Blood viscosity measuring device

Abstract

To provide a blood viscosity measuring device for easily measuring viscosity of blood flowing through a blood vessel at a measurement part of a person to be measured in a noninvasive manner.SOLUTION: A blood viscosity measuring device includes: light projection and reception unit 1 having at least three pairs of light projection parts and light reception parts suitable for facing each other with a measurement part through which the light of a person to be measured is transmitted sandwiched in-between; transmitted light intensity measuring means 2 for measuring the intensity of transmitted light of three kinds of wavelengths emitted from each light projection part of the at least three pairs of light projection parts and light reception parts of the light projection and reception unit, transmitted through the measurement part, and received by the light reception part by a signal from the light reception part; and blood viscosity output means for measuring the intensity of light absorption by hemoglobin in a blood vessel of the person to be measured, the intensity of light absorption by in-vivo water of the person to be measured, and the intensity of light scattering by a biological tissue of the person to be measured from the intensity of the transmitted light of three kinds of wavelengths, obtaining a blood hematocrit value of the blood in the blood vessel of the person to be measured by calculation on the basis of those intensities, and obtaining and outputting the blood viscosity from the relationships between the hematocrit value and the blood viscosity.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus for non-invasively measuring the viscosity of blood flowing through blood vessels in the human body. [Background technology]

[0002] It is generally known that if the viscosity of blood flowing through the human blood vessels is higher than normal, it can cause blood flow disorders such as myocardial infarction and cerebral infarction, increasing the risk of sudden death. For this reason, in recent years, people whose vascular walls have been weakened due to chronic conditions such as the elderly, high blood pressure, and diabetes, in particular, have been required to take medicines or supplements to maintain low blood viscosity in order to prevent blood flow disorders.

[0003] However, taking blood from the human body every time the viscosity of blood is measured places a heavy burden on the subject. For this reason, a method for measuring the viscosity of blood without taking blood from the human body, i.e., non-invasively, has been studied, and a device for measuring the viscosity of blood without taking blood from the human body, such as the device described in Patent Document 1, has been known so far.

[0004] This conventional device comprises an electrocardiograph which measures the electrocardiogram signal of the person being measured, a pulse wave meter which measures the blood pulse wave of the person being measured, a sphygmomanometer which measures the blood pressure of the subject, and a calculation means which determines an apparent pulse wave velocity from the time difference between the electrocardiogram signal and the pulse wave and the distance between their measurement positions, and which calculates and outputs a blood condition index which indicates blood information from the apparent pulse wave velocity and the blood pressure. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4323560 Summary of the Invention [Problem to be solved by the invention]

[0006] However, this conventional device uses an electrocardiograph, a pulse wave meter, and a blood pressure meter, and these must be accurately attached to the subject, which means that measuring the blood condition is time-consuming and expensive, and it is not possible to easily measure the viscosity of blood flowing through the human blood vessels in a non-invasive manner. On the other hand, it has long been known that there is a certain correlation between the hematocrit value, which indicates the proportion of red blood cells in the blood flowing through the human blood vessels, and blood viscosity, and when the hematocrit value is 30% or less, blood viscosity increases almost in proportion to the hematocrit value, but when the hematocrit value is higher than 30% in adults, etc., blood viscosity increases exponentially with the increase in the hematocrit value. [Means for solving the problem]

[0007] The present invention aims to advantageously solve the above problems by determining blood viscosity from the hematocrit value of blood. The blood viscosity measuring device of the present invention comprises: A device for non-invasively measuring the viscosity of a subject's blood, The light passes through the subject. Common a light-emitting / receiving unit having three pairs of light-emitting and light-receiving parts suitable for facing each other with a measurement point therebetween; The light emitted from each of the three pairs of light-emitting and light-receiving parts of the light-emitting and light-receiving unit is Common a transmitted light intensity measuring means for measuring the intensity of the transmitted light of the three wavelengths that is transmitted through a measurement point and received by the light receiving unit based on a signal from the light receiving unit; a blood viscosity output means for measuring the intensity of light absorption by hemoglobin in the blood vessels of the subject, the intensity of light absorption by water in the body of the subject, and the intensity of light scattering by the body tissues of the subject from the intensities of transmitted light of the three wavelengths, calculating a hematocrit value of blood in the blood vessels of the subject based on these intensities, and calculating and outputting the blood viscosity from the relationship between the hematocrit value and the blood viscosity based on the hematocrit value; The present invention is characterized by comprising: Effect of the Invention

