JP2008154687A - Optical measurement unit and optical measurement method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce measuring errors of an optical measurement unit and an optical measurement method using it. <P>SOLUTION: The optical measurement unit 1 used for an optical type measuring apparatus has a plurality of contact sensing parts 30 on a cabinet 3 which becomes in close contact with a site 25 to be measured and the contact sensing parts are brought into contact with the site to be measured. When the site to be measured is elastic and deflectable like a skin of a living body, though slightly inclined, the optical measurement unit can keep all of the contact sensing parts in contact with the site to be measured. The positions and angles of a light emitting part 11 and a photodetecting part 12 and the height H of the contact sensing parts of the optical measurement unit are properly set to be held within an allowable range of measuring variations when measurement is conducted with all of the contact sensing parts made to contact the site to be measured. This enables a measuring person to sense or visually recognize the contact between all of the contact sensing parts and the site to be measured and can confirm that those are within the allowable range of measuring variations, thereby making the optical measurement unit and the optical measurement method applicable for reducing the measuring errors requiring no contact sensor or the like. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical measurement unit and an optical measurement method using the same, and more particularly to a non-invasive optical measurement unit that achieves miniaturization and high accuracy and an optical measurement method using the same.

  There are an invasive method and a non-invasive method as a method for detecting a specific component (for example, sugar) inside the measurement site. As an example of a non-invasive measurement method, a method of optical measurement using near infrared light is known. Hereinafter, a blood glucose concentration (blood glucose level) measurement method will be described as an example of an optical measurement method for a specific component.

As a method for measuring blood glucose concentration (blood glucose level), there is a method of irradiating a site to be measured with near-infrared light (800 nm to 2500 nm) and calculating the blood glucose level by obtaining the absorbance at a specific wavelength from the transmitted light. (For example, refer to Patent Document 1). In addition, a method using spectroscopic analysis and a method of performing spectral analysis using Fourier transform (Fourier Transform Infrared Spectrometer: FTIR) and obtaining the change from the spectrum and a statistical method have been proposed. The optical system of the FTIR analyzer constitutes, for example, a Michelson interferometer (see, for example, Patent Document 2).
JP 2002-202258 A (page 1-2, FIG. 1-11) JP 2006-512979 Gazette (pages 1-4, 6 and 1-7)

  Considering the usage environment for blood glucose level measurement, improving the portability by reducing the size of the measuring device is a market requirement, but in conventional optical measurement units, it is necessary to reduce the size by securing a long optical path and the presence of moving parts. There is a limit and there is a big problem in terms of portability.

  Therefore, development of a small optical measurement unit that can easily perform measurement with high accuracy is also desired. However, a measuring device equipped with a small and highly portable optical measurement unit can be easily measured by using, for example, a biological arm or finger as a measurement site, but it is free from measurement errors due to variations in the measurement site. Reduction is an issue.

  As an example, when measuring a blood glucose level optically, a method is known in which an optical measurement unit is brought into contact with a measurement site and irradiated with near-infrared light (laser light). However, there is a problem that measurement accuracy and stability (reproducibility) of measurement values vary depending on the emission state of the laser light.

  In particular, in the case of a measuring device having an optical measuring unit that is small and has improved portability, it is difficult to always maintain the correct position and direction (angle) of the optical measuring unit to be in contact with the measurement site. For example, there are many cases where laser light is irradiated in a state shifted (tilted) from an angle suitable for measurement.

In particular, when there is a measurement point inside the living body, the incident angle of the laser beam is adjusted so that the focus point of the laser beam coincides with the vicinity of the measurement point. Therefore, if the contact of the optical measurement unit is tilted with respect to the measurement site, the measurement error increases.
In the case of a measurement point inside the living body, not only the incident angle of the laser beam but also the depth of the focus point is important. That is, there is a problem that, for example, the depth of the focus point of the laser beam at the time of measurement becomes unstable and the measurement error becomes large due to the adjustment of the optical measurement unit in contact with the measurement site.

  As a method of stabilizing the measurement value, it is conceivable to increase the contact area between the measurement site and the measurement device, but if the contact area is large, the measurement site will eventually vary within the contact surface. There is a high possibility of reducing the reproducibility of the measured value.

  In addition, it is conceivable to guide the measurement site with a fiber or the like and ensure the stability of the measurement value by the mobility of the fiber, but this method is not sufficient.

  In actual use, in particular in the case of a simple measuring device used for home use etc., slight variations are allowed in the irradiation state (incident angle and focus point depth) of the optical measurement unit. The However, the allowable range is small, and it is difficult for the measurer to recognize how much is the allowable range. If a contact sensor or the like is used to make this possible, there is a problem that the configuration becomes complicated and the cost increases.

  The present invention has been made in view of the above points, and an object thereof is to provide an optical measurement unit capable of reducing measurement errors and an optical measurement method using the same.

