KR102401133B1 - Apparatus and method for measuring glucose - Google Patents

Abstract

Disclosed are a blood glucose measurement apparatus and method in which a large error does not occur in a blood glucose measurement value according to a temperature and a blood glucose level by analyzing the degree to which a temperature affects a blood glucose measurement value according to the blood glucose level. A blood glucose measurement apparatus for measuring a blood glucose concentration in blood according to an embodiment includes: a sensor strip for outputting a measurement current in response to the blood; A first relation value defining a relationship between a reference current for each blood glucose concentration at a reference temperature and a current measured for each blood glucose concentration of the sensor strip at a plurality of temperatures and a second relation value defining a change according to temperature, respectively an analysis device including a memory for storing the third relation value and the fourth relation value; and a temperature sensor for measuring a temperature, wherein the analysis device includes the temperature measured by the temperature sensor, the first relation value and the second relation value stored in the memory, respectively, the third relation value and the second relation value 4 Using the relation value, the measurement current output from the sensor strip may be corrected, and the blood glucose concentration may be calculated using the corrected measurement current.

Description

Blood glucose measurement device and method {APPARATUS AND METHOD FOR MEASURING GLUCOSE}

The present invention relates to a blood glucose measurement system and method, and more particularly, to a blood glucose measurement apparatus and method capable of accurately correcting the effect of temperature when measuring blood glucose.

A biosensor is an analysis system that combines a biological element and a physicochemical detector to investigate the composition of a substance. A blood glucose measurement apparatus, which is one of the most widely known biosensors, includes an analysis apparatus, a sensor strip, and a blood collection device. The blood glucose measurement apparatus analyzes a receptor that receives electrons generated by reaction of glucose present in blood with a glucose oxidase or a glucose dehydrogenase using an electrochemical or spectroscopic method to indicate a blood glucose level as a recognizable signal.

Diabetes is a very frightening disease for modern people who have abundant food and lack of exercise. The number of diabetic patients and risk groups is increasing every year. Diabetes is a condition in which the amount of glucose in the blood is higher than normal. Since diabetes causes various microvascular complications, arteriosclerosis, and cardiovascular disease, it is essential for diabetic patients and people in risk groups to manage blood sugar through a blood sugar measuring device.

As with all types of sensors, it is important for a blood glucose measurement device to calculate an accurate blood glucose value. In general, factors affecting blood glucose measurement include humidity, hematocrit, and temperature, and in particular, temperature affects the blood glucose measurement value very directly due to the characteristics of a blood glucose measurement device using an enzyme. When the ambient temperature is low, the blood glucose measurement value comes out lower than the true value due to the decrease in enzyme activity. Conversely, when the ambient temperature is high, the blood sugar measurement value comes out higher than the true value.

In order to correct this, in general, a method of measuring a temperature using a temperature sensor and correcting a blood glucose measurement value by adding or subtracting a certain % of the blood glucose measurement value to the blood glucose measurement value according to the measured temperature is used. For example, when the ambient temperature of the blood glucose measurement device deviates from an appropriate temperature (usually around 22° C.), a certain % of the blood glucose measurement value is added or subtracted from the blood glucose measurement value in proportion to the temperature difference. For easy understanding, for example, if blood glucose measurement is performed in an environment 3°C lower than the appropriate temperature, 3% of the blood glucose measurement value is added to the blood glucose measurement value, and the blood glucose measurement is performed in an environment 3°C higher than the optimum temperature. If you lose, subtract 3% of your blood sugar reading from your blood sugar reading. However, the degree to which temperature affects blood glucose readings depends on the blood glucose level. Therefore, if correction is performed by simply adding or subtracting a certain percentage of the blood glucose measurement value according to the temperature, a large error may occur depending on the blood glucose level.

Research to overcome these shortcomings includes 'methods of scaling data used to construct biosensor algorithms, as well as devices, devices and systems (METHODS OF SCALING DATA USED TO CONSTRUCT BIOSENSOR ALGORITHMS AS WELL AS) DEVICES, APPARATUSES AND SYSTEMS INCORPORATING THE SAME)' (Korean Patent Application No.: 10-2015-7026570). In the electrochemical blood glucose measurement system, the electrochemical factor admittance changes according to the hematocrit and temperature. However, in order to utilize the AC impedance method, an electrode must be added to the sensor strip, which increases the material cost.

