 is visible.
　管４０は、流路４２を画定する管壁４１を備えている。管壁４０の外面の一部に、凹部３０が形成されている。管４０は患者の体内にある血管（図示省略）に接続されており、患者の血管から管４０の流路４２に血液Ｂが流入する。管４０の流路４２を流れた血液Ｂは、再び患者の血管に送り返される。このように、患者の血液Ｂが患者の血管から体外に一旦取り出され、再び患者の血管に送り戻されることにより、血液Ｂの体外循環が行われる。血液Ｂには、様々な成分が含まれている。例えば、血液Ｂには、赤血球、白血球、血小板、血漿、リンパ球などの成分が含まれている。 The tube 40 includes a tube wall 41 that defines a flow path 42. A recess 30 is formed in a part of the outer surface of the tube wall 40. The tube 40 is connected to a blood vessel (not shown) in the patient's body, and blood B flows into the flow path 42 of the tube 40 from the patient's blood vessel. The blood B flowing through the flow path 42 of the tube 40 is sent back to the patient's blood vessel again. Thus, the patient's blood B is once taken out of the patient's blood vessel and sent back to the patient's blood vessel, whereby blood B is extracorporeally circulated. Blood B contains various components. For example, blood B contains components such as red blood cells, white blood cells, platelets, plasma, and lymphocytes.
　管壁４１は、例えば透明な樹脂やガラスにより形成されている。管壁４１は、光透過性を有しており、レーザー光Ｌおよび可視光を透過可能である。管壁４１が透明に形成されているので、管壁４１を通じて管壁４１の内側が視認でき、管壁４１の内側の流路４２を流れる血液Ｂが視認できる。 The tube wall 41 is made of, for example, transparent resin or glass. The tube wall 41 is light transmissive and can transmit the laser light L and visible light. Since the tube wall 41 is formed transparently, the inside of the tube wall 41 can be visually recognized through the tube wall 41, and the blood B flowing through the flow path 42 inside the tube wall 41 can be visually recognized.
　流路４２は、管４０の中心軸４０ａに沿って延びており、血液Ｂが管４０の中心軸４０ａに沿って流路４２を流れる。図２に示すように、流路４２は、血液Ｂの流れ方向（本実施例ではｘ方向）に直交する断面（管４０の中心軸４０ａに直交する断面）において長方形状となっている。流路４２の形状は、扁平した形状である。また、血液Ｂの流れ方向に直交する断面において直交する２方向を第１方向（本実施例ではｚ方向）と第２方向（本実施例ではｙ方向）としたときに、流路４２の第１方向（ｚ方向）の幅ｗ１が、流路４２の第２方向（ｙ方向）の幅ｗ２より狭い。第２方向における流路４２の幅ｗ２は、第１方向における流路４２の幅ｗ１の１０倍以上であることが好ましい。すなわち、ｗ２＞１０×ｗ１が好ましい。 The flow path 42 extends along the central axis 40 a of the tube 40, and the blood B flows through the flow path 42 along the central axis 40 a of the tube 40. As shown in FIG. 2, the flow path 42 has a rectangular shape in a cross section (cross section orthogonal to the central axis 40 a of the tube 40) perpendicular to the blood B flow direction (x direction in this embodiment). The shape of the flow path 42 is a flat shape. Further, when the two directions orthogonal to the cross-section orthogonal to the flow direction of blood B are defined as a first direction (z direction in this embodiment) and a second direction (y direction in this embodiment), The width w1 in one direction (z direction) is narrower than the width w2 in the second direction (y direction) of the flow path 42. The width w2 of the flow path 42 in the second direction is preferably 10 times or more the width w1 of the flow path 42 in the first direction. That is, w2> 10 × w1 is preferable.
　凹部３０は、管壁４１の外面４３に形成されている。凹部３０は、管壁４１の外面４３から流路４２に向かって窪んだ形状になっている。凹部３０と流路４２は第１方向に沿って並んで形成されている。第２方向における凹部３０の幅ｗ３０は、流路４２の幅ｗ２より狭い。凹部３０は、底面３２を備えている。底面３２は、平坦に形成されている。 The recess 30 is formed on the outer surface 43 of the tube wall 41. The recess 30 has a shape that is recessed from the outer surface 43 of the tube wall 41 toward the flow path 42. The recess 30 and the channel 42 are formed side by side along the first direction. The width w30 of the recess 30 in the second direction is narrower than the width w2 of the flow path. The recess 30 has a bottom surface 32. The bottom surface 32 is formed flat.
　図１に示すように、発光素子１０と受光素子２０は、血液Ｂの流れ方向に沿って並んで配置されている。発光素子１０が、血液Ｂの流れ方向の上流側に配置されており、受光素子２０が血液Ｂの流れ方向の下流側に配置されている。発光素子１０と受光素子２０は、カバー７０に固定されている。 As shown in FIG. 1, the light emitting element 10 and the light receiving element 20 are arranged side by side along the flow direction of the blood B. The light emitting element 10 is disposed on the upstream side in the blood B flow direction, and the light receiving element 20 is disposed on the downstream side in the blood B flow direction. The light emitting element 10 and the light receiving element 20 are fixed to the cover 70.
