Blood sugar level measuring device

Abstract

This blood sugar level measuring device comprises: a light output unit that includes a green light source that outputs incident light; a light detection unit that detects transmitted light that has passed through a living body; and a computation unit that calculates the blood sugar level of the living body. In the spectrum of the incident light, the center wavelength is located at 430-580 nm, the intensity at 600-615 nm is at least 0.01% of the intensity at the center wavelength, and the intensity at 480-515 nm is at least 1% of the intensity at the center wavelength. The light detection unit includes a first light detector having a first detection wavelength range of 460-535 nm and a second light detector having a second detection wavelength range of at least 580 nm. The computation unit calculates the blood sugar level of the living body on the basis of the intensity of the transmitted light detected by the first light detector and the intensity of the transmitted light detected by the second light detector.

Description

Blood glucose measuring device

[0001] The present disclosure relates to a blood glucose measuring device.

[0002] Known devices for non-invasively measuring biological information include the device described in Patent Document 1. The device described in Patent Document 1 has a function of measuring the pulse rate of a living body by, for example, emitting light to the living body.

[0003] JP 2011-147469 A

[0004] The above-mentioned device may be required to measure blood glucose levels, but a green light source may be used to measure the pulse of a living body, and adding a new light source for measuring blood glucose levels, for example, may increase the size of the device or increase power consumption.

[0005] An object of the present disclosure is to provide a blood glucose measuring device that can measure blood glucose levels using a green light source.

[0006] A blood glucose level measuring device according to one aspect of the present disclosure is [1] "a blood glucose level measuring device for measuring a blood glucose level of a living organism, comprising: a light output unit including a green light source that outputs incident light to the living organism; a light detection unit that detects transmitted light that has passed through the living organism; and a calculation unit that calculates the blood glucose level of the living organism based on the detection result of the light detection unit, wherein the spectrum of the incident light has a center wavelength in a first wavelength range of 430 nm to 580 nm, an intensity in a second wavelength range of 600 nm to 615 nm is 0.01% or more of the intensity at the center wavelength, and an intensity in a third wavelength range of 480 nm to 515 nm is 1% or more of the intensity at the center wavelength, the light detection unit has a first photodetector having a first detection wavelength range of 460 nm to 535 nm and a second photodetector having a second detection wavelength range of 580 nm or more, and the calculation unit calculates the blood glucose level of the living organism based on the intensity of the transmitted light detected by the first photodetector and the intensity of the transmitted light detected by the second photodetector."

[0007] In the blood glucose measuring device described in [1] above, the spectrum of incident light output to a living body has a central wavelength located in a first wavelength range of 430 nm to 580 nm, an intensity in a second wavelength range of 600 nm to 615 nm that is 0.01% or more of the intensity at the central wavelength, and an intensity in a third wavelength range of 480 nm to 515 nm that is 1% or more of the intensity at the central wavelength. When such incident light enters a living body, transmitted light having a spectrum with central wavelengths located in the wavelength range of 460 nm to 535 nm and the wavelength range of 580 nm or more is emitted from the living body. The calculation unit calculates the blood glucose level of the living body based on the intensity of transmitted light detected in the first detection wavelength range of 460 nm to 535 nm and the intensity of transmitted light detected in the second detection wavelength range of 580 nm or more. Therefore, this blood glucose measuring device can measure blood glucose levels using a green light source.

[0008] A blood glucose level measuring device according to one aspect of the present disclosure may be [2] "the blood glucose level measuring device according to [1] above, wherein in the spectrum of the incident light, the central wavelength is located in a fourth wavelength range of 470 nm to 540 nm, the intensity in a fifth wavelength range of 605 nm to 615 nm is 0.1% or more of the intensity at the central wavelength, and the intensity in a sixth wavelength range of 490 nm to 515 nm is 40% or more of the intensity at the central wavelength." This allows for the acquisition of transmitted light suitable for calculating blood glucose levels, thereby enabling more accurate calculation of blood glucose levels in a living body.

[0009] A blood glucose level measuring device according to one aspect of the present disclosure may be the blood glucose level measuring device described in [1] or [2] above, [3] in which "the first photodetector includes a first photodetector region and a first optical filter provided on the first photodetector region and having a first transmission wavelength range of 460 nm to 535 nm, the second photodetector includes a second photodetector region and a second optical filter provided on the second photodetector region and having a second transmission wavelength range of 580 nm or more, and the calculation unit calculates the blood glucose level of the living body based on the intensity of the transmitted light that has passed through the first optical filter and detected by the first photodetector region, and the intensity of the transmitted light that has passed through the second optical filter and detected by the second photodetector region." This allows the first photodetector region and the second photodetector region to have a common configuration, since the transmitted light is selectively transmitted by the first optical filter and the second optical filter, respectively.

