JP4363130B2 - Optical blood glucose level pickup - Google Patents

Description

The invention receives the diffuse reflection light from the skin tissue irradiates near infrared light on the skin tissue, the blood glucose level measurement pickup for use in non-invasive blood glucose measurement for measuring the blood glucose level from the obtained received signal It is related.

  Near-infrared spectroscopy, which qualitatively and quantitatively analyzes biological tissue from spectral signals obtained by irradiating biological tissue with near-infrared light and measuring diffusely reflected light within biological tissue, Has been attracting attention in many bioanalytical applications, for example, the absorption intensity at a specific wavelength of near-infrared light is the presence of glucose. Japanese Patent Application Laid-Open No. 60-236631 (patent No. 60-236631) detects a glucose concentration in a living body by measuring a spectrum of diffuse reflected light from a living tissue having a specific wavelength and performing multivariate analysis. Document 1), Japanese Patent Publication No. 3-47099 (Patent Document 2), Japanese Patent Application Laid-Open No. 11-70101 (Patent Document 3), and the like.

  Here, as means for irradiating a living tissue with near-infrared light and receiving diffuse reflection light for spectrum measurement of diffuse reflection light from the living tissue, the above-mentioned Patent Document 3 also shows. As described above, a probe using an optical fiber is common.

  The probe includes an irradiating optical fiber that guides near-infrared light and emits it from the tip surface, and a light-receiving optical fiber that makes diffuse reflected light from a living tissue incident from the tip surface and guides it to a light receiving means. The tip of the seed optical fiber is positioned on the probe tip, and light is projected and received in a state where the probe tip is in contact with the living tissue (for example, the forearm of the human body) with a predetermined pressure. Irradiation of outside light and diffused reflected light are guided to the light receiving element.

However, the forearm of the human body is prone to tissue deformation when the probe is pressed, and because sweat and sebaceous glands are present, sweat and sebum tend to intervene between the probe and these are near infrared. Since it acts as an error factor in measuring the glucose concentration based on the absorption spectrum, the detection result varies every measurement, and high reproducibility cannot be obtained. In addition, since normal skin tissue is flexible, the probe is likely to vibrate, and is susceptible to artifacts associated with body movements.
JP 60-236631 A Japanese Examined Patent Publication No. 3-47099 Japanese Patent Laid-Open No. 11-70101

The present invention was invented in view of the conventional problems described above, the blood glucose level measurement pickup capable of measuring without being affected by the state change of the skin surface by skin tissue deformation and sweat sebum The issue is to provide.

In order to solve the above problems, an optical blood glucose level measurement pickup according to the present invention is a biological spectrum measurement pickup for optical blood glucose level measurement using near-infrared light, and an optical fiber for irradiation and an optical fiber for light reception And a guide that keeps the tip of the probe in contact with the surface of the nail of the human body, and the guide is a surface of the nail. Positioning means for positioning with the mark provided on the mark, and the mark is a recess formed on the surface of the nail, and the positioning means is a positioning pin whose tip fits into the recess. there are particularly characterized.

Even if the probe is pressed, tissue deformation does not occur and measurement is performed on the nail part without sweat glands and sebaceous glands. Since the irradiation optical fiber and the light receiving optical fiber are arranged at a center-to-center distance of 0.2 to 2 mm, the diffuse reflected light in the dermis tissue under the nail can be obtained with certainty. In addition, since the guide is provided with alignment means for alignment with the mark provided on the surface of the nail, measurement can be performed with the probe in contact with a certain position of the nail, and the time interval When a plurality of measurements are taken with the, the conditions can be kept the same and high-precision measurements can be made. In particular, the concaves formed on the surface of the nail are marks provided on the surface of the nail. Since the positioning means is a positioning pin whose tip fits into the recess, measurement can be performed over a long period of time with the probe in contact with a certain position of the nail .

  The guide may include a biasing unit that biases the probe toward the surface of the nail. Since the probe can be kept in contact with the nail at a predetermined contact pressure, it is possible to eliminate a decrease in measurement accuracy due to contact pressure fluctuation.

