Biosensor, and a method and a device for quantifying a substrate in a sample liquid using the same

• US 5,650,062 A
• Filed: 09/12/1995
• Issued: 07/22/1997
• Est. Priority Date: 03/17/1995
• Status: Expired due to Term

• Current Assignee: Panasonic Healthcare Holdings Co., Ltd.
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Tokuno, Yoshinobu, Miyazaki, Syoji, Tsutsumi, Haruhiro, Ikeda, Shin, Yoshioka, Toshihiko, Nankai, Shiro, Baba, Hideyuki
• Primary Examiner(s): Bell, Bruce F.
• Application Number:
  US08/526,557
• Time in Patent Office: 679 Days
• Field of Search: 204/403, 204/412, 204/415, 204/418, 205/775, 205/778, 205/777.5, 435/817, 435/288, 435/291
• US Class Current: 205/778
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: Y10S 435/817 Enzyme or microbe electrode

Abstract

The biosensor of this invention can quantify a substrate in a sample liquid by electrochemically measuring the amount of an electron acceptor that has been reduced by electrons generated in a reaction between the substrate and an oxidoreductase. The biosensor has an electrically insulating substrate and an electrode system formed on the substrate including a working electrode, a counter electrode and a third electrode used for detecting a liquid junction. The third electrode can be used merely for detecting a liquid junction, or can be used as both a reference electrode and a liquid junction detecting electrode.

Claims

1. A method for quantifying a substrate in a sample liquid by using a biosensor comprising:

an electrically insulating substrate;

an electrode system formed on the substrate including a working electrode, a counter electrode and a third electrode used for detecting a liquid junction; and

a reaction layer that is formed over at least the working electrode and the counter electrode of the electrode system and includes an oxidoreductase;

wherein the method of quantifying the substrate comprises the steps of;

applying a voltage between the counter electrode and the third electrode;

supplying a sample liquid to the reaction layer;

detecting an electrical change between the counter electrode and the third electrode caused by supplying the sample liquid to the reaction layer;

applying a voltage between the working electrode and both of the third electrode and the counter electrode after detecting the electrical change; and

measuring a current flowing between the counter electrode and the working electrode after applying the voltage.

2. A method for quantifying a substrate according to claim 1, wherein the step of applying a voltage between the counter electrode and both of the third electrode and the counter electrode is conducted while a voltage is continuously applied between the counter electrode and the third electrode.

3. A method for quantifying a substrate in a sample liquid by using a biosensor comprising:

an electrically insulating substrate;

an electrode system formed on the substrate including a working electrode, a counter electrode and a third electrode used for detecting a liquid junction; and

a reaction layer that is formed over at least the working electrode and the counter electrode of the electrode system and includes an oxidoreductase;

wherein the method of quantifying the substrate comprises the steps of;

applying a voltage between the counter electrode and the third electrode;

supplying a sample liquid to the reaction layer;

detecting an electrical change between the counter electrode and the third electrode caused by supplying the sample liquid to the reaction layer;

applying a voltage between the working electrode and the counter electrode after detecting the electrical change; and

measuring a current flowing between the counter electrode and the working electrode after applying the voltage.

4. A method for quantifying a substrate according to claim 3, wherein the step of applying a voltage between the working electrode and the counter electrode is conducted while a voltage is continuously applied between the counter electrode and the third electrode.

5. A quantifying device for a substrate contained in a sample liquid comprising:

a biosensor comprising;

an electrically insulating substrate;

an electrode system formed on the substrate including a working electrode, a counter electrode and a third electrode used for detecting a liquid junction; and

a reaction layer that is formed over at least the working electrode and the counter electrode of the electrode system and includes an oxidoreductase;

wherein the quantifying device additionally comprises;

means for detecting an electrical change between the counter electrode and the third electrode caused by supplying a sample liquid to the reaction layer;

means for applying a voltage between the working electrode and both of the third electrode and the counter electrode after detecting the electrical change; and

means for measuring a current flowing between the working electrode and the counter electrode.

6. A quantifying device according to claim 5, wherein the means for applying a voltage between the working electrode and both of the third electrode and the counter electrode applies the voltage while a voltage is continuously applied between the counter electrode and the third electrode.