[0008] In the blood viscosity measuring device of the present invention, the three pairs of light projecting parts and light receiving parts of the light projecting and receiving unit are arranged so that the light of the subject passes through the three pairs of light projecting parts and light receiving parts. Common The measuring point is sandwiched between the light-transmitting and receiving units, and the transmitted light intensity measuring means measures the intensity of the light emitted from each of the light-transmitting units and the light-receiving units. Common The intensity of the transmitted light of the three wavelengths that passes through the measurement point and is received by the light receiving unit is measured using a signal from the light receiving unit, and the blood viscosity output means measures the intensity of light absorption by hemoglobin in the subject's blood vessels, the intensity of light absorption by water in the subject's body, and the intensity of light scattering by the subject's biological tissue from the intensities of the transmitted light of the three wavelengths. Based on these intensities, the hematocrit value of the blood in the subject's blood vessels is calculated, and based on that hematocrit value, the blood viscosity is calculated and output from a relational equation or comparison table showing the relationship between hematocrit value and blood viscosity.

[0009] Therefore, according to the blood viscosity measuring device of the present invention, the blood viscosity of the subject through which light passes is Common At the measurement point 、 By simply attaching the light-emitting and light-receiving unit so that the three sets of light-emitting and light-receiving elements face each other with the measurement point in between, the viscosity of blood flowing through the subject's blood vessels at the measurement point can be measured non-invasively and easily.

[0010] In the blood viscosity measuring device of the present invention, Common The measurement points are the subject's earlobes. Set to This is preferable because the thickness of the material is relatively thin, so that light scattering is weak, and because blood vessels pass through the material, light absorption by water in the living body and hemoglobin in the blood vessels is likely to occur.

[0011] In the blood viscosity measuring device of the present invention, the three types of wavelengths are determined by biological tissue. the law of nature scattering Easily Wavelength and water in the body the law of nature absorption Easily The wavelength and the hemoglobin in the blood the law of nature absorption Easily Set the wavelength to Be do. This , coveredThe strength of light absorption by hemoglobin in the blood vessels of the person being measured, the strength of light absorption by water in the body of the person being measured, and the strength of light scattering by the body tissue of the person being measured can each be reliably measured. R .

[0012] In this case, the hemoglobin in the blood the law of nature absorption Easily The wavelength is selected from the wavelengths at which the amount of light absorbed by oxygenated hemoglobin and deoxygenated (reduced) hemoglobin is equal. Be do. This Compared to other wavelengths, the concentration does not change due to oxidation and deoxidation of hemoglobin, so The intensity of light absorption by hemoglobin in the subject's blood vessels can be measured more accurately. .

[0013] Furthermore, in the blood viscosity measuring device of the present invention, especially The biological tissue the law of nature scattering Easily wavelength but 810nm and Be The water in the living body the law of nature absorption Easily wavelength but 1300nm and Be The hemoglobin in the blood the law of nature absorption Easily wavelength but 525nm and Be This is preferable since LEDs of these wavelengths are readily available on the market.

[0014] Furthermore, in the blood viscosity measuring device of the present invention, it is preferable that the light projecting and receiving unit uses an optical filter to pre-align the relationship characteristics between the amount of projected light and the amount of received light for scattering by the biological tissue, absorption by water in the biological body, and absorption by hemoglobin in the blood, since this makes it easier to calculate the viscosity of blood.

[0015] In the blood viscosity measuring device of the present invention, the light projecting and receiving unit receives light from each of the three light projecting units and the three light receiving units. So that its optical axis coincides with the common optical axis. Concentrate and CommonIt is preferable to have an optical element that transmits light to the measurement points and an optical element that disperses the transmitted light and causes each light-receiving element in the three sets of light-projecting units and light-receiving units to receive it, since the measurement points of the three sets of light-projecting units and light-receiving units are not dispersed, thereby improving measurement accuracy. [Brief description of the drawings]

