JP2003156469A - Biosensor, measuring device for biosensor and quantitative determination method of substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a quantitative determination method for reducing a measurement error generated by a biosensor for quantitatively determining substrate included in a sample liquid. SOLUTION: This measuring device has a support part for supporting detachably this biosensor constituted by forming at least a pair of electrode on an insulating substrate, a plurality of connection terminals to be connected electrically to each electrode, and a driving power source for applying a voltage to each electrode through the connection terminals. The biosensor has an electrode structure wherein, when inserted into the measuring device, either of the electrodes of the biosensor is connected to a first connection terminal and a second connection terminal provided on the measuring device only when the biosensor is inserted into the support part of the measuring device in a prescribed direction, and conduction is established between the first connection terminal and the second connection terminal by applying a voltage by the driving power source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biosensor for quantifying a substrate contained in a sample solution and a measuring device for this biosensor, and more particularly to a novel sensor for reducing measurement error by the biosensor. It also provides various quantitative methods.

[0002]

2. Description of the Related Art A biosensor is a quantification of a substrate content in a sample solution, which utilizes the molecular recognition ability of biological materials such as microorganisms, enzymes, antibodies, DNA, RNA, etc. It is a sensor that That is, the substrate contained in the sample solution is quantified by utilizing the reaction that occurs when the biological material recognizes the target substrate, such as oxygen consumption due to the respiration of microorganisms, enzyme reaction, luminescence and the like.
Among various biosensors, enzyme sensors are being put to practical use. For example, enzyme sensors, which are biosensors for glucose, lactic acid, cholesterol, and amino acids, are used in medical measurement and the food industry. This enzyme sensor
For example, an electron carrier is reduced by electrons generated by the reaction between a substrate contained in a sample solution as a sample and an enzyme,
The measuring device electrochemically measures the reduced amount of the electron carrier to quantitatively analyze the sample.

Various types of biosensors have been proposed. Therefore, the biosensor Z which is a conventional biosensor will be described below. FIG.
(A) is an exploded perspective view of the biosensor Z,
FIG. 6B is a diagram showing the configuration of the electrode portion formed at the tip of the biosensor Z. Regarding the method for quantifying the substrate of the sample liquid in the biosensor Z configured as described above
(B) Description will be given with reference to the figure.

First, the biosensor Z is inserted into a measuring device, and the measuring device measures the counter electrode 1103a and the measuring electrode 1.
The sample solution is supplied to the inlet 1106b of the sample supply path while a constant voltage is applied between 103b. The sample liquid is sucked into the sample supply path by the capillary phenomenon, and its inlet 11
It passes on the counter electrode 1103a closer to 06b, reaches the measurement electrode 1103b, and the dissolution of the reagent layer 1105 starts. At this time, the measuring device uses the counter electrode 1103a and the measuring electrode 110.
The electrical change occurring between 3b is detected, and the quantitative operation is started. In this way, the substrate content of the sample solution is quantified.

Specifically, the oxidoreductase and the electron acceptor supported on the reagent layer are dissolved in the sample solution, and the enzyme reaction proceeds with the substrate in the sample solution to reduce the electron acceptor. .
After completion of the reaction, the reduced electron acceptor is electrochemically oxidized, and the concentration of the substrate in the sample solution is measured from the oxidation current value obtained at this time.

[0006]

However, the conventional biosensor Z has a problem to be solved.
In particular, when detecting an electrical change in the reagent layer 1105, there is a problem that various factors affect the measurement accuracy and sensitivity of the measurement device.

First, it is caused by an erroneous operation by the user. For example, after the user once supplies the sample solution to the sample supply path, before the quantification by the measuring device is completed, the sample solution is further supplemented and supplied, and re-quantification using an already used biosensor is tried, There has been a demand for a means capable of avoiding a user's operation error that affects measurement accuracy, such as supplying a sample solution to a wrong place or inserting a biosensor into a measuring device in a wrong direction. In particular, a means that can avoid an erroneous operation by an elderly user is desirable.

Secondly, it is due to the characteristics of the measuring object. For example, when a glucose concentration in blood taken from a human body is quantified using a biosensor, the viscosity of blood may affect the measurement accuracy. Generally, hematocrit is known as an index of blood viscosity. Hematocrit is the percentage of the volume of red blood cells in blood (%). Generally, in people without anemia, blood has a water content of 50-6.
Red blood cells account for 40-50% at 0%. When the patient has chronic renal failure and renal anemia, hematocrit is lowered, and it may fall below 15%. Therefore, in order to carry out an appropriate therapeutic treatment, it is necessary to suppress the influence of hematocrit in blood and accurately measure the glucose concentration in blood, for example, in a diabetic patient.

Thirdly, it is caused by the influence of environmental temperature on the measurement. The measuring devices for biosensors that are currently in widespread use are becoming smaller so that users can carry them.
Therefore, the measurement may be started before the temperature inside the measuring device is stabilized, such as when the user tries to measure immediately after moving from the outdoors to the indoor. The oxidation current value corresponding to the substrate concentration may be affected by a rapid temperature change, resulting in poor measurement accuracy. Further, there is a concern that the body temperature of the user's own hand or the like is transmitted to the measuring device, and the temperature change due to the body temperature affects the measurement accuracy.

In view of the above, it is an object of the present invention to provide a biosensor which is easy for a user to operate and has good measurement accuracy, a quantification method and a measurement device using the biosensor.

[0011]

In order to solve the above-mentioned problems, according to a first aspect of the present invention, a support portion for detachably supporting a biosensor having at least a pair of electrodes formed on an insulating substrate. And a substrate contained in the sample liquid, which is inserted into a measuring device having a plurality of connection terminals electrically connected to each of the electrodes and a drive power source for applying a voltage to each of the electrodes via the connection terminals. A biosensor for quantifying, wherein any one of the electrodes of the biosensor is provided in the measuring device only when the biosensor is inserted into a supporting portion of the measuring device in a predetermined direction. An electrode structure that is electrically connected between the first connection terminal and the second connection terminal by being connected to the first connection terminal and the second connection terminal and being applied with a voltage by the driving power supply is provided. I have It has become.

A conductive layer is formed on at least a part of the insulating substrate, and the conductive layer is divided by slits to form the counter electrode and the measurement electrode, and further, if necessary, a detection electrode. You may be allowed to.

Further, according to the second aspect of the present invention, a biosensor having at least a pair of electrodes formed on an insulating substrate is detachably supported, and the biosensor is electrically connected to each of the electrodes. A biosensor measuring device for quantifying a substrate contained in a sample solution supplied to the biosensor, which has a plurality of connection terminals and a driving power supply that applies a voltage to each of the electrodes via the connection terminals. In the measuring device, the first connection terminal and the second connection terminal are connected to any one of the electrodes of the biosensor only when the biosensor is inserted into the support portion in a predetermined direction. And a first connection terminal and a second connection terminal according to the drive power source.
A voltage is applied to each of the connection terminals to detect whether or not the first connection terminal and the second connection terminal are electrically connected.

The measuring device may determine that the biosensor is not inserted in a predetermined direction when the conduction between the first connection terminal and the second connection terminal is not detected.

The measuring device may further include an output unit for outputting the determination result to the outside when it is determined that the biosensor is not inserted in the predetermined direction.

According to the third aspect of the present invention, the counter electrode formed on at least a part of the insulating substrate, the electrode portion including the measurement electrode and the detection electrode, and the sample for supplying the sample liquid to the electrode portion. A support part that detachably supports a biosensor having a supply path and a reagent layer that reacts with a sample solution supplied through the sample supply path, a connection terminal for applying a voltage to the electrode part, and a drive A method for quantifying a substrate for quantifying a substrate contained in the sample solution, which is inserted into a measuring device having a power source, wherein the biosensor is inserted into a supporting portion of the measuring device, A voltage is applied by the drive power source to each of the first set of electrodes and the measurement electrode, and the second set of the measurement electrode or counter electrode and the detection electrode.

In the biosensor, a detection electrode among the counter electrode, the measurement electrode and the detection electrode is formed on the most downstream side along the sample supply path in the direction of the sample flow from the sample supply port. Whether or not a sufficient amount of the sample solution necessary for measurement is supplied is determined by whether or not the currents output from the first set and the second set of the electrode sections each exceed a predetermined threshold value. You may make it discriminate.