  The present invention has been made in view of the various circumstances described above. First, by irradiating the measurement site with near-infrared laser light, the measurement point is at a predetermined depth from the surface of the measurement site. An optical measurement unit for measuring a specific component, which detects a light-emitting unit that outputs the near-infrared laser light to the measurement site and diffuse reflection light of the near-infrared laser light reflected at the measurement point A plurality of light receiving units, a housing in which the light emitting unit and the light receiving unit are incorporated, and a plurality of light receiving units that are equidistant from the center of the housing that is close to the measured site during measurement. The problem is solved by providing a contact sensing unit in contact with the contact sensing unit.

  Second, a light emitting unit that outputs near-infrared laser light to the measurement site, and diffuse reflection light of the near-infrared laser light reflected at a measurement point at a predetermined depth from the surface of the measurement site A plurality of light receiving portions, a housing in which the light emitting portion and the light receiving portion are incorporated, and a plurality of light receiving portions provided at equidistant positions from the center of the housing in proximity to the measured portion during measurement. An optical measurement method for measuring a specific component at the measurement point using an optical measurement unit including a first contact sensing unit and a second contact sensing unit that are in contact with each other. Is solved by starting the measurement in a state of being in contact with the portion to be measured.

  According to the present invention, in a non-invasive optical measurement unit that realizes miniaturization, by stabilizing the emission angle of the laser light that irradiates the measurement site and the reception angle of the diffusely reflected light reflected by the measurement site, Measurement error can be reduced.

First, a plurality of contact sensing units that come into contact with the measurement site are provided in the housing of the optical measurement unit adjacent to the measurement site. The optical measurement unit is set so that the incident state of the output near-infrared laser light can perform normal measurement in a state where all the contact sensing units are in contact with the measurement site.
The measurer can confirm that the optical measurement unit is in contact with the measurement site in a normal state by sensing and visually checking the contact of all the contact detection units, and can measure in a normal state.

  A small and portable optical measuring device is easy to measure, but it is difficult to keep the contact between the measurement site and the device constant, and it is actually suitable for such an optical measuring device. In such an optical measurement unit, slight variations in the contact state are within an allowable range.

  When the measurement site is, for example, living body skin, the contact sensing unit is pushed down a predetermined depth from the measurement site (skin) surface by its elasticity. In the present invention, even if the optical measurement unit is tilted in this state, the optical measurement is performed so that the tilt is within the allowable range of the measurement variation while the contact of all the contact sensing units is maintained. The light emitting part and light receiving part of the unit are adjusted. The measurer can recognize that it is in a normal state (within an allowable range of measurement variation) by performing measurement after confirming contact of all the contact sensing units with the measurement site. Thus, by providing the contact sensing unit, it is possible to greatly reduce measurement errors due to variations in the contact state of the optical measurement unit.

  Second, the contact sensing unit is connected to the housing by an elastic body (for example, a spring), and the depth of the focus point of the laser beam from the focus point of the laser beam when the elastic body is not contracted to the maximum contraction is measured. The height of the light emitting unit, the light receiving unit, and the contact sensing unit, the height of the elastic body, the elastic force, and the like are adjusted so that the variation is within the allowable range. The measurer performs measurement after confirming the contact of all the contact sensing units with the measurement site, so that even if there is a variation due to the pressure of the contact of the optical measurement unit with the measurement site, the measurement variation does not occur. Measurement can be performed within the allowable range.

  Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5. Below, the case where the optical measurement unit 1 of this embodiment is employ | adopted as the blood glucose level measuring apparatus 100 as an example is demonstrated to an example.

  FIG. 1 is a diagram illustrating an example of a blood glucose level measuring apparatus using the optical measurement unit of the present embodiment, in which FIG. 1 (A) is an external view, and FIG. 1 (B) is aa in FIG. 1 (A). Line sectional drawing and FIG.1 (C) (D) are internal top views.

  As shown in FIGS. 1A and 1B, for example, a power switch 4, a measurement start / stop button 5, a display unit 2, and the like are provided on one main surface of the external housing 8 of the blood glucose level measuring apparatus 100. In the present embodiment, as an example, a part of the housing 3 constituting the optical measurement unit 1 protrudes from the upper portion of the external housing 8 and the measurement is performed by bringing the housing 3 close to the measurement site. The housing 3 has, for example, a shape (for example, a cylindrical shape) and a material such that light emitted from the light emitting unit in the optical measurement unit 1 and light irradiated to the light receiving unit do not leak to the outside. The housing 3 may be provided integrally with the external housing 8 of the blood sugar level measuring apparatus 100.

  As shown in FIG. 1C, the optical measurement unit 1 has a light emitting unit, a light receiving unit (both not shown here) and a control unit 6, and is used when measuring a blood glucose level at a measurement site of a living body. . The control unit 6 is configured by, for example, a semiconductor integrated circuit integrated on a printed circuit board, and includes an arithmetic processing unit.