[0016] [Figure 1] 1 is a block diagram showing the configuration of one embodiment of a blood viscosity measuring device of the present invention. [Diagram 2] 2(a) and 2(b) are a schematic assembled perspective view and an exploded perspective view showing a light emitting and receiving unit of the blood viscosity measuring device of the embodiment shown in FIG. [Diagram 3] 3 is a cross-sectional view showing an optical path of the light emitting and receiving unit shown in FIG. 2. [Figure 4] FIG. 1A is a characteristic diagram showing the relationship between the wavelength of light passing through the human body and the absorption coefficient and scattering degree for hemoglobin, water, and biological tissue, and FIG. 1B is a characteristic diagram showing an extracted and enlarged view of the relationship between the wavelength of light and the absorption coefficient shown in FIG. 1A for oxygenated hemoglobin and deoxygenated hemoglobin. [Diagram 5] 3 is an explanatory diagram of the operation of the light emitting and receiving unit shown in FIG. 2. [Figure 6] This is a characteristics diagram showing the relationship between the amount of emitted light and the amount of attenuation of light for three types of wavelengths. (a) shows the state before the characteristics were aligned, (b) shows the amount of attenuation of light for three types of wavelengths when the amount of emitted light is reduced by 50% and 80%, and (c) shows the relationship between the amount of emitted light and the amount of attenuation of light after the characteristics of the three types of wavelengths have been aligned by performing two-point correction based on the relationship between the amount of emitted light and the amount of attenuation of light. [Figure 7] FIG. 1 is an explanatory diagram showing scattering at three wavelengths and the attenuation ratio of hemoglobin to water, where (a) shows the case of a wavelength of 805 nm, (b) shows the case of a wavelength of 1450 nm, and (c) shows the case of a wavelength of 550 nm. [Figure 8] FIG. 4 is an explanatory diagram showing settings of each variable in the blood viscosity measurement device of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a block diagram showing the configuration of one embodiment of the blood viscosity measuring device of the present invention in functional blocks. As shown in this figure, the blood viscosity measuring device of this embodiment comprises a light projecting and receiving unit 1, a transmitted light intensity measuring means 2, and a blood viscosity output means 3.

[0018] Figures 2(a) and 2(b) are a schematic assembled perspective view and an exploded perspective view showing the light projecting and receiving unit in the blood viscosity measuring device of the embodiment shown in Figure 1, and Figure 3 is a cross-sectional view showing the optical path of the light projecting and receiving unit shown in Figure 2. As shown in these figures, the light projecting and receiving unit 1 has a light projecting unit case 1c and a light receiving unit case 1d, each of which has an opening 1a for the optical path in the front wall and an openable and closable lid 1b at the rear opening, and a connecting part 1e that connects the light projecting unit case 1c and the light receiving unit case 1d so that they can move linearly toward and away from each other.

[0019] An LED holder 1f made of resin or glass that is generally transparent or translucent and roughly shaped like a truncated triangular pyramid is arranged as an optical element within the light-projecting unit case 1c. In this embodiment, the LED holder 1f holds three LEDs (light-emitting diodes) 1g as a light-projecting unit that emit light of different wavelengths, tilted so that the optical axes of the LEDs 1g are directed toward a common optical axis C that coincides with the central axis of the LED holder 1f. The LED holder 1f has a diffuser plate 1h at the tip on the common optical axis C. A focusing lens 1i is arranged in the opening 1a of the light-projecting unit case 1c so that its optical axis coincides with the common optical axis C of the LED holder 1f.

[0020] Also, a detector holder 1j made of resin or glass that is generally transparent or translucent and roughly shaped like a truncated triangular pyramid is arranged within the light-receiving unit case 1d as an optical element. In this embodiment, the detector holder 1j holds three detectors (phototransistors) 1k as light-receiving units that receive light of different wavelengths, at an angle such that the optical axes of the detectors 1k are directed toward a common optical axis C that coincides with the central axis of the detector holder 1j. The detector holder 1j has a diffuser 1h at the tip of the detector holder 1j on the common optical axis C. A focusing lens 1i is arranged within the light-receiving unit case 1d so that its optical axis coincides with the common optical axis C of the detector holder 1j.

[0021] As a result, light emitted from any of the three LEDs (light-emitting diodes) 1g in the light-projecting unit case 1c travels toward the common optical axis C within the LED holder 1f, passes through the diffusion plate 1h and is diffused in multiple directions, then is focused in the extension direction of the common optical axis C by the focusing lens 1i in front of the LED holder 1f and travels toward the light-receiving unit case 1d, is focused by the focusing lens 1i in front of the detector holder 1j, passes through the diffusion plate 1h and is diffused in multiple directions within the detector holder 1j, and reaches each of the three detectors (phototransistors) 1k in the detector holder 1j, is received by the detector 1k corresponding to the wavelength of that light, and a signal indicating the intensity of the received light is output from that detector 1k by photoelectric conversion.