If the current from the second set does not exceed the predetermined threshold value within a predetermined elapsed time after the current from the first set exceeds the predetermined threshold value, the sample solution May be determined to be insufficient.

When it is determined that the sample liquid is insufficient,
The fact may be output from the measuring device to the outside.

If the current from the second set does not exceed the predetermined threshold within a predetermined elapsed time after the current from the first set exceeds the predetermined threshold, the measurer However, the measurement step may be temporarily suspended again for the work of additionally supplying the sample liquid.

In the sample supply path of the present biosensor, a detection electrode of the counter electrode, the measurement electrode and the detection electrode is formed on the most downstream side in the direction of the sample flow from the sample supply port, and the detection is performed. An exhaust port for promoting the flow of the sample liquid is provided on the downstream side of the electrode,
The current from the first set exceeds the predetermined threshold value before the first set, and the current from the first set within the predetermined elapsed time has a predetermined threshold value. When it does not exceed, it may be determined that the sample liquid is erroneously sucked from the exhaust port.

According to the elapsed time from the detection of the current from the first set exceeding a predetermined threshold to the time the current from the second set exceeds the predetermined threshold, You may make it correct | amend the quantitative value of the board | substrate corresponding to the electric current detected by the said electrode part.

The measuring device further comprises a storage unit for storing calibration data indicating the correspondence between the current detected by the biosensor and the content of the substrate contained in the sample solution,
The quantitative value of the substrate corresponding to the detected current may be determined by referring to the calibration data stored in the storage unit.

When the reaction of the sample solution with the reagent layer is incubated for a certain period of time after the sample solution is supplied to the sample supply path and the substrate is quantified, the current from the first set is set to a predetermined threshold value. The culture time may be changed according to the elapsed time from the detection of exceeding the value until the current from the second set exceeds a predetermined threshold value.

In either the first group or the second group, the voltage application destination may be switched at regular intervals.

According to a fourth aspect of the present invention, there is provided a method for quantifying a substrate, comprising a biosensor having a reagent layer that specifically reacts with a substrate in a measurement sample, a measurement sample and a reagent in the reagent layer. And a measuring device for determining the amount of the substrate contained in the measuring sample from the reacted sample, wherein the measuring device measures the temperature at which the reaction between the measuring sample solution and the reagent layer proceeds. A temperature correction data storage unit having a plurality of measurement values and correction tables for measurement values, which are different for each temperature range, is provided, and the correction table corresponding to the temperature measured by the temperature measurement unit is selected to select the substrate. The correction value is calculated according to the measured value of, and the correction is performed.

The biosensor has an electrode portion including a counter electrode and a measurement electrode formed on at least a part of an insulating substrate, and the measuring device applies a voltage to the electrode portion, It may be a measuring device that detects the current output from the electrodes.

According to a fifth aspect of the present invention, there is provided a substrate quantification method for measuring a substrate contained in a sample solution supplied to a biosensor by a measuring device, wherein the measuring device is a temperature inside the device. A temperature measuring means for measuring the temperature, the temperature obtained prior to the measurement of the substrate, and the temperature at the time of quantification of the substrate, the temperature change is detected, and the substrate is measured based on the temperature change. It is designed to determine whether or not to do.

A temperature change between the temperature obtained prior to the measurement of the substrate and the temperature during the measurement of the substrate is detected, and when the temperature change exceeds a predetermined threshold value, the measurement of the substrate is stopped. You may do it.

The temperature measurement prior to the substrate measurement may be performed intermittently.

According to the sixth aspect of the present invention, a counter electrode formed on at least a part of an insulating substrate, an electrode portion including a measurement electrode, and a reagent layer which reacts with a sample solution supplied to the electrode portion. And a measuring device having a supporting portion that detachably supports the biosensor and a connecting terminal and a driving power source for applying a voltage to each electrode of the electrode portion, and the measuring device having the driving power source A method for quantifying a substrate for quantifying a substrate contained in the sample solution by detecting a current output by applying a voltage to an electrode part, wherein the measuring device is supported by the supporting part. The first potential is applied to the electrode portion of the biosensor for a first period, and the first potential is applied to the electrode portion after applying the first potential to the electrode portion in the first period. Stop during the waiting period, After the machine period has elapsed, the substrate is quantified by applying a second potential to the electrode portion for a second period and measuring the output current, and the first potential is larger than the second potential. Has become.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a biosensor system 1 according to an embodiment of the present invention. The biosensor system 1
It has a biosensor 30 and a measuring device 10 to which the biosensor 30 is detachably attached. The amount of the substrate contained in the sample spotted on the sample spotting portion 30a located at the tip of the biosensor 30 is quantified by the measuring device 10.

The measuring device 10 is, for example, a biosensor 3
It has a support part 2 to which 0 is detachably mounted, and a display part 11 for displaying the quantitative result of the substrate contained in the sample solution spotted on the sample spotting part 30a of the biosensor 30.

In order to quantify the substrate content in the sample solution using the present biosensor system 1, the user first inserts the biosensor 30 into the measuring device 10, and then the measuring device is attached to the electrodes of the biosensor 30 described later. The sample solution is supplied to the sample spotting section 30a while a constant voltage is applied by 10. The spotted sample solution is sucked into the biosensor 30 and the dissolution of the reagent layer starts. The measuring device 10 is adapted to detect an electrical change occurring between the electrodes of the biosensor 30 and start a quantitative operation.

Here, in the biosensor system 1 according to the present embodiment, in particular, the blood of the human body is used as the sample liquid, and glucose, lactic acid contained in the blood as the substrate,
It is suitable for quantifying the content of cholesterol.
The quantification of a substrate contained in a human body fluid is very important in the diagnosis and treatment of specific physiological abnormalities. Especially for diabetic patients, it is necessary to frequently grasp the glucose concentration in blood.

Although the following description discloses the quantification of glucose contained in human blood, the biosensor system 1 according to the present embodiment is provided with lactate, cholesterol, etc. by selecting an appropriate enzyme. It is also possible to quantify the substrate.

Next, members constituting the biosensor 30 will be described with reference to FIG. Figure 2 shows biosensor 3
It is an exploded perspective view of 0. Reference numeral 31 denotes an insulating substrate made of polyethylene terephthalate or the like (hereinafter, simply referred to as “substrate”). The surface of the substrate 31 is made of, for example, a noble metal such as gold or palladium, or an electrically conductive substance such as carbon. The conductive layer is formed by a screen printing method or a sputtering vapor deposition method. The conductive layer may be formed on the entire surface of the substrate 31 or at least a part thereof. Reference numeral 32 denotes an insulative substrate having an air hole 33 provided in the center thereof, and a spacer 34 having a cutout is sandwiched between the substrate 31 and the substrate 32, and the substrate 32 is arranged integrally with the substrate 31.

On the substrate 31, a conductive layer is divided by a plurality of slits to form a counter electrode 37, a measuring electrode 38 and a detecting electrode 39. Specifically, the substantially arc-shaped slit 40 formed on the counter electrode 37, 41a and 41c formed vertically on the side surface of the substrate 31, and the slits 41b, 41d and 41f formed in the direction parallel to the substrate 31.
Further, the conductive layer is divided by the slit 41e having a V-shape, and the counter electrode 37, the measurement electrode 38, and the detection electrode 39 are formed. In addition, each electrode is the substrate 3
It suffices that it is formed on at least a part of No. 1, and the measuring device 10 and each electrode may be connected by a lead wire.

The spacer 34 is a counter electrode 37 on the substrate 31,
The sample supply path 35 is formed by a rectangular notch provided in the center of the front edge of the spacer 34 so as to cover the measurement electrode 38 and the detection electrode 39. Also, 30
Reference numeral a denotes an inlet of the sample supply path, and the sample liquid spotted at the inlet 30a is sucked toward the air hole 33 in a substantially horizontal direction (arrow AR direction in FIG. 2) by a capillary phenomenon.

Reference numeral 36 denotes a counter electrode 37, a measurement electrode 38 and a detection electrode 39 which are exposed from the notch of the spacer 34,
It is a reagent layer formed by applying a reagent containing an enzyme, an electron acceptor, an amino acid, a sugar alcohol and the like.

Here, as the enzyme, glucose oxidase, lactate oxidase, cholesterol oxidase, cholesterol esterase, uricase,
Ascorbate oxidase, bilirubin oxidase, glucose dehydrogenase, lactate dehydrogenase, lactate dehydrogenase and the like can be used.