In summary, a blood glucose measurement device using an enzyme has a problem that a blood glucose measurement value is greatly affected by the temperature due to the characteristic that the activity of the enzyme changes according to the temperature. Accordingly, it is essential for the blood glucose measurement device to apply temperature correction to the blood glucose measurement value, but the conventional method has the disadvantage of applying an inaccurate correction factor. This has the disadvantage of incurring additional costs in terms of materials.

An object of the present invention is to provide an apparatus and method for measuring a blood sugar in which a large error does not occur in a blood sugar measurement value depending on temperature and blood sugar level by analyzing the degree of temperature on a blood sugar measurement value according to the blood sugar level.

A blood glucose measurement apparatus for measuring a blood glucose concentration in blood according to an embodiment includes: a sensor strip for outputting a measurement current in response to the blood; A first relation value defining a relationship between a reference current for each blood glucose concentration at a reference temperature and a current measured for each blood glucose concentration of the sensor strip at a plurality of temperatures and a second relation value defining a change according to temperature, respectively an analysis device including a memory for storing the third relation value and the fourth relation value; and a temperature sensor for measuring a temperature, wherein the analysis device includes the temperature measured by the temperature sensor, the first relation value and the second relation value stored in the memory, respectively, the third relation value and the second relation value 4 Using the relation value, the measurement current output from the sensor strip may be corrected, and the blood glucose concentration may be calculated using the corrected measurement current.

The first relation value is a slope indicating the relation when the reference current is an X-axis value and the measured current is a Y-axis value, and the second relation value is the reference current as an X-axis value and the measurement When current is a value of the Y-axis, it may be a Y-intercept value representing the relationship.

The third relation value is a slope indicating the relation when the temperature is the value of the X axis, and the first relation value or the second relation value is the value of the Y axis, and the fourth relation value is the temperature of the X axis. When the value, the first relational value, or the second relational value is the value of the Y-axis, it may be a Y-intercept value indicating the relation.

The analysis device may calculate the corrected measured current according to the following equation.

(Equation)

Calibrated measuring current = (Measuring current before calibration - (Temperature×C+D))/(Temperature×A+B)

here,

A is a third relation value of the first relation value,

B is a fourth relation value of the first relation value,

C is a third relation value of the second relation value,

D is a fourth relation value of the second relation value.

Alternatively, the first relation value is a slope indicating the relation when the measured current is the value of the X axis and the reference current is the value of the Y axis, and the second relation value is the measured current as the value of the X axis; When the reference current is a value of the Y-axis, it may be a Y-intercept value representing the relationship.

In this case, the third relation value is a slope indicating the relation when the temperature is the value of the X axis, the first relation value or the second relation value is the value of the Y axis, and the fourth relation value is the temperature When the value of the X axis, the first relation value, or the second relation value is the value of the Y axis, it may be a Y-intercept value indicating the relation.

A method for measuring a blood glucose concentration in blood in a blood glucose measurement apparatus according to another embodiment includes a method for defining a relationship between a reference current for each blood glucose concentration at a reference temperature and a current measured for each blood glucose concentration of the sensor strip at a plurality of temperatures storing a third relation value and a fourth relation value defining a change according to temperature, respectively, of the first relation value and the second relation value; receiving a measurement current output from a sensor strip by reaction of a reagent with blood; measuring the temperature; correcting the measured current by using the measured temperature and the third and fourth relation values of the first relation value and the second relation value, respectively; and calculating the blood glucose concentration by using the corrected measurement current.

The present invention can reduce the error according to the temperature in measuring the blood glucose concentration. Accordingly, it is possible to secure the reliability of blood glucose measurement.

In addition, according to the present invention, it is possible to secure reliability of blood glucose measurement by reducing measurement errors of blood glucose concentration that occur depending on not only temperature but also blood glucose level.

1 is a view showing a blood glucose measurement apparatus according to an embodiment of the present invention.
2 is a view showing the structure of a sensor strip according to an embodiment of the present invention.
FIG. 3 is a graph showing the blood glucose concentrations measured at each temperature before correction of Table 4 in comparison with the blood glucose concentration values measured at 22.4° C., which is an appropriate temperature.
4 is a graph showing the measured blood sugar concentrations for each temperature corrected according to the present invention in Table 3, compared to the blood sugar concentration values measured at an appropriate temperature of 22.4°C.
5 is a graph showing the measured blood sugar concentrations for each temperature corrected by applying the % correction method of Table 5 in comparison with the blood sugar concentration values measured at an appropriate temperature of 22.4°C.
6 is a flowchart illustrating a method of measuring a blood glucose concentration in a blood glucose measurement apparatus according to an embodiment of the present invention.