  Further, as shown in FIG. 1D, in the internal structure of the optical measuring apparatus 100, the display unit 2 is connected to a display driver that is a part of the control unit 6. The display unit 2 is, for example, an LCD (Liquid Crystal Display) panel, an organic EL (Electronic Luminescent) display panel, etc., and displays a blood glucose level and other measurement information (for example, notification of measurement error, date and time) so that the measurer can recognize it. Anything can be used. A power supply unit 7 connected to the control unit 6 is also provided. The power source is charging by an AC adapter, a battery, or a combination thereof.

  FIG. 2 is a schematic diagram showing a site to be measured where blood glucose levels are measured. FIG. 2A is a diagram showing the blood glucose level measuring device 100 and the site to be measured 25, and FIG. 2B is a schematic cross-sectional view of the site to be measured 25.

  When blood glucose level is measured using the blood glucose level measuring device 100, the contact sensing unit 30 provided in the casing 3 of the blood glucose level measuring device 100 is in close contact with the inside of the arm or wrist as shown in FIG. And measure the blood sugar level.

  As shown in FIG. 2B, the dermis layer 252 is inside the epidermis 251 of the measurement site 25, and the subcutaneous tissue 253 is inside the dermis layer 252. When optical measurement of the blood glucose level is performed, the contact sensing unit 30 provided in the housing 3 is brought into close contact with the skin 251 of the living body as the measurement site 25. Then, a partial area of the dermis layer 252 inside (lower layer) of the epidermis 251 having a predetermined depth from the epidermis 251 is set as a measurement point P, and the near-infrared laser beam (hereinafter referred to as laser beam) 21 is irradiated to the measurement point P. An optical measurement of the value is made. Under the dermis layer 252, there is a subcutaneous tissue 253.

  In the present embodiment, the laser light 21 emitted from the optical measurement unit 1 is diffusely reflected by the dermis layer 252. The laser beam 21 is emitted from the light emitting portion at an emission angle θ at which the laser beam 21 incident from the skin 251 is diffusely reflected at the measurement point P of the dermis layer 252.

  In order to measure the blood glucose level, it is efficient to detect the blood glucose concentration. In addition, when measuring blood sugar levels non-invasively (without blood sampling), light in a wavelength band that is transparent to the human body is used. In the case of glucose, some spectra of near-infrared light are used. It is known to have light absorption characteristics. Therefore, when blood glucose level measurement is performed using a conventional optical blood glucose level measurement device, blood glucose level measurement is performed by transmitting near-infrared rays through blood vessels and detecting the absorption rate by glucose.

  However, in addition to glucose, there are various substances in the blood, and the absorbance of glucose is very small. In particular, in the case of transmitted light, there is a problem that the blood glucose level cannot be accurately measured as a result of the strong influence of hemoglobin, which is a component in blood, to change the amount of light.

  Therefore, in the present embodiment, glucose in the dermis layer 252 is measured so as not to be affected by blood components (hemoglobin). Since the dermis layer 252 is located at a very shallow position from the outside of the living body (skin 251), the aperture angle of the beam of the laser light 21 (eg, setting the lens numerical aperture NA to an appropriate value) and the emission angle should be appropriately selected. Thus, it is possible to obtain reflected light sufficient for calculating the blood sugar level. In addition, since measurement using reflected light does not pass through the subcutaneous tissue 253, measurement errors due to components other than glucose can be avoided, which is more advantageous than using transmitted light.

  However, in this case, it is important to irradiate the measurement site 25 with the laser beam 21 at an appropriate emission angle, and variations in the emission angle of the laser beam 21 with respect to the measurement site 25 and the focus point of the laser beam 21 are connected. Measurement errors also increase due to variations in depth from the surface of the skin 251.

  Therefore, in the present embodiment, the contact sensing unit 30 that comes into contact with the measurement site 25 is provided in the housing 3 of the optical measurement unit 1.

  This will be described in detail below.

  3A and 3B are diagrams showing the optical measurement unit 1 of the first embodiment, in which FIG. 3A is a plan view that is a surface facing the measurement site, and FIG. 3B is a plan view of FIG. It is a bb line sectional view.

  As shown in FIG. 3A, the housing 3 is, for example, circular on the surface facing the measurement site, and the light emitting unit 11 side and the light receiving unit 12 side are separated by a shielding plate 17. The black circles near the center indicate the spot diameters of the emitted light and the diffuse reflected light, respectively. Since it is desirable to collect as much reflected light 22 as possible in the light receiving unit 12, the spot diameter is set larger than that of the light emitting unit 11.

  A pair of contact sensing units 30 and 30 are provided on the surface of the housing 3 adjacent to the measurement site. The contact sensing unit 30 is formed as a substantially rectangular parallelepiped protrusion 30 that protrudes from a substantially circular flat portion that constitutes the housing 3 and faces the measurement site to the measurement site. As shown in FIG. 3A, a plurality of protrusions 30 are provided at equidistant positions from the center point C of the substantially circular flat portion of the housing 3 in a state where the substantially cylindrical housing 3 is viewed in plan view. At the time of measurement, the protrusion 30 is brought into contact with the part to be measured.