As the electron acceptor, potassium ferricyanide is preferable, but in addition to potassium ferricyanide, p
-Benzoquinone and its derivatives, phenazine metholsulfate, methylene blue, ferrocene and its derivatives and the like can be used.

In the case of the biosensor system 1 according to the present embodiment, in order to measure the glucose concentration in the blood of the human body, glucose oxidase as an oxidoreductase carried on the reagent layer 36 and potassium ferricyanide as an electron acceptor. Is used. The oxidoreductase and the electron acceptor are dissolved in the sample solution (blood taken from the human body in the case of the present embodiment) sucked into the sample supply path, and the enzyme reacts with glucose, which is the substrate in the sample solution. The reaction proceeds and the electron acceptor is reduced to produce a ferrocyanide (potassium ferrocyanide in the case of the present embodiment). After completion of the reaction, the reduced electron acceptor is electrochemically oxidized,
The glucose concentration in the sample solution is measured from the current obtained at this time. Such a series of reactions mainly proceeds in the area from the slit 40 to the detection electrode 39 via the slit 41e, and the counter electrode 37, the measurement electrode 38, and the detection electrode 39 read the current associated with the electrochemical change. Will be done.

Reference numeral 42 is an identification unit for identifying the difference in the output characteristics between the types of the biosensor 30 and each manufacturing lot by the measuring device 10. Counter electrode 37, detection electrode 39
By forming the combination of the slits 41g and 41h as shown in FIG. 2 in the portion corresponding to the identification portion 42 of FIG.
The measuring device 10 can electrically identify the difference in the output characteristics.

FIG. 3 shows a combination of the identification portions 42 of the biosensor 30 depending on whether or not the slits 41g and 41h are formed. In FIG. 3, seven types of combinations are shown as an example.

For example, FIG. 3A shows an identification unit 42 of the biosensor 30 when cholesterol is a quantitative target. In this case, the slits 41g and 41h are not provided. FIGS. 3B, 3C, and 3D show the identification unit 42 of the biosensor 30 when lactic acid is used as a quantitative target. Figure 3
In (b), the slit 41h is provided only in the counter electrode 37, and the correction portion 43 is formed. In FIG. 3C, the slit 41 g is provided only in the detection electrode 39, and the correction unit 4 is provided.
4 are formed. In FIG. 3D, the counter electrode 37 and the detection electrode 39 are provided with slits 41h and 41g, respectively, and correction portions 43 and 44 are formed. Furthermore, FIG.
(E), (f), and (g) are the identification parts 42 of the biosensor 30 when making glucose into a fixed_quantity | quantitative_assay object. Figure 3
In (e), the slit 41g is provided only on the detection electrode 39, and the slit 41d is formed only up to the slit 41g. Therefore, the correction unit 44 and the measurement electrode 38
And are integrally formed. In FIG.
In the state of (e), the slit 41h is further formed to form the correction portion 43. In FIG. 3 (g), the slit 41f is formed only up to the slit 41h in the state of FIG. 3 (f). Therefore, the correction units 43 and 44 and the measurement electrode 38
And are integrally formed.

By changing the pattern of the slits of the identification section 42 in this way, the area of the conductive portion with each electrode can be varied. Therefore, the output characteristics of the biosensor 30 (glucose, cholesterol,
Difference in lactate concentration) and manufacturing error due to manufacturing lot are identified by the measuring device 10, and data suitable for substrate concentration measurement,
It becomes possible to obtain an accurate measurement value by switching the control program. Since it is not necessary for the user to input the correction data using the correction chip or the like as in the conventional case, the trouble is eliminated and the operation error can be prevented. Note that although a biosensor having three electrodes is disclosed in this embodiment, the number of electrodes can be changed as appropriate in other cases as long as at least one pair of electrodes is included. Further, as the slit formation pattern, a pattern other than the pattern shown in FIG. 3 may be used.

Next, details of the configuration of the measuring apparatus 10 will be described. FIG. 4 shows the configurations of the biosensor 30 (top view) and the measuring device 10. In the biosensor 30,
Among the counter electrode 37, the measurement electrode 38, and the detection electrode 39, the detection electrode 39 is formed on the most downstream side along the sample supply path 35 in the direction in which the sample flows from the sample spotting portion 30a. In addition, the arrangement order of the counter electrode 37 and the measurement electrode 38 may be exchanged. Also, the slits 41c, 41e
By providing a predetermined distance between the measurement electrode 38 and the detection electrode 39 via the electrode, it is possible to determine whether the sample liquid has been reliably and sufficiently sucked due to the change in the electric current due to the electrical change of the substrate. It is designed to be determined.

Further, in the measuring device 10, 12, 1
3, 14, 15, 16, and 17 are areas A, B, C, and D in which the identification unit 42 of the biosensor 30 is divided into six.
It is a connector connected corresponding to each of E and F.
Areas A, B, C, D, E, F have slits 41d, f
And the slits 41g and 41h. Area A corresponds to measurement electrode 38, area C corresponds to detection electrode 39, and area E corresponds to counter electrode 37. Area B is formed integrally with area A, and areas D and F correspond to the correction units 43 and 44 in FIG. 3, respectively. Further, reference numerals 18, 19, 20, 21, 22 denote respective connectors 13, 14, 15, 16, 17 and ground (constant potential, and do not necessarily have to be “0”. The same applies hereinafter in the present specification. There is a switch provided between them. At this ground, the voltage applied to each electrode can be variably controlled. Each connector 13, 14,
15, 16, 17 are connected in parallel to the ground,
The required connectors are selected from the connectors 13 to 17 by on / off control of the switches 18 to 22 and used at the time of measurement.

Reference numeral 23 is a current / voltage conversion circuit connected to the connector 12 for converting a current flowing between the measurement electrode 38 and the other electrodes into a voltage and outputting the voltage. Reference numeral 24 is connected to the current / voltage conversion circuit 23 for a current / voltage conversion circuit. An A / D conversion circuit that converts the voltage value from the voltage conversion circuit 23 into a pulse, 25 controls the on / off of each switch, and the content of the substrate of the sample liquid based on the pulse from the A / D conversion circuit 24. CP to calculate
U and 11 are LCDs (liquid crystal display: output unit) that display the measured values calculated by the CPU 25. Also, 26,
Reference numeral 28 denotes a temperature measuring unit that measures the temperature inside the measuring device 10. One of the temperature measuring units 26 and 28 is connected to the ground, and the other is connected in parallel between the connector 12 and the current / voltage conversion circuit 23 via the switches 27 and 29.

In the measuring device 10 according to the present embodiment, the current value between the electrodes of the biosensor 30 is converted by the current / voltage conversion circuit 23 using the voltage value (mv). A change is detected. That is, the voltage value is an index indicating the magnitude of the current between the electrodes.

5 to 7 of the operation of the biosensor 30 and the measuring device 10 when the content of the substrate of the sample solution is quantified by the quantification method using the biosensor 30 according to the embodiment of the present invention. It demonstrates using.

First, it is determined whether or not the biosensor 30 has been securely inserted into the supporting portion 2 of the measuring device 10 (step S1). Specifically, it is determined whether or not the biosensor 30 is inserted by the switch (not shown) in the connector of FIG. When the biosensor 30 is inserted (step S1; Yes), conduction detection between areas A and B (measurement electrode 38) is then performed (step S2).
As shown in FIG. 3, the measurement electrode 38 has a slit 41h,
No slit is provided to insulate one electrode from each other like g. Since the connectors 12 and 13 are connected to the measurement electrodes 38 in the areas A and B, respectively, the biosensor 30 is oriented in a direction (predetermined direction) such that the conductive layer of the biosensor 30 is located in the normal direction. Measuring device 10
When it is inserted into the area AB, the area AB always comes into conduction.

Therefore, the switch 18 is controlled to be turned on,
By checking the presence / absence of conduction between the areas AB, it is possible to distinguish between the front and back of the biosensor 30. If conduction cannot be detected between the areas AB (step S2; No), it is recognized that the biosensor 30 has been inserted upside down, and the measurement process ends as a front-back discrimination error (step S).
3). When a front / back discrimination error is detected, it is preferable to warn the user by displaying an error on the display unit 11, sounding a warning sound from a speaker, or the like. As a result, it becomes possible to easily prevent the user from accidentally spotting blood on the biosensor 30 with the biosensor 30 being inserted upside down.