[0010] A blood glucose measuring device according to one aspect of the present disclosure may be [4] "the blood glucose measuring device according to any one of [1] to [3] above, wherein the light detecting unit further includes a third photodetector having a third detection wavelength range of 500 nm to 600 nm, and the calculation unit calculates the pulse rate of the living body based on the intensity of the transmitted light detected by the third photodetector." This makes it possible to measure both blood glucose levels and pulse rates using a green light source, and prevents the device from becoming larger and its power consumption from increasing.

[0011] A blood glucose level measuring device according to one aspect of the present disclosure may be [5] "the blood glucose level measuring device according to the above [4], wherein the third photodetector further includes a third photodetection region and a third optical filter provided on the third photodetection region and having a third transmission wavelength range of 500 nm to 600 nm, and the calculation unit calculates the pulse rate of the living body based on the intensity of transmitted light that has passed through the third optical filter and been detected by the third photodetection region." In this way, the first optical filter, the second optical filter, and the third optical filter each selectively transmit transmitted light, making it possible to standardize the configurations of the first photodetection region, the second photodetection region, and the third photodetection region.

[0012] A blood glucose measuring device according to one aspect of the present disclosure may be [6] "the blood glucose measuring device according to any one of [1] to [5] above, wherein the first photodetector is one of a plurality of first photodetectors, the second photodetector is one of a plurality of second photodetectors, and the first photodetectors and the second photodetectors are arranged alternately to surround the light output unit." This reduces loss of incident light output from the light output unit.

[0013] The blood glucose measuring device according to one aspect of the present disclosure may be [7] "the blood glucose measuring device according to any one of [1] to [5] above, wherein the green light source is each of a plurality of green light sources, and each of the plurality of green light sources is arranged so as to surround the light detecting unit." In this way, the plurality of green light sources surround the light detecting unit, ensuring the intensity of the transmitted light incident on the light detecting unit.

[0014] According to the present disclosure, it is possible to provide a blood glucose level measuring device that can measure blood glucose levels using a green light source.

[0015] Fig. 1 is a conceptual diagram of a blood glucose level measuring device according to one embodiment. Fig. 2 is a rear view of the blood glucose level measuring device shown in Fig. 1. Fig. 3 is a diagram showing the spectra of incident light output from a first light source shown in Fig. 2 and transmitted light that has passed through a living body. Fig. 4 is a diagram showing the spectrum of the transmitted light shown in Fig. 3. Fig. 5 is a rear view of a blood glucose level measuring device according to a modified example.

[0016] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0017] Fig. 1 is a cross-sectional view of a blood glucose level measuring device and a living body according to this embodiment. Fig. 1 is merely a conceptual diagram for explaining the function of the blood glucose level measuring device 1, and does not necessarily show an actual cross-section of the blood glucose level measuring device 1.

[0018] The blood glucose level measuring device 1 shown in Fig. 1 is, for example, a wearable device, a smartphone, or a pulse oximeter. Examples of wearable devices include a smart watch and a smart ring. In this embodiment, the blood glucose level measuring device 1 is a smart watch that has a function of measuring the blood glucose level of a living body 6. The living body 6 has a superficial tissue 61 and an internal tissue 62 that is located more internally than the superficial tissue 61. The surface 61a of the superficial tissue 61 is the surface of the skin of the living body 6. The living body 6 is, for example, a human body.

[0019] The blood glucose level measuring device 1 comprises a main body 2, a light output unit 3, a light detection unit 4, and an ECU (Electronic Control Unit) 5. The main body 2 has a front face 2a and a back face 2b facing the opposite side to the front face 2a. The front face 2a functions as a display screen that displays various information about the blood glucose level measuring device 1. The blood glucose level measuring device 1 is attached to a living body 6 so that the back face 2b comes into contact with the skin of the living body 6.

[0020] The light output unit 3 is provided in the main body 2. The light output surface of the light output unit 3 is exposed from the rear surface 2b of the main body 2. The light output unit 3 outputs measurement light L. The measurement light L is emitted from the rear surface 2b. The measurement light L emitted from the light output unit 3 propagates inside the living body 6 and is then emitted from the living body 6 again. The light output unit 3 is controlled by the ECU 5.

[0021] The light detection unit 4 is provided in the main body 2. The light detection unit 4 is separated from the light output unit 3. The light detection surface of the light detection unit 4 is exposed from the rear surface 2b of the main body 2. The light detection unit 4 detects measurement light L (transmitted light) that has passed through the living body 6. The light detection unit 4 transmits a signal related to the intensity of the measurement light L to the ECU 5.