[0022] The connecting portion 1e has a linear guide mechanism 1o which has a rod-shaped slider 1m and a groove-shaped holder 1n which supports the slider 1m, for example via a ball guide, within a groove-shaped guide cover 1l which is formed integrally with the bottom of the light-projecting unit case 1c, and which guides the linear reciprocating movement of the slider 1m in its longitudinal direction relative to the holder 1n, and the holder 1n of the linear guide mechanism 1o is fixed within the groove-shaped guide cover 1l of the light-projecting unit case 1c, and the slider 1m of the linear guide mechanism 1o is fixed to the underside of an elongated plate-shaped bracket 1p which is formed integrally with the bottom of the light-receiving unit case 1d and which is slidably fitted within the groove-shaped guide cover 1l of the light-projecting unit case 1c.

[0023] Furthermore, the light-emitting and receiving unit 1 has adhesive surfaces 1q made of double-sided tape or the like (not shown) on the front walls of each of the light-emitting unit case 1c and the light-receiving unit case 1d, facing each other. As a result, when the light-emitting and receiving unit 1 is used, as shown in Figure 2, the light-emitting unit case 1c and the light-receiving unit case 1d are moved toward each other while facing each other with a measurement point set on the subject P's earlobe EL, for example, between them, and the front walls of the light-emitting unit case 1c and the light-receiving unit case 1d are adhered to the front and back surfaces of the earlobe EL, and the unit is attached and fixed to the measurement point on the earlobe EL of the subject P with the earlobe EL lightly pinched so as not to interfere with blood circulation in the earlobe EL.

[0024] Fig. 4(a) is a characteristic diagram showing the relationship between the wavelength of light passing through the human body and the absorption coefficient and scattering degree for hemoglobin, water, and biological tissue, and Fig. 4(b) is a characteristic diagram showing the relationship between the wavelength of light and the absorption coefficient shown in Fig. 4(a) extracted and enlarged for oxygenated hemoglobin and deoxygenated hemoglobin. When light propagates through a living body, the amount of light that can be transmitted decreases due to absorption and scattering. The main causes of absorption and scattering are absorption by hemoglobin (shown by characteristic line B in Fig. 4(a)), absorption by water (shown by characteristic line W in Fig. 4(a)), and scattering by biological tissue (shown by characteristic line A in Fig. 4(a)).

[0025] The strength of the absorption and scattering depends strongly on the wavelength of the light. The absorption and scattering spectra are shown in Figure 4(a). Therefore, in the device of this embodiment, 550 nm, 805 nm, and 1450 nm were selected as wavelengths suitable for measuring the absorption by hemoglobin, scattering by biological tissue, and absorption by water, respectively. Here, 550 nm has the following characteristics: high absorption by hemoglobin (Hb), good sensitivity (Hb (approx. 260) > scattering (approx. 100) >> water (0)), equal absorbance by oxyhemoglobin and deoxyhemoglobin (isobestic point), and no absorption by water; 805 nm has the following characteristics: low absorbance by water and hemoglobin (scattering (approx. 70) >> Hb (approx. 4)), equal absorbance by oxyhemoglobin and deoxyhemoglobin (isobestic point); and 1450 nm has the following characteristics: relatively high absorbance by water (water (approx. 26 > Hb (approx. 1)) and LEDs are relatively easy to obtain.

[0026] The three LEDs 1g in the light-projecting unit case 1c are configured to emit light of three different wavelengths: light with a wavelength of 550 nm that is easily absorbed by hemoglobin, light with a wavelength of 805 nm that is easily scattered by biological tissue, and light with a wavelength of 1450 nm that is easily absorbed by water. The three detectors 1k in the light-receiving unit case 1d are configured to receive light of three different wavelengths: light with a wavelength of 550 nm that is easily absorbed by hemoglobin, light with a wavelength of 805 nm that is easily scattered by biological tissue, and light with a wavelength of 1450 nm that is easily absorbed by water. As a result, the three LEDs 1g and the three detectors 1k are paired with LEDs 1g and detectors 1k of the same type of wavelength, constituting three pairs of light-projecting units and light-receiving units.

[0027] The transmitted light intensity measuring means 2 and blood viscosity output means 3 in the blood viscosity measuring device of the embodiment shown in FIG. 1 are specifically constituted by, for example, an ordinary personal computer having a central processing unit, a memory for temporary storage of processed data, a hard disk drive for long-term storage of processing programs and data such as processing results, input devices such as a mouse and a keyboard, and output devices such as a liquid crystal display and a printer, and each function can be performed by the operation of the personal computer based on a previously given and stored processing program.