If conduction can be detected between areas AB (step S2; Yes), it is judged whether or not the voltage value detected between areas A and CE is greater than 5 (mv) (step S2; Yes). S4). The switch switching control is performed so that both the switches 19 and 21 are turned on, and the voltage value is detected between the area A and the areas C and E which are considered to be electrically integrated. It is determined whether or not the detected biosensor 30 has already been used. If the biosensor 30 has been used, the reagent layer 3
The reaction between 6 and glucose in blood has already progressed,
This is because the detected voltage value tends to increase.

When it is determined that the voltage value detected between the area A and the areas C and E is larger than 5 (mv) (step S4; Yes), it is recognized that the used biosensor 30 is inserted. Then, the measurement process ends as a used error (step S5). When a used error is detected, it is preferable to warn the user by displaying an error on the display unit 11, sounding a warning sound from a speaker, or the like. This makes it easy for the user to avoid accidentally spotting blood on the biosensor 30 with the used biosensor 30 inserted.

Next, when the voltage value detected between the area A and the areas C and E is determined to be 5 (mv) or less (step S4; No), the biosensor 30 inserted and detected in step S1. By identifying the slit pattern of the identification unit 42, the CPU 25 switches the data or program suitable for the output characteristic according to the identification result (steps S6 to 10). In the case of the present embodiment, the blood glucose level sensor for measuring the glucose concentration is shown in FIG.
In the above example, there are three types of slit patterns shown in FIGS. 3 (e), (f), and (g). Specifically, first, continuity detection between areas AD is performed (step S6). By performing switch switching control so that the switch 20 is turned on and performing conduction detection between the area A and the area D, the biosensor 30 corresponding to a blood glucose sensor, not a sensor for lactic acid or cholesterol. It becomes possible to determine whether or not

If the conduction between the areas AD is not confirmed (step S6: No), it is determined that the biosensor 30 for the blood glucose level sensor is not compatible and the display unit 11
The user is warned by, for example, an error display in step (1), sounding a warning sound from a speaker, etc., and the measurement process ends (step S7). As a result, it is possible to prevent the user from erroneously performing quantification and misleading the quantification result as the glucose concentration in advance.

If the conduction between the areas AD is confirmed (step S6: Yes), the conduction is detected between the areas AF (step S8). The switch switching control is performed so that the switch 22 is turned on, and the conduction detection is performed between the area A and the area F, so that the biosensor 30 corresponding to the blood glucose level sensor further depends on the manufacturing lot. It is possible to identify the difference in output characteristics. The data and programs that take into consideration the output characteristics of the manufacturing lot in advance are used by the user without using the correction chip.
Automatically switched by U25.

Therefore, not only the operability is improved, but also the measurement accuracy can be improved. If there is continuity detection between the area AF (step S8; Yes), the result record “I” is stored in the memory not shown as the type of the biosensor 30 is shown in FIG. 3 (g) (step S8).
9). When there is no continuity detection between the area AF (step S8; No), the type of the biosensor 30 is as shown in FIG.
Alternatively, the result record “II” is stored in the memory (not shown) assuming that it is FIG. 3F (step S10).

After the confirmation of the type of the biosensor 30 is completed, it is determined again whether the voltage value detected between the area A and the areas C and E is larger than 5 (mv) (step S11). . Switch switching control is performed so that both switches 19 and 21 are turned on, and area A and area C / E are
A current is detected between the measuring device 10 and
It is determined whether or not the sample solution has been spotted by the user before the preparation for quantitative determination is completed on the side. As a result, not only the use of the used biosensor 30 can be reliably avoided, but also the spotting of the sample liquid by the user before the preparation for the quantitative determination is completed on the measuring device 10 side can be detected.

When it is determined that the voltage value detected between the area A and the areas C and E is larger than 5 (mv) (step S11; Yes), the sample solution is spotted before the preparation for measurement is completed. It is determined that the measurement has been performed, and the measurement process ends as a spotting error (step S12). When a spotting error is detected, it is preferable to warn the user by an error display on the display unit 11, a warning sound emitted from a speaker, an LED display (not shown), and the like. As a result, it is possible to reliably avoid a user's operation error that affects measurement accuracy, and it is possible to maintain high measurement accuracy.

When it is determined that the voltage value detected between the area A and the areas C and E is 5 (mv) or less (step S11; No), the sample liquid is turned on by the user before preparation for quantitative determination is completed. It is determined that the wear has not been performed, and the user is notified by LED display or the like that the quantitative preparation is completed (step S13). When a used error is detected, it is preferable to notify the user not only by LED display but also by display on the display unit 11, sounding an alarm sound from a speaker, or the like. The user who confirms this notification collects blood as a sample liquid from his / her own human body, and
The blood collected on the sample spotting part 30a of the biosensor 30 inserted in the sample is spotted.

Next, it is judged whether or not a sufficient amount of the sample liquid has been sucked through the sample supply path from the sample spotting section 30a (steps S14 to 20). In the biosensor 30, the counter electrode 37, along the sample supply path 35, in the direction in which the sample flows from the sample spotting part 30a.
The measurement electrode 38 and the detection electrode 39 are formed, and the detection electrode 3
9 is formed on the most downstream side. Therefore, the counter electrode 37
And a set of the measurement electrode 38, the measurement electrode 38 and the detection electrode 3
9 is selected at regular intervals and a voltage is applied to each electrode of the selected group, thereby determining whether or not a sufficient amount of sample solution necessary for measurement has been supplied. . Whether or not the measurement is not started even though the sample solution has been injected into the sample supply path, or only the amount necessary and sufficient for the measurement, is detected only by identifying the change in the current between the measurement electrode 38 and the detection electrode 39 as in the conventional case. On the other hand, it was difficult to identify the cause of whether the measurement was not performed due to the insufficient injection amount of the sample liquid.

Specifically, the counter electrode 37 and the measuring electrode 3
In the case of the combination with 8, the switch 19 is turned off and the switch 21 is turned on so that a potential difference is generated between the areas AE. In the case of the set of the measurement electrode 38 and the detection electrode 39, the switch 19 is turned on and the switch 21 is turned off so that a potential difference is generated between the areas AC. In this way, turn on the switches 19 and 21, respectively.
By performing the off control, it is possible to easily select and switch either the set of the counter electrode 37 and the measurement electrode 38 or the set of the measurement electrode 38 and the detection electrode 39.
For convenience of explanation, in the following description, when a potential difference is generated in the pair of the counter electrode 37 and the measurement electrode 38, a potential difference is generated in the pair of the measurement electrode 38 and the detection electrode 39 that generates a potential difference between the areas AE. Area A
It is said that a potential difference is generated between C.

Further, in the case of the present embodiment, as an example,
The switching control between the areas AE and AC is performed every 0.2 (second), and 0.2 V is applied to each.
The voltage value measured between area AE and AC is 10 (mv)
Whether or not (predetermined threshold value) is reached is detected. These numerical values can be appropriately changed according to the type of biosensor.

Returning to the flowchart of FIG. 6, the description will be continued. First, a potential difference of 0.2 V is generated between the areas AE located on the upstream side of the sample supply path, and it is determined whether or not the voltage value measured between the areas AE has reached 10 mv or more (step S14). . If the voltage value measured between the areas AE does not reach 10 mV or more (step S14; N
o), a potential difference of 0.2 V is generated between the areas AC on the downstream side, and it is determined whether or not the voltage value measured between the areas AE has reached 10 mv or more (step S15).

The voltage value measured between the areas AC is 10 m
If it does not reach v or more (step S15; No), 3 after the potential difference is generated between the areas AE in step S14.
It is determined whether or not minutes have passed (step S16).
If it has not reached 3 minutes (step S16; No), the process from step S14 is repeated again. Area A
If the voltage value does not reach 10 mV for 3 minutes for both E and AC (step S16; Yes), the measurement process ends.

