METHOD FOR MEASURING HEMATOCRIT VALUE OF BLOOD SAMPLE, METHOD FOR MEASURING CONCENTRATION OF ANALYTE IN BLOOD SAMPLE, SENSOR CHIP AND SENSOR UNIT

• US 20100243476A1
• Filed: 10/17/2007
• Published: 09/30/2010
• Est. Priority Date: 10/19/2006
• Status: Active Grant

• Current Assignee: PHC Holdings Corporation
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Nakaminami, Takahiro, Fujiwara, Masaki, Ikeda, Shin
• Granted Patent: US 8,691,072 B2
• Time in Patent Office: Days
• US Class Current: 205/777.500
• CPC Class Codes: G01N 27/3272 Test elements therefor, i.e. disposable laminated substrates with electrodes, reagent and channels optical biosensors G01N33/52
• CPC Class Codes: G01N 27/3274 Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771
• CPC Class Codes: G01N 27/413 Concentration cells using liquid electrolytes measuring currents or voltages in voltaic cells

Abstract

Voltage is applied across a counter electrode and a working electrode, with which a blood sample is in contact, in such a state that an oxidant in a redox substance is not substantially in contact with a working electrode but is in contact with a counter electrode and a reductant is not substantially in contact with the counter electrode but is in contact with the working electrode, whereby the reductant and the oxidant are respectively oxidized and reduced to measure current produced upon the oxidation and reduction. According to the above constitution, while lowering the voltage applied across the working electrode and the counter electrode, the Hct value of the blood sample can be measured stably with a satisfactory detection sensitivity. This measurement can be carried out with a sensor chip comprising a working electrode (11), a counter electrode (12), and a blood sample holding part (14) having branch parts (18a, 18b). A first reagent (13) consisting essentially of an oxidant in a redox substance is disposed in contact with the surface of a counter electrode which faces the branch part (18b), and a second reagent (19) consisting essentially of a reductant is disposed in contact with the surface of a working electrode that faces the branch part (18a).

Claims

1. A method for electrochemically measuring a hematocrit value of a blood sample, the method comprising:

applying a voltage across a working and a counter electrode in contact with the blood sample;

detecting a resulting current flown between the working electrode and the counter electrode; and

calculating a hematocrit value of the blood sample based on the current,

wherein the voltage is applied across the working electrode and the counter electrode while an oxidant of a redox substance is in contact with the counter electrode and substantially not in contact with the working electrode, and a reductant of the redox substance in contact with the working electrode and substantially not in contact with the counter electrode, and

wherein the current is detected by measuring a current that results from the oxidation of the reductant and the reduction of the oxidant caused by the voltage application.

2. The method according to claim 1, wherein the voltage applied across the working electrode and the counter electrode is 3.0 V or less, when the working electrode is anode and the counter electrode is cathode.

3. The method according to claim 2, wherein the voltage is 1.0 V or less.

4. The method according to claim 3, wherein the voltage is 0.5 V or less.

5. The method according to claim 1, wherein the oxidant is a ferricyanide.

6. (canceled)

7. A method for electrochemically measuring a concentration of an analyte in a blood sample, the method comprising:

electrochemically detecting a current A reflecting a hematocrit value of the blood sample so as to obtain data A representing the current A or an equivalent of the current A and corresponding to the hematocrit value;

electrochemically detecting a current B that results from the oxidation or reduction of the analyte in the blood sample caused, in the presence of a redox substance, by a redox enzyme that uses the analyte as a substrate, so as to obtain data B representing the current B or an equivalent of the current B; and

determining a concentration of the analyte in the blood sample based on data C obtained by correcting the data B using the data A,

wherein the current A is detected by detecting a current that results from the oxidation of a reductant and the reduction of an oxidant of the redox substance caused by application of a voltage across a working electrode and a counter electrode, the voltage being applied while the oxidant of the redox substance is in contact with the counter electrode and substantially not in contact with the working electrode, and the reductant of the redox substance in contact with the working electrode and substantially not in contact with the counter electrode.

