JP2006275710A - Concentration measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems wherein a measuring range of a chemical sensor which is one of concentration measuring means is insufficient, and extreme shortage of a contact time or dilution causes decline of measurement accuracy, and a measuring error is large, compared with the chemical sensor, in measurement by optical rotation. <P>SOLUTION: A measuring system is selected corresponding to a concentration range. A casing 17 holds the chemical sensor 15, and collected urine is circulated by a conductor 16 and brought into contact with the chemical sensor 15, and the result is transmitted to an overall control means 76 through a signal wire group 77. An optical system 72 determines an optical rotation component density inside a measuring container, and the result is transmitted to the overall control means 76 through a signal wire group 89. The overall control means 76 receives the result from a chemical sensor control means 11 through the signal wire group 77, receives the result from an optical control means 72 through the signal wire group 89, and adopts either of them. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for measuring components contained in urine, particularly for measuring glucose concentration with high accuracy.

  It is well known that measuring components in urine is useful in managing health. In particular, measurement of urinary glucose concentration is important because it is an indicator of diabetes that is increasing year by year. As a method for discriminating the glucose concentration in urine, that is, urine sugar, a method using a test paper is generally used. Usually, an enzyme is used for the test paper, but since it is disposable, no maintenance or the like is required. However, this method is unsanitary because it has a high possibility of touching urine, and the work is troublesome, such as collecting urine once with a paper cup and then immersing the test paper. Moreover, since the test paper method itself is qualitatively judged, there is a problem that quantitative measurement cannot be performed.

As a typical quantitative method, a chemical sensor using an enzyme such as GOD (glucose oxidase) method is known. In the above method, an enzyme membrane having GOD fixed thereon is provided on an electrode coated with a selectively permeable membrane. The following reactions occur when in contact with urine:
C6H12O6 → C6H10O6 + H2O2 (1)
H2O2 → H2O + 1 / 2O2 + e -... (2)
C6H12O6 is glucose and C6H10O6 is gluconic acid. However, since the amount of oxygen in urine is limited, the reaction (1) is saturated at a predetermined concentration. For this reason, it is necessary to limit urine dilution and sensor contact time.

  FIG. 6 shows a schematic diagram of a urine sugar measuring apparatus according to the conventional invention. In the figure, a housing 47 holds a chemical sensor 45 and is connected to a conduit 46. The conduit 46 allows the collected urine to pass through and contact the chemical sensor 45. The control means 41 measures the concentration of urine sugar from the electrical signals of the reference conductor 42, the action conductor 43 and the counter electrode wiring 44. The chemical sensor 45 is based on the GOD method described above. At the time of measurement, urine is passed through the conduit 46 for a predetermined time, comes into contact with the chemical sensor 45, is calculated by the control means 43 and measures the urine and urine sugar concentration, and then passed through the conduit 46 and discharged.

  FIG. 7 shows the effect of widening the measurement range by setting the contact time of the chemical sensor 45 based on Patent Document 1 to 2 seconds. In the figure, the horizontal axis indicates the glucose concentration, and the vertical axis indicates the output (current) of the sensor. The correlation curve 7 shows the correlation between the glucose concentration and the sensor output when the urine is sufficiently contacted as usual, and the correlation curve 8 shows the correlation between the glucose concentration and the sensor output when the urine is contacted for only 2 seconds. The correlation curve 52 is in an equilibrium state in the vicinity of about 150 mg / dl, and measurement at a concentration higher than that becomes difficult. On the other hand, the correlation curve 53 shows a good concentration dependency up to about 800 mg / dl. That is, the measurement range can be expanded by limiting the contact time.

  On the other hand, the concentration of urine sugar can also be measured optically. In the optical method using optical rotation, it is possible to measure without touching the sample directly, and dirt does not adhere to the sensor part, so there is no need for parts replacement or consumables, Measurement is possible over a long period.

The principle of the method for obtaining the concentration of the optically rotatory substance in the sample from the optical rotation is based on Equation 1.
θ = 1/100 × [α] _λ ^T × c × L (Formula 1)
Here, θ is the optical rotation, and generally the right optical rotation direction is + and the left optical rotation direction is −. [α] _λ ^T is the specific rotation of the optical rotatory material when the wavelength of the light beam is λ and the temperature is T, and is a coefficient specific to the material. C is the concentration of the optical rotatory substance in the sample, and L is the optical path length of the sample. In Equation 1, as described above, the specific rotation [α] _λ ^T is a known coefficient before the concentration measurement, and the optical path length L of the sample is also a known value. By measuring the optical rotation angle θ, the concentration c of the optical rotatory substance in the sample can be obtained.

