Abstract:
In the present invention, without decreasing measurement accuracy, a biological component information measurement device can have a miniaturized device structure. In a biological component information measurement device ( 100 ), a sample container ( 104 ) accommodates a measurement target ( 105 ) such as blood, cultured cells, or urine, and a light from a light source ( 101 ) is separated into spectral components using a rotating diffraction grating ( 110 ) and caused to be incident on the measurement target ( 105 ). Due to this configuration, it is possible to reduce the number of parts of a spectral optical system and the amount of space required therefor. As a result, it is possible to, in particular, miniaturize the spectral optical system without decreasing measurement accuracy.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a biological component information measurement device which measures information of a biological component such as a blood component and a urine component by use of light. 
       BACKGROUND ART 
       [0002]    Conventionally, devices are known which measure the blood component by irradiating a sample (human body) with a near infrared ray, and analyzing reflection light from the sample. Such devices are disclosed in PTLS 1 to 4, for example. 
         [0003]    In general, such devices include a first optical system that guides light from the light source to the measurement target, a second optical system that guides the light reflected by the measurement target, an optical system that separates the reflection light guided by the second optical system, a photodetector that receives the separated light, and a reference signal optical system for obtaining the reference signal for calibration. 
         [0004]    In addition, a method is widely used in which a sample is put in an analysis cell, and the biological component is analyzed in a spectral manner. Examples of such a method include UV-Vis-NIR spectrophotometers available from Shimadzu Corporation, and spectrophotometers available from Hitachi High-Technologies Corporation. 
         [0005]    In addition, conventionally, a method of measuring the urine component by use of light is disclosed in PTL 5 and the like, for example. In the method disclosed in PTL 5, the urine sample is irradiated with visible light or near infrared light, and the light absorbance at the wavelengths corresponding to the urine components to be measured is measured to simultaneously perform quantitative analysis of the urine components. 
         [0006]    Advantageously, such a method of measuring the urine component using light can be implemented without using consumables such as reagent, test paper or the like unlike other methods using reagent, test paper, chemical light emission, or the like, and does not require complicated procedures. 
       CITATION LIST 
     Patent Literature 
       [0000]    
       
         PTL 1 
         Japanese Patent Application Laid-Open No. 2006-87913 
         PTL 2 
         Japanese Patent Application Laid-Open No. 2002-65465 
         PTL 3 
         Japanese Patent Application Laid-Open No. 2007-259967 
         PTL 4 
         Japanese Patent Application Laid-Open No. 2012-191969 
         PTL 5 
         Japanese Patent Application Laid-Open No. 7-294519 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0017]    In the conventional biological component information measurement devices disclosed in PTLS 1 to 4, however, the photodetector, which is a principal component, is composed of an array type sensor, and as such there is a room for improvement in terms of downsizing and cost reduction. 
         [0018]    In addition, in the method disclosed in PTL 5, a plurality of light sources (see  FIGS. 2A to 2C  of PTL 5), or, a light separation part (see  FIGS. 5A to 5D  of PTL 5) is provided for the purpose of obtaining light for irradiating the sample. Disadvantageously, when a plurality of light sources are provided, the configuration is accordingly complicated, and downsizing of the device is limited. In addition, when the light separation part is provided, a plurality of filters are required as the components of the light separation part, and downsizing of the device and cost reduction are limited. 
         [0019]    In view of the foregoing, an object of the present invention is to provide a biological component information measurement device which can achieve downsizing of the device configuration without reducing the measurement accuracy. 
       Solution to Problem 
       [0020]    A biological component information measurement device of a mode of the present invention includes: a light source; a measurement target placement part in which a measurement target is disposed, in which light from the light source passes through the measurement target and is emitted therefrom; a photodetector configured to receive light passed through the measurement target; and a rotation diffraction grating disposed on an optical path from the light source to the measurement target, or an optical path from the measurement target to the photodetector, the rotation diffraction grating being configured to separate the light from the light source such that the light is incident on the measurement target, or separate the light passed through the measurement target such that the light is incident on the photodetector. 