The present invention does not cause tissue deformation even when the probe is pressed, and performs measurement at the nail portion without sweat glands or sebaceous glands, so that measurement without disturbance due to tissue deformation can be performed and the influence of sweat and sebum In addition to being able to perform measurements without being damaged, there is almost no tissue damage even if the probe is in contact for a long time, so long-term continuous measurement is also possible, and when measuring at the nail part However, the optical fiber for irradiation and the optical fiber for light reception are arranged at a center-to-center distance of 0.2 to 2 mm so that diffuse reflected light in the dermal tissue under the nail can be reliably obtained. Therefore, the nail does not interfere with the measurement.In addition, when used in combination with the invasive measurement, the measurement is performed at almost the same location as the fingertip that performs invasive blood collection. In It never between lag exits, is capable of performing accurate predictions of blood glucose levels as a result. In addition, the guide is provided with alignment means for aligning with the mark provided on the surface of the nail, and the mark is a recess formed on the surface of the nail, and the alignment means is the recess. This is a positioning pin that fits the tip of the pin, so that measurement can be performed over a long period of time with the probe in contact with a certain position on the nail, and even when multiple measurements are taken at long intervals, It can be kept the same and measurement with high accuracy is possible.

  Hereinafter, the present invention will be described based on an embodiment shown in the accompanying drawings. FIG. 1 shows an example of a blood glucose level measurement pickup using near-infrared light according to the present invention. As described above, the probe 9 in the pickup composed of the guide 23 that holds the light guides the irradiation optical fiber 20 that guides near-infrared light and emits it from the front end surface, and causes diffuse reflected light from the living tissue to enter from the front end surface. The optical fiber group 5 which is a bundle with the light receiving optical fiber 19 guided to the light receiving means is led out from the rear end, and as shown in FIG. 20 end faces are located.

  Here, the light receiving optical fiber 19 is positioned at the center position of the tip surface of the probe 9, and a plurality of irradiation optical fibers 20 are arranged at equal intervals on a circle surrounding the light receiving optical fiber 19. In addition, the distance L between the light receiving optical fiber 19 and the irradiation optical fiber 20 is set to 0.2 to 2 mm.

The guide 23 is ring-shaped, and the probe 9 is inserted into the central through hole so as to be slidable in the axial direction, and the probe 9 can be fixed by screwing from the side surface of the guide 23. The guide 23 is fixed on the nail 24 of the human finger 25 with an adhesive, for example. In order to enable fixing to the claw 24, the probe 9 has an outer diameter D1 of about 4 mm, a length H1 of about 6 mm , and the guide 23 has an outer diameter D2 of about 6 mm and a length H2 of about 3 mm. Forming. Further, the surface of the claw 24 with which the end faces of the optical fibers 19 and 20 in the probe 9 come into contact is planarized by a polishing process using a polishing paper in advance, thereby reducing disturbance caused by the claw 24.

  In measuring the blood glucose level, the guide 23 is bonded and fixed to the surface of the nail 24 with an adhesive (preferably an epoxy adhesive), and the tip surface of the probe 9 passed through the guide 23 is applied to the surface of the nail 24 with a predetermined pressure. In this state, the probe 9 is screwed and fixed.

  Then, near-infrared light is irradiated to the subcutaneous tissue (dermis tissue) under the nail 24 through the irradiation optical fiber 20, and diffuse reflection light from the subcutaneous tissue is guided to the light receiving means by the light-receiving optical fiber 19 to measure the absorbance spectrum. The blood glucose level is calculated from the measurement result (the glucose level in the dermal tissue is measured as a substitute characteristic of the blood glucose level to estimate the blood glucose level). More precisely, the blood glucose level is calculated by substituting the measured value of the spectrum into a calibration formula obtained by multivariate analysis of a database of a large number of measurement data and variables related to the living body and the measurement result by the invasive formula. This is the correlation between the blood cell level and the interstitial cell station (ISF) used in the glucowatch (by Cygnus, USA), a microinvasive blood glucose meter using reverse iontophoresis that is currently in practical use in the United States. It is similar to the blood glucose measurement used.