[0022] The ECU 5 is provided in the main body 2. The ECU 5 is an electronic control unit having a central processing unit (CPU) and a storage unit such as a read-only memory (ROM) or a random access memory (RAM). In the ECU 5, for example, a program stored in the storage unit is executed by the CPU. The ECU 5 functions as a calculation unit that calculates biological information of the living body 6. The ECU 5 calculates the blood glucose level, pulse rate, oxygen saturation concentration, etc. of the living body 6 based on a signal transmitted from the light detection unit 4 (the detection result of the light detection unit 4).

[0023] Fig. 2 is a rear view of the blood glucose level measuring device 1. Fig. 2 shows the light output unit 3 and the light detection unit 4 as seen from the rear surface 2b of the main body 2. As shown in Fig. 2, the light output unit 3 has a first light source 31, a second light source 32, and a third light source 33. The first light source 31, the second light source 32, and the third light source 33 are aligned in a row. The first light source 31 is disposed between the second light source 32 and the third light source 33.

[0024] The first light source 31 is a green light source. The first light source 31 outputs green light as the measurement light L. The green light is, for example, probe light with a center wavelength of approximately 515 nm. The green light is different from white light. When observed by the human eye, the green light appears green or green-blue. The color of the green light corresponds to, for example, 5G, 10G, 5BG, or 10BG in the Munsell color system. The first light source 31 outputs green light at a predetermined pulse interval in response to a control signal transmitted from the ECU 5. In other words, the green light output from the first light source 31 flashes at a predetermined pulse interval. The first light source 31 continuously outputs green light. In other words, the green light output from the first light source 31 flashes constantly. The first light source 31 is, for example, a light-emitting diode (LED), a laser diode (LD), a superluminescent diode (SLD), or the like.

[0025] The second light source 32 is a red light source. The second light source 32 outputs red light as the measurement light L. The red light is, for example, probe light with a center wavelength of approximately 660 nm. The second light source 32 outputs the red light at a predetermined pulse interval in response to a control signal transmitted from the ECU 5. That is, the red light output from the first light source 31 flashes at a predetermined pulse interval. The second light source 32 outputs the red light intermittently. That is, the red light output from the second light source 32 flashes intermittently. The second light source 32 operates at predetermined intervals. While the second light source 32 is operating, both the green light and the red light flash, and while the second light source 32 is stopped, the green light flashes and the red light is turned off. The second light source 32 is, for example, a light-emitting diode (LED), a laser diode (LD), a superluminescent diode (SLD), or the like.

[0026] The third light source 33 is an infrared light source. The third light source 33 outputs infrared light as the measurement light L. The infrared light is, for example, probe light with a center wavelength of approximately 880 nm or 910 nm. The third light source 33 outputs the infrared light at a predetermined pulse interval in response to a control signal transmitted from the ECU 5. That is, the infrared light output from the third light source 33 flashes at a predetermined pulse interval. The third light source 33 outputs the infrared light intermittently. That is, the infrared light output from the third light source 33 flashes intermittently. The third light source 33 operates at predetermined intervals. While the third light source 33 is operating, both the green light and the infrared light flash, and while the third light source 33 is stopped, the green light flashes and the infrared light is turned off. The third light source 33 is, for example, a light-emitting diode (LED), a laser diode (LD), a superluminescent diode (SLD), or the like.

[0027] The light detection unit 4 has a plurality of first light detectors 401, a plurality of second light detectors 402, and a plurality of third light detectors 403. The plurality of first light detectors 401, the plurality of second light detectors 402, and the plurality of third light detectors 403 are arranged in a circular ring shape to surround the light output unit 3. The first light detectors 401, the second light detectors 402, and the third light detectors 403 are arranged alternately to surround the light output unit 3. In this embodiment, the light detection unit 4 has two first light detectors 401, two second light detectors 402, and three third light detectors 403. In the circumferential direction of the light detection unit 4, one first light detector 401, one second light detector 402, one third light detector 403, one first light detector 401, one third light detector 403, one second light detector 402, and one third light detector 403 are arranged in this order.

[0028] The first photodetector 401 has a first detection wavelength range S1 (see FIG. 4). That is, the first photodetector 401 detects light having a wavelength included in the first detection wavelength range S1. The first detection wavelength range S1 is 460 nm to 535 nm. The second photodetector 402 has a second detection wavelength range S2 (see FIG. 4). That is, the second photodetector 402 detects light having a wavelength included in the second detection wavelength range S2. The second detection wavelength range S2 is 580 nm or longer. The third photodetector 403 has a third detection wavelength range S3 (see FIG. 4). That is, the third photodetector 403 detects light having a wavelength included in the third detection wavelength range S3. The third detection wavelength range S3 is 500 nm to 600 nm.