[0028] That is, the transmitted light intensity measuring means 2 measures the intensity of the transmitted light of three kinds of wavelengths emitted from each LED 1g of the three pairs of light projecting and receiving parts of the light projecting and receiving unit 1, transmitted through the measurement part of the earlobe EL of the subject P, and received by each detector 1k of the three pairs of light projecting and receiving parts, by the signal from the detector 1k. In this embodiment, as shown in FIG. 5, the relationship between the amount of emitted light and the amount of attenuation of light is examined when a 50% attenuation filter is interposed between the measurement part of the earlobe EL of the subject P and each detector 1k of the three pairs of light projecting and receiving parts, and as shown in FIG. 6, sensitivity calibration is performed to align the sensitivity (height and slope) of the relationship line between the amount of emitted light and the amount of attenuation of light of three kinds of wavelengths on a single straight line by two-point correction based on the relationship. Then, the above-mentioned filter is removed and the intensity of the transmitted light of three kinds of wavelengths is measured.

[0029] The transmitted light intensity measuring means 2 sequentially operates the three pairs of light projecting sections and light receiving sections of the light projecting and receiving unit 1, and for example, projects and receives light with a wavelength of 550 nm, projects and receives light with a wavelength of 805 nm, and projects and receives light with a wavelength of 1450 nm, respectively. In this way, interference between lights with different wavelengths can be avoided, and the amount of attenuated light at each wavelength can be measured more accurately.

[0030] From the results of measuring the amount of attenuated light at each wavelength by the transmitted light intensity measuring means 2 as described above, the blood viscosity output means 3 calculates the amount of water and hemoglobin in the body, as well as the hematocrit value, in the following manner, and calculates and outputs the blood viscosity from the hematocrit value.

[0031] FIG. 7 is an explanatory diagram showing scattering and the attenuation ratio of hemoglobin to water at each of the three wavelengths mentioned above, where FIG. 7(a) shows the case of a wavelength of 805 nm, FIG. 7(b) shows the case of a wavelength of 1450 nm, and FIG. 7(c) shows the case of a wavelength of 550 nm.

[0032] In the device of this embodiment, the blood viscosity output means 3 first calculates the amount of attenuation light at a wavelength of 805 nm, as shown in FIG. 7(a). It is clear from the graph of FIG. 4(a) that this amount of attenuation light is almost entirely due to scattering in biological tissue. Next, the blood viscosity output means 3 calculates the amount of attenuation light at a wavelength of 1450 nm, as shown in FIG. 7(b). By subtracting the amount of attenuation light due to scattering calculated earlier from this amount of attenuation light, the amount of absorption by water, and therefore the amount of water in the body, can be calculated. Next, the blood viscosity output means 3 calculates the amount of attenuation light at a wavelength of 550 nm, as shown in FIG. 7(c). By subtracting the amount of attenuation light due to scattering calculated earlier from this amount of attenuation light, the amount of absorption by hemoglobin, and therefore the amount of hemoglobin in the blood, can be calculated. Finally, the blood viscosity output means 3 calculates the hematocrit value from the amount of hemoglobin.

[0033] 8 is an explanatory diagram showing the setting (definition) of each variable in the blood viscosity measuring device of the above embodiment. That is, for each of the wavelengths of 805 nm, 550 nm, and 1450 nm, the light emission amount P0 of the LED 1g and the light reception amount P C of,

number

number

[0034] According to the Beer-Lambert law, the relation at a wavelength of 805 nm is:

number

[0035] Moreover, the relation at a wavelength of 550 nm is

number

[0036] At wavelengths of 805nm and 550nm, the absorption by water is almost zero,

number

number

[0037] Taking the above into consideration, equations (1) and (2) can be written as follows:

number

[0038] From equations (3) and (4),

number

number

[0039] Furthermore, the relation at a wavelength of 1450 nm is

number

[0040] Equation (5) can be written as follows:

number

[0041] The blood volume (hemoglobin volume) C calculated as above B and water content C W From the constant X determined by experiment, the hematocrit value C is calculated by the following formula (12): H is required.

number

[0042] The hematocrit value can also be determined in the same manner by using 525 nm instead of 550 nm as a wavelength that is easily absorbed by hemoglobin, 810 nm instead of 805 nm as a wavelength that is easily scattered by biological tissue, and 1300 nm instead of 1450 nm as a wavelength that is easily absorbed by water, and LEDs with these wavelengths are more readily available on the market.