　発光素子１０は、レーザー光Ｌを発光する。発光素子１０としては、例えばレーザーダイオード（ＬＤ）を用いることができる。発光素子１０が発光するレーザー光Ｌの周波数は特に限定されるものではない。発光素子１０は、管４０に対向して配置されている。また、発光素子１０は、凹部３０に対向して配置されている。発光素子１０は、第１方向（ｚ方向）の幅を画定する管壁４１の外面に配置されている。 The light emitting element 10 emits laser light L. As the light emitting element 10, for example, a laser diode (LD) can be used. The frequency of the laser beam L emitted from the light emitting element 10 is not particularly limited. The light emitting element 10 is disposed to face the tube 40. Further, the light emitting element 10 is disposed to face the recess 30. The light emitting element 10 is disposed on the outer surface of the tube wall 41 that defines the width in the first direction (z direction).
　発光素子１０は、透明な管４０および管４０の中を流れる血液Ｂに向けてレーザー光Ｌを発光する。発光素子１０は、管４０の外側から管４０の内側に向けてレーザー光Ｌを発光する。また、発光素子１０は、凹部３０に向けてレーザー光Ｌを発光する。発光素子１０が発光したレーザー光Ｌは、血液Ｂの流れ方向に直交する断面で視ると第１方向に進む。 The light emitting element 10 emits laser light L toward the transparent tube 40 and blood B flowing through the tube 40. The light emitting element 10 emits laser light L from the outside of the tube 40 toward the inside of the tube 40. The light emitting element 10 emits laser light L toward the recess 30. The laser light L emitted from the light emitting element 10 travels in the first direction when viewed in a cross section perpendicular to the blood B flow direction.
　発光素子１０が発光したレーザー光Ｌの一部は、凹部３０の底面３２で反射して、受光素子２０に入射する。凹部３０の底面３２で反射したレーザー光Ｌは、ドップラー効果を受けていない参照光となる。また、発光素子１０が発光したレーザー光Ｌの他の一部は、管４０の凹部３０および管壁４１を通過する。管壁４１を通過したレーザー光Ｌの一部は、管壁４１と流路４２の境界（管壁４１の内面）で反射する。あるいは、レーザー光Ｌの一部は、管壁４１の内面に接する部分の血液Ｂに含まれる静止した赤血球で反射する。管壁４１と流路４２の境界で反射したレーザー光Ｌは、受光素子２０に向かって進行する。管壁４１と流路４２の境界で反射したレーザー光Ｌは、ドップラー効果を受けていない参照光である。受光素子２０に向かって進行するレーザー光Ｌは、管壁４１および凹部３０を通過した後、受光素子２０に入射する。 Part of the laser light L emitted from the light emitting element 10 is reflected by the bottom surface 32 of the recess 30 and enters the light receiving element 20. The laser light L reflected by the bottom surface 32 of the recess 30 becomes reference light that has not been subjected to the Doppler effect. Further, another part of the laser light L emitted from the light emitting element 10 passes through the recess 30 and the tube wall 41 of the tube 40. Part of the laser light L that has passed through the tube wall 41 is reflected at the boundary between the tube wall 41 and the flow path 42 (the inner surface of the tube wall 41). Alternatively, a part of the laser light L is reflected by stationary red blood cells contained in the blood B in the part in contact with the inner surface of the tube wall 41. The laser light L reflected at the boundary between the tube wall 41 and the flow path 42 travels toward the light receiving element 20. The laser light L reflected at the boundary between the tube wall 41 and the flow path 42 is reference light that has not been subjected to the Doppler effect. The laser light L traveling toward the light receiving element 20 enters the light receiving element 20 after passing through the tube wall 41 and the recess 30.
　このように、レーザー光Ｌの一部が管４０内で反射するときは、凹部３０の底面３２で反射する場合、管壁４１の内面で反射する場合、および、管壁４１の内面に接する部分の血液Ｂ内の動いていない赤血球で反射する場合がある。一方、管壁４１を通過したレーザー光Ｌの他の一部は、流路４２に入射する。 As described above, when a part of the laser light L is reflected in the tube 40, it is reflected on the bottom surface 32 of the recess 30, is reflected on the inner surface of the tube wall 41, and is a portion in contact with the inner surface of the tube wall 41. May be reflected by non-moving red blood cells in blood B. On the other hand, another part of the laser light L that has passed through the tube wall 41 enters the flow path 42.
　管壁４１と流路４２の境界から流路４２に入射したレーザー光Ｌは、血液Ｂの中を進む。流路４２に入射するレーザー光Ｌは、管壁４１と流路４２の境界において屈折する。血液Ｂの中を進むレーザー光Ｌは、血液Ｂに含まれる成分に当たって反射する。具体的には、レーザー光Ｌが血液Ｂに含まれる赤血球Ｒに当たって反射し、反射光Ｓが生じる。移動する赤血球Ｒに反射することで、反射の前後で光の周波数が変化する。よって、レーザー光Ｌの周波数と反射光Ｓの周波数は異なる。赤血球Ｒで反射した反射光Ｓは、ドップラー効果を受けている計測光である。反射光Ｓは、受光素子２０に向かって進行する。反射光Ｓは、流路４２と管壁４１の境界から管壁４１に入射し、管壁４１および凹部３０を通過した後、受光素子２０に入射する。管壁４１に出射する反射光Ｓは、流路４２と管壁４１の境界において屈折する。 The laser light L incident on the flow path 42 from the boundary between the tube wall 41 and the flow path 42 travels in the blood B. The laser light L incident on the flow path 42 is refracted at the boundary between the tube wall 41 and the flow path 42. The laser light L traveling in the blood B strikes and reflects the components contained in the blood B. Specifically, the laser light L strikes and reflects the red blood cells R contained in the blood B, and the reflected light S is generated. By reflecting on the moving red blood cell R, the frequency of light changes before and after the reflection. Therefore, the frequency of the laser light L and the frequency of the reflected light S are different. The reflected light S reflected by the red blood cells R is measurement light that has been subjected to the Doppler effect. The reflected light S travels toward the light receiving element 20. The reflected light S enters the tube wall 41 from the boundary between the flow path 42 and the tube wall 41, passes through the tube wall 41 and the recess 30, and then enters the light receiving element 20. The reflected light S emitted to the tube wall 41 is refracted at the boundary between the flow path 42 and the tube wall 41.