When it is determined that the voltage value has reached 10 mv between the areas AE (step S14; Yes), it is determined whether the voltage value has reached 10 mv between the areas AC (step S17). If the voltage value measured between the areas AC does not reach 10 mV (step S17; No),
It is determined whether or not 2 seconds (predetermined period) have elapsed since it was determined that the voltage value reached 10 mv between the areas AE (step S18). If 10 seconds has not elapsed, the processing of steps S17 and 18 is repeated until the voltage value measured between the areas AC reaches 10 mv (step S18; No) until 10 seconds have elapsed. It will be in a temporary standby state. In this case, since it is highly likely that the spotted sample solution is insufficient, in order to prompt the user to lack the sample solution and to supplement the sample solution,
It is preferable that the error message be displayed on the display unit 11 or the like or that a warning sound be emitted. If the voltage value measured between the areas AC does not reach 10 mv even after 10 seconds have passed (step S18; Yes), the measurement process ends as a sample shortage error (step S19).

Here, when the user supplements the sample solution for 10 seconds after it is determined that the voltage value between the areas AE has reached 10 mv in step S14, the final measurement accuracy becomes poor. The inventors of the present invention have found that. In particular, while being supplemented by the user,
Since the enzymatic reaction is proceeding between the substrate in the sample solution deposited previously and the enzyme in the reagent layer 36, the reductant has already been generated before the start of the measurement. After that, when the amount of the substrate is quantified after the supplemented sample solution reaches between the areas AC, it is affected by the reductant that has already been generated.
Apparently, the voltage value tends to increase. That is,
As the elapsed time increases from the time when it is determined that the voltage value between the areas AE has reached 10 mv in step S14, the influence on the measurement accuracy increases.

In order to eliminate the measurement error due to the addition of the sample liquid, the measuring apparatus 10 of the present embodiment uses step S
According to the elapsed time (hereinafter, delay time) from when it is determined that the voltage value between the areas AE reaches 10 mv in 14 to when it is determined that the voltage value between the areas AC reaches 10 mv in step S17, The base mass corresponding to the measured voltage value is corrected.

FIG. 8 is a sensitivity correction table showing the relationship between the delay time and the correction rate indicating the rate at which the measured base mass is corrected. The vertical axis shows the correction rate and the horizontal axis shows the delay time. For example, when the delay time is 5 seconds, the measured base mass is corrected 10% lower, and as a result, 90% of the measured base mass becomes the corrected base mass.
Such a sensitivity correction table is stored in the memory (not shown) of the measuring device 10 and is referred to when the final base mass is calculated.

In the biosensor 30 shown in FIG. 2, the slit 41f formed on the substrate 31 is extended in the direction of the slit 41c and the counter electrode 37 is formed so as to be completely connected to the slit 41b. It is possible to detect a spotting position error in which the spot is accidentally spotted in the air hole 33. In the flowchart of FIG. 6, when it is determined that the voltage value has reached 10 mV or more between the areas AC first, not between the areas AE (step S15; Yes), the area AE is then switched between the areas AE within 0.2 seconds. It is determined whether or not the voltage value has reached 10 mV or higher (step S2).
0). When the voltage value does not reach 10 mV or more between the areas AE, it is determined that the sample liquid has been spotted on the wrong position of the sample liquid, and the measurement process ends (step S50).

As normal, the sample solution spotted on the sample spotting section 30a is directed toward the air hole 33 along the sample supply path 35 so that the counter electrode 37, the measurement electrode 38, and the detection electrode 39 are immersed in this order. Sucked. However, in the case where the voltage value only between the areas AC changes significantly, the probability that the user accidentally spotted the sample liquid in the air hole 33 becomes high. In such a case, it is determined that it is difficult to perform accurate measurement, and the measurement process is forcibly terminated as a spotting position error. This makes it possible to reliably eliminate the measurement error caused by the user's erroneous operation.

Further, when it is determined that the voltage value has reached 10 mv between the areas AC (step S17; Yes) or when it has been determined that the voltage value has reached 10 mv or more between the areas AE (step S20; Yes). ), The sufficient amount of the sample liquid has been detected, the preliminary measurement process for quantifying the substrate is started, and the time is counted by the timer (not shown) of the measuring device 10 (step S21). ).

Next, conduction detection between the area AF is performed (step S22). Switch switching control is performed so that the switch 22 is turned on, and conduction detection between the area A and the area F is executed. When the conduction is detected between the area AF (step S22; Yes), the result record “I” which is the type of the biosensor 30 in step S9.
Is stored in the memory (step S2
3). When the result record “I”, which is the type of the biosensor 30, is stored (step S23; Yes), it is determined that the type of the biosensor 30 is FIG. 3G, and the reduced electron acceptor is electrically charged. A calibration curve F7 is set as calibration curve data for specifying the glucose concentration in the sample solution from the voltage value obtained when chemically oxidizing (step S24).

On the other hand, when the result record "II" is stored (step S23; No), it is determined that the type of the biosensor 30 is the one shown in FIG. 3 (e), and the calibration curve F5 is set as the calibration curve data. (Step S25). Area AF
If there is no continuity detection between them (step S22; No), it is determined that the type of the biosensor 30 is FIG. 3 (f), and the calibration curve F6 is set as the calibration curve data (step S).
26).

In this way, the identification unit 42 of the biosensor 30 is
The difference in the output characteristics of the biosensor 30 is automatically recognized according to the slits, and the calibration curve data suitable for the characteristics is automatically selected and set. The calibration curve data in which the output characteristics according to the manufacturing lot are taken into consideration in advance is automatically switched by the CPU 25 without the user using the correction chip. Therefore, erroneous measurement by the user using erroneous data can be avoided, and high accuracy of measurement can be maintained.

After the calibration curve is set in steps S24 to S26, the preliminary measurement process is started (steps S27 to S29). First, the preliminary measurement process will be described with reference to FIG. FIG. 9 shows a profile of preliminary measurement processing according to the present embodiment.

In the profile shown in FIG. 9, this preliminary process is started at time t0. Specifically, it indicates the time when the timer (not shown) of the measuring device 10 starts counting time. The profile of this preparatory process consists of three consecutive periods, for example, from time t0 to t.
1, a first potential period, a standby period from time t1 to t2, and a second potential period from time t2 to t3.

In the first potential period, the potential V1 is in the areas A and C.
And the enzymatic reaction proceeds by being applied to E and E, the voltage value obtained by electrochemically oxidizing the produced ferrocyanide increases exponentially. Next, in the standby period, the potential V1 applied in the first potential period is set to zero. During this period, the ferrocyanide is not electrochemically oxidized, and the enzymatic reaction continues to proceed and the amount of ferrocyanide is accumulated. Then, the potential V2 is applied to the areas A, C, and E in the second potential period, and the ferrocyanide accumulated in the standby period is oxidized at once and the amount of electrons released increases, so that it is high at time t2. The response value is shown. The voltage value showing a high response value decreases with the lapse of time, and finally at time t3, the stabilized voltage value i3 is measured. In the preliminary measurement process, the switches 19 and 21 of the measuring device 10 are both turned on so that the counter electrode 37 and the detection electrode 39 are integrally applied with a potential.

Here, as the specifications required for recent biosensors, it has been desired to shorten the measurement time. The inventors of the present invention have found that the viscosity of the sample solution has a great influence on the measurement accuracy when the substrate is rapidly quantified by the biosensor. In particular, when the blood of the human body is used as the sample solution, the measurement sensitivity is lowered and the viscosity is low (Hc) when the blood has a high viscosity (high Hct: hereinafter, high viscosity).
Low t: hereinafter, low viscosity) Blood has high measurement sensitivity. This phenomenon is derived from the lysis rate of the reaction reagent layer and blood, which is slow in high-viscosity blood and fast in low-viscosity blood, which affects the measurement sensitivity of the biosensor.

FIG. 10 is a diagram showing the relationship between blood viscosity, reaction time between the reaction reagent layer and blood, and measurement sensitivity. The data in FIG. 10 is measured by the conventional measurement method. The conventional method is a method in which the potential is applied only during the period corresponding to the second potential period in FIG. 9 and the voltage value is measured. As is clear from FIG. 10, the shorter the reaction time, the higher the viscosity (in the case of blood, Hc
It can be seen that the influence of measurement sensitivity due to the difference in t) becomes large. In particular, during the reaction time of about 5 seconds, there is a large difference in measurement sensitivity between low viscosity blood and high viscosity blood. Therefore, in the conventional measuring method, the measurement error due to the viscosity of blood tends to be remarkable.