[0043] The blood viscosity output means 3 further outputs the hematocrit value C H From the hematocrit value, the viscosity of blood is calculated using a relational expression obtained by experiment or a known relational expression showing the relationship between the hematocrit value and the blood viscosity, and the viscosity is output to an output device such as a liquid crystal display. HThe relationship between the hematocrit value C and blood viscosity is expressed in the form of a table. H In this way, a person can quickly and easily know his / her own blood viscosity and use this information to help manage his / her health.

[0044] Although the above description is based on the illustrated embodiment, the blood viscosity measuring device of the present invention is not limited to the above embodiment and can be modified as appropriate within the scope of the claims, for example, the transmitted light intensity measuring means 2 may simultaneously project light of three different wavelengths onto three LEDs 1g and simultaneously receive the light with three detectors 1k. Also, the blood viscosity output means 3 may obtain the viscosity of blood from the intensity of transmitted light of three different wavelengths using a calculation method other than the above.

[0045] Furthermore, four or more pairs of light projecting and receiving units may be provided to further increase the types of wavelengths of transmitted light used to measure the transmitted light intensity, or multiple measurement points may be measured while the light projecting and receiving units are fixedly attached to the subject. Also, the blood viscosity output means 3 outputs the hematocrit value C calculated by the above calculation so that the subject P can calculate his / her own blood viscosity using a correspondence table or a graph of the relational expression. H may be output to an output device such as a liquid crystal display. [Industrial Applicability]

[0046] Thus, with the blood viscosity measuring device of this invention, the viscosity of blood flowing through the blood vessels at the measurement location of the subject can be measured non-invasively and easily by simply attaching the light-emitting and light-receiving units to the measurement location of the subject through which light passes, so that three sets of light-emitting and light-receiving units face each other with the measurement location in between. [Explanation of symbols]

[0047] 1 Light emitting / receiving unit 1a Open hole 1b Lid 1c Emitter case 1d Receiver case 1e Connecting part 1f LED holder 1g LED 1h Diffuser 1i Condenser lens 1j Detector holder 1k detector 1l Guide cover 1m slider 1n Holder 1o Linear guide mechanism 1p bracket 1q Adhesive surface 2. Transmitted light intensity measurement means 3 Blood viscosity output means C Common optical axis P Person to be measured EL earlobe

Claims

1. A device for non-invasively measuring the viscosity of a subject's blood, a light-emitting / receiving unit having three pairs of light-emitting and light-receiving parts that are suitable for facing each other across a common measurement point on the subject through which light passes; a transmitted light intensity measuring means for measuring the intensity of transmitted light of three types of wavelengths emitted from each of the three sets of light-projecting sections and light-receiving sections of the light-projecting and light-receiving unit, transmitted through the common measurement location, and received by the light-receiving section, based on a signal from the light-receiving section; a blood viscosity output means for measuring the intensity of light absorption by hemoglobin in the blood vessels of the subject, the intensity of light absorption by water in the body of the subject, and the intensity of light scattering by the body tissues of the subject from the intensities of transmitted light of the three types of wavelengths, calculating a hematocrit value of blood in the blood vessels of the subject based on these intensities, and calculating and outputting the blood viscosity from the relationship between the hematocrit value and the blood viscosity based on the hematocrit value; Equipped with The three types of wavelengths are set to a wavelength that is easily scattered by biological tissue, a wavelength that is easily absorbed by water in the biological body, and a wavelength that is easily absorbed by hemoglobin in the blood, a wavelength that is easily scattered by biological tissue being 805 nm or 810 nm, a wavelength that is easily absorbed by water in the living body being 1450 nm or 1300 nm, and a wavelength that is easily absorbed by hemoglobin in the blood being 550 nm or 525 nm, both of which are selected from wavelengths at which the amount of light absorbed by oxyhemoglobin and deoxyhemoglobin is equal.

2. 2. The blood viscosity measuring device according to claim 1, wherein the common measuring point is set on an earlobe of the subject.

3. 3. The blood viscosity measuring device according to claim 1, wherein the light projecting and receiving unit uses an optical filter to adjust the relationship between the amount of projected light and the amount of received light in advance for scattering by the biological tissue, absorption by water in the biological body, and absorption by hemoglobin in the blood.

4. 4. The blood viscosity measuring device according to claim 1, wherein the light-projecting and light-receiving unit includes an optical element that concentrates light from each of the three sets of light-projecting and light-receiving units so that the optical axis of the light from each of the three sets of light-projecting and light-receiving units coincides with a common optical axis, and transmits the light to the common measurement location, and an optical element that disperses the transmitted light and causes each of the three sets of light-projecting and light-receiving units to receive the light.

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