　受光素子２０は、受光素子２０に入射する光を受光し、受光した光量に対応する電気信号を出力する。受光素子２０には、フォトダイオード（ＰＤ）を用いることができる。受光素子２０は、管４０に対向して配置されている。また、受光素子２０は、凹部３０に対向して配置されている。受光素子２０は、第１方向（ｚ方向）の幅を画定する管壁４１の外面に配置されている。受光素子２０は、管４０で反射された光（ドップラー効果を受けていない参照光）と、赤血球Ｒで反射された光（ドップラー効果を受けている計測光）を受光する。受光素子２０は、管壁４１および凹部３０を通過した光を受光する。受光素子２０が受光した光（管４０による反射光と赤血球Ｒによる反射光）は、管４０の中を流れる血液Ｂの流速を計算するために用いられる。 The light receiving element 20 receives light incident on the light receiving element 20 and outputs an electrical signal corresponding to the received light quantity. A photodiode (PD) can be used for the light receiving element 20. The light receiving element 20 is disposed to face the tube 40. In addition, the light receiving element 20 is disposed to face the recess 30. The light receiving element 20 is disposed on the outer surface of the tube wall 41 that defines the width in the first direction (z direction). The light receiving element 20 receives light reflected by the tube 40 (reference light not receiving the Doppler effect) and light reflected by the red blood cells R (measurement light receiving the Doppler effect). The light receiving element 20 receives light that has passed through the tube wall 41 and the recess 30. The light received by the light receiving element 20 (the light reflected by the tube 40 and the light reflected by the red blood cell R) is used to calculate the flow velocity of the blood B flowing through the tube 40.
　カバー７０は、発光素子１０および受光素子２０を覆っている。カバー７０に発光素子１０および受光素子２０が固定されている。カバー７０は、不透明であり、遮光性を有している。カバー７０の色は、黒色が好ましい。また、カバー７０は、無光沢であることが好ましい。カバー７０は、発光素子１０および受光素子２０に不要な光が入らないように光を遮断する。カバー７０は、接触面７１を有している。接触面７１は、管４０の外面４３に接触する。接触面７１は、管４０の外面４３の形状と一致する形状になるように形成されている。カバー７０は、管４０の外面４３の一部を覆っている。 The cover 70 covers the light emitting element 10 and the light receiving element 20. The light emitting element 10 and the light receiving element 20 are fixed to the cover 70. The cover 70 is opaque and has a light shielding property. The color of the cover 70 is preferably black. The cover 70 is preferably matte. The cover 70 blocks light so that unnecessary light does not enter the light emitting element 10 and the light receiving element 20. The cover 70 has a contact surface 71. The contact surface 71 contacts the outer surface 43 of the tube 40. The contact surface 71 is formed to have a shape that matches the shape of the outer surface 43 of the tube 40. The cover 70 covers a part of the outer surface 43 of the tube 40.
　図３に示す制御部９０は、発光素子１０および受光素子２０を制御する。制御部９０は、受光素子２０が受光した光に基づいて、管４０の中を流れる血液Ｂの流速を計算することができる。また、制御部９０は、血液Ｂの流量を計算することができる。制御部９０は、ヘテロダイン技術を用いて計算を行う。ヘテロダイン技術は、周波数が異なる２つの波（光）を重ね合わせてうなり（ビート）を生じさせ、このうなりを用いて計算を行う方法である。ヘテロダイン技術は、２つの波（光）の周波数の差、すなわち、ドップラーシフトを利用して計算を行う方向である。制御部９０は、ヘテロダイン技術を用いて、参照光と計測光の周波数の差を計算し、その計算結果から血液Ｂの流速を計算する。ヘテロダイン技術については公知であるので、詳細な説明を省略する。制御部９０は、計算した血液Ｂの流速および流量をモニタ（図示省略）に出力する。 3 controls the light-emitting element 10 and the light-receiving element 20. The controller 90 can calculate the flow rate of the blood B flowing through the tube 40 based on the light received by the light receiving element 20. Further, the control unit 90 can calculate the flow rate of blood B. The control unit 90 performs calculation using a heterodyne technique. The heterodyne technique is a method in which two waves (lights) having different frequencies are superimposed to generate a beat (beat), and calculation is performed using this beat. The heterodyne technique is a direction in which calculation is performed using the difference between the frequencies of two waves (light), that is, Doppler shift. The control unit 90 calculates the frequency difference between the reference light and the measurement light using the heterodyne technique, and calculates the blood B flow velocity from the calculation result. Since the heterodyne technique is known, a detailed description is omitted. The control unit 90 outputs the calculated blood B flow velocity and flow rate to a monitor (not shown).