       Advantageous Effects of Invention 
       [0021]    According to the present invention, it is possible to achieve a biological component information measurement device which can achieve downsizing of the device configuration without reducing the measurement accuracy. 
         [0022]    In addition, for example, quantitative analysis of urine component is achieved without requiring reagent or test paper, and the size of the device can be reduced, and therefore, urine inspection can be simply performed at any place. As a result, kidney function or lever function can be determined on a daily basis, which helps health maintenance. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0023]      FIG. 1  is a schematic view illustrating a general configuration of a biological component information measurement device according to an embodiment; 
           [0024]      FIGS. 2A to 2C  are used for describing a diffraction operation of a rotation diffraction grating; 
           [0025]      FIG. 3  is a plan view illustrating an external appearance of a MEMS device provided with the rotation diffraction grating; 
           [0026]      FIGS. 4A and 4B  illustrate variation of the signal size which is measured by a photodetector (PD) in the case where the position of the rotation diffraction grating is changed in the direction perpendicular to the mirror surface without changing the rotation position of the rotation diffraction grating; 
           [0027]      FIGS. 5A to 5D  are used for describing lock-in amplifier detection; 
           [0028]      FIG. 6  is a schematic view illustrating a general configuration of a biological component information measurement device according to another embodiment; 
           [0029]      FIG. 7  is a perspective view illustrating a detailed configuration of the biological component information measurement device; 
           [0030]      FIG. 8  illustrates a spectrum of the rotation diffraction grating of the embodiment; 
           [0031]      FIG. 9  illustrates a light source output in the case where a light source is pulse driven; 
           [0032]      FIG. 10  is a schematic view illustrating a general configuration of the biological component information measurement device according to another embodiment; and 
           [0033]      FIG. 11  is used for describing an exemplary use of the biological component information measurement device according to the embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0034]    In the following, embodiments of the present invention are described in detail with reference to the accompanying drawings. 
         [0035]      FIG. 1  is a schematic view illustrating a general configuration of biological component information measurement device  100  according to the embodiment of the present invention. 
         [0036]    In biological component information measurement device  100 , light from light source  101  is incident on rotation diffraction grating  110  through optical system  102 . Light source  101  is composed of a light emitting diode (LED), a halogen lamp or a xenon lamp. Rotation diffraction grating  110  turns as illustrated with the arrow in the figure. The incidence surface of rotation diffraction grating  110  is a mirror surface which reflects incident light. That is, rotation diffraction grating  110  turns such that the incident angle to the mirror surface is changed. Rotation diffraction grating  110  reflects light having a wavelength corresponding to the rotation angle in a direction toward slit  103  to separate the incident light. 
         [0037]    Light separated by rotation diffraction grating  110  is incident on sample container  104 . Sample container  104  is a transparent container formed of quartz, glass or the like, and blood, cultured cells, urine and the like are stored in sample container  104  as measurement target  105 . Light having passed through sample container  104  and measurement target  105  stored in sample container  104  is incident on PD  107  through optical system  106 . A light reception signal obtained through photoelectric conversion of PD  107  is output to computation device  120  through analog digital conversion circuit (A/D conversion)  108 . Computation device  120  is a device having an analysis program such as a personal computer and a smartphone, and obtains information of biological components such as a blood component and a urine component from the light reception signal by executing the analysis program. It is to be noted that all of the optical systems of biological component information measurement device  100  are housed in case  109 . 
         [0038]    For example, in the case of measurement of a urine component, computation device  120  calculates an transmission spectrum and an absorption spectrum from a signal detected for each wavelength, and performs the spectrum analysis for quantitative analysis of a urine component containing glucose, creatinine, bilirubin, an urea nitrogen, albumin, a ketone body, sodium chloride, occult blood, nitrites, urobilinogen and the like. Known methods such as the method disclosed in PTL 5, for example, may be used as the way of the spectrum analysis, and therefore detailed description thereof is omitted. 