8. A sensor chip comprising a hematocrit value analyzer that electrochemically detects a current reflecting a hematocrit value of a blood sample,

wherein the hematocrit value analyzer includes:

a working electrode and a counter electrode;

a blood sample holder for holding the blood sample in contact with the working electrode and the counter electrode; and

a blood sample inlet through which the blood sample is introduced into the blood sample holder, and

wherein a first reagent containing an oxidant of a redox substance and substantially not containing a reductant of the redox substance is disposed to cover a surface of the counter electrode facing the blood sample holder, and wherein a second reagent containing the reductant and substantially not containing the oxidant is disposed to cover a surface of the working electrode facing the blood sample holder.

11. The sensor chip according to claim 8, wherein the oxidant is a ferricyanide, and wherein the reductant is a ferrocyanide.

12. A sensor unit comprising a sensor chip of claim 8, and a sensor main body including a voltage applying circuit for applying a predetermined voltage across the working electrode and the counter electrode,

wherein the sensor chip is detachable with respect to the sensor main body, and the voltage applying circuit is capable of applying a predetermined voltage across the working electrode and the counter electrode with the sensor chip attached to the sensor main body, and

wherein the predetermined voltage is 3.0 V or less, when the working electrode is anode and the counter electrode is cathode.

13. The sensor unit according to claim 12, wherein the predetermined voltage is 1.0 V or less.

14. The sensor unit according to claim 13, wherein the predetermined voltage is 0.5 V or less.

9. A sensor chip comprising a hematocrit value analyzer that electrochemically detects a current reflecting a hematocrit value of a blood sample,

wherein the hematocrit value analyzer includes:

a working electrode and a counter electrode;

a blood sample holder for holding the blood sample in contact with the working electrode and the counter electrode; and

a blood sample inlet through which the blood sample is introduced into the blood sample holder,

wherein the blood sample holder includes an inlet portion in communication with the blood sample inlet; and

a first and a second branch portion branching out of the inlet portion, the first branch portion facing the counter electrode, and the second branch portion facing the working electrode,

wherein a first reagent containing an oxidant of a redox substance and substantially not containing a reductant of the redox substance is disposed on the first branch portion, and

wherein a second reagent containing the reductant and substantially not containing the oxidant is disposed on the second branch portion.

10. A sensor chip comprising a hematocrit value analyzer that electrochemically detects a current reflecting a hematocrit value of a blood sample,

wherein the hematocrit value analyzer includes:

a working electrode and a counter electrode;

a blood sample holder for holding the blood sample in contact with the working electrode and the counter electrode; and

a blood sample inlet through which the blood sample is introduced into the blood sample holder,

wherein the blood sample holder includes a first reagent, disposed on the blood sample holder, containing an oxidant of a redox substance and substantially not containing a reductant of the redox substance, and a second reagent, disposed on the blood sample holder, containing the reductant and substantially not containing the oxidant,

wherein one of the first reagent and the second reagent is disposed on the upstream side of the other reagent with respect to a flow of the blood sample introduced into the blood sample holder through the blood sample inlet;

(a) wherein, when the other reagent is the first reagent, the counter electrode is disposed on the downstream side of the working electrode with respect to the flow of the blood sample, and the first reagent is disposed to cover a surface of the counter electrode facing the blood sample holder, the working electrode is disposed on the upstream side of the counter electrode with respect to the flow of the blood sample, and the second reagent is separately disposed from the working electrode on the upstream side of the working electrode with respect to the flow of the blood sample, or disposed in contact with the working electrode;

(b) when the other reagent is the second reagent, the working electrode is disposed on the downstream side of the counter electrode with respect to the flow of the blood sample, and the second reagent is disposed to cover a surface of the working electrode facing the blood sample holder, the counter electrode is disposed on the upstream side of the working electrode with respect to the flow of the blood sample, and the second reagent is separately disposed from the counter electrode on the upstream side of the counter electrode with respect to the flow of the blood sample, or disposed in contact with the counter electrode.