Therefore, in the first potential period of this preliminary measurement process, the reaction product generated at the initial stage of dissolution with the reagent layer 36 is forcibly consumed by applying the potential V1.
In the first potential period, the low-viscosity blood has a higher enzymatic reaction rate than the high-viscosity blood, so that more reaction products are produced and more reaction products are consumed. However, if the potential is applied for an excessively long time, the reaction product may be excessively consumed, and the responsiveness of the voltage value detected during the second potential period may deteriorate. Therefore, the effective length t1-t0 of the first potential period can be set to 3 to 13 seconds, but it is preferable that the application time is set to 2 to 10 seconds by further increasing the applied potential. The potential V1 is preferably 0.1V to 0.8V.

Next, during the waiting time, the enzymatic reaction proceeds again, the product from the low-viscosity blood consumed in the first potential period is rapidly recovered, and the same amount as the high-viscosity blood is accumulated. However, if the waiting time is too long or too short, the influence on the final measurement sensitivity is different. If the standby time is too short, the response value of the voltage value i3 measured at the time t3 becomes too low, and the measurement error becomes large. If the waiting time is too long, the difference in enzyme reaction rate between low-viscosity blood and high-viscosity blood may be further widened. Therefore, the length of the waiting time is determined so that the difference in the enzyme reaction rate between the low viscosity blood and the high viscosity blood does not spread further. Therefore, the length t2-t1 of the waiting period can be set to 1 to 10 seconds, and more preferably 2 to 10 seconds.

In the second potential period, the voltage value is not stable immediately after the time t2 when the application of the potential V2 is started, and an elapsed time for stabilizing the voltage value is necessary. Furthermore, it is not necessary to apply the same potential as in the first potential period, and a potential lower than the potential V1 in the first potential period is preferable. It is sufficient that the voltage is low enough to oxidize potassium ferrocyanide. Therefore, the length t3 to t2 of the second potential period is 2 to 10
Seconds are preferred. The potential V2 is 0.05 to
0.6V is preferred. Finally, the voltage value i3 between the areas A, C, and E at time t3 is read, and the amount of the substrate (glucose) in the sample solution is calculated from the read voltage value i3.

Such a time setting is a biosensor using an electrode of a noble metal such as palladium, and the reagent formulation includes not only glucose oxidase or / and glucose dehydrogenase and potassium ferricyanide but also an amino acid and a sugar alcohol. It is particularly suitable for quantitative measurement using a sensor. It is also suitable when it contains an organic acid.

After the sample solution is supplied to the sample supply path 35, when the reaction between the sample solution and the reagent layer 36 is incubated for a certain period of time and then the substrate is quantified, it is measured between the areas AE in step S14. After detecting that the voltage value exceeds the threshold value (10 mv or more), the voltage value measured between the areas AC in step S17 is the predetermined threshold value (10 mV).
The culturing time may be changed according to the elapsed time until v) is exceeded.

FIG. 11 shows a hematocrit (hereinafter referred to as Hc
t) using blood of 25%, 45%, and 65%, the glucose concentration (mg / d) between the conventional method and the preliminary measurement process.
It is a figure which shows the measurement result of l). R in FIG. 11 is the result of measurement by this pretreatment, and in addition, the result of measurement when the reaction time is 15 seconds and 30 seconds using the conventional method is shown. In the pretreatment, the length of the first potential period is 6 seconds,
The potential V1 is 0.5V, the waiting time is 6 seconds, the second potential period is 3 seconds, and the potential V2 is 0.2V. Hc
tct = 45%, glucose concentration 100 mg / dl, Hct25% low viscosity blood, Hct
When the viscosity of blood is high at 65%, a large variation occurs in the measurement result. The lower the viscosity of the blood, the higher the response, and the higher the viscosity of the blood, the lower the response value.

Furthermore, the shorter the reaction time, the larger the variation. 10% higher (Hct
25% of low viscosity blood) and 10% lower (Hct 65% low viscosity blood) have variations. When the reaction time is 30 seconds, it is 5% higher (Hct 25% low viscosity blood), 5
% Lower (Hct 65% low viscosity blood) is uneven. In this pretreatment, 3% higher (Hct25%
Low viscosity blood), and 3% lower (Hct 65% low viscosity blood). It is possible to reduce the variation due to Hct even though the total reaction time is equal to the measurement result of the reaction time of 15 seconds.

Returning to FIG. 7 again, the description of the measurement process will be continued. The preliminary measurement process is started, and a potential of 0.5 V is applied for 6 seconds between the areas A, C, and E as the first potential period (step S27). After the end of the first potential period, the standby state is maintained for 6 seconds, during which the potential is removed (step S28). After the waiting period ends, as the second potential period,
A potential of 0.2 V is applied between areas A, C, and E for 3 seconds (step S29), and after 3 seconds, the voltage value i3 at that time is read (step S30).

After the voltage value i3 is read in step S30, the temperature measuring unit 26 and its switch 27 arranged in the measuring apparatus 10 and the temperature measuring unit 28 and the switch 2 are arranged.
By controlling 9, the temperature measurement in the measuring device 10 is carried out. Specifically, the switch 27 is ON-controlled and the temperature is measured by the temperature measuring unit 26 (step S31). Subsequently, the switch 27 is turned off and the switch 29 is turned on, and the temperature is measured by the temperature measuring unit 28 (step S32).

The two temperature measurement results measured by the temperature measuring unit 26 and the temperature measuring unit 28 are compared, and it is determined whether the difference is within a predetermined threshold value (step S33). If the difference is not within the threshold range, the measurement process is terminated because one of the temperature measuring units 26 and 28 has failed (step S33; No). By installing a plurality of temperature measuring units of the temperature measuring units 26 and 28 in the measuring device 10 and comparing the measurement results, it becomes possible to accurately and easily detect the failure. This makes it possible to avoid measurement errors due to irregular temperature measurement. Although the timing of measuring the temperature is immediately after the voltage value is read in step S30, the temperature may be measured at the timing when the preliminary measurement process is started in step S21.

When the difference between the two temperature measurement results is within the predetermined threshold value (step S33; Yes), the temperature measurement result is temporarily stored in the memory (not shown). On this occasion,
Either the temperature measuring unit 26 or 28 may be selected and stored, or the average value of two measured temperatures may be stored. Then, the calibration curve to which the voltage value i3 measured in step S30 should be referred is specified (step S34). Step S
The calibration curve set in 24, 25, and 26 is referred to, and in the case of the biosensor 30 corresponding to step S24, the calibration curve F7 is referred to (step S35). Similarly, in the case of the biosensor 30 corresponding to step S25, the calibration curve F5 is referred to (step S36). Also,
In the case of the biosensor 37 corresponding to step S26, the calibration curve F6 is referred to (step S37).

FIG. 12 shows an example of the calibration curve data CA measured in steps S34, 35 and 36. Calibration curve CA
The biosensor 30 includes the voltage value measured in step S30 and the concentration (mg / dl) of the substrate contained in the sample solution.
Is defined for each of the output characteristics F1 to F7. For example,
When the measured voltage value is 25 (mV), the concentration of the substrate is 14 if the biosensor corresponds to the calibration curve F5.
(Mg / dl) is stored in memory.

Next, step S35, S36 or S3.
The concentration of the substrate extracted in step 7 is
The correction is performed according to the correction factor corresponding to the delay time obtained in step S38 and stored in the memory (step S38). Specifically, it is corrected by the following equation (1). D1 = (concentration of extracted substrate) × {(100-sensitivity correction rate) / 100} Here, D1 represents the corrected concentration of the substrate. As a result, the measurement error associated with the sample liquid supplement operation by the user is reliably eliminated.

Next, the concentration of the substrate corrected in step S38 is corrected according to the temperature measured in steps S31 to S33 (step S39). In particular,
In step S33, the temperature stored in the memory (hereinafter, measured temperature) is read out, and the temperature correction rate for the substrate concentration D1 is determined by referring to the temperature correction table shown in FIG.