[0029] The first photodetector 401 has a first photodetection region 41 and a first optical filter 44. The second photodetector 402 has a second photodetection region 42 and a second optical filter 45. The third photodetector 403 has a third photodetection region 43 and a third optical filter 46. Each of the photodetection regions 41, 42, and 43 detects transmitted light that has passed through the living body 6. Each of the photodetection regions 41, 42, and 43 has a photodetection element and a preamplifier. The photodetection element is, for example, a photodiode (PD). The preamplifier amplifies the photocurrent output from the photodetection element. In this embodiment, the configurations of the photodetection regions 41, 42, and 43 are the same.

[0030] The first optical filter 44 is provided on the first light detection region 41. The first optical filter 44 is provided on the light detection surface of the first light detection region 41. The outer edge of the first optical filter 44 is located outside the outer edge of the first light detection region 41. The outer edge of the first optical filter 44 may substantially coincide with the outer edge of the first light detection region 41. The first optical filter 44 has, for example, a film shape. The first optical filter 44 has a first transmission wavelength range T1 (see FIG. 4). The transmittance of light having wavelengths included in the first transmission wavelength range T1 through the first optical filter 44 is greater than the transmittance of light having wavelengths not included in the first transmission wavelength range T1 through the first optical filter 44. The first optical filter 44 transmits light within the first transmission wavelength range T1 and does not transmit light outside the first transmission wavelength range T1. The first transmission wavelength range T1 is 460 nm to 535 nm.

[0031] The second optical filter 45 is provided on the second light detection region 42. The second optical filter 45 is provided on the light detection surface of the second light detection region 42. The outer edge of the second optical filter 45 is located outside the outer edge of the second light detection region 42. The outer edge of the second optical filter 45 may approximately coincide with the outer edge of the second light detection region 42. The second optical filter 45 has, for example, a film shape. The second optical filter 45 has a second transmission wavelength range T2 (see FIG. 4). The transmittance of light having wavelengths included in the second transmission wavelength range T2 through the second optical filter 45 is higher than the transmittance of light having wavelengths not included in the second transmission wavelength range T2 through the second optical filter 45. The second optical filter 45 transmits light within the second transmission wavelength range T2 and does not transmit light outside the second transmission wavelength range T2. The second transmission wavelength range T2 is 580 nm or more, preferably 610 nm or more.

[0032] The third optical filter 46 is provided on the third photodetection region 43. The third optical filter 46 is provided on the photodetection surface of the third photodetection region 43. The outer edge of the third optical filter 46 is located outside the outer edge of the third photodetection region 43. The outer edge of the third optical filter 46 may substantially coincide with the outer edge of the third photodetection region 43. The third optical filter 46 has, for example, a film shape. The third optical filter 46 has a third transmission wavelength range T3 (see FIG. 4). The transmittance of light having wavelengths included in the third transmission wavelength range T3 through the third optical filter 46 is higher than the transmittance of light having wavelengths not included in the third transmission wavelength range T3 through the third optical filter 46. The third optical filter 46 transmits light within the third transmission wavelength range T3 and does not transmit light outside the third transmission wavelength range T3. The third transmission wavelength range T3 is 500 nm to 600 nm.

[0033] Each of the first optical filter 44, the second optical filter 45, and the third optical filter 46 is, for example, a dielectric multilayer filter. Each of the first optical filter 44, the second optical filter 45, and the third optical filter 46 may be, for example, a color filter for an image sensor formed from a color resist, or a color filter in which a pigment is mixed into gelatin or triacetate. Each of the first optical filter 44, the second optical filter 45, and the third optical filter 46 may be the same as or different from one another.

[0034] Next, blood glucose level measurement using green light emitted from the first light source 31 will be described in detail. Fig. 3 shows the spectra of incident light L1 (dashed line) emitted from the first light source 31 and transmitted light L2 (solid line) that has passed through the living body 6. In Fig. 3, the horizontal axis represents wavelength and the vertical axis represents light intensity. Note that in Fig. 3, the vertical axis is expressed as a logarithmic scale.

[0035] As shown in Fig. 3, the first light source 31 of the light output unit 3 outputs incident light L1 to the living body 6, and the light detection unit 4 detects transmitted light L2 that has passed through the living body 6. The incident light L1 is the green light described above. In the spectrum of the incident light L1, the center wavelength is located in a first wavelength range R1. In other words, the incident light L1 has a peak value in the first wavelength range R1. The center wavelength of the incident light L1 is any value within the first wavelength range R1. The first wavelength range R1 is 430 nm to 580 nm.