The above-described objects, features and advantages will become more apparent through the following detailed description in relation to the accompanying drawings, and accordingly, those of ordinary skill in the art to which the present invention pertains can easily implement the technical idea of the present invention. There will be. In addition, in the description of the present invention, if it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a blood glucose measurement apparatus according to an embodiment of the present invention. Referring to FIG. 1 , the blood glucose measurement apparatus 100 according to the present embodiment includes a temperature sensor 110 , a sensor strip 120 , a connector 130 , and an analysis apparatus 140 .

The temperature sensor 110 measures a temperature at a location where the blood glucose measurement apparatus 100 is located.

The sensor strip 120 is a means used to analyze blood glucose from a specimen such as blood or body fluid collected from a human or animal, and outputs a current corresponding to the blood glucose level of the supplied specimen. Here, the sensor strip 120 may be a consumable item that is replaced for each sample measurement. The sensor strip 120 includes a measurement target electrode unit for measuring blood sugar, and a reagent is applied on the measurement target electrode unit. The measurement target electrode unit may include a working electrode and a reference electrode. The sensor strip 120 will be described in detail below.

The connector 130 is for connecting the sensor strip 120 to the analysis device 140 , and serves as an interface between the sensor strip 120 and the analysis device 140 . The connector 130 may include a terminal for applying a voltage to the measurement target electrode part of the sensor strip 120 and a terminal for detecting a current received from the measurement target electrode part.

The analysis device 140 controls the overall operation of the blood glucose measurement device 100 , applies a voltage to the sensor strip 120 through the connector 130 , and controls the current received from the sensor strip 120 . Analyze and measure the blood glucose concentration of the sample. The analysis device 140 may include a computing device, a battery, a memory, and the like. In the present embodiment, the analysis device 140 measures the blood glucose concentration in the sample based on the current received from the measurement target electrode unit of the sensor strip 120 .

In the memory of the analysis device 140 , a first relationship value and a second relationship defining a relationship between a reference current for each blood sugar concentration at a reference temperature and a current measured for each blood sugar concentration at a plurality of temperatures of the sensor strip 120 . Stores a third relational value and a fourth relational value defining a change with temperature, respectively, of the values. That is, in the memory, a third relation value and a fourth relation value defining a change according to the temperature of the first relation value, and a third relation value and a fourth relation value defining a change according to the temperature of the second relation value The value is saved.

The arithmetic unit of the analysis device 140 , the temperature measured by the temperature sensor 110 and the third relation value and the fourth relation value, respectively, of the first relation value and the second relation value stored in the memory is used to correct the measurement current output from the sensor strip 120, and calculate the blood glucose concentration using the corrected measurement current. The calculation device outputs the calculated value of the blood glucose concentration. For example, the arithmetic device may output the value of the blood sugar concentration using an LED or the like, or may output the value of the blood sugar concentration as a digital value through a display means.

In an embodiment, the first relation value may include a reference current for each blood glucose concentration at the reference temperature as an X-axis value and a Y-axis value for a measured current for each blood glucose concentration according to the temperature of the sensor strip 120 , It is a slope representing the relationship, and the second relationship value is a Y-intercept value representing the relationship. And the third relation value is a slope indicating the relation when the temperature is the value of the X axis, the first relation value or the second relation value is the value of the Y axis, and the fourth relation value is the relation This is the Y-intercept value.

The arithmetic unit of the analysis device 140 corrects the measurement current output from the sensor strip 120 , that is, the measurement current before correction according to Equation 1 below.

(Equation 1)

Measured current after calibration = (Measured current before calibration - (Temperature×C+D))/(Temperature×A+B)

here,

A is a third relation value of the first relation value,

B is a fourth relation value of the first relation value,

C is a third relation value of the second relation value,

D is a fourth relation value of the second relation value,

The temperature is a temperature measured by the temperature sensor 110 .

In general, the electrochemical blood glucose measurement system measures the blood glucose concentration using the amperometric technique. That is, the blood glucose concentration is measured using the current generated when a constant voltage is applied to the sensor strip for a predetermined time. When a constant voltage is applied to the sensor strip for a predetermined time, a current proportional to the blood glucose concentration is generated, and the blood glucose concentration is calculated by applying the current value to the relational expression between the blood glucose concentration and the current. However, in the present invention, before converting the current value output from the sensor strip 120 into the blood glucose concentration, the current value is corrected according to the temperature, and then the blood glucose concentration is calculated from the corrected current value. (Equation 1) indicates that the current value output from the sensor strip 120 is corrected according to the temperature. Hereinafter, the derivation process of (Equation 1) will be described in more detail.