  As shown in FIG. 3B, the optical measurement unit 1 includes a light emitting unit 11 and a light receiving unit 12. The light emitting unit 11 includes a light emitting element LD and lenses 11a and 11a '. The light emitting element LD is, for example, a semiconductor laser diode that outputs near-infrared laser light to the measurement site 25. One or a plurality of light emitting elements LD are provided according to the measuring method, and each outputs a laser beam 21 having a single wavelength.

  The laser beam 21 is condensed by the first condenser lens 11a having a lens numerical aperture NA, and is irradiated to the measurement site 25 with a small spot. Note that the optical measurement unit 1 shown in FIG. 3B includes a light emitting unit 11 including two lenses 11a and 11a ′ provided with other condensing lenses 11a ′ in addition to the first condensing lens 11a. However, the number of lenses 11a and 11a ′ is not limited to this number.

  The light receiving unit 12 includes a second condensing lens 12a and a photo detector PD, and detects the diffuse reflected light 22 of the laser light 21 reflected by the measurement site 25, respectively. The light detection element PD is, for example, a photodiode.

  The reflected light 22 is also collected by the second condenser lens 12 a having the lens numerical aperture NA ′ and detected by the light receiving unit 12.

  The light emitting unit 11 and the light receiving unit 12 are arranged adjacent to each other with a light shielding plate 17 interposed therebetween. For example, as shown in FIG. 3B, the light emitting unit 11 and the light receiving unit 12 are arranged in the same housing 3, and a light shielding plate 17 is arranged in the center. Here, the case where the light emitting unit 11 and the light receiving unit 12 are arranged in the housing 3 is shown as an outline of the optical measurement unit 1, but for example, the external housing 8 of the blood glucose level measuring apparatus 100 (see FIG. 1). And the housing 3 illustrated in FIG. 3B may be integrated.

  The light shielding plate 17 is provided at such a height that incident light does not enter the reflected light. This height is, for example, substantially the same height as the outer periphery of the housing 3. When the protrusion 30 is brought into contact with the measurement site 25 and the measurement site 25 is irradiated with the laser beam 21, a part of the laser beam 21 is reflected by the skin 251. In order to prevent such directly reflected light from reaching the light receiving unit 12, a light shielding plate 17 is provided. The light-emitting unit 11 and the light-receiving unit 12 are arranged in separate spaces by the light-shielding plate 17.

  The light shielding plate 17 is, for example, a material that has a black surface and absorbs near-infrared without transmitting or reflecting.

  More specifically, for example, a metal plate whose surface is coated, specifically, a metal plate whose surface is coated with a black brushed painted material may be mentioned. Examples of the light shielding plate 17 include a resin plate formed by using a resin material containing at least one resin selected from the group consisting of acrylic and polycarbonate resins. In that case, in order to improve light-shielding properties, it is preferable to use a resin plate in which at least one black filler selected from the group consisting of carbon fiber and graphite is contained in the resin material. Further, as the light shielding plate 17, for example, a black polarizing plate may be used. In that case, it is preferable to use the board | substrate which used glass as a base material as a polarizing plate, for example. Further, as the light shielding plate 17, for example, a stone material or the like may be used.

  The laser light 21 is affected by the return light, but the light shielding plate 17 can reduce the influence. Therefore, the laser beam 21 can be stably oscillated, and measurement noise can be reduced.

  Furthermore, since the light receiving unit 12 is also used in a space partitioned by the light shielding plate 17, it can be made less susceptible to the influence of electrical noise.

  In order to avoid intrusion of outside light, the housing 3 is also formed by selecting a material having a light shielding property. Further, although the laser spot from the light emitting unit 11 is very small and the spot on the light receiving unit 12 is large, the spread of diffuse reflected light is about 1 mm (for example, 0.1 mm to 0.5 mm on the photodiode surface). Degree). In order to improve the measurement accuracy, it is desirable to avoid the intrusion of external light. If a sufficient opening for allowing the laser light 21 and the reflected light 22 to pass through is secured, the upper surface of the housing 3 has no gap from the side surface. It is preferable that the shape is continuous and covers the inside as much as possible.

  The laser beam 21 of the light emitting unit 11 is focused by an appropriate lens numerical aperture NA, and irradiated to the measurement point P of the dermis layer 252 of the measurement site 25 at an emission angle θ. This emission angle θ is an angle formed by the center line in the vertical direction (up and down in the drawing) of the light shielding plate 17 and the optical axis of the laser beam 21.

  In the present embodiment, the light emitting unit 11 (first condenser lens) is set so that the emission angle θ is an appropriate angle for measuring the glucose concentration at the measurement point P in a state where all the protrusions 30 are in contact with the measurement site 25. The position and angle of 11a) are set, and the position of the focus point of the irradiated beam is such that the focus point can be adjusted to a position where reflected light (diffuse reflected light) from glucose of the dermis layer 252 can be efficiently obtained. The height H of the protrusion 30 is also set.