         [0039]      FIGS. 2A to 2C  illustrate a diffraction operation of rotation diffraction grating  110 . It is to be noted that optical system  106  is omitted in  FIGS. 2A to 2C . At the rotation position illustrated in  FIG. 2A , rotation diffraction grating  110  reflects a λ1 component of incident light in a direction toward slit  103  such that the λ1 component enters sample container  104 . In addition, at the rotation position illustrated in  FIG. 2B , rotation diffraction grating  110  reflects a λ2 component of the incident light in a direction toward slit  103  such that the λ2 component enters sample container  104 . Further, at the rotation position illustrated in  FIG. 2C , rotation diffraction grating  110  reflects a λ3 component of the incident light in a direction toward slit  103  such that the λ3 component enters sample container  104 . In this manner, rotation diffraction grating  110  emits the light having a wavelength corresponding to the rotation angle to thereby separate the incident light. 
         [0040]    In the present embodiment, light is separated using rotation diffraction grating  110 , and thus a photodetector having a single light reception surface, not an array sensor, can be used as photodetector (PD)  107  unlike the case where a fixed diffraction grating is used. As a result, photodetector  107  having a simple configuration can be used, and accordingly, the cost can be reduced. In addition, unlike the case where a fixed diffraction grating is used, it is not necessary to provide a space for separating the light between the diffraction grating and photodetector  107 , and accordingly, the size of the device can be reduced. 
         [0041]    Here, in diffraction grating  110  of the present embodiment rotation, the movable portion of the micro electro mechanical system (MEMS) is the mirror surface, and the diffraction grating is formed on the mirror surface. That is, in rotation diffraction grating  110 , a grating is formed on the mirror surface of the MEMS mirror. 
         [0042]      FIG. 3  is a plan view illustrating an external appearance of MEMS device  200  provided with rotation diffraction grating  110 . MEMS device  200  includes driving section  201  composed of a driving circuit, an actuator and the like, rotation diffraction grating  110 , fixation frame  202 , movable frame  203 , and beam parts  204  and  205 . Driving section  201  has a function of driving rotation diffraction grating  110 . In addition, driving section  201  includes fixation frame  202  and serves also as the base of rotation diffraction grating  110 . Beam part  204  is composed of two beams  204   a  and  204   b . Two beams  204   a  and  204   b  are provided to extend between two opposite edges of movable frame  203  and fixation frame  202 . With this configuration, movable frame  203  is suspended with fixation frame  202  by beams  204   a  and  204   b . In addition, beam part  205  is composed of two beams  205   a  and  205   b . Two beams  205   a  and  205   b  are provided to extend between two opposite edges of rotation diffraction grating  110  and movable frame  203 . With this configuration, rotation diffraction grating  110  is suspended with movable frame  203  by beams  205   a  and  205   b.    
         [0043]    Rotation diffraction grating  110  rotates when beams  204   a  and  204   b  are driven by driving section  201 . To be more specific, when the left and the right of beams  204   a  and  204   b  are changed by driving section  201  in a staggered manner in the depth direction of the drawing, rotation diffraction grating  110  is driven into rotation in a predetermined angle range. Meanwhile, rotation diffraction grating  110  is driven into rotation at a rotational speed of 1 to 100 [Hz]. It should be noted that the rotational speed is not limited to this. The rotational speed may be set in accordance with the arithmetic speed of computation device  120  and the like. Rotation diffraction grating  110  may be driven by piezoelectric methods, electrostatic methods, electromagnetic driving methods, and the like. 
         [0044]    The surface of rotation diffraction grating  110  is a mirror surface, and further, diffraction grating  111  is formed on the mirror surface. Diffraction grating  111  is parallel to the rotation axis of beams  204   a  and  204   b . In the present embodiment, the pitch of diffraction grating  111  is 0.1 to 4 [μm]. In addition, the depth of diffraction grating  111  is 0.01 to 4 [μm]. With this configuration, rotation diffraction grating  110  can favorably separate a near infrared ray with the rotation. In the case where the measurement is performed by use of light other than near infrared rays, it suffices to select the pitch and/or the depth of diffraction grating  111  in accordance with the light. 
