JP5237914B2 - Measuring device, biosensor, and measurement display device for substrate component amount of specimen - Google Patents

Description

  The present invention relates to a measurement device, a biosensor, and a measurement display device for measuring a component amount (concentration) of a substrate of a specimen.

  Conventionally, various biosensors and measurement display devices including the following patent documents have been developed and disclosed. 7 and 8 show an example of the biosensor 102 and the measurement display device 104 included in the substrate component amount measurement device 100. FIG.

  The biosensor 102 includes an insulating substrate 16, a plurality of electrodes 18, 20, 22, 24 a, 24 b provided on the substrate 16, and the electrodes 18, 20, 22, 24 a, 24 b. The reaction part 26 provided is provided.

  Moreover, the cover 28 which opposes the reaction part 26 at fixed intervals is provided. A spacer 30 is provided on the substrate 16 to support the cover 28, but the spacer 30 is not provided at least at the tip of the substrate 16, and the opening 32 is formed by the tip of the substrate 16 and the tip of the cover 28. When a sufficient amount of sample is supplied to the opening 32, the sample spreads between the reaction unit 26 and the cover 28 by capillary action, and the sample is inhaled into the reaction unit 26.

  The plurality of electrodes are the measurement working electrode 18, the measurement counter electrode 20, the detection working electrode 22, and the detection counter electrodes 24a and 24b. Terminals 34 provided from the electrodes 18, 20, 22, 24 a and 24 b are connected to attachment terminals T 1 to T 5 of the measurement display device 104.

  The measuring working electrode 18 and the measuring counter electrode 20 are substantially semicircular, and the straight portions are opposed to each other with a constant interval. The measurement working electrode 18 and the measurement counter electrode 20 are used to measure the amount of the component of the substrate of the specimen.

  The detection working electrode 22 and the detection counter electrode 24a are provided closer to the opening than the measurement working electrode 18 and the measurement counter electrode 20, and face each other at a constant interval. This is used to detect that the sample has started inhalation into the reaction unit 26.

  The detection working electrode 24 b is provided on the opposite side of the opening 32 with respect to the measurement counter electrode 20. The detection working electrode 22 and the measurement counter electrode 24b face each other so that the measurement working electrode 18 and the measurement counter electrode 20 are inclined. This is used to detect that the sample has been sufficiently inhaled into the reaction unit 26.

  The reaction part 26 is a film containing an oxidoreductase and an electron acceptor. The reaction unit 26 is formed by dropping a liquid material at a desired position with a dispenser and drying it. Since the reaction unit 26 and the sample cause an irreversible reaction, the biosensor 102 is replaceable.

  When the sample is inhaled into the reaction unit 26, the reaction unit 26 and the sample react. At this time, when a potential difference is generated between the electrodes, transfer of electrons occurs. By utilizing this, the amount of the component of the substrate of the specimen is measured. The measurement is performed according to the following procedures (i) to (iii). (I) A potential difference is generated between the detection working electrode 22 and the detection counter electrode 24a, thereby confirming the start of inhalation of the specimen into the reaction unit 26. (Ii) A potential difference is generated between the detection working electrode 22 and the detection counter electrode 24b to confirm that the specimen has been sufficiently inhaled into the reaction unit 26. (Iii) After a certain period of time, a potential difference is generated between the measurement working electrode 18 and the measurement counter electrode 20 to measure the amount of the component of the substrate of the specimen.

  A measurement display device 104 as shown in FIG. 8 is used in order to generate a potential difference as described above or to measure the amount of a substrate component of a specimen. Terminals 34 extending from the electrodes 18, 20, 22, 24a, 24b of the biosensor 102 are connected to terminals T1 to T5 of the measurement display device 104, and measurement is performed with the electrodes 18, 20, 22, 24a, 24b of the biosensor 102. The electronic circuit of the display device 104 is electrically connected.

  Which electrode 18, 20, 22, 24a, 24b is to be operated is determined by controlling on / off of the switches SW1 to SW5. The switches SW1 to SW5 use semiconductor switches that can be turned on and off electrically, such as MOSFETs. A signal is sent from the control unit 108 of the microcomputer 106 to control the switches SW1 to SW5.