  The focus point is connected at a predetermined depth D from the surface of the epidermis 251 and is connected as a measurement point P in the dermis layer 252 suitable for glucose measurement. The depth D is a numerical value indicating how much the focus point is connected from the surface of the skin 251. Further, the focus point is connected as one point separated from the substantially central portion of the thickness of the light shielding plate 17 by a predetermined distance Wa. The distance Wa is a numerical value indicating how far the focus point is from the center or end of the thickness of the light shielding plate 17 at the depth D position from the surface of the epidermis 251 into the dermis layer 252.

  Another reason for irradiating the laser beam 21 at a predetermined emission angle θ is to prevent the reflected light 22 from returning as much as possible to the laser oscillation point.

  On the other hand, the light receiving angle θ ′ of the laser light (diffuse reflected light) received on the light receiving unit 12 side is an angle at which the reflected light 22 is efficiently acquired. The light receiving angle θ ′ is an angle formed by the vertical center line of the light shielding plate 17 and the optical axis of the reflected light 22.

  The focus points are respectively connected to a depth D ′ from the skin 251 and a distance Wa ′ from the approximate center or end of the thickness of the light shielding plate 17.

  The diffusely reflected beam is basically reflected light from every layer. In the present embodiment, with all the protrusions 30 in contact with the measurement site 25, the light receiving angle θ ′, the focus point D ′ (the same as the focus point D of the beam emitted from the light emitting unit 11), Wa ′. The position and angle of the light receiving unit 12 (second condensing lens 12a) are set so that the reflected light from the dermis layer 252 is selectively condensed by the lens numerical aperture NA ′.

  As described above, the light emitting unit 11 and the light receiving unit 12 are set in a state where normal measurement is possible in consideration of the height H of the protrusion 30.

  Here, the state in which normal measurement is possible in the present embodiment refers to a state in which accurate measurement is theoretically possible when the measurement site 25 is smooth and hard, for example, as shown in FIG. It is a state within a range including a slight error with respect to the state.

  As described above, the skin of the living body serving as the measurement site 25 has elasticity and flexibility, and the surface thereof is not a perfect flat surface. Therefore, in the optical measurement unit 1 employed in the blood glucose level measuring apparatus 100 that is small and has excellent portability, the optical measurement unit 1 may be tilted and brought into contact with the measurement site from a state in which theoretically accurate measurement is possible. . If this is too large, it causes measurement variations. However, in the optical measurement unit 1 suitable for use in the simple measuring apparatus 100 as in the present embodiment, a slight inclination is an allowable range of measurement variations in actual use. Inside. However, in this case, a slight inclination is allowed, but it is difficult for the measurer to know the extent to which the inclination is allowed.

  Therefore, in the present embodiment, the protrusions 30 are provided on the housing 3 of the optical measurement unit 1, and all the protrusions 30 are brought into contact with the measurement site 25 during measurement. In the optical measurement unit 1, the light emitting unit 11 and the light receiving unit 12 are configured so that normal measurement (within an allowable range of measurement variation) is possible in a state in which all the protrusions 30 are in contact with the measurement site 25. Has been adjusted.

  When the measurement site 25 has elasticity and flexibility such as the skin of a living body, the contact between all the projections 30 and the measurement site 25 can be maintained even if the optical measurement unit 1 is slightly inclined. That is, the position and inclination of the light emitting unit 11 and the light receiving unit 12 and the height H of the protrusion 30 are appropriately selected so that the measurement within this range is within the allowable range of measurement variation.

  The measurer can recognize that all the protrusions 30 are in contact with each other and that the measurement variation is within the allowable range, and based on this, normal measurement (measurement within the allowable range of measurement variation) is possible.

  In order to detect a normal contact state, it may be possible to provide a contact sensor in the optical measurement unit 1, but in this case, the configuration of the optical measurement unit 1 is complicated and expensive. However, in the present embodiment, the normal measurement state can be easily and inexpensively determined without providing a contact sensor or the like at the contact portion with the measurement site 25.

  Therefore, it is desirable that the shape and arrangement of the protrusions 30 can be sensed independently.

  Specifically, for example, rather than providing the protrusions in a continuous ring shape along the circumference of the housing 3, it is better to dispose the protrusions 30 on the housing 3 at a predetermined distance as shown in the figure. The measurer can easily sense the contact / non-contact state of each protrusion 30 in the measurement site 25. In addition, projections smaller than those shown in the figure may be scattered on the substantially circular plane portion of the housing 3, but if the number of projections is too large, the measurer It is difficult to detect the contact / non-contact state. Therefore, it is preferable that the projections 30 at about two to four locations be arranged on the substantially circular plane portion of the housing 3 at equal intervals. In the present embodiment, as an example, the thin portions having a substantially rectangular cross section are used. The two rod-shaped protrusions 30 were arranged opposite to each other at an equal distance from the center of the substantially circular flat portion of the housing 3. In this case, the length L of the protrusion 30 is about the radius of the housing 3, the width W is about several mm, and the height H is about several mm (see FIGS. 3A and 3B). As described above, the height H also affects the depths of the focus points of the laser light 21 and the reflected light 22, and therefore an appropriate value is selected in consideration of these. The protrusions 30 shown in FIGS. 3A and 3B are formed as, for example, a substantially rectangular parallelepiped projecting portion which is erected from the substantially circular flat portion constituting the housing 3 toward the outside of the housing 3. Has been.