　上述の説明から明らかなように、血流センサ１は、血液Ｂが流れる流路４２を画定する管４０と、レーザー光Ｌを発光する発光素子１０と、受光素子２０とを備えている。発光素子１０は、管４０の流路４２を流れる血液Ｂに向けてレーザー光Ｌを発光する。受光素子２０は、発光素子１０が発光して管４０内で反射された反射光（ドップラー効果を受けていない光）と、発光素子１０が発光して管４０の中を流れる血液成分で反射された反射光（ドップラー効果を受けた光）を受光する。管４０の流路４２は、血液Ｂの流れ方向に直交する断面において、第１方向における幅ｗ１が、第２方向における幅ｗ２より狭い。また、発光素子１０は、図２の断面において、第１方向にレーザー光Ｌを発光する。 As is clear from the above description, the blood flow sensor 1 includes a tube 40 that defines a flow path 42 through which blood B flows, a light emitting element 10 that emits laser light L, and a light receiving element 20. The light emitting element 10 emits laser light L toward the blood B flowing through the flow path 42 of the tube 40. The light receiving element 20 is reflected by reflected light (light not subjected to the Doppler effect) that is emitted from the light emitting element 10 and reflected within the tube 40 and blood components that are emitted from the light emitting element 10 and flow through the tube 40. The reflected light (light subjected to the Doppler effect) is received. The flow path 42 of the tube 40 has a width w1 in the first direction narrower than a width w2 in the second direction in a cross section orthogonal to the blood B flow direction. The light emitting element 10 emits laser light L in the first direction in the cross section of FIG.
　このような構成によれば、流路４２の第１方向の幅ｗ１が狭いので、第１方向における流路４２の中心部と周縁部の距離を短くすることができる。流路４２の中心部と周縁部の距離が短くなると、中心部を流れる血液Ｂの流速と周縁部を流れる血液Ｂの流速の差が小さくなる。その結果、流路４２の周縁部を流れる血液Ｂの流速が平均流速に近づく。これにより、血流センサ１により血液Ｂの流速を計測したときに、血液Ｂの平均流速に近い流速を計測できる。また、計測した血液Ｂの流速から補正係数を用いて平均流速を補正計算する場合に、補正係数を小さくすることができ、実際の流速との誤差を小さくすることができる。 According to such a configuration, since the width w1 in the first direction of the flow path 42 is narrow, the distance between the center portion and the peripheral edge portion of the flow path 42 in the first direction can be shortened. When the distance between the central portion and the peripheral portion of the flow path 42 becomes short, the difference between the flow velocity of the blood B flowing through the central portion and the flow velocity of the blood B flowing through the peripheral portion becomes small. As a result, the flow rate of blood B flowing through the peripheral edge of the flow path 42 approaches the average flow rate. Thereby, when the blood flow rate of the blood B is measured by the blood flow sensor 1, a flow rate close to the average flow rate of the blood B can be measured. In addition, when the average flow rate is corrected and calculated from the measured blood B flow rate using the correction coefficient, the correction coefficient can be reduced, and the error from the actual flow rate can be reduced.
　また、上記の血流センサ１によれば、発光素子１０と受光素子２０が凹部３０に対向して配置されているので、発光素子１０と受光素子２０が管４０の管壁４１に接触しない。これにより、発光素子１０と受光素子２０が管壁４１によって傷付くことを抑制できる。また、第２方向における流路４２の幅ｗ２が第１方向における流路４２の幅ｗ１の１０倍以上であると、流路４２の中心部と、第１方向の幅を画定する管壁の近傍を流れる血液Ｂの流速をほぼ同じ流速にすることができる。 Further, according to the blood flow sensor 1 described above, since the light emitting element 10 and the light receiving element 20 are arranged to face the recess 30, the light emitting element 10 and the light receiving element 20 do not contact the tube wall 41 of the tube 40. Thereby, it is possible to suppress the light emitting element 10 and the light receiving element 20 from being damaged by the tube wall 41. Further, when the width w2 of the flow path 42 in the second direction is 10 times or more than the width w1 of the flow path 42 in the first direction, the central portion of the flow path 42 and the tube wall defining the width in the first direction The flow rate of the blood B flowing in the vicinity can be made substantially the same.
　以上、一実施形態について説明したが、具体的な態様は上記実施形態に限定されるものではない。以下の説明において、上述の説明における構成と同様の構成については、同一の符号を付して説明を省略する。 As mentioned above, although one embodiment was described, a specific mode is not limited to the above-mentioned embodiment. In the following description, the same components as those described above are denoted by the same reference numerals and description thereof is omitted.
（第２実施例）
　上記の実施例では、凹部３０の底面３２が平坦に形成されていたが、この構成に限定されるものではない。第２実施例では、図４に示すように、凹部３０の底面３２が湾曲面３３を有している。湾曲面３３は、発光素子１０および受光素子２０に向かって凸状に湾曲している。湾曲面３３は、流路４２と反対側に突出している。湾曲面３３は、血液Ｂの流れ方向に直交する断面において湾曲している。湾曲面３３によって、管壁４１に凸レンズが形成されている。湾曲面３３による凸レンズは、流路４２の中心部が焦点になるように形成されている。 (Second embodiment)
In the above embodiment, the bottom surface 32 of the recess 30 is formed flat, but the present invention is not limited to this configuration. In the second embodiment, the bottom surface 32 of the recess 30 has a curved surface 33 as shown in FIG. The curved surface 33 is curved in a convex shape toward the light emitting element 10 and the light receiving element 20. The curved surface 33 protrudes on the side opposite to the flow path 42. The curved surface 33 is curved in a cross section orthogonal to the flow direction of the blood B. A convex lens is formed on the tube wall 41 by the curved surface 33. The convex lens formed by the curved surface 33 is formed so that the central portion of the flow path 42 is a focal point.