2 is a view showing the structure of a sensor strip according to an embodiment of the present invention. Referring to FIG. 2 , the sensor strip 120 according to the present embodiment includes a lower insulating substrate 210 , a working electrode 220 , a reference electrode 230 , a film 240 , a measurement reagent 250 , and a hydrophilic film. (260).

The lower insulating substrate 210 may be a glass or inorganic material substrate, a plastic substrate or a film, and according to an embodiment, polyethylene terephthalate (PET), a polycarbonate film, or the like may be used. A pair of electrodes formed on the lower insulating substrate 210 , that is, the working electrode 220 and the reference electrode 230 are spaced apart from each other by a predetermined distance and disposed on the lower insulating substrate 210 . The working electrode 220 and the reference electrode 230 may be formed of gold or silver as a raw material, or may be formed by printing with carbon ink, thereby reducing the manufacturing cost of the product. The working electrode 220 and the reference electrode 230 may be formed by applying a conductive material on the lower insulating substrate 210 and then laser patterning or masking the shape of the electrode. On the lower insulating substrate 210 , in addition to the working electrode 220 and the reference electrode 230 , a blood recognition electrode for detecting an inflow of a sample, for example, blood may be further formed.

The film 240 covers the upper surface of the lower insulating substrate 210 on which the working electrode 220 and the reference electrode 230 are formed. The film 240 is also called a spacer. The film 240 may be formed by applying an insulating ink to a predetermined thickness on the upper surface of the lower insulating substrate 210 on which the working electrode 220 and the reference electrode 230 are formed, but is not limited thereto. . The film 240 may be another insulating substrate made of the same material as the lower insulating substrate 210 . In the film 240 , a slit is formed in a portion facing the working electrode 220 and the reference electrode 230 , and a portion of the working electrode 220 and the reference electrode 230 is formed through the slit. exposed A measurement reagent 250 is positioned in the slit of the film 240 . The measurement reagent 250 is positioned across the working electrode 220 and the reference electrode 230 exposed through the slit.

In the measurement reagent 250, enzymes such as GOX and GOD, which will react directly with blood sugar, and surfactants such as Triton X-100 and Tween-20, which help the enzyme solution spread evenly on the electrode, and enzyme activity Bovine serum albumin, which acts as a stabilizer to help maintain blood sugar, may be included. In addition, a polymer such as polyvinylpipolydone, polyvinyl alcohol, or arginine may be included, which serves as a mediator, one of a ferricyanide-based compound and a ruthenium-based compound, and helps to stabilize the enzyme and disperse the solution composition material.

The hydrophilic film 260 is placed on the film 240 so that a sample such as blood flows through the slit well by capillary action. Meanwhile, although not shown in FIG. 2 , an upper insulating substrate is placed on the hydrophilic film 260 .

[Table 1] below shows the ideal current (ie, reference current) of the sensor strip 120 for each blood glucose concentration at an appropriate temperature (22.4° C.), and the sensor strip 120 for each blood glucose concentration at 11.7° C., 22.4° C. and 38.1° C., respectively. indicates the actual measured current (ie, the measured current). Each measurement current in [Table 1] is an average of 10 measurements for each temperature condition and each sample condition combination.

division reference current measuring current of the specimen
blood sugar concentration
(mg/dL) Temperature (℃) 22.4 11.7 22.4 38.1 Current (も) 8.0 7.4 7.8 8.6 58 13.0 12.3 13.2 14.8 159 20.7 18.8 21.0 24.0 315 29.6 25.9 29.4 32.9 496 slope 0.850 1.000 1.126 Y-intercept 0.92 0.00 -0.02

In Table 1, 22.4° C. is an appropriate temperature desired by the manufacturer of the sensor strip 120 . And the blood sugar concentration of the sample is the exact blood sugar concentration confirmed by the reference equipment. In [Table 1], the reference current can be obtained in the following way. That is, the relational expression between the blood glucose concentration and the current is calculated using the measured currents obtained from each sample having a blood glucose concentration of 58 mg/dL, 159 mg/dL, 315 mg/dL, and 496 mg/dL at 22.4°C. The relational expression is the expression of the trend line and is expressed as a linear equation as shown below (Equation 2-1). After replacing the measured current of (Equation 2-1) with the reference current, and rearranging the equation based on the reference current, it is derived as shown in (Equation 2-2). When each blood glucose concentration of 58 mg/dL, 159 mg/dL, 315 mg/dL, and 496 mg/dL is substituted into (Equation 2-2), the reference current of [Table 1] is obtained.