  The shape and number of the protrusions 30 are not limited to those illustrated. For example, two or more elliptical protrusions (not shown) or circular protrusions (not shown) may be provided on the housing 3 instead of the protrusions 30 formed as substantially rectangular parallelepiped protrusions. . Depending on the design / specification contents of the optical measurement unit 1, the shape of the protrusion may be elliptical or circular.

  Although not shown, the optical measurement unit 1 includes, for example, a laser driver, a mirror, an FMD (Front Monitor Diode), an APC (Auto Power Control), and the like.

  The optical measurement unit 1 is connected to the control unit 6 (see FIG. 1) in the external housing 8 by wiring. A control unit in the external housing 8 drives the light emitting element LD by a laser driver and outputs a laser beam 21. A part of the laser beam 21 is input to the APC via the mirror and the FMD. The APC performs control such as maintaining the power of the laser beam 21 constant for each wavelength, and thereby the laser beam 21 is applied to the measurement site 25 at a predetermined irradiation angle and a beam aperture angle (eg, lens aperture). The number NA is set to an appropriate value).

  The light receiving unit 12 is, for example, an InGaAs photodiode, and receives the reflected light 22 from the dermis layer 252 of the measurement site 25 and converts it into an electrical signal. The electric signal is proportional to the intensity of the received light, amplified by an amplifier, and output to the A / D converter of the control unit 6.

  Moreover, the optical measurement unit 1 has a temperature detection part (for example, temperature sensor). The temperature sensor measures the temperature of the measurement site 25 (or in addition to the outside air temperature). The light absorption characteristics of glucose vary with temperature. Therefore, the temperature is measured by the temperature sensor before measuring the blood glucose level, and the wavelength of the laser beam 21 is corrected within a minute range from the measurement result. Specifically, since the laser beam 21 has a characteristic that the oscillation wavelength changes depending on the current or temperature, the temperature or drive current of the laser beam 21 is controlled based on the temperature dependence of the glucose absorption characteristic measured in advance. For example, when controlling by the drive current of the laser beam 21, the laser drive amount is calculated and fed back to the laser driver. As a result, the wavelength of the laser beam 21 is selected as the most efficient wavelength according to the temperature of the measurement site 25, and is shifted by, for example, several nm. Thereby, an accurate blood glucose level can be measured.

  The control unit includes a DSP (Digital signal processor), an A / D conversion circuit, an arithmetic processing unit, and the like, a display driver for outputting data such as measurement results to the display unit, and the light emitting unit 11 described above. Also, it has a desired circuit necessary for other control such as control of a driving means for moving the light receiving unit 12 to a position where normal measurement is possible.

  A signal (reception signal) based on the amount of received light amplified by the optical measurement unit 1 is converted into a digital signal by an A / D conversion circuit and input to an arithmetic processing unit in the DSP.

  The arithmetic processing unit converts the received signal at a predetermined wavelength into an absorptance that is a ratio of the laser beam having the wavelength absorbed by glucose at the site to be measured, and calculates blood glucose level data based on this.

  The control unit causes the display driver to display the blood glucose level data as a measurement result on the display unit 2 (see FIG. 1). In addition to this, the measurement unit 6 performs various known controls corresponding to pressing of a measurement start / stop button, monitoring of a measurement state, and the like.

  With reference to FIG. 4, the optical measuring method using said optical measuring unit 1 is demonstrated.

  When measuring the blood glucose level, the blood glucose level measuring device 100 is brought into contact with the measurement site 25 as shown in FIG. At this time, the measurement of the blood glucose level is started in a state where all the protrusions 30 of the optical measurement unit 1 are in contact with the measurement site 25.

  FIG. 4 is a schematic diagram showing a contact state between the optical measurement unit 1 and the part to be measured 25, and FIGS. 4A and 4B show a normal measurement state (within an allowable range of measurement variation). 4 (C) shows a measurement abnormal state.

  When the measurement site 25 is biological skin, it has elasticity and flexibility, so that the tip of the protrusion 30 (30a, 30b) is positioned at the measurement site 25 according to the pressure with which the optical measurement unit 1 is brought into contact. (Skin layer 251) Pressed down from the surface with a predetermined depth Dc as a limit.