[0036] In the spectrum of incident light L1, the intensity in the second wavelength range R2 is 0.01% or more of the intensity at the central wavelength (peak intensity of incident light L1). In the spectrum of incident light L1, the intensity in the second wavelength range R2 is 10% or less of the intensity at the central wavelength, preferably 5% or less of the intensity at the central wavelength. "Intensity in a wavelength range" refers to the intensity corresponding to any wavelength value within the wavelength range. The second wavelength range R2 is 600 nm to 615 nm. At least a portion of the inner region of the spectrum of incident light L1 (the region between L1 and the horizontal axis in Figure 3) overlaps with region D1. In Figure 3, region D1 is a region within the second wavelength range R2 that is 0.01% or more of the intensity at the central wavelength.

[0037] In the spectrum of incident light L1, the intensity in the third wavelength range R3 is 1% or more of the intensity at the central wavelength, and preferably 50% or more of the intensity at the central wavelength. In the spectrum of incident light L1, the intensity in the third wavelength range R3 is 100% or less of the intensity at the central wavelength. The third wavelength range R3 is 480 nm to 515 nm. At least a portion of the inner region of the spectrum of incident light L1 overlaps with region D2. In FIG. 3, region D2 is a region within the third wavelength range R3 that is 1% or more of the intensity at the central wavelength.

[0038] In the spectrum of the incident light L1, the center wavelength is preferably located in a fourth wavelength range R4. The fourth wavelength range R4 is included in the first wavelength range R1. In other words, the minimum value of the fourth wavelength range R4 is equal to or greater than the minimum value of the first wavelength range R1, and the maximum value of the fourth wavelength range R4 is equal to or less than the maximum value of the first wavelength range R1. The fourth wavelength range R4 is, for example, 470 nm to 540 nm.

[0039] In the spectrum of the incident light L1, the intensity in a fifth wavelength range R5 is preferably 0.1% or more of the intensity at the center wavelength. The fifth wavelength range R5 is included in the second wavelength range R2. That is, the minimum value of the fifth wavelength range R5 is equal to or greater than the minimum value of the second wavelength range R2, and the maximum value of the fifth wavelength range R5 is equal to or less than the maximum value of the second wavelength range R2. The fifth wavelength range R5 is, for example, 605 nm to 615 nm. At least a portion of the inner region of the spectrum of the incident light L1 preferably overlaps with region D3. In FIG. 3, region D3 is a region within the fifth wavelength range R5 that is 0.1% or more of the intensity at the center wavelength.

[0040] In the spectrum of the incident light L1, the intensity in the sixth wavelength range R6 is preferably 40% or more of the intensity at the central wavelength. The sixth wavelength range R6 is included in the third wavelength range R3. That is, the minimum value of the sixth wavelength range R6 is equal to or greater than the minimum value of the third wavelength range R3, and the maximum value of the sixth wavelength range R6 is equal to or less than the maximum value of the third wavelength range R3. The sixth wavelength range R6 is, for example, 490 nm to 515 nm. At least a portion of the inner region of the spectrum of the incident light L1 overlaps with region D4. In FIG. 3, region D4 is a region within the sixth wavelength range R6 that is equal to or greater than 40% of the intensity at the central wavelength.

[0041] The transmitted light L2 is the light of the incident light L1 that has passed through the living body 6. Fig. 4 is a diagram showing the spectrum of the transmitted light L2 shown in Fig. 3. In Fig. 4, the horizontal axis represents wavelength and the vertical axis represents light intensity. Note that in Fig. 4, the vertical axis is expressed as a linear scale.

[0042] 3 and 4, the spectrum of the transmitted light L2 has center wavelengths located in each of a first transmitted wavelength range T1 (first detected wavelength range S1), a second transmitted wavelength range T2 (second detected wavelength range S2), and a third transmitted wavelength range T3 (third detected wavelength range S3). The transmitted light L2 has a first peak P1 in the first transmitted wavelength range T1, a second peak P2 in the second transmitted wavelength range T2, and a third peak P3 in the third transmitted wavelength range T3.

[0043] The transmitted light L2 having the first peak P1, the second peak P2, and the third peak P3 is incident on the first optical filter 44, the second optical filter 45, and the third optical filter 46, respectively. The transmitted light L2 (first peak P1) in the first transmission wavelength range T1 is transmitted through the first optical filter 44 and detected by the first optical detection region 41. The transmitted light L2 (second peak P2) in the second transmission wavelength range T2 is transmitted through the second optical filter 45 and detected by the second optical detection region 42. The transmitted light L2 (third peak P3) in the third transmission wavelength range T3 is transmitted through the third optical filter 46 and detected by the third optical detection region 43.

[0044] The ECU 5 measures the blood glucose level of the living organism 6 based on the intensity of the transmitted light L2 detected by the first photodetector 401 and the intensity of the transmitted light L2 detected by the second photodetector 402. The ECU 5 calculates the blood glucose level of the living organism 6 based on the intensity of the transmitted light L2 (first peak P1) that passes through the first optical filter 44 and is detected by the first photodetector region 41, and the intensity of the transmitted light L2 (second peak P2) that passes through the second optical filter 45 and is detected by the second photodetector region 42.