  A predetermined voltage is output from the power supply unit 58 of the microcomputer 106 and is converted into an analog voltage by the D / A conversion circuits D / A0 and D / A1. This voltage is applied to the measurement working electrode 18 and the detection working electrode 22 connected to the terminals T1 and T2 via the operational amplifier 54. When the reaction part 26 and the sample react, a current flows between the working electrodes 18 and 22 to which a voltage is applied and the counter electrodes 20, 24 a and 24 b.

  If the detection unit 62 detects that a current has flowed between the detection working electrode 22 and the detection counter electrode 24a, it indicates that the sample has started to be inhaled into the reaction unit 26. Further, if the detection unit 62 detects that a current has flowed between the detection working electrode 22 and the detection counter electrode 24b, it can be understood that the specimen has been sufficiently inhaled into the reaction unit 26. Thereafter, after a predetermined time has passed and the specimen and the reaction unit 26 have sufficiently reacted, the amount of the substrate component of the specimen is measured.

  In the measurement of the amount of the substrate component of the sample, the flowing current varies depending on the state of the sample being sucked into the reaction unit 26 and the amount of the substrate component of the sample. A voltage corresponding to the current flowing between the electrodes is input to the measurement unit 60 of the microcomputer 106 via the current-voltage conversion circuit 56 and the A / D conversion circuits A / D0, A / D1, and A / D2. The calculation unit 64 of the microcomputer 106 checks the inhalation state between the reaction unit 26 and the sample and obtains the amount of the substrate component of the sample based on the input voltage value. The measurement display device 104 includes a small display (not shown), and displays the obtained amount of the component of the substrate on the display.

  The control unit 108 synchronizes the on / off timings of the switches SW1 to SW5, the voltage application timing between the electrodes, and the timing at which the calculation unit 64 receives the current value from the measurement unit 60. This is for recognizing which electrode has been operated and for matching whether the inhalation state of the specimen is to be measured or the amount of the component of the substrate is to be measured.

  However, although the amount of the substrate component can be measured by the measuring device 100, the connection between the biosensor 102 and the measurement display device 104 cannot be confirmed. Even if a sample is spotted on the opening 32 with poor connection, the amount of the substrate component cannot be measured. The reaction proceeds in the reaction unit 26, and it is necessary to start over from the beginning. Even if the biosensor 102 is detached from the measurement display device 104 halfway, measurement cannot be performed. The power consumption can be reduced by automatically turning off the measurement display device 104 after the biosensor 102 is removed.

  In addition, the enzyme in the reaction unit 26 varies depending on the substrate of the specimen to be measured. If the wrong biosensor 102 is attached, a desired measurement cannot be performed. In the following patent document, the type of the biosensor 102 cannot be specified.

JP 2008-304197 A Japanese Patent No. 2708276

  An object of the present invention is to provide a measurement device, a biosensor, and a measurement display device that can confirm the connection between a biosensor and a measurement display device and that can specify the type of the biosensor.

  The substrate component amount measuring device of the present invention includes a biosensor and a measurement display device to which the biosensor is attached.

The biosensor includes an insulating substrate, a working electrode provided on the substrate, a counter electrode provided at a predetermined interval with respect to the working electrode, and the working electrode and the counter electrode. a reaction section comprising an enzyme for covering, and a check electrode connected connection or be short-circuited via a resistor to the working electrode備Ru.

  The measurement display device includes an attachment terminal for the working electrode, an attachment terminal for the counter electrode, an attachment terminal for the check electrode, a means for applying a voltage between the working electrode and the counter electrode, and a counter to the working electrode. A means for measuring the current flowing between the electrodes, a constant voltage is applied to the check electrode mounting terminals, and whether or not the biosensor is connected to each mounting terminal and the type of biosensor depending on the potential of the check electrode And a check circuit for discriminating between them.

  The check circuit includes a first check circuit that detects a high level voltage or a low level voltage from the potential of the check electrode, and a second check circuit that detects the value of the potential of the check electrode.

  The first check circuit includes means for outputting the constant voltage and means for detecting a high level voltage or a low level voltage from the potential of the check electrode. The second check circuit includes means for outputting the constant voltage and means for detecting the value of the potential of the check electrode. The first check circuit and the second check circuit are selected by selecting a plurality of switches.

  When the first check circuit is selected by the plurality of switches, the working electrode is connected to ground, and when the second check circuit is selected, the working electrode is connected to means for applying a voltage. .

  The first check circuit operates only until the connection of the biosensor is detected.