  Here, as shown in FIG. 4 (A), the surface (broken line) connecting the tips of the two protrusions 30 (30a, 30b) is pushed down substantially parallel to the surface of the measurement site 25, and this is used as a reference surface. The angle θc formed by the reference surface and the surface connecting the tips of the two protrusions 30a and 30b is defined as the tilt angle of the optical measurement unit 1. That is, in the case of FIG. 4A, the inclination angle θc = 0.

  From this state, for example, when the optical measurement unit 1 is tilted little by little in a state where the tip of the first protrusion 30a is substantially centered, for example, the second protrusion 30b is connected to the measurement site 25 (skin layer). 251) It will begin to float from the surface. However, up to a certain inclination, the second projecting portion 30b does not float from the surface of the measured site 25 (skin layer 251), and the surface of the measured site 25 and the tip of the second projecting portion 30b appear as circles. The contact is maintained (FIG. 4B).

  Therefore, in this embodiment, while the contact between all the protrusions 30 (tips) and the surface of the measurement site 25 is maintained, optical measurement is performed up to an inclination angle θc = θ1, for example, as shown in FIG. Even if the unit 1 is tilted (0 = <θc = <θ1), the depth D and Dc are also taken into consideration so that the measured value is within the allowable range of measurement variation. The position and angle are set. Further, the position of the focus point of the irradiated beam including the height H of the protrusion 30 is set in the vicinity of the measurement point P.

  After measuring or visually recognizing this state, the measurer starts measuring the blood glucose level by, for example, pressing a measurement start switch of the blood glucose level measuring device 100. Thereby, the measurement error due to the tilt of the optical measurement unit can be greatly reduced.

  On the other hand, as shown in FIG. 4C, when the inclination angle θc of the optical measurement unit 1 is further increased (θ2> θ1), the second protrusion 30b moves away from the measurement site 25 (circle), and at this time The measured value is outside the allowable range of measurement variation.

  Since the measurer can sense or visually recognize that all the protrusions 30 are not in contact with the measurement site 25, the measurer can recognize that the measurement variation is outside the allowable range.

  As described above, slight measurement variations due to the inclination of the optical measurement unit 1 are allowed, but it is difficult for the measurer to know how much the tolerance is within the allowable range. However, according to the present embodiment, the measurable state can be easily determined at low cost.

  Since the blood glucose level optical measurement shown in FIGS. 4 (A) and 4 (B) is performed, the reflected light 22 reflected at the measurement point P is obtained as the received light amount. The absorbance of the laser beam 21 by glucose is determined from the amount of irradiation of the laser beam 21 irradiated from.

  For example, if the intensity of the light having the wavelength λ incident on the measurement site 25 is L0 (λ) and the intensity of the reflected light having the received wavelength λ is L (λ), the light absorption rate I (λ) at the measurement point P Is obtained by ln (L (λ) / L0 (λ)) (in the case where the incident light is constant, the received light intensity itself is equivalent to the absorbance).

  In general, when the blood glucose level is optically measured at the measurement site 25, the measurement is performed in a state including components (for example, water) other than glucose. Therefore, correction is performed so that the absorbance of glucose itself is obtained as necessary.

  The correction can be performed by software, for example, by measuring the absorbance of pure water in advance and holding it in the control unit, and calculating the difference between the measured value and the absorbance of pure water. Alternatively, a part of the laser beam 21 is transmitted through a reference body (for example, a gypsum board) having an absorption characteristic equivalent to that of pure water, and the laser output is controlled based on this transmittance. Is possible.

  Next, a second embodiment will be described with reference to FIG. In the second embodiment, the contact sensing unit 30 and the housing 3 are connected by an elastic body 31. In addition, about the structure which overlaps with 1st Embodiment, it is set as the same code | symbol, and the description is abbreviate | omitted.

  FIG. 5 is a schematic cross-sectional view showing the optical measurement unit 1 and the measurement site 25, and the plan view is the same as FIG.

  The contact sensing unit 30 having a substantially rectangular bar shape is connected by the housing 3 and the elastic body 31 adjacent to the measurement site 25. The elastic body 31 is, for example, a coil spring. More specifically, a “compression coil spring” was used as the elastic body 31. The elastic body 31 is not limited to this, and may be, for example, a leaf spring or a low resilience cushion.

  The elastic body 31 is attached and fixed to the housing 3 so as to be stretchable. One end of the elastic body 31 is attached to the housing 3 without separating the contact sensing unit 30 having a substantially rectangular parallelepiped shape, the elastic body 31 having a coil shape, and the housing 3 having a substantially cylindrical shape. In addition, a contact sensing unit 30 is attached to the other end of the elastic body 31.

  As described above, the focus point of the laser beam 21 output from the light emitting unit 11 is connected at a predetermined depth D from the surface of the epidermis 251 and is connected as a measurement point P in the dermis layer 252 suitable for glucose measurement. It is. The depth D is a numerical value indicating how much the focus point is connected from the surface of the skin 251. Further, the focus point is connected as one point separated from the substantially central portion of the thickness of the light shielding plate 17 by a predetermined distance Wa.