[0045] Specifically, the ECU 5 calculates a difference between the intensity of the first peak P1 at the first time and the intensity of the first peak P1 at the second time (amount of change over time in the intensity of the first peak P1), a difference between the intensity of the second peak P2 at the first time and the intensity of the second peak P2 at the second time (amount of change over time in the intensity of the second peak P2), and a ratio of oxygenated hemoglobin (O ２ The extinction coefficients of deoxygenated hemoglobin (HHb) and deoxygenated hemoglobin (HHb), and the O ２ Based on the respective extinction coefficients of Hb and HHb, ２ The relative change in Hb over time (ΔO ２ The ECU 5 calculates the relative change in HHb (ΔHHb) over time. ２ The ECU 5 continues to calculate ΔHHb and ΔHHb at predetermined time intervals (for example, about 16 milliseconds). ２The ECU 5 calculates the blood glucose level of the living body 6 based on the time difference between a characteristic point (for example, a peak point) of Hb and a characteristic point (for example, a peak point) of ΔHHb. ２ The ECU 5 may calculate a differential value of Hb (first differential value) and a differential value of ΔHHb with respect to a time series (second differential value). The ECU 5 may calculate the blood glucose level of the living body 6 based on the time difference between a first feature point of the first differential value (e.g., a peak point of the first differential value) and a second feature point of the second differential value (e.g., a peak point of the second differential value). In this embodiment, the methods disclosed in Japanese Patent No. 6846152, for example, are used as a method for calculating the blood glucose level.

[0046] The ECU 5 calculates the pulse rate of the living organism 6 based on the intensity of the transmitted light L2 detected by the third photodetector 403. The ECU 5 calculates the pulse rate of the living organism 6 based on the intensity of the transmitted light (third peak P3) that has passed through the third optical filter 46 and been detected by the third photodetector region 43. The ECU 5 calculates the pulse rate of the living organism 6 based on the time interval between adjacent third peaks P3. For example, if the time interval between adjacent third peaks P3 is 0.8 seconds (e.g., an average value), the ECU 5 calculates the pulse rate of the living organism 6 as 60 seconds divided by 0.8 seconds (75 BPM [beats per minute]).

[0047] The red light output from the second light source 32 and the infrared light output from the third light source 33 are each detected by the third photodetector 403. The red light output from the second light source 32 and the infrared light output from the third light source 33 are each transmitted through the third optical filter 46 and detected by the third photodetector 43. The ECU 5 calculates the blood oxygen saturation level of the living body 6 based on the intensities of the red light and the infrared light (the transmitted red light and the transmitted infrared light) transmitted through the third optical filter 46 and detected by the third photodetector 43. In this embodiment, a known method is used to calculate the blood oxygen saturation level. The ECU 5 may also calculate the blood glucose level of the living body 6 based on the intensities of the red light and the infrared light detected by the third photodetector 43 using the same method as the method using green light described above.

[0048] As described above, in the blood glucose measuring device 1, the spectrum of incident light L1 output to the living body 6 has a center wavelength located in a first wavelength range R1 of 430 nm to 580 nm, an intensity in a second wavelength range R2 of 600 nm to 615 nm that is 0.01% or more of the intensity at the center wavelength, and an intensity in a third wavelength range R3 of 480 nm to 515 nm that is 1% or more of the intensity at the center wavelength. When such incident light L1 is incident on the living body 6, transmitted light L2 having a spectrum (a spectrum having a first peak P1 and a second peak P2) with center wavelengths located in the wavelength range of 460 nm to 535 nm and the wavelength range of 580 nm or more, respectively, is emitted from the living body 6. The ECU 5 calculates the blood glucose level of the living body 6 based on the intensity of the transmitted light L2 detected in a first detection wavelength range S1 of 460 nm to 535 nm (the intensity of the first peak P1) and the intensity of the transmitted light L2 detected in a second detection wavelength range S2 of 580 nm or more (the intensity of the second peak P2). Therefore, the blood glucose level measuring device 1 can measure blood glucose levels using a green light source.

[0049] The inventors of the present application came up with the idea of ​​using a green light source to measure blood glucose levels in order to achieve device miniaturization and power savings. Based on this idea, the inventors conducted extensive research and discovered that biospectroscopic measurements are possible when green light is used, which has a spectrum with a central wavelength in the 430 nm to 580 nm wavelength range, an intensity in the 600 nm to 615 nm wavelength range that is 0.01% or more of the intensity at the central wavelength, and an intensity in the 480 nm to 515 nm wavelength range that is 1% or more of the intensity at the central wavelength. That is, the inventors of the present application discovered that when green light having such a spectrum is incident on a living body, transmitted light is obtained, which has a spectrum with central wavelengths in both the 460 nm to 535 nm wavelength range and the 580 nm or greater wavelength range, and with the intensity at each central wavelength at the same level. The inventors of the present application successfully measured blood glucose levels using this transmitted light.