FIG. 13 is a diagram showing an example of the temperature correction table. In FIG. 13, as an example, T10 shows a temperature correction table when the measured temperature is 10 ° C. Hereinafter, similarly, T15 shows a temperature correction table when the measurement temperature is 15 ° C., and T20 shows a temperature correction table when the measurement temperature is 20 ° C. Each temperature correction table defines the relationship between the substrate concentration D1 in the sample solution and the temperature correction rate. The temperature correction rate is set on the basis of the substrate concentration at a temperature of 25 ° C., and indicates the rate of correction to the corresponding substrate concentration. Specifically, the temperature correction is executed according to the following equation (2). D2 = D1 × (100−Co) / 100 where D2 is the substrate concentration after temperature correction, D1 is the substrate concentration calculated in step 38, and Co is the temperature correction rate specified by referring to the temperature correction table. Show.

Further, the inventors of the present invention have
It was found from the experiment that it was influenced by the combination of the measurement temperature and the substrate concentration. The influence on the measurement accuracy will be specifically described. FIG. 14 is a diagram showing the relationship between the measurement temperature and the measurement variation (bias) as the substrate concentration for each glucose concentration. The measurement variation in FIG. 13 indicates the rate at which the glucose concentration measured at the measurement temperature of 25 ° C. changes with the change of the measurement temperature. 14
(A) is a glucose concentration of 50 mg / d at 25 ° C.
It is a figure which shows the relationship between the measurement variation and measurement temperature in case of 1. Similarly, FIG. 14 (b) shows the case where the glucose concentration is 100 mg / dl at 25 ° C., FIG. 14 (c) shows the case where the glucose concentration is 200 mg / dl at 25 ° C., and FIG. 14 (d) shows the glucose concentration at 25 ° C. Thirty
In the case of 0 mg / dl, FIG. 14 (e) shows the relationship between each measurement variation and the measurement temperature in the case of glucose concentration of 420 mg / dl at 25 ° C., and FIG. 14 (f) in the case of glucose concentration of 550 mg / dl at 25 ° C. Indicates.

From these experimental data, the following two tendencies are clear. First, in the relationship of the same glucose concentration, it can be seen that the greater the difference between the reference temperature of 25 ° C. and the measured temperature, the greater the measurement variation. Specifically, the measurement variation tends to increase in the negative direction as the measurement temperature is lower than the reference temperature, and the measurement variation tends to increase in the positive direction as the measurement temperature exceeds the reference temperature. Secondly, it can be seen that even if the glucose concentration is increased, the measurement variations converge at the boundary of the glucose concentration of 300 mg / dl. Specifically, for example, FIG.
In FIG. 14A, the measurement variation at the measurement temperature of 40 ° C. is about 28%, and in FIG.
The transition is about 60% in FIG. 14 (d) and about 50% in FIG. 14 (f). There is a similar tendency even in a low temperature range such as a measurement temperature of 10 ° C.

Therefore, such a tendency is reflected in the temperature measurement table shown in FIG. Specifically, in the relationship of the same glucose concentration, the greater the difference between the reference temperature of 25 ° C. and the measured temperature, the greater the variation in measurement, and even if the glucose concentration is increased, the case where the glucose concentration is 300 mg / dl is the boundary. Is a table that takes into account the convergence of measurement variations.
By performing the correction by referring to the temperature correction table according to the combination of the measurement temperature and the substrate concentration, the measurement accuracy can be dramatically improved as compared with the case where the correction is simply performed according to the measurement temperature.

It should be noted that the biosensor 30 may have a temperature correction table in units of 1 ° C. in the operating temperature range (10 ° C. to 40 ° C. in the present embodiment, for example),
You may specify by the predetermined temperature range (for example, 5 degreeC).
When the measured temperature located in the middle of the predetermined temperature range is detected, the temperature correction rate may be calculated by linear linear interpolation using the temperature correction table sandwiching the detected measured temperature.

Returning to the flowchart of FIG. 7, the substrate concentration D2 after such temperature correction is output to the display unit 11 of the measuring apparatus 10 as the final substrate concentration (step S40). In this way, since the base mass is quantified in consideration of the additional time, the measurement temperature, the effect of the combination of the measurement temperature and the substrate concentration, or the viscosity of the Hct sample solution, the measurement accuracy is significantly improved compared to the conventional method. Can be achieved.

The following method is also possible in order to further suppress the measurement error due to temperature. Biosensor 30
The temperature is continuously measured in advance without being inserted into the measuring device 10, and the measured temperature is accumulated. After the biosensor 30 is inserted, steps S31 to S32
It suffices to make a comparison between the measured temperature measured in 1 and the temperature accumulated in advance. When there is a large difference between the temperature accumulated in advance and the measured temperature measured in steps S31 to S32, the measurement process is forcibly terminated because there is a temperature change that affects the measurement error. Will be able to.

Since the portable biosensor system as in this embodiment is easy to carry, it is exposed to various temperature changes depending on the external environment. For example, there are cases in which the temperature of the user's hand and a sudden change in the environmental temperature when the user moves from the outdoor to the indoor are accompanied. While the environmental temperature changes rapidly, it takes a considerable time for the temperature change in the measuring device 10 to stabilize.

For example, FIG. 15 is a diagram showing a temperature change in the measuring device 10. The diagram shown in FIG. 15 shows the temperature change in the measuring device 10 when the measuring device 10 is moved from the temperature of 10 ° C. to the temperature of 25 ° C. and when the temperature of the measuring device 10 is moved from the temperature of 40 ° C. to the temperature of 25 ° C. From FIG. 15, it can be seen that it takes about 30 minutes for the temperature once generated to stabilize at the operating temperature of 10 ° C to 40 ° C. If temperature correction is executed while the temperature is changing, accurate temperature correction may not be possible.

Therefore, when there is a large difference between the temperature accumulated in advance and the measured temperature measured in steps S31 to S32, it is assumed that there is a temperature change that affects the measurement error, and the measurement process is performed. There is a need to forcefully terminate it. As a result, the accuracy of temperature correction in the measuring device 10 can be further improved. In addition, the pre-measurement of the temperature when the biosensor 30 is not inserted in the measuring device 10 may be performed in a predetermined time period (for example, 5 minutes) or may be continuously performed. Further, the degree of temperature change may be judged, and if the temperature change is large, the measurement process may not be executed even if the user tries to perform the measurement.

[0109]

According to the present invention, it is possible to easily provide a biosensor which is easy for the user to operate and has good measurement accuracy, a quantification method and a measurement device using the biosensor.

[Brief description of drawings]

FIG. 1 is a diagram showing a biosensor system according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of the biosensor according to the same embodiment.

FIG. 3 is a view showing a combination of identification parts of the biosensor according to the same embodiment with or without a slit formed.

FIG. 4 is a diagram showing a configuration of a biosensor and a measuring device according to the same embodiment.

FIG. 5 is a diagram showing a processing flow of the biosensor and the measuring device when quantifying the content of the substrate in the sample liquid.

FIG. 6 is a diagram showing a process flow of a biosensor and a measuring device when quantifying the content of a substrate in a sample solution.

FIG. 7 is a diagram showing a process flow of the biosensor and the measuring device when quantifying the content of the substrate in the sample liquid.

FIG. 8 is a diagram showing a relationship between a correction rate and a delay time, which shows a ratio of applying a correction to the measured base mass.

FIG. 9 is a diagram showing a profile of preliminary measurement processing.

FIG. 10 is a diagram showing the relationship between blood viscosity, reaction time between reaction reagent layer and blood, and measurement sensitivity.

FIG. 11 is a diagram showing measurement results of glucose concentration (mg / dl) between the conventional method and the preliminary measurement process.

FIG. 12 is a diagram showing an example of calibration curve data CA.

FIG. 13 is a diagram showing an example of a temperature correction table.

FIG. 14 is a diagram showing the relationship between measurement temperature and measurement variation for each substrate concentration.

FIG. 15 is a diagram showing a temperature change in the measuring device.

FIG. 16 is an exploded perspective view of a conventional biosensor.

[Explanation of symbols]

1 biosensor system, 2 support parts, 10
Measuring device, 11 Display unit, 30 Biosensor, 30
a sample spotting section, 35 sample supply path, 36 reagent layer, 3
7 counter electrode, 38 measurement electrode, 39 detection electrode, 42
Identification unit, CA calibration curve, T10 T15 T20 temperature correction table

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI Theme Coat (reference) G01N 27/46 338 336H 27/30 353Z (72) Inventor Hiroyuki Tokunaga 1 Matsushita 1-8 Koshinmachi, Takamatsu City, Kagawa Prefecture Judenko Industry Co., Ltd.