　発光素子１０および受光素子２０は、湾曲面３３に対向して配置されている。発光素子１０は、湾曲面３３に向けてレーザー光Ｌを発光する。発光素子１０から発光されたレーザー光Ｌは、湾曲面３３で屈折して管壁４１に入射し、管壁４１を通過して流路４２に入射する。レーザー光Ｌは、湾曲面３３で屈折することにより、流路４２の中心部に向かって進む。流路４２に入射したレーザー光Ｌは、流路４２を流れる血液Ｂに含まれる赤血球Ｒで反射する。赤血球Ｒで反射した反射光Ｓは、流路４２と管壁４１を通過して、湾曲面３３から出射する。反射光Ｓは、湾曲面３３で屈折して、受光素子２０に向かって進む。受光素子２０は、湾曲面３３を通過した光を受光する。 The light emitting element 10 and the light receiving element 20 are arranged to face the curved surface 33. The light emitting element 10 emits laser light L toward the curved surface 33. The laser light L emitted from the light emitting element 10 is refracted by the curved surface 33 and enters the tube wall 41, passes through the tube wall 41, and enters the flow path 42. The laser light L travels toward the center of the flow path 42 by being refracted by the curved surface 33. The laser light L incident on the flow path 42 is reflected by the red blood cells R contained in the blood B flowing through the flow path 42. The reflected light S reflected by the red blood cells R passes through the flow path 42 and the tube wall 41 and exits from the curved surface 33. The reflected light S is refracted by the curved surface 33 and travels toward the light receiving element 20. The light receiving element 20 receives light that has passed through the curved surface 33.
　このような構成によれば、発光素子１０が第２方向（ｙ方向）にずれた場合であっても、発光素子１０から発光されたレーザー光Ｌが湾曲面３３で屈折して、流路４２の中心部に向かって進んでゆく。流路４２が扁平になると、流路４２の第２方向の幅ｗ２が第１方向の幅ｗ１に対して広くなり、流路４２の中心部から第２方向の幅を画定する管壁４１までの距離が長くなる。その結果、第２方向では、流路４２の中心部を流れる血液Ｂの流速と周縁部を流れる血液Ｂの流速の差が大きくなる。そのため、大きなドップラー効果を得るために、流路４２の第２方向の中心部にレーザー光Ｌを導くことが好ましい。上記の構成によれば、レーザー光Ｌを流路４２の中心部に導くことができ、流路４２の中心部を流れる血液Ｂの流速を計測できる。また、血液Ｂに含まれる赤血球Ｒで反射した反射光Ｓが湾曲面３３で屈折して受光素子２０に向かって進む。これにより、反射光Ｓを受光素子２０に導くことができる。 According to such a configuration, even when the light emitting element 10 is displaced in the second direction (y direction), the laser light L emitted from the light emitting element 10 is refracted by the curved surface 33 and the flow path 42. Go towards the center of the city. When the flow path 42 becomes flat, the width w2 in the second direction of the flow path 42 becomes wider than the width w1 in the first direction, and from the center of the flow path 42 to the tube wall 41 that defines the width in the second direction. The distance becomes longer. As a result, in the second direction, the difference between the flow rate of the blood B flowing through the central portion of the flow path 42 and the flow rate of the blood B flowing through the peripheral portion becomes large. Therefore, in order to obtain a large Doppler effect, it is preferable to guide the laser light L to the central portion of the flow path 42 in the second direction. According to said structure, the laser beam L can be guide | induced to the center part of the flow path 42, and the flow velocity of the blood B which flows through the center part of the flow path 42 can be measured. Further, the reflected light S reflected by the red blood cells R contained in the blood B is refracted by the curved surface 33 and travels toward the light receiving element 20. Thereby, the reflected light S can be guided to the light receiving element 20.
（第３実施例）
　第３実施例に係る血流センサ１は、図５に示すように、管４０と発光素子１０および受光素子２０との間に配置された透明な導光体５０を備えている。導光体５０は、例えば透明な樹脂やガラスにより形成されている。導光体５０は、光透過性を有しており、レーザー光Ｌおよび可視光を透過可能である。 (Third embodiment)
As shown in FIG. 5, the blood flow sensor 1 according to the third embodiment includes a transparent light guide 50 disposed between the tube 40, the light emitting element 10, and the light receiving element 20. The light guide 50 is made of, for example, transparent resin or glass. The light guide 50 is light transmissive and can transmit the laser light L and visible light.
　導光体５０の屈折率および管４０の屈折率は、同じ屈折率であることが好ましい。なお、両者の屈折率は異なっていてもよい。導光体５０と管４０の間には、グリス（図示省略）が塗布されている。導光体５０は、グリスを介して管４０に密着している。グリスは、光透過性を有しており、レーザー光Ｌおよび可視光を透過可能である。 The refractive index of the light guide 50 and the refractive index of the tube 40 are preferably the same refractive index. In addition, both refractive indexes may differ. Grease (not shown) is applied between the light guide 50 and the tube 40. The light guide 50 is in close contact with the tube 40 via grease. The grease is light transmissive and can transmit the laser light L and visible light.