In the present invention, since the check circuit can confirm that the biosensor is connected to the measurement display device, it is possible to prevent re-measurement due to a connection failure. In addition, since the types of biosensors can be automatically discriminated, the substrate component amount can be measured without changing the setting of a plurality of types of biosensors with the same measuring device.

It is a figure which shows the structure of the measuring apparatus of the amount of substrate components of this invention. It is a figure which shows the structure of a biosensor. It is the figure which expanded a part of biosensor, (a) is a figure which used the resistance element for check resistance, (b) is the figure which used the ultrafine metal wire meandered to check resistance, (c) Is a diagram using a straight ultrafine metal wire for the check resistor, and (d) is a diagram short-circuited using a metal wire having a normal line width for the check resistor. It is a figure which shows the structure of a 1st check circuit. It is a figure which shows the structure of a 2nd check circuit. It is a flowchart of a measurement of the amount of substrate components of a sample. It is a figure which shows the structure of the conventional biosensor. It is a figure which shows the structure of the conventional measurement display apparatus.

  The substrate component amount measuring device, biosensor, and measurement display device of the present invention will be described with reference to the drawings. The same means as in the past may be omitted.

  As shown in FIG. 1, the substrate component amount measuring device 10 includes a biosensor 12 and a measurement display device 50 to which the biosensor 12 is attached. Since the biosensor 12 causes an irreversible reaction, it is replaceable. First, the biosensor 12 will be described.

  The biosensor 12 of FIG. 2 is provided with an insulating substrate 16, a plurality of working electrodes 18, 22 provided on the substrate 16, and a certain distance from each working electrode 18, 22. The counter electrode 20, 24a, 24b, and the reaction part 26 containing the enzyme which covers the working electrode 18, 22 and the counter electrode 20, 24a, 24b are provided. Further, the cover 28 is opposed to the reaction part 26 at a predetermined interval by the spacer 30. An opening 32 is formed at the tip of the biosensor 12. These configurations are the same as those of the conventional biosensor 102.

  The substrate 16 is, for example, a polyester resin sheet such as polyethylene terephthalate (PET), polyethylene naphthalate, a biodegradable polyester resin composed of an aliphatic unit and an aromatic unit, a polyamide sheet excellent in heat resistance, chemical resistance, strength, and the like. , A plastic sheet such as a polyimide film sheet, and an inorganic substrate such as a ceramic.

  The plurality of electrodes are the measurement working electrode 18, the measurement counter electrode 20, the detection working electrode 22, and the detection counter electrodes 24a and 24b. Each electrode 18, 20, 22, 24a, 24b is formed of a conductor such as platinum, gold, palladium, indium-tin oxide. Examples of the forming method include hot stamping and the like, but a method by vacuum evaporation or sputtering is preferable because a fine electrode pattern can be formed with high accuracy. In the case of sputtering, it can be formed all at once by masking other than the electrode forming portion. Each electrode 18, 20, 22, 24a, 24b is formed in a semicircular shape or a band shape. The electrodes 18 and 20 have a semicircular shape, but may have a strip shape.

  The material of the reaction unit 26 can cause transfer of electrons in proportion to the component amount of the substrate of the specimen. For example, when measuring glucose present in blood, for example, glucose oxidase is used as an oxidoreductase, and ferricyan is used as an electron acceptor. The amount of electrons exchanged depends on the glucose concentration. Therefore, the component amount of the substrate can be measured.

  The biosensor 12 of the present invention includes a check electrode 40 connected to the detection working electrode 22 via a check resistor Rx. The check electrode 40 is provided next to the detection working electrode 22. The material and the formation method of the check electrode 40 are the same as those of the detection working electrode 22 and the like. Similar to the detection working electrode 22 and the like, an attachment terminal 34 extends from the check electrode 40, and the attachment terminal 34 is connected to the measurement display device 50.

  The check electrode 40 and the detection working electrode 22 are connected via a check resistor Rx. A check resistor Rx is provided at a position that does not get in the way when the biosensor 12 is attached to the measurement display device 50. An example of the check resistor Rx is a resistor element Rx1 such as a chip resistor (FIG. 3A). Further, as shown in FIG. 3B, the check resistor Rx may be formed by the fine metal wire Rx2 simultaneously with the formation of the check electrode 40 and the like. The metal itself is a good conductor, but its cross-sectional area is very narrow so that resistance is generated. The ultrafine metal wire Rx2 changes the meandering distance according to the resistance value. In addition to the fine metal wire Rx2 meandered as shown in FIG. 3B, a straight fine metal wire Rx3 as shown in FIG. 3C may be used. Although the ultrafine metal wire Rx3 is folded once, depending on the resistance value, the ultrafine metal wire Rx3 is connected to the detection working electrode 22 without being folded back.