(Equation 2-1)

Blood glucose concentration = (measured current - 5.2) / 0.0493

(Equation 2-2)

Reference current = blood glucose concentration × 0.0493 + 5.2

If the measured current of the sensor strip 120 is always the same as the measured current at an appropriate temperature regardless of the temperature for a sample with a constant blood glucose concentration, that is, the measured current of the sensor strip 120 is measured at 22.4° C. regardless of the temperature. If it is the same as the current, the blood glucose concentration may be calculated by the above (Equation 2-1) regardless of the temperature. However, as shown in [Table 1], the measured current of the sensor strip 120 varies according to the temperature for a sample having the same blood glucose concentration. Therefore, it is necessary to correct the measurement current that changes according to the temperature as the reference current as much as possible. After correcting the measured current, by substituting the corrected measured current into (Equation 2-1) above, the blood glucose concentration can be obtained.

In order to correct the measured current, the relationship between the measured current and the reference current should be derived from [Table 1]. In the relationship between the measurement current and the reference current, the measurement current corresponds to the measurement current before correction, and the reference current corresponds to the measurement current after correction. Therefore, the relationship between the measurement current and the reference current becomes the relationship between the measurement current before correction and the measurement current after correction. The relationship factor between the measured current and the reference current is the slope and the Y-intercept in [Table 1]. If the measured current is a different value from the reference current but is constant depending on the temperature, the slope and the Y-intercept will all be the same at all temperatures except 22.4℃ in [Table 1]. In this case, the relationship between the measured current before correction and the measured current after correction can be expressed as follows (Equation 3-1) when the reference current is the X axis and the measured current is the Y axis, and the measured current after correction is If (Equation 3-1) is arranged as a reference, it can be expressed as the following (Equation 3-2).

(Equation 3-1)

Measured current before calibration = Measured current after calibration × S + I

where S is the slope and I is the Y-intercept.

(Equation 3-2)

Measured current after calibration = (Measured current before calibration-I)/S

However, as shown in [Table 1], the measured current varies with temperature. Therefore, the slope (S) and the Y-intercept value (I) in (Equation 3-2) are not fixed values, but are values that change according to temperature. It is necessary to find the relational expression for the change according to the temperature of the slope (S) and the Y-intercept value (I) and substitute it into the above (Equation 3-2).

In [Table 1], the slope is the slope of the relational expression between the reference current and the measured current. As described above, the slope is the slope when the reference current is the value of the X-axis and the measured current is the value of the Y-axis, and the intercept value of the Y-axis is the Y-intercept value of the relation. Here, the relational expression is the expression of the trend line. Specifically, reference currents (8.0, 13.0, 20.7, 29.6) for each blood glucose concentration sample at an appropriate temperature of 22.4°C, and actually measured currents (7.4) for each blood glucose concentration sample at 11.7°C , 12.3, 18.8, 25.9) has a slope of 0.850 and a Y-intercept value of 0.92. In addition, reference currents (8.0, 13.0, 20.7, 29.6) for each blood glucose concentration sample at an appropriate temperature of 22.4°C, and measured currents (7.8, 13.2, 21.0, 29.4), the slope of the relation between them is 1.000 and the Y-intercept value is 0.00. Since the reference current was calculated from the measured currents actually measured at 22.4°C, the slope is 1 and the Y-intercept value is 0. In addition, reference currents (8.0, 13.0, 20.7, 29.6) for each blood glucose concentration sample at an appropriate temperature of 22.4°C, and actually measured currents for each blood glucose concentration sample at 38.1°C (8.6, 14.8, 24.0, 32.9), the slope of the relationship is 1.126 and the Y-intercept value is -0.02.

As shown in [Table 1], since the measured current differs depending on the temperature for a sample with the same blood glucose concentration, the slope and Y-intercept value of the measured current for each temperature with respect to the reference current also differ depending on the temperature. [Table 2] shows only the slope and Y-intercept for each temperature.

Temperature (℃) slope Y-intercept 11.7 0.850 0.92 22.4 1.000 0.00 38.1 1.126 -0.02

If obtained by generalizing the relational expression between temperature and slope in [Table 2], it is as follows (Equation 4). This relational expression is the expression of a trend line.

