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

• US 20100276303A1
• Filed: 10/17/2007
• Published: 11/04/2010
• Est. Priority Date: 10/19/2006
• Status: Abandoned Application

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Ikeda, Shin, Takasu, Takahiro, Nakaminami, Takahiro, Fujiwara, Masaki
• Application Number:
  US12/377,497
• Publication Number:
  US 20100276303A1
• Time in Patent Office: Days
• US Class Current: 205/792
• CPC Class Codes: G01N 27/3274 Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771

Abstract

A voltage is applied across a counter electrode and a working electrode while an oxidant of a redox substance is in contact with the counter electrode and is not substantially in contact with the working electrode, and thereby metal that readily undergoes electrolytic oxidation forming at least part of a surface of the working electrode is oxidized while the oxidant in contact with the working electrode is reduced, such that a current produced upon the oxidation and the reduction is measured. According to the above constitution, while lowering the voltage applied across the working electrode and the counter electrode, a hematocrit value of a blood sample can be measured stably with satisfactory detection sensitivity. This measurement can be carried out, for example, with a sensor chip comprising a working electrode 11, a counter electrode 12, and a blood sample holder 14 in communication with a blood sample inlet 16, wherein a portion 31 of the working electrode 11 is disposed closer to the blood sample inlet 16 than a portion 32 of the counter electrode is, a surface of the portion 31 includes the metal that readily undergoes electrolytic oxidation, and a reagent 13 containing the oxidant is disposed in contact with the portion 32.

Claims

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

applying a voltage across a working electrode and a counter electrode in contact with the blood sample while an oxidant of a redox substance is in contact with the counter electrode and is not substantially in contact with the working electrode;

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

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

wherein at least part of a surface of the working electrode is in contact with the blood sample and is composed of a material including metal that readily undergoes electrolytic oxidation,

wherein the voltage applied across the working electrode and the counter electrode causes reduction of the oxidant and oxidation of the metal that readily undergoes electrolytic oxidation, and

wherein the current is detected by measuring a current that results from the oxidation and the reduction.

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. The method according to claim 1, wherein the metal that readily undergoes electrolytic oxidation is at least one metal selected from silver, copper, and nickel.

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 a voltage is applied across the working electrode and the counter electrode in contact with the blood sample while an oxidant of the redox substance is in contact with the counter electrode and is substantially not in contact with at least part of a surface of the working electrode,

wherein the voltage causes reduction of the oxidant and oxidation of metal that readily undergoes electrolytic oxidation forming the at least part of the surface of the working electrode, and

wherein the current A is detected by measuring a current flowing between the working electrode and the counter electrode that results from the oxidation and the reduction.

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,

wherein at least part of a surface of the working electrode facing the blood sample holder is composed of a material including metal that readily undergoes electrolytic oxidation, and

wherein an oxidant of a redox substance is disposed in contact with a surface of the counter electrode facing the blood sample holder or is disposed in the vicinity of the surface of the counter electrode.

9. The sensor chip according to claim 8, wherein the working electrode is disposed on the upstream side of the counter electrode with respect to a flow of a blood sample introduced from the blood sample inlet to the blood sample holder, and the oxidant is disposed between the at least part of the surface of the working electrode and the surface of the counter electrode or is disposed in contact with the surface of the counter electrode.

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

12. The sensor chip according to claim 8, wherein the metal that readily undergoes electrolytic oxidation is at least one metal selected from silver, copper, and nickel.

13. The sensor chip according to claim 8, further comprising a film of a water soluble polymer, wherein the film covers the at least part of the surface of the working electrode so as to isolate the at least part of the surface from outside air.

14. A sensor unit comprising:

the sensor chip according to 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, 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.

15. The sensor unit according to claim 14, wherein the predetermined voltage is 1.0 V or less.

16. The sensor unit according to claim 15, wherein the predetermined voltage is 0.5 V or less.

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;

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 at least part of a surface of the working electrode facing the second branch portion is composed of a material including metal that readily undergoes electrolytic oxidation, and

wherein an oxidant of a redox substance is disposed at the first branch portion while being in contact with a surface of the counter electrode facing the first branch portion or while being separated from the surface of the counter electrode.