[0050] In the spectrum of the incident light L1, the central wavelength is preferably located in a fourth wavelength range R4 of 470 nm to 540 nm, the intensity in a fifth wavelength range R5 of 605 nm to 615 nm is 0.1% or more of the intensity at the central wavelength, and the intensity in a sixth wavelength range R6 of 490 nm to 515 nm is 40% or more of the intensity at the central wavelength. This provides transmitted light L2 suitable for calculating blood glucose levels, allowing the blood glucose level of the living body 6 to be calculated more accurately.

[0051] The first photodetector 401 includes a first photodetection region 41 and a first optical filter 44 provided on the first photodetection region 41 and having a first transmission wavelength range T1 of 460 nm to 535 nm. The second photodetector 402 includes a second photodetection region 42 and a second optical filter 45 provided on the second photodetection region 42 and having a second transmission wavelength range T2 of 580 nm or more. The ECU 5 calculates the blood glucose level of the living body 6 based on the intensity (intensity of the first peak P1) of transmitted light L2 that passes through the first optical filter 44 and is detected by the first photodetection region 41, and the intensity (intensity of the second peak P2) of transmitted light L2 that passes through the second optical filter 45 and is detected by the second photodetection region 42. As a result, the first photodetector 41 and the second photodetector 42 can have a common configuration because the transmitted light L2 is selectively transmitted by each of the first optical filter 44 and the second optical filter 45.

[0052] The light detection unit 4 has a third photodetector 403 having a third detection wavelength range S3 of 500 nm to 600 nm. The ECU 5 calculates the pulse rate of the living body 6 based on the intensity of the transmitted light L2 detected by the third photodetector 403. This makes it possible to measure both the blood glucose level and the pulse rate using a green light source, while suppressing increases in the size of the device and power consumption.

[0053] The third photodetector 403 includes a third photodetection region 43 and a third optical filter 46 provided on the third photodetection region 43 and having a third transmission wavelength range T3 of 500 nm to 600 nm. The ECU 5 calculates the pulse of the living body 6 based on the intensity of transmitted light L2 (third peak P3) that passes through the third optical filter 46 and is detected by the third photodetection region 43. As a result, the first optical filter 44, the second optical filter 45, and the third optical filter 46 each selectively transmit the transmitted light L2, so that the first photodetection region 41, the second photodetection region 42, and the third photodetection region 43 can have a common configuration.

[0054] The first photodetectors 401, the second photodetectors 402, and the third photodetectors 403 are alternately arranged to surround the light output unit 3. This reduces loss of the measurement light L emitted from the light output unit 3.

[0055] Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above-described embodiment.

[0056] 5 is a rear view of a blood glucose level measuring device according to a modified example. As shown in FIG. 5 , in the blood glucose level measuring device 1 according to the modified example, the light output unit 3 has a plurality of first light sources 31, a plurality of second light sources 32, and a plurality of third light sources 33. The first light sources 31, the second light sources 32, and the third light sources 33 are arranged in a circular ring shape to surround the light detection unit 4. The first light sources 31, the second light sources 32, and the third light sources 33 are arranged alternately to surround the light detection unit 4. The light output unit 3 has, for example, three first light sources 31, two second light sources 32, and two third light sources 33. In the circumferential direction of the light output unit 3, one first light source 31, one third light source 33, one second light source 32, one first light source 31, one third light source 33, one first light source 31, and one second light source 32 are arranged in this order. In this case, the photodetectors of the photodetector unit 4 may be arranged alternately in a matrix. Furthermore, each photodetector of the photodetector unit 4 may have a CCD image sensor or a CMOS image sensor instead of a PD. With this configuration, the photodetector unit 4 is surrounded by a plurality of first light sources 31, a plurality of second light sources 32, and a plurality of third light sources 33, ensuring the intensity of the transmitted light L2 incident on the photodetector unit 4. In the blood glucose level measuring device 1 according to the modified example, the light output unit 3 may have a first light source 31 instead of each of the second light source 32 and the third light source 33. The light output unit 3 may be composed of a plurality of first light sources 31 surrounding the photodetector unit 4. In this case, the second transmission wavelength range T2 may be 580 nm to 635 nm, preferably 610 nm to 635 nm.

[0057] In the embodiment, the light output unit 3 has the second light source (red light source) 32 and the third light source (infrared light source) 33, but the light output unit 3 does not have to have the second light source 32 and the third light source 33. The light output unit 3 may be constituted by the first light source 31. In this case, the second transmission wavelength range T2 may be 580 nm to 635 nm, and preferably 610 nm to 635 nm.