Claims (24)

[Claims] 1. A support portion detachably supporting a biosensor having at least a pair of electrodes formed on an insulating substrate,
The substrate contained in the sample solution is quantified by inserting it into a measuring device that has a plurality of connection terminals electrically connected to each of the electrodes and a driving power supply that applies a voltage to each of the electrodes via the connection terminals. The biosensor for performing any one of the electrodes of the biosensor, the biosensor being provided on the measuring device only when the biosensor is inserted into a supporting portion of the measuring device in a predetermined direction. Connection terminal and second
A biosensor having electrical connection between the first connection terminal and the second connection terminal when a voltage is applied by the drive power source. . 2. A conductive layer is formed on at least a part of the insulating substrate, and the conductive layer is divided by slits to form the counter electrode and the measurement electrode, and further, if necessary, a detection electrode. The biosensor according to claim 1, wherein the biosensor is formed. 3. A support part for detachably supporting a biosensor having at least a pair of electrodes formed on an insulating substrate, a plurality of connection terminals electrically connected to each of the electrodes, and the connection terminals. A biosensor measuring device having a driving power supply for applying a voltage to each of the electrodes via the electrodes and quantifying a substrate contained in a sample solution supplied to the biosensor, wherein the measuring device is the support part. Only when the biosensor is inserted in a predetermined direction, is provided a first connection terminal and a second connection terminal for connecting to any one of the electrodes of the biosensor, A biosensor measuring device, characterized in that a voltage is applied to each of the connection terminal and the second connection terminal to detect whether or not there is conduction between the first connection terminal and the second connection terminal. 4. The measuring device comprises the first connection terminal,
The biosensor measuring device according to claim 3, wherein when the conduction between the second connection terminals is not detected, it is determined that the biosensor is not inserted in a predetermined direction. 5. The measuring device according to claim 4, further comprising an output unit that outputs a determination result to the outside when it is determined that the biosensor is not inserted in a predetermined direction. Measuring device for biosensors. 6. A counter electrode formed on at least a part of an insulating substrate, an electrode section including a measurement electrode and a detection electrode, a sample supply path for supplying a sample solution to the electrode section, and a supply via the sample supply path. A biosensor having a reagent layer that reacts with a sample liquid to be inserted, is inserted into a measuring device having a support portion that detachably supports, and a connection terminal and a driving power source for applying a voltage to the electrode portion, A method for quantifying a substrate for quantifying a substrate contained in the sample solution, wherein the biosensor is inserted into a supporting portion of the measuring device, and a first pair of the counter electrode and the measuring electrode is provided. A method for quantifying a substrate, characterized in that a voltage is applied by the driving power source to each of the second set of the measurement electrode or the counter electrode and the detection electrode. 7. The biosensor includes a counter electrode, a measurement electrode and a detection electrode, which are formed on the most downstream side along the sample supply path in the direction of the sample flow from the sample supply port. Whether or not a sufficient amount of sample liquid necessary for measurement is supplied depending on whether or not each of the currents output from the first set and the second set of the electrode section exceeds a predetermined threshold value. The method for quantifying a substrate according to claim 6, wherein the determination is made. 8. If the current from the second set does not exceed a predetermined threshold within a predetermined elapsed time after the current from the first set exceeds the predetermined threshold, The method for quantifying a substrate according to claim 7, wherein it is determined that the sample liquid is insufficient. 9. The method for quantifying a substrate according to claim 8, wherein when it is determined that the sample liquid is insufficient, the fact is output from the measuring device to the outside. 10. If the current from the second set does not exceed a predetermined threshold value within a predetermined elapsed time after the current from the first set exceeds the predetermined threshold value, 8. The method for quantifying a substrate according to claim 7, wherein the measurer temporarily suspends the measurement step for the work of adding and supplying the sample solution again. 11. The sample supply path of the biosensor comprises:
From the sample supply port toward the sample flow direction, the counter electrode,
Of the measurement electrode and the detection electrode, the detection electrode is formed on the most downstream side, and on the downstream side of the detection electrode, an exhaust port for promoting the flow of the sample liquid is provided, When the current exceeds the predetermined threshold value before the first set and the current from the first set does not exceed the predetermined threshold value within a predetermined elapsed time. 8. The method for quantifying a substrate according to claim 7, wherein it is determined that the sample liquid is mistakenly sucked from the exhaust port. 12. The elapsed time from when the current from the first set exceeds a predetermined threshold to when the current from the second set exceeds the predetermined threshold. Therefore, the quantification method of the substrate according to claim 7, wherein the quantification value of the substrate corresponding to the current detected by the electrode unit is corrected. 13. The measurement device further includes a storage unit that stores calibration data indicating a correspondence between an electric current detected by the biosensor and a content of a substrate contained in the sample solution, and the storage unit includes 13. The method for quantifying a substrate according to claim 12, wherein the quantified value of the substrate corresponding to the detected current is determined by referring to the stored calibration data. 14. After supplying the sample solution to the sample supply path,
In quantifying the substrate after culturing the reaction between the sample solution and the reagent layer for a certain period of time, after detecting that the current from the first set exceeds a predetermined threshold value, the second The method for quantifying a substrate according to claim 7, wherein the culturing time is changed according to the elapsed time until the current from the set exceeds a predetermined threshold value. 15. In either the first set or the second set,
The method for quantifying a substrate according to claim 6 or 7, wherein the application destination of the voltage is switched at regular intervals. 16. The amount of the substrate contained in the measurement sample is determined from a biosensor having a reagent layer that specifically reacts with the substrate in the measurement sample and a sample obtained by reacting the measurement sample with the reagent in the reagent layer. And a measuring device, the measuring device,
A temperature measurement unit that measures the temperature when the reaction between the measurement sample solution and the reagent layer proceeds, and a temperature correction data storage unit that has a plurality of measurement value correction tables that differ for each temperature range are provided. A method for quantifying a substrate, comprising selecting a correction table according to a temperature measured by the temperature measuring unit, calculating a correction value according to a measured value of the substrate, and performing correction. 17. The biosensor has an electrode portion including a counter electrode and a measurement electrode formed on at least a part of an insulating substrate, and the measuring device applies a voltage to the electrode portion. The measuring method according to claim 16, wherein the measuring device is a measuring device for detecting a current output from the electrode. 18. A substrate quantification method for measuring a substrate contained in a sample solution supplied to a biosensor by a measuring device, wherein the measuring device comprises temperature measuring means for measuring a temperature in the device, The temperature obtained prior to the measurement of the substrate,
A method for quantifying a substrate, characterized in that a temperature change is detected from a temperature at which the substrate is quantified and whether or not the substrate is measured is determined based on the temperature change. 19. A method for detecting a substrate when the temperature change between the temperature obtained prior to the measurement of the substrate and the temperature during the measurement of the substrate is detected and the temperature change exceeds a predetermined threshold value. The method for quantifying a substrate according to claim 18, wherein the step is stopped. 20. The method for quantifying a substrate according to claim 18, wherein the temperature measurement prior to the measurement of the substrate is intermittently performed. 21. A biosensor having a counter electrode formed on at least a part of an insulating substrate, an electrode part including a measurement electrode, and a reagent layer that reacts with a sample solution supplied to the electrode part, and the biosensor. Using a measuring device having a supporting portion that removably supports and a connecting terminal for applying a voltage to each electrode of the electrode portion and a driving power supply, and applying a voltage to the electrode portion by the driving power supply to output A method for quantifying a substrate for quantifying a substrate contained in the sample solution by detecting an electric current generated by the method, wherein the measuring device includes a first electrode unit of the biosensor supported by the supporting unit. The first potential is applied for a first period, and the first
After applying the first potential to the electrode portion during the period of, the application of the first potential is stopped for a standby period, and after the standby period elapses, a second potential is applied to the electrode portion. The substrate is quantified by measuring a current applied and output for a second period, and the first potential is higher than the second potential. 22. The method for quantifying a substrate according to claim 21, wherein the waiting period is 2 seconds or more and less than 10 seconds. 23. The first potential is 0.1 V or more and 0.
23. The method for quantifying a substrate according to claim 22, wherein it is 8 V or less and the first period is 2 seconds or more and 10 or less. 24. The second potential is 0.05 V or more and 0.6 V or less, and the second period is 2 seconds or more and 1 or more.
24. The method for quantifying a substrate according to claim 23, which is 0 second or less.