  Further, the focus points of the diffusely reflected light 22 received by the light receiving unit 12 are the depth D ′ (= depth D) from the skin 251 and the distance from the approximate center or end of the thickness of the light shielding plate 17, respectively. Connected to Wa '.

  The depth of the focus point is changed by the elasticity and flexibility of the measurement site 25 and the pressure at the time of measurement, and the depth of the focus point varies.

  Therefore, in the second embodiment, the height H of the contact sensing unit 30, the elastic force and height H 'of the coiled spring 31, and the positions and angles of the light receiving unit 11 and the light emitting unit 12 are appropriately selected, and the coiled spring is selected. The depth D of the focus point from the non-shrinkage time 31 to the most shrinkage time 31 is set to be within an allowable range of measurement variation (D1 = <D = <D2). Thereby, the measurement error by the variation in the depth of a focus point of the optical measurement unit 1 can be significantly reduced.

  For example, as shown in FIG. 5A, when all the contact sensing units 30 come into contact with the measurement site 25 in a state where the coil spring 31 is not contracted, the depth D of the focus point at that time is D = D1. The measurement in this state is within the allowable range of measurement variation. The measurer senses or visually recognizes that all the contact sensing units 30 are in contact with the measurement site 25 and recognizes that the measurement is possible, and then presses the measurement start switch of the blood glucose level measuring device 100, for example. For example, blood glucose level measurement is started.

  Further, as shown in FIG. 5B, the optical measurement unit 1 is pressed with a certain pressure. In this case, the most contracted state of the coiled spring 31 is the limit of pressing, and the focus point depth D = D2 including the bending (several millimeters) of the measurement site (skin) 25. Even in this state, the contact of all the contact sensing units 30 with the measurement site 25 is maintained, so that the measurement variation is within an allowable range.

As described above, the case where the optical measurement unit 1 of the present embodiment is employed in the blood glucose level measuring device 100 has been described as an example. However, the present invention is not limited to this, and may be used for a sugar content detecting device such as fruits and vegetables. In this case, the contact sensing unit 30 can maintain the parallelism of the optical measurement device 100 with respect to the surface of the measurement site 25.

It is (A) external view, (B) sectional drawing, (C) top view, (D) top view for demonstrating this invention. BRIEF DESCRIPTION OF THE DRAWINGS (A) The schematic diagram which shows a to-be-measured site | part for demonstrating this invention, (B) The cross-sectional schematic diagram of a to-be-measured site | part. It is (A) top view and (B) sectional drawing for demonstrating this invention. It is sectional drawing for demonstrating this invention. It is sectional drawing for demonstrating this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical measuring unit 3 Housing | casing 11 Light emission part 12 Light receiving part 21 Laser beam 22 Reflected light 25 Measured part 30 Contact sensing part 30a, 30b Protrusion part 31 Elastic body

Claims (9)

An optical measurement unit that measures a specific component at a measurement point at a predetermined depth from the surface of the measurement site by irradiating the measurement site with a near-infrared laser beam,
A light emitting unit that outputs the near-infrared laser light to the measurement site;
A light receiving unit for detecting diffuse reflected light of the near-infrared laser light reflected at the measurement point;
A housing containing the light emitting unit and the light receiving unit;
A plurality of contact sensing units that are provided at a position equidistant from the center of the casing that is close to the measurement site at the time of measurement;
An optical measurement unit comprising:   The optical measurement unit according to claim 1, wherein two contact sensing units are provided in a thin rod shape and are arranged to face each other.   The optical measurement unit according to claim 1, wherein the contact sensing unit and the housing are connected by an elastic body.   The optical measurement unit according to claim 3, wherein the elastic body is a spring. A light emitting unit that outputs near-infrared laser light to the measurement site, and light reception that detects diffuse reflection light of the near-infrared laser light reflected at a measurement point at a predetermined depth from the surface of the measurement site , A housing in which the light emitting unit and the light receiving unit are incorporated, and a plurality of parts provided at equidistant positions from the center of the housing in proximity to the measurement site at the time of measurement. An optical measurement method for measuring a specific component at the measurement point using an optical measurement unit including a first contact sensing unit and a second contact sensing unit,
An optical measurement method, wherein measurement is started in a state where all of the contact sensing units are in contact with the measurement site. The measurement can be performed within an allowable range of measurement variation by maintaining contact between the first contact sensing unit and the second contact sensing unit and the measurement target portion. An optical measurement method as described in 1.   While the first contact sensing unit and the second contact sensing unit are kept in contact with the part to be measured, the inclination of the housing is within an allowable range of measurement variation. The optical measurement method according to claim 5.   The contact sensing unit and the casing are connected by an elastic body, and the depth of the focus point of the near-infrared laser light from the non-contraction to the maximum contraction of the elastic body is within an allowable range of measurement variation. The optical measurement method according to claim 5, wherein:   The optical measurement method according to claim 5, wherein the measurement is started by pressing a measurement start switch provided in the housing.

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