         [0045]    Further, in the present embodiment, rotation diffraction grating  110  is driven also in the direction perpendicular to the mirror surface as illustrated in  FIG. 4 . It is to be noted that sample container  104  and optical system  106  are omitted in  FIG. 4 . To be more specific, when beams  205   a  and  205   b  are simultaneously deflected by driving section  201  in the same depth direction of the drawing, rotation diffraction grating  110  is driven in the direction perpendicular to the mirror surface. For example, rotation diffraction grating  110  is driven into a high-frequency simple harmonic motion of several 10 [KHz] in the direction perpendicular to the mirror surface.  FIG. 4A  and  FIG. 4B  illustrate variation of the signal size measured by PD  107  in the case where the position of rotation diffraction grating  110  is changed in the direction perpendicular to the mirror surface without changing the rotation position of rotation diffraction grating  110 . Even with the same rotation position, when the position in the direction perpendicular to the mirror surface is changed, the quantity of light which passes through slit  103  is changed, and the quantity of light incident on PD  107  is changed as illustrated in  FIG. 4A  and  FIG. 4B . With this configuration, a chopper signal can be superimposed on the measurement signal, and noise component can be removed by performing lock-in amplifier detection. As a result, a signal having improved S/N can be obtained, and analysis accuracy is improved. It is to be noted that rotation diffraction grating  110  may be rotated by driving beams  205   a  and  205   b . To be more specific, when beams  205   a  and  205   b  are twisted in the same direction, rotation diffraction grating  110  is driven into rotation in a predetermined angle range. 
         [0046]      FIGS. 5A to 5D  are used for describing lock-in amplifier detection.  FIG. 5A  illustrates an ideal spectrum without noise. Various frequency noises as illustrated in  FIG. 5B  are superimposed on an actual measurement signal.  FIG. 5C  illustrates a spectrum in the case where rotation diffraction grating  110  is driven into high-frequency simple harmonic motion in the direction perpendicular to the mirror surface at frequency f 0 . As illustrated in  FIG. 5C , a chopper signal of frequency f 0  is superimposed on a measurement signal.  FIG. 5D  illustrates a measurement signal after a lock-in amplifier detection. Only a signal of frequency f 0  can be taken out as a direct current signal (A and B illustrated in  FIG. 5C ). With this configuration, the signals having frequencies other than f 0  are removed as noise. 
         [0047]    As described, in the present embodiment, measurement light is separated by turning rotation diffraction grating  110 , and rotation diffraction grating  110  is driven into high-frequency simple harmonic motion in the direction perpendicular to the mirror surface to improve S/N of the measurement signal. In other words, rotation diffraction grating  110  is biaxially driven in the rotational direction and the direction perpendicular to the mirror surface. 
         [0048]    Light composed of λ1 component, light composed of λ2 component, and light composed of λ3 component which are separated in accordance with rotation of rotation diffraction grating  110  sequentially enter sample container  104 . The light composed of λ1 component, the light composed of λ2 component, and the light composed of λ3 component which sequentially entered sample container  104  are modulated by measurement target  105  in sample container  104 , and thereafter emitted from sample container  104 . Here, when passing through measurement target  105 , the light composed of λ1 component, the light composed of λ2 component, and the light composed of λ3 component are subjected to respective modulations which are different from each other on the component basis. In this manner, by analyzing the modulations of the wavelength components with computation device  120 , the biological component of measurement target  105  can be analyzed. 
         [0049]    With the above-mentioned configuration, light is separated using rotation diffraction grating  110 . Thus, the optical system can be downsized, and as a result, biological component information measurement device  100  having a small device configuration can be achieved without reducing the measurement accuracy. 
         [0050]    In addition, by measuring a urine component with use of biological information measurement device  100 , quantitative analysis of the urine component is achieved without requiring reagent or test paper, and the size of the device can be reduced, and therefore, urine inspection can be simply performed at any place. As a result, kidney function or lever function can be determined on a daily basis, which helps health maintenance. Meanwhile, the biological information measurement device of the embodiment of the present invention is applicable to a mobile portable device as well as to a device provided in a toilet. 