A detailed system structure will be described with reference to FIG. Urine is collected in the measurement container 55, and the optical rotation is measured by the optical system 51 as follows. The measurement container 55 is a container having a window portion made of glass so as to transmit light. The light beam emitted from the laser diode 21 is collimated by the lens 22, becomes parallel light, and becomes linearly polarized light that vibrates in a direction inclined by 45 ° from the vertical direction by the polarizer 23A. Next, the polarization component in the horizontal direction or the vertical direction is phase-modulated by the liquid crystal element 31. The liquid crystal element 31 is a homogeneously aligned liquid crystal element in which the liquid crystal molecular long axes are aligned in the horizontal direction or the vertical direction, and the liquid crystal molecules stand by voltage application, the refractive index in the molecular long axis direction changes, and phase modulation is performed. Can do.
Here, if phase modulation is applied to only one polarization component by the liquid crystal element 31, the orthogonal polarization components interfere with each other.

  Next, the transmitted light is branched into reflected light and straight light by the half mirror 24, and the straight light enters the quarter-wave plate 26A whose horizontal axis and vertical axis are inclined by 45 °, and vibrates in the horizontal and vertical directions. The components can be converted into circularly polarized components that rotate in opposite directions. Further, the straight light enters the urine measurement container 55, and a phase difference of ± θ is given between the clockwise circularly polarized light and the counterclockwise circularly polarized light according to the optical rotation of the urine. Further, the light passes through the quarter-wave plate 26B whose optical axis coincides with or is orthogonal to the quarter-wave plate 26A, and the left and right circularly polarized light is converted into polarized light components that are orthogonal to the horizontal or vertical direction, respectively.

  By transmitting the polarizer 23B inclined at 45 ° from the horizontal or vertical direction, an interference signal between the above-mentioned orthogonal polarization components is obtained, and a beat signal is obtained because one of the light speeds is phase-modulated. It is converted into an electric signal by 29A. The beat signal obtained from the photodiode 29B is not affected by the optical rotation of the sample, and the concentration can be obtained by detecting the optical rotation of the urine based on the phase difference between the signals of the photodiodes 29A and 29B. it can.

  The control signal circuit 52 controls the liquid crystal element 31 by a liquid crystal drive signal via the signal line 53. The control signal circuit 52 receives a signal from the photodiode 29A through the signal line 56 and also receives a signal from the photodiode 29B through the signal line 54, and is calculated based on these signals to obtain a sugar concentration. Is calculated.

JP 2003-177112 A (FIGS. 1 and 10) JP 2004-28889 A (FIG. 8)

In the chemical sensor which is one of the concentration measuring means described above, the measurement range is not sufficient, and extreme shortening of the contact time or dilution causes a decrease in measurement accuracy. In addition, the measurement error in the measurement based on the optical rotation is larger than that of the chemical sensor.
Accordingly, an object of the present invention is to solve the above-described problems and to provide a structure of a concentration measuring apparatus that measures a wide range of component concentrations in urine without error.

  In order to solve these problems, the concentration measuring apparatus according to the present invention employs the following means.

  The concentration measuring device of the present invention is a concentration measuring device comprising a means for quantitatively measuring a predetermined component, comprising a chemical sensor and an optical sensor as means for quantitatively measuring the predetermined component, and having a predetermined concentration In the first concentration region, the measurement result by the measuring means using the chemical sensor is used as the concentration measurement result, and in the second concentration region, the measurement is performed by the measuring means using the optical sensor. The result is a density measurement result.

  Further, it is effective that the measurement means for measuring the predetermined component is the urine component measurement means, and the first concentration region is a concentration region lower than the predetermined concentration. In addition, when the measurement value obtained by the measurement means using the chemical sensor and the optical sensor is in the first concentration region, the measurement result obtained by the measurement means using the chemical sensor is set as the concentration measurement result, and the second concentration region is obtained. In this case, it is preferable that the measurement result by the measuring means using an optical sensor is used as the concentration measurement result. Furthermore, it is also preferable that the chemical sensor is provided in a measurement container provided in the optical sensor and provided at a position that does not obstruct the optical path.

(Function)
A conventional urine sugar meter usually measures the concentration by means using an enzyme. The problem with this means is that the output reaches a peak (saturates) without a reaction exceeding a predetermined amount due to the limit of the amount of oxygen in urine. That is, the measurement range is limited. For this reason, the measurement range is being expanded by diluting urine or shortening the contact time of the sensor. However, the test paper can be qualitatively measured up to about 2000 mg / dl, which is a difficult measurement range only by the above-mentioned device. Moreover, excessive dilution of urine and shortening of measurement time lead to a decrease in accuracy, and the mechanism for dilution becomes complicated.