7. A quantifying device for a substrate contained in a sample liquid comprising:

a biosensor comprising;

an electrically insulating substrate;

an electrode system formed on the substrate including a working electrode, a counter electrode and a third electrode used for detecting a liquid junction; and

a reaction layer that is formed over at least the working electrode and the counter electrode of the electrode system and includes an oxidoreductase;

wherein the quantifying device additionally comprises;

means for detecting an electrical change between the counter electrode and the third electrode caused by supplying a sample liquid to the reaction layer;

means for applying a voltage between the working electrode and the counter electrode after detecting the electrical change; and

means for measuring a current flowing between the working electrode and the counter electrode.

8. A quantifying device according to claim 7, wherein the means for applying a voltage between the working electrode and the counter electrode applies the voltage while a voltage is continuously applied between the counter electrode and the third electrode.

9. A quantifying device for a substrate contained in a sample liquid, comprising a biosensor comprising:

an electrically insulating substrate;

an electrode system formed on the substrate including a working electrode, a counter electrode and a third electrode used for detecting a liquid junction; and

a reaction layer that is formed over at least the working electrode and the counter electrode of the electrode system and includes an oxidoreductase;

wherein the quantifying device additionally comprises a measuring device to which the biosensor is removably connected,

wherein the measuring device includes;

current/voltage converting circuits connected to the third electrode of the biosensor;

A/D converting circuits connected to the current/voltage converting circuits;

current/voltage converting circuits which connects the working electrode of the biosensor via a switch;

A/D converting circuits connected to the current/voltage converting circuits; and

a controller connected to the respective A/D converting circuits, the switch being turned ON or OFF with respect to the working electrode by a control of the controller, and

wherein an electrical change between the counter electrode and the third electrode, caused by a supply of a sample liquid to the reactive layer, is detected by the control portion under a condition that the switch is insulated from the working electrode, and then a voltage is applied between the working electrode and both of the third electrode and the counter electrode under a condition that the switch is connected to the working electrode and a current flowing between the working electrode and the counter electrode is measured.

10. A quantifying device according to claim 9, wherein the application of a voltage between the working electrode and both of the third electrode and the counter electrode is conducted while a voltage is continuously applied between the counter electrode and the third electrode.

11. A quantifying device for a substrate contained in a sample liquid, comprising a biosensor comprising:

an electrically insulating substrate;

an electrode system formed on the substrate including a working electrode, a counter electrode and a third electrode used for detecting a liquid junction; and

a reaction layer that is formed over at least the working electrode and the counter electrode of the electrode system and includes an oxidoreductase;

wherein the quantifying device additionally comprises a measuring device to which the biosensor is removably connected,

wherein the measuring device includes;

current/voltage converting circuits connected to the third electrode of the biosensor;

A/D converting circuits connected to the current/voltage converting circuits;

current/voltage converting circuits which connects the working electrode of the biosensor via a switch;

A/D converting circuits connected to the current/voltage converting circuits; and

a controller connected to the respective A/D converting circuits, the switch being turned ON or OFF with respect to the working electrode by a control of the controller, and

wherein an electrical change between the counter electrode and the third electrode, caused by a supply of a sample liquid to the reactive layer, is detected by the control portion under a condition that the switch is insulated from the working electrode, and then a voltage is applied between the working electrode and the counter electrode under a condition that the switch is connected to the working electrode and a current flowing between the working electrode and the counter electrode is measured.

12. A quantifying device according to claim 11, wherein the application of a voltage between the working electrode and the counter electrode is conducted while a voltage is continuously applied between the counter electrode and the third electrode.

13. A quantifying device for a substrate contained in a sample liquid, comprising a biosensor comprising:

an electrically insulating substrate;

an electrode system formed on the substrate including a working electrode, a counter electrode and a third electrode used for detecting a liquid junction; and

a reaction layer that is formed over at least the working electrode and the counter electrode of the electrode system and includes an oxidoreductase;

wherein the quantifying device additionally comprises a measuring device to which the biosensor is removably connected,

wherein the measuring device includes;

current/voltage converting circuits switchably connected to the third electrode of the biosensor and the working electrode;

A/D converting circuits connected to the current/voltage converting circuits;

a controller connected to the respective A/D converting circuits, the switch being alternatively connected to the working electrode and the third electrode by a control of the controller, and

wherein an electrical change between the counter electrode and the third electrode, caused by a supply of a sample liquid to the reactive layer, is detected by the control portion under a condition that the switch is connected to the third electrode, and then a voltage is applied between the working electrode and the counter electrode under a condition that the switch is connected to the working electrode and a current flowing between the working electrode and the counter electrode is measured.