　導光体５０は、第１接触面５１および第２接触面５２を備えている。第１接触面５１は、カバー７０の接触面７１に接触する。第１接触面５１は、カバー７０の接触面７１の形状と一致する形状になるように形成されている。第２接触面５２は、管４０の外面４３に接触する。第２接触面５２は、管４０の外面４３の形状と一致する形状になるように形成されている。 The light guide 50 includes a first contact surface 51 and a second contact surface 52. The first contact surface 51 contacts the contact surface 71 of the cover 70. The first contact surface 51 is formed to have a shape that matches the shape of the contact surface 71 of the cover 70. The second contact surface 52 contacts the outer surface 43 of the tube 40. The second contact surface 52 is formed to have a shape that matches the shape of the outer surface 43 of the tube 40.
　また、導光体５０は、素子側凹部６０および管側凹部８０を備えている。素子側凹部６０は、導光体５０において発光素子１０および受光素子２０側の面に形成されている。素子側凹部６０は、導光体５０の素子１０、２０側の面から流路４２に向かって窪んだ形状になっている。素子側凹部６０と流路４２は、第１方向に沿って並んでいる。第２方向における素子側凹部６０の幅ｗ６０は、流路４２の幅ｗ２より狭い。素子側凹部６０は、底面６２を備えている。底面６２は、平坦に形成されている。 The light guide 50 includes an element-side recess 60 and a tube-side recess 80. The element-side recess 60 is formed on the surface of the light guide 50 on the light-emitting element 10 and light-receiving element 20 side. The element-side recess 60 has a shape that is recessed from the surface of the light guide 50 on the elements 10 and 20 side toward the flow path 42. The element-side recess 60 and the flow path 42 are arranged along the first direction. The width w60 of the element-side recess 60 in the second direction is narrower than the width w2 of the flow path. The element side recess 60 has a bottom surface 62. The bottom surface 62 is formed flat.
　管側凹部８０は、導光体５０において管４０側の面に形成されている。管側凹部８０は、管４０に対向している。管側凹部８０は、導光体５０の管４０側の面から素子側凹部６０に向かって窪んだ形状になっている。管側凹部８０、素子側凹部６０、および流路４２は、第１方向に沿って並んでいる。第２方向における管側凹部８０の幅ｗ８０は、流路４２の幅ｗ２より狭い。管側凹部８０は、底面８２を備えている。 The tube side recess 80 is formed on the surface of the light guide 50 on the tube 40 side. The tube-side recess 80 faces the tube 40. The tube side recess 80 has a shape that is recessed from the surface of the light guide 50 on the tube 40 side toward the element side recess 60. The tube side recessed part 80, the element side recessed part 60, and the flow path 42 are located in a line along the first direction. The width w80 of the tube-side recess 80 in the second direction is narrower than the width w2 of the flow path 42. The tube-side recess 80 has a bottom surface 82.
　管側凹部８０の底面８２は、湾曲面８３を有している。湾曲面８３は、管４０に向かって凸状に湾曲している。湾曲面８３は、管４０側に突出している。湾曲面８３は、血液Ｂの流れ方向に直交する断面において湾曲している。湾曲面８３によって、導光体５０に凸レンズが形成されている。 The bottom surface 82 of the tube-side recess 80 has a curved surface 83. The curved surface 83 is curved in a convex shape toward the tube 40. The curved surface 83 protrudes toward the tube 40 side. The curved surface 83 is curved in a cross section orthogonal to the blood B flow direction. A convex lens is formed on the light guide 50 by the curved surface 83.
　発光素子１０および受光素子２０は、素子側凹部６０に対向して配置されている。発光素子１０は、素子側凹部６０に向けてレーザー光Ｌを発光する。発光素子１０から発光されたレーザー光Ｌの一部は、素子側凹部６０の底面６２で反射して受光素子２０に入射する。また、レーザー光Ｌの他の一部は、素子側凹部６０、導光体５０の内部、および管側凹部８０を通過して、管４０に向かって進む。レーザー光Ｌは、湾曲面８３から出射するときに、湾曲面８３で屈折する。その後、レーザー光Ｌは、管４０の管壁４１を通過して流路４２に入射する。流路４２に入射したレーザー光Ｌは、流路４２を流れる血液Ｂに含まれる赤血球Ｒで反射する。 The light emitting element 10 and the light receiving element 20 are disposed so as to face the element side recess 60. The light emitting element 10 emits laser light L toward the element side recess 60. A part of the laser light L emitted from the light emitting element 10 is reflected by the bottom surface 62 of the element side recess 60 and enters the light receiving element 20. The other part of the laser light L passes toward the tube 40 through the element-side recess 60, the inside of the light guide 50, and the tube-side recess 80. The laser light L is refracted by the curved surface 83 when it exits from the curved surface 83. Thereafter, the laser light L passes through the tube wall 41 of the tube 40 and enters the flow path 42. The laser light L incident on the flow path 42 is reflected by the red blood cells R contained in the blood B flowing through the flow path 42.
　赤血球Ｒで反射した反射光Ｓは、流路４２および管壁４１を通過して、導光体５０に向かって進む。また、反射光Ｓは、管側凹部８０、導光体５０の内部、および素子側凹部６０を通過して受光素子２０に向かって進む。反射光Ｓは、湾曲面８３から導光体５０に入射するときに、湾曲面８３で屈折する。受光素子２０は、素子側凹部６０を通過したレーザー光Ｌを受光する。 The reflected light S reflected by the red blood cells R travels toward the light guide 50 through the flow path 42 and the tube wall 41. Further, the reflected light S travels toward the light receiving element 20 through the tube side recess 80, the inside of the light guide 50, and the element side recess 60. The reflected light S is refracted by the curved surface 83 when entering the light guide 50 from the curved surface 83. The light receiving element 20 receives the laser light L that has passed through the element-side recess 60.