FIG. 5 shows the correlation between the measured urine sugar concentration and the actual concentration for illustrating the concept of the present invention. In the figure, curve 3 shows the correlation of measurement with a chemical sensor (enzymatic formula). Curve 1 shows the measurement correlation of the upper limit error by optical measurement, and curve 2 shows the measurement correlation of the lower limit error by optical measurement. That is, the measurement by optical measurement is performed within the error range of curve 1 and curve 2. In addition, since the error range by an enzyme method is small, it is not illustrated. Here, the curve 2 is saturated at 800 mg / dl and the correlation becomes worse. In the concentration region 4 (0 mg / dl to less than 600 mg / dl), measurement is performed by enzymatic measurement (curve 3), and in the concentration region 5 (from 600 mg / dl to 2000 mg / dl or less), measurement is performed by optical measurement (curve). 1. Curve 2).

  That is, in the present invention, taking advantage of the polarimeter capable of measuring even in a high concentration region, the measurement unit is equipped with an enzyme sensor and a polarimeter, and in the high concentration region where the enzyme sensor is difficult to measure, the measurement result with the polarimeter Is valid. As a result, a high-precision (accuracy ± 1 mg / dl) enzyme sensor is used in the low concentration region and a polarimeter (± 10 mg / dl) is used in the high-concentration region. For example, the accuracy is ± 1 mg / dl (error range ± 1%) in the low concentration range of 100 mg / dl, whereas the accuracy is ± 10 mg / dl (error range ± 1%) in the high concentration of 1000 mg / dl. Thus, the error range is comparable.

As described above, the concentration measuring device of the present invention has the effects described below. A wide measurement range can be covered without diluting urine or limiting the measurement time. Further, since the buffer solution is unnecessary, the user's troublesomeness is reduced and the cost is not increased. In addition, a space for storing the buffer solution is not necessary, and the entire concentration measuring device can be downsized. For example, it can be provided in the toilet seat.

Hereinafter, an optimum embodiment of a concentration measuring apparatus using the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is an example of the first embodiment of the present invention.

  FIG. 1 shows a schematic diagram of a concentration measuring apparatus according to the present invention. In the figure, the conduit 20 is bifurcated into a direction connected to the valve 18 and a direction connected to the valve 75. Urine is introduced into the housing 17 through the conduit 16 by opening the valve 18, and urine is introduced into the measurement container 71 through the conduit 19 by opening the valve 75. The measurement container 71 is a container having a window made of glass so as to transmit the optical path 78.

  The housing 17 holds the chemical sensor 15 and is connected to the conduit 16. The conduit 16 allows the collected urine to flow and contact the chemical sensor 15. The chemical sensor control means 11 processes the electrical signals from the reference conducting wire 12, the working conducting wire 13 and the counter electrode wiring 14 to obtain the concentration, and sends the result to the comprehensive control means 76 via the signal line group 77.

  In the optical system 72, a signal associated with the optical rotation component concentration inside the measurement container 71 is transmitted to the optical control means 75 via the connection line group 74. The optical control means 75 processes the signal from the optical system 72 to obtain the density, and sends the result to the general control means 76 via the signal line group 89.

  The overall control means 76 receives the result from the chemical sensor control means 11 via the signal line group 77 and receives the result from the optical control means 72 via the signal line group 89 to determine either result. The overall control means 76 also controls the entire measurement system.

  FIG. 2 shows a system flowchart of the comprehensive control means 76. When measurement is started (execution step 91), valve 18 is opened by execution step 92, valve 15 is closed, and urine is passed through conduit 16. Next, in the execution step 93, the urine sugar concentration by the enzyme measurement method is measured. Next, at decision step 94, it is determined whether or not the result is 600 mg / dl or more. If the result is less than 600 mg / dl, the execution result 95 sets the result as the urine sugar value and ends the measurement. If the result is 600 mg / dl or more, the valve 18 is closed and the valve 75 is opened in the execution step 96 to pass urine through the conduit 19. Next, the urine sugar concentration accumulated in the measurement container 71 in the execution step 97 is measured by the optical control means 75 using the optical system 72, and the above result is set as the urine sugar value in the execution step 98, and the measurement is terminated. That is, when the concentration is less than 600 mg / dl as a measurement result, the value is measured by an enzyme equation, and when the concentration is 600 mg / dl or more, the value is measured by an optical method.

(Second embodiment)
FIG. 3 shows an example of the second embodiment of the present invention.

