Electrochemical biosensor

• US 20050000808A1
• Filed: 02/12/2004
• Published: 01/06/2005
• Est. Priority Date: 06/09/2003
• Status: Active Grant

• Current Assignee: i-SENS, Inc.
• Original Assignee: i-SENS, Inc.
• Inventors: Kim, Ju-Yong, Cui, Gang, Nam, Hakhyun, Yoo, Jae-Hyun, Cha, Geun-Sig, Uhm, Jung-Hee, Kim, Moon-Hwan
• Granted Patent: US 7,288,174 B2
• Time in Patent Office: Days
• US Class Current: 204/403.140
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: C12Q 1/004 mediator-assisted

Abstract

There is provided the reagent layer composition that can substantially reduce the measurement bias arising from hematocrits. The addition of fatty acid (4-20 carbons) and quaternary ammonium salt to a commonly used reagent layer composition composed of an enzyme, an electron transfer mediator, and several water soluble polymers not only reduce the hematocrit level-dependent bias but also provide very stable performance for an extended period of time. Disclosed are also various types of sub microliter sample volume electrochemical biosensors that are suitable to use with the reagent layer composition of present invention.

Claims

1. An electrochemical biosensor comprising:

a lower substrate;

an upper substrate;

a working electrode and a reference (or counter) electrode respectively formed on either the lower substrate or the upper substrate;

a reaction layer containing enzyme, electron transfer mediator, water soluble polymers and a fatty acid or its salt formed over the working electrode; and

a spacer formed between the lower and the upper substrates, wherein the spacer is provided with a cut out pattern of a sample introducing bay, an air discharge channel, and a void at the cross of sample introducing bay and air discharge channel.

2. The biosensor according to claim 1, wherein the working electrode and the reference electrode are formed on the same substrate.

3. The biosensor according to claim 1, wherein the working electrode and the reference electrode are formed on the different substrate.

4. The biosensor according to claim 1, further comprising a fluidity determining electrode on the lower substrate.

5. The biosensor according to claim 1, wherein the fatty acid or its salt has an alkyl chain of 4˜

20 carbons and is added in a range of 0.1 to 20 weight percent of all components.

6. The biosensor according to claim 1, wherein the fatty acid is selected from the group consisting of saturated fatty acid, caproic acid, heptanoic acid, caprylic acid, nonanoic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nonadecanoic acid, and arachidic acid.

7. The biosensor according to claim 1, wherein said fatty acid results in the effect of reducing the measurement bias arising from the hematocrits.

8. The biosensor according to claim 1, wherein said reaction layer further contains quaternary ammonium salt in 0.1-30 wt % of all components.

9. The biosensor according to claim 8, wherein the quaternary ammonium salt is selected from the group consisting of the halide compounds of dodecyltrimethylammonium, myristyltrimethylammonium, cetyltrimethylammonium, octadecyltrimethylammonium and tetrahexylammonium.

10. The biosensor according to claim 1, wherein the enzyme is selected from the group consisting of glucose oxidase, glucose dehydrogenase, cholesterol oxidase, cholesterol esterase, lactate oxidase, ascorbic acid oxidase, alcohol oxidase, alcohol dehydrogenase, and bilirubin oxidase.

11. The biosensor according to claim 1, wherein the electron transfer mediator is selected from the group consisting of hexaamineruthenium (III) chloride, potassium ferricyanide, potassium ferrocyanide, dimethylferrocene, ferricinium, ferocene-monocarboxylic acid, 7,7,8,8-tetracyanoquinodimethane, tetrathiafulvalene, nickelocene, N-methylacidinium, tetrathiatetracene, N-methylphenazinium, hydroquinone, 3-dimethylaminobenzoic acid, 3-methyl-2-benzothiozolinone hydrazone, 2-methoxy-4-allylphenol, 4-aminoantipyrin, dimethylaniline, 4-aminoantipyrene, 4-methoxynaphthol, 3,3′

, 5,5′

-tetramethylbenzidine, 2,2-azino-di-[3-ethylbenzthiazoline sulfonate], o-dianisidine, o-toluidine, 2,4-dichloro phenol, 4-aminophenazone, and benzidine and Prussian blue.

12. The biosensor according to claim 11, wherein the electron transfer mediator is hexaamineruthenium (III) chloride.

13. The biosensor according to claim 1, wherein the water soluble polymers are used to disperse and stabilize the enzyme and selected from the group consisting of polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), perfluoro sulfonate, hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), carboxy methyl cellulose (CMC), cellulose acetate, dextran, and polyamide.

14. The biosensor according to claim 1, wherein the ratio of the width of the air discharge channel to that of the sample introducing bay is no more than 1:

2.

15. The biosensor according to claim 1, wherein the sample introducing bay has a capacity to hold 0.1-1.0 μ

l of liquid sample.

16. The biosensor according to claim 1, wherein the sample introducing bay is crossed with the air discharge channel at an angle of 75-105°

and the void is provided from the crossing point to the bay end.

17. The biosensor according to claim 4, wherein the fluidity determining electrode is used to correct the hematocrit level-dependent measurement bias.

18. The biosensor according to claim 1, further comprising a viewing window on the upper substrate, which is located at the crossing cover of the sample channel