　このような構成によれば、管４０と発光素子１０および受光素子２０との間に導光体５０が配置されており、発光素子１０および受光素子２０が素子側凹部６０に対向している。したがって、発光素子１０および受光素子２０が管４０および導光体５０に接触することがない。これにより、発光素子１０および受光素子２０が管４０および導光体５０によって傷付くことを抑制できる。また、導光体５０は交換可能である。また、レーザー光Ｌが素子側凹部６０の底面６２で反射した光を、参照光として受光できる。 According to such a configuration, the light guide 50 is disposed between the tube 40 and the light emitting element 10 and the light receiving element 20, and the light emitting element 10 and the light receiving element 20 face the element side recess 60. Therefore, the light emitting element 10 and the light receiving element 20 do not contact the tube 40 and the light guide 50. Thereby, it can suppress that the light emitting element 10 and the light receiving element 20 are damaged by the pipe | tube 40 and the light guide 50. FIG. The light guide 50 is replaceable. Further, the light reflected by the bottom surface 62 of the element-side recess 60 can be received as the reference light.
　また、発光素子１０が第２方向（ｙ方向）にずれた場合であっても、発光素子１０から発光されたレーザー光Ｌが湾曲面８３で屈折して、流路４２の中心部に向かって進んでゆく。これにより、レーザー光Ｌを流路４２の中心部に導くことができ、流路４２の中心部を流れる血液Ｂの流速を計測できる。また、血液Ｂに含まれる赤血球Ｒで反射した反射光Ｓが湾曲面８３で屈折して受光素子２０に向かって進む。これにより、反射光Ｓを受光素子２０に導くことができる。 Further, even when the light emitting element 10 is displaced in the second direction (y direction), the laser light L emitted from the light emitting element 10 is refracted by the curved surface 83 toward the center of the flow path 42. Go ahead. As a result, the laser light L can be guided to the center of the flow path 42, and the flow rate of the blood B flowing through the center of the flow path 42 can be measured. Further, the reflected light S reflected by the red blood cells R contained in the blood B is refracted by the curved surface 83 and travels toward the light receiving element 20. Thereby, the reflected light S can be guided to the light receiving element 20.
　また、上記実施例では、導光体５０の素子側凹部６０の底面６２が平坦に形成されていたが、この構成に限定されるものではない。他の実施例では、素子側凹部６０の底面６２が湾曲面を有していてもよい。 In the above embodiment, the bottom surface 62 of the element-side recess 60 of the light guide 50 is formed flat. However, the present invention is not limited to this configuration. In another embodiment, the bottom surface 62 of the element-side recess 60 may have a curved surface.
（第４実施例）
　上記の実施例では、流路４２は、血液Ｂの流れ方向に直交する断面において長方形状となっていたが、この構成に限定されるものではない。第４実施例では、図６に示すように、流路４２は、血液Ｂの流れ方向に直交する断面において長円形状あるいは楕円形状であってもよい。この構成においても、第１方向における流路４２の幅ｗ１が、第１方向と直交する第２方向における流路４２の幅ｗ２より狭い。このような構成によっても、第１方向において流路４２の周縁部と中心部の距離を近づけることができる。 (Fourth embodiment)
In the above-described embodiment, the flow path 42 has a rectangular shape in a cross section perpendicular to the flow direction of the blood B, but is not limited to this configuration. In the fourth embodiment, as shown in FIG. 6, the channel 42 may have an oval shape or an oval shape in a cross section orthogonal to the flow direction of the blood B. Also in this configuration, the width w1 of the flow path 42 in the first direction is narrower than the width w2 of the flow path 42 in the second direction orthogonal to the first direction. Even with such a configuration, the distance between the peripheral edge portion and the central portion of the flow path 42 in the first direction can be reduced.
　また、発光素子１０の構成は上記の実施例に限定されるものではない。他の実施例では、発光素子１０におけるレーザー光Ｌが出射する部分にレンズ（図示省略）を取り付けてもよい。レンズは、発光素子１０の先端部に固定される。このような構成では、発光素子１０から発光されたレーザー光Ｌがレンズにより拡散し、拡散したレーザー光Ｌが管４０および血液Ｂに向かって進む。そして、レーザー光Ｌの一部が管壁４１と流路４２の境界（管壁４１の内面）で反射し、他の一部が流路４２を流れる血液Ｂに入射し、血液Ｂに含まれる移動する赤血球Ｒで反射する。このような構成によっても、ドップラー効果を受けていない参照光とドップラー効果を受けた計測光をそれぞれ受光できる。 Further, the configuration of the light emitting element 10 is not limited to the above embodiment. In another embodiment, a lens (not shown) may be attached to a portion of the light emitting element 10 where the laser light L is emitted. The lens is fixed to the tip of the light emitting element 10. In such a configuration, the laser light L emitted from the light emitting element 10 is diffused by the lens, and the diffused laser light L travels toward the tube 40 and the blood B. A part of the laser light L is reflected at the boundary between the tube wall 41 and the flow path 42 (the inner surface of the tube wall 41), and another part is incident on the blood B flowing through the flow path 42 and is included in the blood B. Reflected by the moving red blood cell R. Even with such a configuration, it is possible to receive the reference light not subjected to the Doppler effect and the measurement light subjected to the Doppler effect.