         [0051]    While rotation diffraction grating  110  including the MEMS mirror and diffraction grating  111  formed on the mirror surface of the MEMS mirror is disposed on the optical path from light source  101  to measurement target  105 , and rotation diffraction grating  110  separates light from light source  101  such that the light enters measurement target  105  in the configuration illustrated in  FIG. 1 , the present invention is not limited to this, and the layout illustrated in  FIG. 6  may also be employed, for example. In biological component information measurement device  300  of  FIG. 6 , rotation diffraction grating  110  is disposed on the optical path from measurement target  105  to photodetector (PD)  107 , and rotation diffraction grating  110  separates the light having passed through measurement target  105  such that the light is incident on photodetector (PD)  107 . 
         [0052]      FIG. 1  and  FIG. 6  schematically illustrate the biological component information measurement device according to the embodiment.  FIG. 7  illustrates the configuration of biological component information measurement device  100  of  FIG. 1  in more detail.  FIG. 7  is a perspective view of biological component information measurement device  100 . 
         [0053]    In biological component information measurement device  100  of  FIG. 7 , in case  109 , parting plate  131  separates optical system  102  and rotation diffraction grating (rotation diffraction grating unit)  110 , from reflection mirror  132 , sample container  104 , optical system  106 , and PD  107 . 
         [0054]    With this configuration, the optical systems can be disposed in two lines, and a well-balanced layout can be achieved. In addition, since the optical systems are disposed in two lines, light separating performance can be improved by increasing the length of the light path from rotation diffraction grating  110  to the measurement target while achieving downsizing. 
         [0055]    Light emitted from light source (light source unit)  101  is incident on rotation diffraction grating  110  through optical system  102 . Optical system  102  is, for example, a collimate system. The light separated by rotation diffraction grating  110  is incident on reflection mirror  132  through opening  133  of parting plate  131 . The light reflected by reflection mirror  132  passes through sample container  104  and thereafter is incident on PD  107  through slit  103  and optical system  106 . While slit  103  is disposed on the light emission side of sample container  104  in  FIG. 7 , slit  103  may be disposed on the light incidence side of sample container  104  as illustrated in  FIG. 1 . Circuit board  134  is provided with a circuit such as AD conversion circuit  108 . In addition, circuit board  134  is connected with output cable  135  that is connected the computation device  120  ( FIG. 1 ). 
         [0056]    Biological component information measurement device  100  specifically illustrated in  FIG. 7  can have a small size that is  10  cm in the longitudinal direction and 5 cm in the width direction, for example. 
         [0057]      FIG. 8  illustrates a calculated spectrum in the case where LED light whose central wavelength is 1.45 μm is separated by rotation diffraction grating  110  described in the embodiment. From  FIG. 8 , it was confirmed that a spectrum similar to that of the case where light is separated by use of a line sensor can be obtained. Meanwhile, in the calculation, the angle of light source  101 , rotation diffraction grating  110 , and PD  107  was set to 50°, and the grating pitch of diffraction grating  111  was set to 2 μm. 
         [0058]    While rotation diffraction grating  110  is driven into high-frequency simple harmonic motion in the direction perpendicular to the mirror surface to superimpose a chopper signal on the measurement signal in the above-described embodiment, the way for superimposing the chopper signal is not limited to this. For example, as illustrated in  FIG. 9 , the chopper signal may be superimposed by pulse driving light source  101 . Here, it suffices to set the light emission cycle of light source  101  that is pulse driven to the frequency which is used in the lock-in amplifier. 
         [0059]    In addition, while sample container  104  is used as a measurement target placement part for placing measurement target  105  at a predetermined position in the above-described embodiment, the measurement target placement part is not limited to this. In addition, measurement target  105  is not limited to solution such as blood, cultured cells, and urine as long as light can pass through measurement target  105 . For example, measurement target  105  may be a section of skin or the like, and in such a case, the measurement target placement part holds the section of skin. In addition, the measurement target placement part may be a space for simply setting the position of measurement target  105 . 