  The conduit 39 is connected to the measurement container 81 and passes urine to the measurement container 81. The measurement container 81 is a container whose window is made of glass so as to transmit the optical path 80. It is possible to hold the chemical sensor 35 in a position avoiding the optical path 80 inside the measurement container 81 and measure the optical rotation component concentration stored inside by the optical system 83 and the sensor 35. The conduit 50 is connected to the measurement container 81 and discharges urine from the measurement container 81.

The chemical sensor control means 38 processes the electrical signals from the reference conducting wire 32, the working conducting wire 33 and the counter electrode wiring 34 to determine the concentration, and sends the result to the comprehensive control means 86 via the signal line group 87. In the optical system 82, a signal associated with the optical rotation component concentration inside the measurement container 81 is transmitted to the optical control means 85 via the connection line group 84. The optical control means 85 processes the signal from the optical system 82 to determine the density, and sends the result to the general control means 86 via the signal line group 90.

  The comprehensive control means 86 receives the result from the chemical sensor control means 38 via the signal line group 87 and receives the result from the optical control means 85 via the signal line group 90 to determine one of the results. The comprehensive control means 86 also controls the entire measurement system.

  FIG. 4 shows a system flowchart of the comprehensive control means 86. When the measurement is started (execution step 61), the urine is passed through the conduit 16 by the execution step 62. Next, in the execution step 63, the urine sugar concentration is measured by the enzyme measurement method and also measured by the optical control means 85. Next, after the urine is discharged in the execution step 64, it is determined in the determination step 65 whether the urine sugar concentration is 600 mg / dl or more. If the result of the chemical sensor control means 38 is less than 600 mg / dl, the execution step 66 ends the measurement with the measurement result of the chemical sensor control means 38 as the urine sugar value. If the result is 600 mg / dl or more, the result of measurement by the optical control means 85 in execution step 67 is taken as the urine sugar value, and the measurement is terminated. That is, when the concentration is less than 600 mg / dl as a measurement result, the value is measured by an enzyme equation, and when the concentration is 600 mg / dl or more, the value is measured by an optical method.

  Although urine sugar has been described in the present embodiment, it is not limited to urine sugar, but is the same for other components such as ascorbic acid and lactic acid, and is not limited to urine components. The type of chemical sensor is also different. Not only optical rotation measurement but also optical absorption can be used in the same manner. Further, although the predetermined concentration is 600 mg / dl which is slightly smaller than the limit of 800 mg / dl which is proportional to the concentration of the chemical sensor, it is not limited to this. Furthermore, although a chemical sensor is used as the measuring means for the predetermined concentration, an optical sensor may be used.

It is a figure which shows the structure of the density | concentration measuring apparatus in 1st embodiment of this invention. It is a figure which shows the flowchart in the case of measuring a density | concentration using the density | concentration measuring apparatus in 1st embodiment of this invention. It is a figure which shows the structure of the density | concentration measuring apparatus in 2nd embodiment of this invention. It is a figure which shows the flowchart in the case of measuring a density | concentration using the density | concentration measuring apparatus in 2nd embodiment of this invention. It is a figure which shows the characteristic of the measurement range in the density | concentration measuring apparatus of this invention. It is a figure which shows the structure of the conventional enzyme type urine sugar meter. It is a figure which shows the measurement characteristic of the conventional enzyme type urine sugar meter. It is a figure which shows the structure of the conventional optical urine sugar meter.

Explanation of symbols

11 Chemical Sensor Control Circuit 15 Enzyme Sensor 18 Valve 71 Measuring Container 72 Optical System 76 General Control Circuit 74 Signal Line Group 92 Execution Step 94 Determination Step

Claims (5)

It has a chemical sensor and an optical sensor, has a means for quantitatively measuring a predetermined component, is divided into two concentration regions with a predetermined concentration as a boundary, and the chemical sensor is used in the first concentration region A concentration measuring apparatus in which a measurement result obtained by the measuring means is a concentration measurement result, and a measurement result obtained by the measuring means using the optical sensor is a concentration measurement result in the second concentration region. 2. The concentration measuring apparatus according to claim 1, wherein the means for quantitatively measuring a predetermined component is a urine component measuring means. The concentration measuring apparatus according to claim 1, wherein the first concentration region is a concentration region lower than the predetermined concentration. When the measurement value by the measurement means using the chemical sensor and the optical sensor is in the first concentration region, the measurement result by the measurement means using the chemical sensor is taken as the concentration measurement result, and the second concentration 4. The concentration measuring apparatus according to claim 1, wherein in the case of an area, a measurement result by a measuring unit using the optical sensor is used as a concentration measurement result. 5. The said chemical sensor is provided in the inside of the measurement container with which the said optical sensor was equipped, and shall be provided in the position which does not block an optical path, The Claim 1 characterized by the above-mentioned. Concentration measuring device.

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