  Depending on the type of biosensor 12, the resistance value of the check resistor Rx may be set to 0Ω. In that case, as shown in FIG. 3D, the check electrode 40 and the detection working electrode 22 are short-circuited by the metal wire Rx4. The metal line Rx4 only needs to have a width that does not cause resistance, and may have the same width as the check electrode 40 or the like.

  As variously shown in FIG. 3, the type, shape, and position of the check resistor Rx are not limited as long as the check resistor Rx having a desired resistance value can be formed in the empty space of the biosensor 12.

  Next, the measurement display device 50 includes a microcomputer 52, attachment terminals T1 to T6 for each electrode, a first operational amplifier 54 provided between the microcomputer 52 and the terminals T1 and T2, a microcomputer 12 and a terminal. A current-voltage conversion circuit 56 provided between T3 and T5 and a plurality of switches SW1 to SW8 are provided.

  The microcomputer 52 performs an operation as described with software, hardware, or both. The microcomputer 52 includes a power supply unit 58 that applies a voltage between the electrodes, a second measurement unit 60 that measures a current flowing between the electrodes, and a detection unit 62 that detects the inhalation state of the specimen from the measured current value. A calculation unit 64 for obtaining the amount of the substrate component of the specimen from the current value, and a control unit 66 for switching on / off of the switches SW1 to SW8. The second measuring unit 60 corresponds to the conventional measuring unit 60 of FIG.

  The power supply unit 58 outputs a voltage when detecting the inhalation of the sample or measuring the amount of the component of the sample substrate. The voltage changes with time at a predetermined timing. A predetermined voltage can be applied to the working electrodes 18 and 22. When the second check circuit 74 is selected, a predetermined voltage is output.

  In the first operational amplifier 54, the positive terminal of the first operational amplifier 54 is connected to the power supply unit 58. In addition, the output terminal and the negative terminal of the first operational amplifier 54 are connected. Digital / analog conversion circuits D / A0 and D / A1 are provided between the first operational amplifier 54 and the power supply unit 58 so that an analog voltage is applied to each electrode.

  Switches SW1 and SW2 are provided between the first operational amplifier 54 and the attachment terminals T1 and T2 of the working electrodes 18 and 22, respectively. The switches SW1 and SW2 connect the power supply unit 58 and the working electrodes 18 and 22. When any one of the switches SW1 and SW2 is turned on, a predetermined voltage can be applied to the selected working electrodes 18 and 22.

  The current-voltage conversion circuit 56 includes a second operational amplifier, and the output terminal of the second operational amplifier is connected to the second measurement unit 60. A feedback resistor is connected between the output terminal and the negative terminal of the second operational amplifier. Furthermore, the attachment terminals T3 to T5 of the counter electrodes 20, 24a, 24b are connected to the negative terminal of the second operational amplifier. If the + terminal of the second operational amplifier is connected to the ground, the − terminal becomes virtual ground, a current flows through the feedback resistor, and a voltage corresponding to this current appears at the output terminal of the second operational amplifier. In addition, the + terminal of the second operational amplifier may be fixed to a predetermined potential instead of ground. For example, when the second operational amplifier is a single power supply operational amplifier, the negative power supply voltage is common with the ground, so that the voltage is ½ of the reference voltage of the A / D conversion circuits A / D0, A / D1, and A / D2. Set to input. The current-voltage conversion circuit 56 converts the current flowing between the electrodes into a voltage.

  A / D conversion circuits A / D0, A / D1, and A / D2 are provided between the current-voltage conversion circuit 56 and the second measurement unit 60. The voltage output from the current-voltage conversion circuit 56 is converted into a digital value so that the microcomputer 52 can perform data processing.

  Switches SW3-SW5 are provided between the current-voltage conversion circuit 56 and the attachment terminals T3-T5 of the counter electrodes 20, 24a, 24b. The switches SW3 to SW5 connect the second measuring unit 60 and the counter electrodes 20, 24a, and 24b. When the switches SW3 to SW5 are turned on, the current flowing through the selected counter electrodes 20, 24a, 24b can be measured.