  By the way, in blood glucose measurement by an optical method, since the signal resulting from the glucose concentration of the measurement target is extremely small and easily affected by the disturbance, the disturbance must be removed as much as possible. At this time, adhesively fixing the guide 23 holding the probe 9 to the claw 24 is effective in reducing the artifacts due to vibrations and the like and eliminating the influence of body movement and the like. Is not damaged by fixing the guide 23 with an adhesive.

  In addition, nail tissue in the human body is usually present in a thickness of about 0.2 to 0.5 mm, and there is a dermis tissue immediately below, and the glucose concentration in this dermis tissue varies in correlation with the blood glucose level, There is no correlation between the glucose concentration in the nail tissue and the blood glucose level. Therefore, the nail 24 is preferable in terms of fixing the pickup, but the nail tissue itself acts as a disturbance.

  However, when the end face that is the light emitting portion of the irradiation optical fiber 20 and the end face that is the light incident face of the light receiving optical fiber 19 are aligned on the distal end face of the probe 9, the near-infrared spectrum measurement of the first overtone region is performed. In addition, it is possible to receive diffuse reflected light of near-infrared light that passes through a living tissue through an arcuate transmission path, and also transmits near-infrared light that passes through the living tissue through an arcuate path. Since the reaching depth in the living tissue can be changed by the distance L between the irradiation optical fiber 20 and the light receiving optical fiber 19, the reaching depth is set at a position deeper than the nail tissue. It is possible to measure the spectrum of the dermis tissue. This is why the distance L is set to 0.2 to 2 mm. Incidentally, if it is smaller than 0.2 mm, the light does not reach the dermis tissue, and if it is 2 mm or more, the amount of diffusely reflected light that can be received becomes too small and measurement becomes difficult.

  An example of the near-infrared spectrum when the probe 9 having the distance L of 0.65 mm is used is shown in FIG. In the figure, (a) shows the case where the probe 9 is applied to the nail of the thumb, and (b) shows the case where the probe 9 is applied to the nail of the little finger. It can be seen that measurement is possible.

  In order to fix the probe 9 to the claw 24 with a constant contact pressure, an example using the guide 23 fixed to the claw 24 with an adhesive has been shown, but the means for fixing the guide 23 to the claw 24 is limited to this. Instead of a clip, a clip or a band may be used.

  As described above, smoothing the surface of the claw 24 by polishing is effective for disturbance removal. However, since the surface of the claw 24 is a curved surface, the surface should be as flat as possible during the above polishing. It is preferable to keep the tip of the probe 9 and the claw 24 in contact with each other and improve adhesion. However, polishing is sufficient within the range where the optical fibers 19 and 20 are in contact, that is, within a circle having a diameter of about 2 mm.

  Furthermore, in order to avoid an air layer being positioned between the probe 9 and the claw 24 and to suppress reflection at the interface between the optical fibers 19 and 20 and the claw 24, the refractive index of the claw 24 and the optical fibers 19 and 20 are reduced. A medium for matching the refractive index may be disposed between the probe 9 and the claw 24. As this medium, for example, water or physiological saline can be preferably used. In addition, the medium does not penetrate into the nail 24 to act as a disturbance, and a medium that is highly irritating can be used for normal skin. In FIG. 3, (b) shows the measurement when the probe 9 is applied to the nail 24 of the little finger without a medium, and (c) shows the case where measurement is performed with heavy water interposed as the medium between the nail 24 of the little finger and the probe 9. ing. By interposing the medium, it can be seen that reflection between the claw 24 and the optical fibers 19 and 20 is reduced, the absorbance is increased, and a good spectrum is obtained.

  FIG. 4 shows another example. This is provided with a jig 26 for fitting the tip of a human finger 25 to the guide 23, and after inserting the finger 25 into the jig 26, the probe 9 is slid with respect to the guide 23 and screwed. Thus, the tip of the probe 9 is pressed against the claw 24 with a predetermined pressure. In this case, it is easy to fix the probe 9 to the claw 24 and the tip of the finger 25 is covered with the jig 26, so that the influence of stray light can be eliminated.