         [0060]    Further, the biological information measurement device of the embodiment of the present invention may employ the layout illustrated in  FIG. 10 . In  FIG. 10 , the components corresponding to those of  FIG. 1  and  FIG. 6  are denoted with the same reference numerals. In biological information measurement device  400  illustrated in  FIG. 10 , light from light source  101  is incident on collimate mirror  402  through slit  401 . Collimate mirror  402  converts the light from the light source into parallel light, and emits the light toward rotation diffraction grating  110 . As with the case of embodiment, the light separated by rotation diffraction grating  110  enters sample container  104 , and passes through the measurement target in sample container  104  (while being partially absorbed). The light having passed through the measurement target is condensed by condensing mirror  403 , and thereafter is incident on PD  107  through slit  404 . It is to be noted that sample container  104  may be disposed between collimate mirror  402  and rotation diffraction grating  110 . In addition, a plurality of PD  107  and optical components may be provided. Further, collimate mirror  402  and condensing mirror  403  may be a lens system. 
         [0061]    Further, while rotation diffraction grating  110  includes a MEMS mirror and a diffraction grating formed on the mirror surface of the MEMS mirror in the above-described embodiment, the present invention is not limited to this. Rotation diffraction grating  110  may include a mirror of an electromagnetic drive type, and a diffraction grating formed on the mirror surface of the mirror of the electromagnetic drive type. In such a configuration, by separating light by driving into rotation the mirror surface of the mirror of the electromagnetic drive type as in the embodiment, an effect similar to that of the embodiment can be obtained. 
         [0062]    Rotation diffraction grating  110  is not limited to the diffraction grating of reflection type (mirror type), and may be a diffraction grating of transmission type as long as the diffraction grating can separate light in accordance with the rotation. 
         [0063]      FIG. 11  illustrates an exemplary use of biological information measurement device  100  ( 300 ,  400 ). Urine collecting part  502  is provided at a front portion in toilet  501 , and biological information measurement device  100  ( 300 ,  400 ) is provided outside toilet  501 . It is to be noted that the position of urine collecting part  502  in toilet  501  is not limited as long as urine can be collected. Urine collected by urine collecting part  502  is sent into sample container  104  of biological information measurement device  100  ( 300 ,  400 ), and the urine component is measured by biological information measurement device  100  ( 300 ,  400 ) with the urine stored therein or the urine flowing therethrough. When the urine component is measured by biological information measurement device  100  ( 300 ,  400 ), the urine in sample container  104  is brought back into toilet  501 . According to the embodiment of the present invention, small-sized biological information measurement device  100  ( 300 ,  400 ) can be achieved, and biological information measurement device  100  ( 300 ,  400 ) can be installed in a space where it does not obstruct the user of toilet  501 . 
         [0064]    It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors in so far as they are within the scope of the appended claims or the equivalents thereof. While the invention made by the present inventor has been specifically described based on the preferred embodiments, it is not intended to limit the present invention to the above-mentioned preferred embodiments but the present invention may be further modified within the scope and spirit of the invention defined by the appended claims. 
         [0065]    This application is entitled to and claims the benefit of Japanese Patent Application No. 2014-140395 filed on Jul. 8, 2014, and Japanese Patent Application No. 2015-014302 filed on Jan. 28, 2015, the disclosure of which including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
       INDUSTRIAL APPLICABILITY 
       [0066]    The present invention is applicable to a biological component information measurement device which analyzes a biological component by use of light. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           100 ,  300 ,  400  Biological component information measurement device 
           101  Light source 
           102 ,  106  Optical system 
           103 ,  401 ,  404  Slit 
           104  Sample container 
           105  Measurement target 
           107  Photodetector (PD) 
           108  Analog digital conversion circuit (AD conversion) 
           109  Case 
           110  Rotation diffraction grating 
           111  Diffraction grating 
           120  Computation device 
           131  Parting plate 
           132  Reflection mirror 
           133  Opening 
           134  Circuit board 
           200  MEMS device 
           201  Driving section 
           202  Fixation frame 
           203  Movable frame 
           204  and  205  Beam part 
           204   a ,  204   b ,  205   a ,  205   b  Beam 
           402  Collimate mirror 
           403  Condensing mirror