(Equation 4)

slope = temperature × A + B

이며, A를 구성하는 각 변수는 다음과 같다.Here, A is the slope of the trend line as a value indicating the degree of change of the slope according to the temperature, and preferably

and each variable composing A is as follows.

a : slope of [Table 2],

a': the average of the slopes of [Table 2],

b: temperature corresponding to a in [Table 2],

b': Average of the temperatures in [Table 2].

And, B is the Y-axis intercept of the trend line, or it can be set empirically or experimentally.

In addition, when obtained by generalizing the relational expression between temperature and Y-intercept in [Table 2], it is as follows (Equation 5). This relational expression is the expression of a trend line.

(Equation 5)

Y-intercept = temperature × C + D

이고, C를 구성하는 각 변수는 다음과 같다. Here, C is the slope of the trend line as a value indicating the degree of change in the Y-intercept according to the temperature, preferably

and each variable composing C is as follows.

c : Y-intercept value of [Table 2],

c': Average of Y-intercept values in [Table 2].

d: temperature corresponding to c in [Table 2],

d': Average of the temperatures in [Table 2].

And, D may be the Y-axis intercept of the trend line or may be set empirically or experimentally.

By substituting (Equation 4) and (Equation 5) obtained in this way into (Equation 3-2), the above (Equation 1), which is a correction equation of the measured current, is derived. Specifically, when each variable of (Equation 4) and (Equation 5) is obtained from [Table 2] and substituted in (Equation 1) above, a specific correction relational expression of the measured current is as follows.

(Relational expression for measurement current)

Measured current after calibration = {Measured current before calibration - (Temperature×-0.033 + 1.10)}/(Temperature×0.010 + 0.74)

After correcting the measured current at each temperature in [Table 1] through the correction relational expression of the measured current, and substituting the measured current after correction into the measured current of (Equation 2-1), the corrected blood glucose concentration is obtained can do. Comparing the blood glucose concentration after correction obtained in this way and the blood glucose concentration before correction obtained by substituting the measured current before correction at each temperature in [Table 1] into (Equation 2-1), the following [Table 3] same as

division Blood sugar concentration after calibration Blood glucose concentration before calibration of the specimen
blood sugar concentration Temperature (℃) 11.7 22.4 38.1 11.7 22.4 38.1 blood sugar
(mg/dL) 51 50 53 45 53 70 58 165 162 165 144 162 196 159 315 322 329 277 321 381 315 478 495 489 419 492 563 496

As shown in [Table 3], when the blood glucose concentration is calculated using the measurement current as it is without correcting it, the blood glucose concentration is obtained differently depending on the temperature for a sample having the same blood glucose concentration. On the other hand, if the measurement current is corrected according to an embodiment of the present invention and the blood glucose concentration is calculated using the measurement current after correction, the blood glucose concentration within a certain range is obtained without significantly changing the blood glucose concentration depending on the temperature for a sample having the same blood glucose concentration. As a result, the difference with the blood glucose concentration of the actual sample is not large.

Hereinafter, the results of the conventional % correction method and the correction method according to the present invention are compared.

The conventional % correction method using the blood glucose concentration before correction in [Table 3] is described as follows. In the blood glucose concentration of each sample, the temperature is set as the X-axis and the measured blood glucose concentration is set as the Y-axis, and the relationship is analyzed to obtain a slope. To summarize, the following [Table 4] shows.

Temperature (℃) 11.7 22.4 38.1 Slope (S) factor of the specimen
blood sugar concentration blood sugar readings
(mg/dL) 45 53 70 0.949 1.6% 58 144 162 196 1.965 1.2% 159 277 321 381 3.952 1.3% 315 419 492 563 5.359 1.1% 496 AVE 1.3%

Here, the slope (S) is the effect of a 1°C change in temperature in the blood sugar concentration of each sample on the measured blood sugar concentration. Next, after dividing each slope (S) by the blood glucose concentration of the corresponding sample, it is multiplied by 100 to convert all of them into a % factor. For example, when the slope (S) of 0.949 of the blood glucose measurement values for each temperature measured with respect to the blood glucose concentration 58 of the sample is divided by the blood glucose concentration 58 of the sample and multiplied by 100, 1.6% is obtained. Finally, the average of the four % factors calculated from the blood glucose concentrations of the four samples obtained in this way is obtained. This value is 1.3%. Using the average of this % factor, a correction equation for the blood glucose concentration according to the prior art is obtained as follows.