  FIG. 5 shows still another example. The point that the jig 26 for covering the tip of the finger 25 is attached to the guide 23 is the same as the above, but here, the pressing of the probe 9 against the nail 23 with a predetermined pressure can be automated. ing. That is, two coils 32 a and 32 b arranged in the axial direction are arranged inside the guide 23, and a cylindrical yoke 33 is arranged on the inner peripheral side thereof. In the movable iron core 28 made of a magnetic material arranged in the yoke 33. The probe 9 is disposed in the cylindrical shaft portion 29.

  The pair of coils 32a, 32b, the yoke 33, and the movable iron core 28 form a bidirectional plunger type solenoid. When the coil 32a is excited, the probe 9 is pulled up as shown in FIG. As shown in FIG. 5B, the probe 9 is pulled down so that the tip of the probe 9 is pressed against the claw 23, and the contact pressure between the probe 9 and the claw 23 at this time is as follows. It becomes a value corresponding to the power supplied to the coil 32b.

  When it is desired to repeat the measurement at a predetermined time interval many times, if the point where the probe 9 contacts the nail 23 is determined more strictly, high reproducibility can be obtained. It can be performed continuously. FIG. 6 shows what copes with this point. In the guide 23 to which the probe 9 is screwed, three through holes 37 are provided at equal intervals on a circle surrounding the probe 9 and are positioned in the through holes 37 respectively. The pin 36 is slidably inserted.

  When performing measurement using this pickup, as shown in FIG. 6A, marks 35 are applied to three points on the surface of the claw 24 where the three positioning pins 36 are applied. The mark 35 may be formed with an oil-based sign pen or a scribing needle, but may be formed as a shallow hole. In the measurement, the tip of the probe 9 held by the guide 23 is nailed by sliding the guide 23 with respect to the positioning pins 36 with the three positioning pins 36 being in contact with the marks 35. Measurement is performed with the contact pressure kept constant by pressing against the surface of 24. At this time, the probe 9 always faces the claw 24 without tilting.

  Even when the measurement is repeated with a time interval, the location where the probe 9 contacts the claw 24 can be made constant by the mark 35 and the positioning pin 36, and the location where the probe 9 contacts varies. It is possible to eliminate a decrease in reproducibility due to the above.

  Since there is no physiological action such as sweating on the nail 24, the mark 35 is unlikely to disappear. Especially when a shallow hole is provided and used as the mark 35, the mark 35 does not disappear for several days to several tens of days. Therefore, the reproducibility of the measurement position during this period can be kept high, and the blood glucose level measurement accuracy can be improved. In addition, although what becomes a point corresponding to each positioning pin 36 was shown as the mark 35, a linear or curved (circular) mark 35 may be used, and the point where the probe 9 contacts is always the same. Anything is possible.

  Further, although the guide 23 holding the probe 9 is slidable with respect to the positioning pin 36, the positioning pin 36 is fixed to the guide 23, and the probe 9 is slidable with respect to the guide 23. It may be.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an example of an embodiment of the present invention, where (a) is a perspective view, (b) is a bottom view, and (c) is a front view. It is explanatory drawing of an example of the spectrum measured using the pickup same as the above. It is explanatory drawing of the other example of the spectrum measured using the pickup same as the above. It is sectional drawing of another example. (a) (b) is sectional drawing of another example. Further, another example is shown, in which (a) is an explanatory view of a mark applied to a nail, and (b) is a perspective view.

Explanation of symbols

9 Probe 23 Guide 24 Claw

Claims (2)

  A probe for measuring a biological spectrum for optical blood glucose level measurement using near-infrared light, in which an optical fiber for irradiation and an optical fiber for light reception are disposed at a center-to-center distance of 0.2 to 2 mm. And a guide that keeps the tip of the probe in contact with the surface of the nail of the human body, and the guide includes alignment means for performing alignment with a mark provided on the surface of the nail. The optical blood sugar level measuring pick-up characterized in that the mark is a recess formed on the surface of the nail, and the positioning means is a positioning pin whose tip is fitted in the recess. 2. The optical blood sugar level measuring pickup according to claim 1, wherein the guide includes biasing means for biasing the probe toward the nail surface .

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