　また、上記実施例では、管４０の外面４３に凹部３０が形成されていたが、この構成に限定されるものではなく、凹部３０を省略することもできる。 In the above embodiment, the recess 30 is formed on the outer surface 43 of the tube 40. However, the present invention is not limited to this configuration, and the recess 30 can be omitted.
　以上、本発明の具体例を詳細に説明したが、これらは例示に過ぎず、特許請求の範囲を限定するものではない。特許請求の範囲に記載の技術には、以上に例示した具体例を様々に変形、変更したものが含まれる。本明細書または図面に説明した技術要素は、単独であるいは各種の組合せによって技術的有用性を発揮するものであり、出願時請求項記載の組合せに限定されるものではない。また、本明細書または図面に例示した技術は複数目的を同時に達成し得るものであり、そのうちの一つの目的を達成すること自体で技術的有用性を持つものである。 Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.
１　　　　：血流センサ
１０　　　：発光素子
２０　　　：受光素子
３０　　　：凹部
３２　　　：底面
３３　　　：湾曲面
４０　　　：管
４０ａ　　：中心軸
４１　　　：管壁
４２　　　：流路
４３　　　：外面
５０　　　：導光体
５１　　　：第１接触面
５２　　　：第２接触面
６０　　　：素子側凹部
６２　　　：底面
７０　　　：カバー
７１　　　：接触面
８０　　　：管側凹部
８２　　　：底面
８３　　　：湾曲面
９０　　　：制御部
Ｂ　　　　：血液
Ｌ　　　　：レーザー光
Ｒ　　　　：赤血球
Ｓ　　　　：反射光
  1: Blood flow sensor 10: Light emitting element 20: Light receiving element 30: Recess 32: Bottom surface 33: Curved surface 40: Tube 40a: Center axis 41: Tube wall 42: Channel 43: Outer surface 50: Light guide 51: First Contact surface 52: Second contact surface 60: Element side recess 62: Bottom surface 70: Cover 71: Contact surface 80: Tube side recess 82: Bottom surface 83: Curved surface 90: Control unit B: Blood L: Laser light R: Red blood cell S :reflected light

Claims (5)

  1. 　血液の流速を計測可能な血流センサであって、
    　血液が流れる流路を画定する管と、
    　レーザー光を発光する発光素子と、
    　受光素子を備えており、
    　前記発光素子は、前記管を流れる血液に向けてレーザー光を発光し、
    　前記受光素子は、前記発光素子が発光して前記管で反射されたドップラー効果を受けていない光と、前記発光素子が発光して前記管を流れる血液成分で反射されたドップラー効果を受けた光を受光し、
    　血液の流れに直交する断面において直交する２方向を第１方向と第２方向としたとき、前記流路の第１方向の幅が前記流路の第２方向の幅より狭く、
    　前記発光素子と前記受光素子が、前記第１方向の幅を画定する管壁の外面に配置されている血流センサ。     A blood flow sensor capable of measuring blood flow velocity,
    A tube defining a flow path through which blood flows;
    A light emitting element that emits laser light;
    It has a light receiving element,
    The light emitting element emits laser light toward the blood flowing through the tube,
    The light receiving element includes light that is emitted from the light emitting element and is not reflected by the tube, and light that is subjected to the Doppler effect that is emitted from the light emitting element and reflected by a blood component flowing through the tube. Receive light,
    When the two directions perpendicular to the cross section perpendicular to the blood flow are defined as the first direction and the second direction, the width of the flow path in the first direction is narrower than the width of the flow path in the second direction,
    The blood flow sensor, wherein the light emitting element and the light receiving element are arranged on an outer surface of a tube wall defining a width in the first direction.
  2. 　前記管壁の外面に凹部が形成されており、
    　前記発光素子と前記受光素子が、前記凹部に対向して配置されている請求項１に記載の血流センサ。     A recess is formed on the outer surface of the tube wall,
    The blood flow sensor according to claim 1, wherein the light emitting element and the light receiving element are disposed to face the recess.
  3. 　前記凹部の底面が、前記発光素子と前記受光素子に向かって凸状に湾曲した湾曲面を有している請求項２に記載の血流センサ。 The blood flow sensor according to claim 2, wherein a bottom surface of the concave portion has a curved surface curved in a convex shape toward the light emitting element and the light receiving element.
  4. 　前記発光素子および前記受光素子と前記管との間に配置された導光体を備え、
    　前記導光体の前記素子側の面に、素子側凹部が形成されており、
    　前記発光素子と前記受光素子が、前記素子側凹部に対向して配置されている請求項１に記載の血流センサ。     A light guide disposed between the light emitting element and the light receiving element and the tube;
    An element side recess is formed on the element side surface of the light guide,
    The blood flow sensor according to claim 1, wherein the light emitting element and the light receiving element are disposed to face the element side recess.
  5. 　前記導光体の前記管側の面に、管側凹部が形成されており、
    　前記管側凹部の底面が、前記管に向かって凸状に湾曲した湾曲面を有している請求項４に記載の血流センサ。     A tube-side recess is formed on the tube-side surface of the light guide,
    The blood flow sensor according to claim 4, wherein a bottom surface of the tube-side recess has a curved surface that is curved in a convex shape toward the tube.
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JP2018009920A (en) * 2016-07-15 2018-01-18 日本電信電話株式会社 Fluid measurement apparatus
JPWO2018123044A1 (en) * 2016-12-28 2019-10-31 パイオニア株式会社 Measuring device, information output device, measuring method, computer program, and recording medium
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