(Correction equation for blood glucose concentration according to the prior art)

Blood sugar concentration after calibration = ((22.4 - temperature)×0.013× blood sugar concentration before calibration) + blood sugar concentration before calibration

When the blood sugar concentration according to the temperature of each sample in [Table 4] is corrected using the blood sugar concentration correction equation according to the prior art, the following [Table 5] is shown.

Temperature (℃) 11.7 22.4 38.1 blood sugar readings
(mg/dL) 55 54 49 177 164 137 339 325 266 514 498 393

FIG. 3 is a graph showing the blood glucose concentrations measured at each temperature before correction of Table 4 in comparison with the blood glucose concentration values measured at 22.4° C., which is an appropriate temperature. 4 is a graph showing the measured blood sugar concentrations for each temperature corrected according to the present invention in Table 3, compared to the blood sugar concentration values measured at 22.4° C., which is an appropriate temperature. 5 is a graph showing the measured blood sugar concentrations for each temperature corrected by applying the % correction method of Table 5 in comparison with the blood sugar concentration values measured at an appropriate temperature of 22.4°C. As generally used in the blood glucose system in FIGS. 3 to 5 , a blood glucose concentration bias of 100 mg/dL or less is expressed in mg/dL, and a blood glucose concentration bias of 100 mg/dL or more is expressed in %.

First, referring to FIG. 3 , if there is no correction at all when measuring the blood glucose concentration, the measured value of the blood glucose concentration greatly differs depending on the temperature for a sample having the same blood glucose concentration. The error range according to temperature is up to 20.6% of the measured value at the appropriate temperature. On the other hand, referring to FIG. 4 , when the blood sugar concentration is corrected according to the present invention, there is no significant difference in the measured blood sugar concentration according to the temperature for a sample having the same blood sugar concentration. The maximum error range is within 4% of the measured value at an appropriate temperature. Referring to FIG. 5 , when % correction is performed according to the prior art, the range of change in the measured blood glucose concentration according to temperature is smaller than when there is no correction as shown in FIG. occurs more There is an error of up to 9% compared to the measured value at the proper temperature.

6 is a flowchart illustrating a method of measuring a blood glucose concentration in a blood glucose measurement apparatus according to an embodiment of the present invention.

Referring to FIG. 6 , in step S601 , the blood glucose measurement apparatus performs a first method defining a relationship between a reference current for each blood glucose concentration at a reference temperature and a measurement current for each blood glucose concentration at a plurality of temperatures of the sensor strip 120 . A third relation value and a fourth relation value defining a change according to temperature, respectively, of the relation value and the second relation value are stored in the memory. That is, in the memory, a third relation value and a fourth relation value defining a change according to temperature of the first relation value, and a third relation value and a fourth relation value defining a change according to temperature of the second relation value The value is saved.

In step S602 , the blood glucose measurement device receives a measurement current according to the reaction between the sample and the reagent through the sensor strip 120 . That is, a sample such as blood may be input to the sensor strip 120 , and a voltage may be applied to the sensor strip 120 to receive a measurement current output from the sensor strip 120 .

In step S603 , the blood glucose measurement apparatus measures the current temperature through the temperature sensor 110 . In step S604, the blood glucose measurement apparatus uses the measured temperature and the third and fourth relation values of the first and second relation values stored in the memory, respectively, to obtain the sensor strip ( 120), correct the measured current output. For the correction of the measured current, the correction relation may be as follows.

Measured current after calibration = {Measured current before calibration - (Temperature×-0.033 + 1.10)}/(Temperature×0.010 + 0.74)

In step S605, the blood glucose measurement apparatus calculates the blood glucose concentration using the corrected measurement current. The blood glucose concentration can be calculated using the above (Equation 2-1). The corrected measurement current is substituted for the measurement current of (Equation 2-1) above. The blood glucose measurement device outputs the calculated value of the blood glucose concentration. For example, the blood sugar concentration value may be output using an LED or the like, or the blood sugar concentration value may be output as a digital value through a display means.

In the above embodiments, when the relationship between the measured current before correction and the measured current after correction is obtained, it is expressed as (Equation 3-1) and (Equation 3-2). And in [Table 1], with the reference current as the X-axis and the measured current as the Y-axis, the slope and Y-intercept are obtained for each temperature, and then the change relational expression of the slope and Y-intercept according to the temperature is obtained (Equation 3 - 2) was substituted. However, it is not limited thereto,

Measured current after calibration = Measured current before calibration × S + I,

In [Table 1], with the measured current as the X-axis and the reference current as the Y-axis, the slope and Y-intercept value for each temperature are obtained, and then the change relational expression of the slope and Y-intercept value according to the temperature is obtained. By substituting the obtained formula, the final correction relation of the measured current can be derived.