  The present invention includes a check circuit 70 that determines whether or not the biosensor 12 is inserted into the measurement display device 50 and the type of the biosensor 12. The check circuit 70 includes a first check circuit 72 and a second check circuit 74 (see FIGS. 4 and 5).

  The insertion of the biosensor 12 into the measurement display device 50 in the description is that the terminal 34 and the terminals T1 to T6 are connected, and the measurement display device 50 and the biosensor 12 are electrically connected.

  The first check circuit 72 detects the presence or absence of insertion of the biosensor 12 by detecting a constant voltage source Vcc1 that outputs a constant voltage and a high level voltage or a low level voltage of the potential of the check electrode 40. Unit 76 and a first resistor R1 provided between the constant voltage source Vcc1 and the first check unit 76. The first resistor R1 is to keep the output of the constant voltage source Vcc1 at an appropriate level, and is about 50 kΩ, for example. Further, when selecting the first check circuit 72, a switch SW7 for connecting the detection working electrode 22 to the ground is provided.

  The second check circuit 74 includes a constant voltage source Vcc2 that outputs a constant voltage, a first measuring unit 78 that measures the potential of the check electrode 40, and a first voltage connected in series between the constant voltage source Vcc2 and the ground. 2 resistance R2 and 3rd resistance R3 are provided. A connection terminal between the second resistor R2 and the third resistor R3 is connected to the check electrode 40. The second resistor R2 and the third resistor R3 are for biasing the analog / digital conversion circuit A / D3 to an appropriate level. For example, the second resistor R2 is about 50 kΩ, and the third resistor R3 is about 50 kΩ. In addition, digital data is input to the first measurement unit 78 by the analog / digital conversion circuit A / D3.

  The second check circuit 74 includes a second check unit 80 that determines the type of the biosensor 12 or the presence or absence of the biosensor 12 from the potential measured by the first measurement unit 78. The second check unit 80 is connected to the first measurement unit 78.

  It is necessary to bias the analog / digital conversion circuit A / D3 to a constant potential. Although the second resistor R2 and the third resistor R3 are provided in FIG. 1, only one of them may be used as long as it can be biased to a constant potential.

  The first check circuit 72 and the second check circuit 74 are provided with the constant voltage sources Vcc1 and Vcc2, respectively, but may be the same or may be independent. However, the output voltage of the constant voltage source Vcc1 of the first check circuit 72 needs to match the high level voltage of the check electrode 40. The output voltage of the constant voltage source Vcc2 of the second check circuit 74 needs to be equal to or lower than the reference voltage of the analog / digital conversion circuit A / D3.

  Switches SW6 and SW8 are provided between the first and second check units 76 and 80 and the check electrode 40, and the first check circuit 72 and the second check circuit 74 are selected by selecting the switches SW6 and SW8. When the second check circuit 74 is selected, the detection working electrode 22 is connected to the first operational amplifier 54. Therefore, according to the selection of the switches SW1 and SW7, the ground is selected in the case of the first check circuit 72, the first operational amplifier 54 is selected in the case of the second check circuit 74, and a predetermined voltage is output from the power supply unit 58. .

  The controller 66 controls on / off of the switches SW1 and SW6 to 8 and selection of the first check unit 76 or the second check unit 80 and the power supply unit 58. If the first check circuit 72 is selected, the result is as shown in FIG. 4, and if the second check circuit 74 is selected, the result is as shown in FIG.

  In addition, the measurement display device 50 includes a housing that houses the circuit shown in FIG. 1, a memory that stores various data, operation buttons, and a display that displays substrate component amounts and operation statuses.

  As described above, the two types of check circuits 72 and 74 are provided. The selection method will be described with reference to the flowchart of FIG. 6 from the insertion of the biosensor 12 until the measurement is completed and removed.

  (1) The insertion of the biosensor 12 into the measurement display device 50 is determined (S1, S2). In this case, the control unit 66 turns on the switches SW6 and SW7 so as to be the first check circuit 72, and turns off the other switches. In this case, the potential V1 of the check electrode 40 (or the terminal INT1) is expressed by Equation 1. In Equation 1, Vcc1 is the output voltage of the constant voltage source Vcc1. The other values are the resistance values of the respective resistors Rx and R1.