[0058] In the embodiment, the light detection unit 4 has the third optical filter 46 , but the light detection unit 4 does not necessarily have to have the third optical filter 46 .

[0059] In the embodiment, the first photodetector 401 includes the first optical filter 44, but if the first photodetection region 41 is selectively sensitive to the first detection wavelength range S1, the first photodetector 401 does not need to include the first optical filter 44. In the embodiment, the second photodetector 402 includes the second optical filter 45, but if the second photodetection region 42 is selectively sensitive to the second detection wavelength range S2, the second photodetector 402 does not need to include the second optical filter 45. In the embodiment, the third photodetector 403 includes the third optical filter 46, but if the third photodetection region 43 is selectively sensitive to the third detection wavelength range S3, the third photodetector 403 does not need to include the third optical filter 46.

[0060] 1...blood glucose level measuring device, 3...light output unit, 4...light detection unit, 5...ECU (calculation unit), 6...living body, 31...first light source (green light source), 41...first light detection region, 42...second light detection region, 43...third light detection region, 44...first optical filter, 45...second optical filter, 46...third optical filter, 401...first photodetector, 402...second photodetector, 403...third photodetector, L1...incident light, L2...transmitted light, R1...first wavelength range, R2...second wavelength range, R3...third wavelength range, R4...fourth wavelength range, R5...fifth wavelength range, R6...sixth wavelength range, S1...first detection wavelength range, S2...second detection wavelength range, S3...third detection wavelength range, T1...first transmitted wavelength range, T2...second transmitted wavelength range, T3...third transmitted wavelength range.

Claims

1. A blood glucose level measuring device for measuring the blood glucose level of a living organism, comprising: a light output unit including a green light source that outputs incident light to the living organism; a light detection unit that detects transmitted light that has passed through the living organism; and a calculation unit that calculates the blood glucose level of the living organism based on the detection result of the light detection unit, wherein the spectrum of the incident light has a central wavelength in a first wavelength range of 430 nm to 580 nm, an intensity in a second wavelength range of 600 nm to 615 nm is 0.01% or more of the intensity at the central wavelength, and an intensity in a third wavelength range of 480 nm to 515 nm is 1% or more of the intensity at the central wavelength, the light detection unit has a first photodetector having a first detection wavelength range of 460 nm to 535 nm and a second photodetector having a second detection wavelength range of 580 nm or more, and the calculation unit calculates the blood glucose level of the living organism based on the intensity of the transmitted light detected by the first photodetector and the intensity of the transmitted light detected by the second photodetector.

2. The blood glucose measuring device of claim 1, wherein in the spectrum of the incident light, the central wavelength is located in a fourth wavelength range of 470 nm to 540 nm, the intensity in a fifth wavelength range of 605 nm to 615 nm is 0.1% or more of the intensity at the central wavelength, and the intensity in a sixth wavelength range of 490 nm to 515 nm is 40% or more of the intensity at the central wavelength.

3. A blood glucose measuring device as described in claim 1 or 2, wherein the first photodetector includes a first photodetector region and a first optical filter provided on the first photodetector region and having a first transmission wavelength range of 460 nm to 535 nm; the second photodetector includes a second photodetector region and a second optical filter provided on the second photodetector region and having a second transmission wavelength range of 580 nm or more; and the calculation unit calculates the blood glucose level of the living body based on the intensity of the transmitted light that passes through the first optical filter and is detected by the first photodetector region, and the intensity of the transmitted light that passes through the second optical filter and is detected by the second photodetector region.

4. A blood glucose measuring device as claimed in any one of claims 1 to 3, wherein the light detection unit further comprises a third photodetector having a third detection wavelength range of 500 nm to 600 nm, and the calculation unit calculates the pulse rate of the living body based on the intensity of the transmitted light detected by the third photodetector.

5. The blood glucose measuring device of claim 4, wherein the third photodetector includes a third photodetection region and a third optical filter provided on the third photodetection region and having a third transmission wavelength range of 500 nm to 600 nm, and the calculation unit calculates the pulse rate of the living body based on the intensity of the transmitted light that passes through the third optical filter and is detected by the third photodetection region.

6. A blood glucose measuring device as described in any one of claims 1 to 5, wherein the first photodetector is each of a plurality of first photodetectors, the second photodetector is each of a plurality of second photodetectors, and each of the plurality of first photodetectors and each of the plurality of second photodetectors are alternately arranged to surround the optical output section.

7. A blood glucose measuring device as claimed in any one of claims 1 to 5, wherein the green light source is one of a plurality of green light sources, and each of the plurality of green light sources is arranged to surround the light detection unit.

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