While this specification contains many features, such features should not be construed as limiting the scope of the invention or the claims. Also, features described in individual embodiments herein may be implemented in combination in a single embodiment. Conversely, various features described herein in a single embodiment may be implemented in various embodiments individually, or may be implemented in appropriate combination.

Although acts are described in the drawings in a specific order, it should not be understood that the acts are performed in the specific order as shown, or that all of the described acts are performed in a continuous order, or to obtain a desired result. . Multitasking and parallel processing can be advantageous in certain circumstances. In addition, it should be understood that the division of various system components in the above-described embodiments does not require such division in all embodiments. The program components and systems described above may generally be implemented as a package in a single software product or multiple software products.

The method of the present invention as described above may be implemented as a program and stored in a computer-readable form in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.). Since this process can be easily performed by a person skilled in the art to which the present invention pertains, it will not be described in detail any longer.

The present invention described above, for those of ordinary skill in the art to which the present invention pertains, various substitutions, modifications, and changes are possible within the scope without departing from the technical spirit of the present invention. It is not limited by the drawings.

110: temperature sensor
120: sensor strip
130: connector
140: analysis device
210: lower insulating substrate
220: working electrode
230: reference electrode
240: film
250: reagent
260: hydrophilic film

Claims (7)

A blood glucose measurement device for measuring a blood glucose concentration in blood, comprising:
a sensor strip for outputting a measurement current in response to the blood;
an analysis device including a memory for storing the third relation value and the fourth relation value; and
a temperature sensor for measuring the temperature;
The analysis device is
Using the temperature measured by the temperature sensor and the third and fourth relation values stored in the memory, the measured current output from the sensor strip is corrected, and the blood glucose concentration is calculated using the corrected measured current. calculate,
The third relation value and the fourth relation value are
Included in the relational expression defining the change according to the temperature of each of the first relational value and the second relational value,
The first relation value and the second relation value are
A blood glucose measurement apparatus included in a relational expression defining a relationship between a reference current for each blood glucose concentration at a reference temperature and a current measured for each blood glucose concentration of the sensor strip at a plurality of temperatures. The method of claim 1,
The first relation value is a slope indicating the relation when the reference current is an X-axis value and the measured current is a Y-axis value,
and the second relation value is a Y-intercept value indicating the relation when the reference current is an X-axis value and the measured current is a Y-axis value. 3. The method of claim 2,
The third relation value is a slope indicating the relation when the temperature is the value of the X axis, the first relation value or the second relation value is the value of the Y axis,
and the fourth relation value is a Y-intercept value representing the relation when temperature is an X-axis value and the first relational value or the second relational value is a Y-axis value. 4. The method of claim 3,
The blood glucose measurement apparatus, wherein the analysis apparatus calculates the corrected measurement current according to the following equation.
(Equation)
Calibrated measuring current = (Measuring current before calibration - (Temperature×C+D))/(Temperature×A+B)
here,
A is a third relation value of the first relation value,
B is a fourth relation value of the first relation value,
C is a third relation value of the second relation value,
D is a fourth relation value of the second relation value. The method of claim 1,
The first relation value is a slope indicating the relation when the measured current is the value of the X-axis and the reference current is the value of the Y-axis,
and the second relation value is a Y-intercept value representing the relation when the measured current is an X-axis value and the reference current is a Y-axis value. 6. The method of claim 5,
The third relation value is a slope indicating the relation when the temperature is the value of the X axis, the first relation value or the second relation value is the value of the Y axis,
and the fourth relation value is a Y-intercept value representing the relation when temperature is an X-axis value and the first relational value or the second relational value is a Y-axis value. A method for measuring a blood glucose concentration in blood in a blood glucose measurement device, the method comprising:
storing the third relation value and the fourth relation value;
receiving a measurement current output from a sensor strip by reaction of a reagent with blood;
measuring the temperature;
correcting the measured current by using the measured temperature, the third relation value, and the fourth relation value; and
Comprising the step of calculating the blood glucose concentration using the corrected measurement current,
The third relation value and the fourth relation value are
Included in the relational expression defining the change according to the temperature of each of the first relational value and the second relational value,
The first relation value and the second relation value are
A method included in a relational expression defining a relationship between a reference current for each blood glucose concentration at a reference temperature and a current measured for each blood glucose concentration of the sensor strip at a plurality of temperatures.

Images