  The first check unit 76 determines a high level voltage and a low level voltage according to the level of the potential V1. For example, a case where Vcc1 × 0.8V or higher is a high level voltage and a case where Vcc1 × 0.2V or lower is set is a low level voltage. If the check resistor Rx is sufficiently smaller than the first resistor R1, the potential V1 becomes a low level voltage. If the working electrode 22 for detection and the check electrode 40 are open (Rx = ∞), V1 becomes a high level voltage, and if the biosensor 12 is inserted (Rx << R1), V1 becomes a low level voltage. . The presence or absence of insertion of the biosensor 12 can be detected by the potential V1.

  When the biosensor 12 having a completely different shape is inserted and the positions of the terminal 34 and the terminals T1 to T6 do not coincide with each other, the gap between the detection working electrode 22 and the check electrode 40 is opened. In this case, since the potential V1 becomes a high level voltage, it is the same as the case where the biosensor 12 is not inserted, and the process cannot proceed to the next step. Misplacement of the biosensor 12 can be prevented.

  (2) After the insertion determination of the biosensor 12, the type of the biosensor 12 is determined (S3, S4). In this case, the control unit 66 turns on the switches SW1 and SW8 so as to be the second check circuit 74, and turns off the other switches. In this case, the potential AD3 of the check electrode 40 (or A / D3) can be expressed by Equation 2.

  In Equation 2, Vx is the potential of the output terminal of the first operational amplifier 54, and Vcc2 is the output voltage of the constant voltage source Vcc2. The other values are the resistance values of the respective resistors Rx, R2, and R3. A predetermined voltage is output from the power supply unit 58, and the potential Vx of the output terminal of the first operational amplifier 54 becomes a fixed value. The check resistance Rx is made different for each type of biosensor 12. In equation 2, the resistance Rx is unknown, and other resistance values are fixed values. As the type of the biosensor 12 changes, the output potential AD3 of the analog / digital conversion circuit A / D3 measured by the first measurement unit 78 changes. By this change, the second check unit 80 can determine the type of the biosensor 12.

  For example, when the check electrode 40 is pulled down, and R2 = ∞ and R3 = 50 kΩ, Expression 2 becomes Expression 3.

  Here, the potential AD3 when the biosensor 12 with Rx of 0Ω is inserted and when the biosensor 12 with 500Ω is inserted is expressed by Equations 4 and 5.

  A difference occurs in the potential AD3, and the biosensor 12 can be determined if the second check circuit 80 has a resolution capable of determining the difference. If the type of the biosensor 12 can be discriminated, it is possible to shift to the measurement of the amount of the substrate component of the specimen according to the type of the biosensor 12.

  When the biosensor 12 is not inserted, Rx = ∞ and the potential AD3 is 0V. It is understood that the biosensor 12 has dropped out during the discrimination of the type of the biosensor 12, and the process does not proceed to the measurement of the substrate component amount.

  (3) After discriminating the type of the biosensor 12, the operator drops the sample on the biosensor 12, and the detection unit 62 detects inhalation of the sample (S5). In the inhalation of the specimen, the start of inhalation of the specimen is detected by the detection working electrode 22 and the detection counter electrode 24a, and the completion of the inhalation of the specimen is detected by the detection working electrode 22 and the detection counter electrode 24b. These detections are performed by generating a potential difference between the electrodes and detecting a current flow. This is because a current flows if the sample is inhaled into the reaction unit 26. The potential difference between the electrodes is changed depending on the type of biosensor 12 obtained in (2) above.

  In order to prevent the specimen from being spotted on the biosensor 12 at the time point (1) or (2) above, a display prompting the spotting of the specimen on the display of the measurement display device 50 at the time point (2) is completed. You may do.

  (4) If the inhalation of the sample can be confirmed, it waits for a certain time (S6). This is because the amount of the substrate component is inspected after the enzyme in the reaction section 26 and the sample have sufficiently reacted.

  During this waiting time, it is inspected whether or not the biosensor 12 has dropped out (S7, S8). At this time, the switches SW1 and SW8 are turned on so that the second check circuit 74 is obtained. The change of the potential AD3 of the check electrode 40 detects the drop of the biosensor 12. The change in the potential AD3 is the same as that described in (2) above. If the biosensor 12 falls off for some reason, the gap between the detection working electrode 22 and the check electrode 40 is opened, and the potential AD3 becomes 0 V from Equation 3. If the insertion state of the biosensor is maintained, Rx becomes a predetermined value, and the potential AD3 becomes a predetermined potential. The second check unit 80 can determine whether or not there is a dropout based on the presence or absence of this potential.

  If it is determined that the biosensor 12 is missing, the subsequent processing is not performed. This is because the specimen is spotted on the biosensor 12 and the biosensor 12 needs to be replaced.

  When the first check circuit 72 is set, the potential of the terminal T1 is forcibly set to the ground potential. Although temporarily, the potential is different from the terminal potential at the time of measurement, the current at the time of sample inhalation may be adversely affected. Therefore, after determining the type of the biosensor 12, the second check circuit 74 is selected instead of the first check circuit 72 until the measurement of the substrate component amount is completed.

  (5) After a certain period of time, a potential difference is generated between the measuring working electrode 18 and the measuring counter electrode 20 to measure the amount of the substrate component of the specimen (S9). Since a current corresponding to the substrate component amount flows to the reaction unit 26, the substrate component amount is measured by measuring the current. The potential difference between the electrodes is changed depending on the type of biosensor 12 obtained in (2) above. Further, the calculation unit 64 performs calculation using the measured potential according to the type of the biosensor 12, and obtains the amount of the substrate component.

  During the measurement of the amount of the substrate component, it is inspected whether the biosensor 12 has dropped out (S10 to S13). At this time, if the measurement current flowing from the measurement working electrode 18 to the measurement counter electrode 20 can be measured, it is understood that the biosensor 12 is not dropped. Note that the measurement current is measured using the current-voltage conversion circuit 56, and thus the second measurement unit 60 measures the voltage value instead of the current value.

  When the measurement current cannot be measured for a certain time and the output from the current-voltage conversion circuit 56 becomes 0 V, the switches SW1 and SW8 are turned on so as to become the second check circuit 74. If the biosensor 12 is missing for some reason, Rx = ∞ and Equation 3 becomes DA3 = 0V. The dropout of the biosensor 12 can be detected. If the biosensor 12 has fallen off, the measurement is stopped. This is because the biosensor 12 needs to be replaced.

  (6) If the biosensor 12 is not dropped and the substrate component amount is measured to the end, the substrate component amount is displayed on the measurement display device 50 (S14). In addition, the substrate component amount data is stored in a memory.

  (7) When the process up to (6) is completed, the biosensor 12 is removed from the measurement display device 50. To confirm removal of the biosensor 12, the switches SW6 and SW7 are turned on so as to become the first check circuit 72 (S15). The presence or absence of the biosensor 12 is the same as the method (1). If the potential V1 becomes a high level voltage, it is understood that the biosensor 12 has been removed (S16). After the potential V1 becomes a high level voltage, the power of the measurement display device 50 is turned off. If the electric potential V1 is a low level voltage, the power supply of the measurement display apparatus 50 is maintained.

  The check resistors Rx (1) to (7) have been described on the assumption that some resistance value exists, but the resistance value may be 0Ω as shown in FIG. In this case, Rx of each numerical formula is set to 0, and the steps (1) to (7) proceed.

  As described above, according to the present invention, the first check circuit 72 and the second check circuit 74 can be appropriately selected to determine the presence / absence of the biosensor 12 and the type of the biosensor 12. Substrate component amount can be measured accurately and re-measurement can be prevented.

  As mentioned above, although this invention was demonstrated, this invention is not limited to said embodiment. For example, it is not necessary to turn on all the functions of the measurement display device 50. All functions may be turned on after the step (1) is completed. That is, as shown in FIG. 4, only the first check circuit 72 is initially activated to detect insertion of the biosensor 12. After detecting the insertion of the biosensor 12, other means are activated. Since all the functions are not turned on suddenly, power is saved.

  Although the check electrode 40 and the detection working electrode 22 are connected by the check resistor Rx or a short circuit, the measurement working electrode 18 may be used instead of the detection working electrode 22. The check electrode 40 and the measuring working electrode 18 are connected by a check resistor Rx or a short circuit. The switch SW7 and the ground are connected to the measuring working electrode 18.

  The first check circuit 72 and the second check circuit 74 use the counter electrodes 18 and 20 and the first operational amplifier 14 included in the conventional measuring apparatus 100, but may be completely independent circuits.

  Although the second check unit 74 determines the type of the biosensor 12 and whether or not the biosensor 12 is inserted, the determination of the type of the biosensor 12 and the determination of whether or not the biosensor 12 is inserted may be divided into different means. . Each part of the microcomputer 52 may be appropriately combined or separated according to the design of software or hardware.

  If the positions of the terminal 34 and the terminals T1 to T5 match, the conventional biosensor 102 may be connected to the measurement display device 50 of the present invention so that the amount of the substrate component of the specimen can be measured. In this case, the control unit 66 does not operate the first check circuit 72 and the second check circuit 74. The switches SW1 to SW5, the power supply unit 58, the second measurement unit 60, the detection unit 62, and the calculation unit 64 are operated as in the conventional case. The measurement display device 50 is provided with a button for selecting the biosensor 12 of the present invention and the conventional biosensor 102, and the control unit 66 performs control according to the selection of the button.

  In addition, the present invention can be carried out in a mode in which various improvements, modifications, and changes are added based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

10: Measurement device for substrate component 12: Biosensor 16: Substrate 18: Working electrode for measurement 20: Counter electrode for measurement 22: Working electrode for detection 24a, 24b: Counter electrode for detection 26: Reaction unit 28: Cover 30: Spacer 32: Opening 34: Terminal 40: Check electrode 50: Measurement display device 52: Microcomputer 54: First operational amplifier 56: Current / voltage conversion circuit 58: Power supply unit 60: Second measurement unit 62: Detection unit 64: Calculation unit 66 Control unit 70: check circuit 72: first check circuit 74: second check circuit 76: first check unit 78: first measurement unit 80: second check unit

Claims (6)

A device for measuring the amount of a substrate component of a specimen, comprising a biosensor and a measurement display device to which the biosensor is attached,
The biosensor is
An insulating substrate;
A working electrode provided on the substrate;
A counter electrode provided at a fixed interval with respect to the working electrode;
A reaction part containing an enzyme covering the working electrode and the counter electrode;
A check electrode connected or short-circuited to the working electrode via a resistor;
With
The measurement display device is
A mounting terminal for the working electrode;
A mounting terminal for the counter electrode;
A mounting terminal for the check electrode;
Means for applying a voltage between the working electrode and the counter electrode;
Means for measuring a current flowing between the working electrode and the counter electrode;
A check circuit that applies a constant voltage to the check electrode mounting terminal, and determines whether the biosensor is connected to the working electrode mounting terminal and the counter electrode mounting terminal and the type of the biosensor according to the potential of the check electrode; ,
A device for measuring the amount of a substrate component of a specimen comprising: The check circuit is
A first check circuit for detecting a high level voltage or a low level voltage from the potential of the check electrode;
A second check circuit for detecting a potential value of the check electrode;
The apparatus for measuring the amount of a substrate component according to claim 1 comprising: The first check circuit comprises:
Means for outputting the constant voltage;
Means for detecting a high level voltage or a low level voltage from the potential of the check electrode;
With
The second check circuit includes:
Means for outputting the constant voltage;
Means for detecting the value of the potential of the check electrode;
With
The first check circuit or the second check circuit is selected by selecting a plurality of switches,
When the first check circuit is selected, the working electrode is connected to ground;
3. The substrate component amount measuring apparatus according to claim 2, wherein when the second check circuit is selected, the working electrode is connected to means for applying a voltage. 4. The substrate component amount measuring apparatus according to claim 2, wherein only the first check circuit operates until the first check circuit detects connection of a biosensor. A biosensor for measuring the amount of a substrate component of a specimen,
An insulating substrate;
A working electrode provided on the substrate;
A counter electrode provided at a fixed interval with respect to the working electrode;
A reaction part containing an enzyme covering the working electrode and the counter electrode;
A check electrode connected or short-circuited to the working electrode via a resistor;
Biosensor equipped with. An insulating substrate;
A working electrode provided on the substrate;
A counter electrode provided at a fixed interval with respect to the working electrode;
A reaction part containing an enzyme covering the working electrode and the counter electrode;
A check electrode connected or short-circuited to the working electrode via a resistor;
A measurement display device to which a biosensor for measuring the amount of a substrate component of a specimen is attached,
A mounting terminal for the working electrode;
A mounting terminal for the counter electrode;
A mounting terminal for the check electrode;
Means for applying a voltage between the working electrode and the counter electrode;
Means for measuring a current flowing between the working electrode and the counter electrode;
A check circuit that applies a constant voltage to the check electrode mounting terminal, and determines whether the biosensor is connected to the working electrode mounting terminal and the counter electrode mounting terminal and the type of the biosensor according to the potential of the check electrode; ,
A measurement display device comprising:

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