Electrochemical biosensor by screen printing and method of fabricating same

• US 20050183953A1
• Filed: 02/23/2004
• Published: 08/25/2005
• Est. Priority Date: 02/23/2004
• Status: Active Grant

• Current Assignee: General Life Biotechnology Co., Ltd.
• Original Assignee: General Life Biotechnology Co., Ltd.
• Inventors: Chang, Chia-Wei, Wu, Tai-Guang, Su, Chein-Shyong, Cheng, Wen-Jing, Hung, Miao-Ling
• Granted Patent: US 7,138,041 B2
• Time in Patent Office: Days
• US Class Current: 204/403.10
• CPC Class Codes: G01N 27/3272 Test elements therefor, i.e. disposable laminated substrates with electrodes, reagent and channels optical biosensors G01N33/52

Abstract

An electrochemical biosensor formed by screen printing and method of fabricating such biosensor is disclosed in the present invention. The biosensor can quickly absorb a sample to be measured therein, effectively control volume of the sample fed and “fill-and-position” the sample therein. The biosensor includes an electrode layer (electrode area) comprising two or three electrodes, which are a working electrode, a reference electrode and an auxiliary electrode (tri-electrode) on an insulating substrate. An active reaction layer containing reactant, reaction catalyst, mediator, wetting agent and surfactant is spread on the surface of the electrode layer. A sample inflow area is formed above the electrode area by adding an upper cover on top of a middle insulating layer with a U-shaped opening formed therein. Sample solution with a minute amount about 0.8 to 1 μl can be rapidly introduced into the electrode area and the active reaction layer via the inflow area by siphon or capillary, where the ingredient of the sample can be analysed by measuring reaction between the sample, reaction catalyst and mediator in the reaction layer using electrochemical potentiometric or amperometric method. An upwardly extended closed space formed within the upper cover above the electrode area adjacent to the front of conductive wires can be effectively used to control sample volume and “fill-and-position” the sample.

Claims

1. An electrochemical biosensor, comprising:

an insulating substrate;

a layer of electrically conductive wires disposed on said insulating substrate;

an electrode layer comprising a plurality of electrodes including a reference electrode and at least one electrode, and at least two contact ports adapted to connect to a measuring device, said electrode layer being disposed on said layer of electrically conductive wires except for said reference electrode;

a middle insulating layer disposed on said electrode layers without covering said electrodes and said contact ports, said middle insulating layer having a slot therein above said electrodes;

an active reaction layer having substances of reactant, reaction catalyst, mediator and surfactant spread on the surface of said electrodes and defining an electrode reaction area; and

an upper cover adhered to said middle insulating layer.

said upper cover having an upwardly extended closed chamber therein containing said substances, said chamber being disposed above and in communication with one end of said slot, said slot defining a capillary inflow channel to enable a sample of said substances to be rapidly introduced into and fill said electrode reaction area by capillary action upon contact with a front tip of said capillary inflow channel, said slot being configured to form said sample such that the sample does not extend beyond said chamber along said capillary inflow channel.

2. The electrochemical biosensor according to claim 1, wherein said biosensor is a bi-electrode system and said at least one electrode is a working electrode.

3. The electrochemical biosensor according to claim 1, wherein said biosensor is a tri-electrode system and said at least one electrode includes a working electrode and an auxiliary electrode.

5. The electrochemical biosensor according to claim 1, wherein said slot is T-shaped.

6. The electrochemical biosensor according to claim 1, wherein said insulating substrate is made of material selected from the group consisting of polycarbonate, polyester, polyether, nylon, polyurethane, polyimide, polyvinylchloride (PVC), glass, glass fibre plate, ceramics and polyethylene terephthalate (PET).

7. The electrochemical biosensor according to claim 1, wherein said layer of electrically conductive wires is made of silver.

8. The electrochemical biosensor according to claim 1, wherein said layer of electrically conductive wires is made of silver chloride.

9. The electrochemical biosensor according to claim 1, wherein said layer of electrically conductive wires is made of gold.

10. The electrochemical biosensor according to claim 1, wherein said electrode layer is made of carbon.

11. The electrochemical biosensor according to claim 1, wherein said electrode layer is made of silver.

12. The electrochemical biosensor according to claim 1, wherein said electrode layer is made of gold.

13. The electrochemical biosensor according to claim 1, wherein said electrode layer is made of platinum.

14. The electrochemical biosensor according to claim 1, wherein said reaction catalyst is a bio catalyst.

16. The electrochemical biosensor according to claim 14, wherein said bio catalyst is an enzyme.

17. The electrochemical biosensor according to claim 1, wherein the thickness of said middle insulating layer is between 20 and 400 μ

m.

18. The electrochemical biosensor according to claim 1, wherein the thickness of said middle insulating layer is between 50 and 200 μ

m.

20. The electrochemical biosensor according to claim 5, wherein the length and width of said slot is between 2 and 8 mm and between 0.5 and 5 mm, respectively.

21. The electrochemical biosensor according to claim 1, wherein the volume of said closed chamber is between 0.5 and 4 μ

l.

22. The electrochemical biosensor according to claim 3, wherein said sample can be detected when it is introduced above said working electrode and said auxiliary electrode.

23. The electrochemical biosensor according to claim 1, wherein said biosensor contains a device activation line which can activate said measuring device automatically.

31. The electrochemical biosensor according to claim 1, further comprising a thin plate disposed on top of said upper cover.

4. (canceled)

19. The electrochemical biosensor according to claim 4, wherein the length and width of said slot is between 2 and 8 mm and between 0.5 and 5 mm, respectively.

15. (canceled)

24-26. -26. (canceled)

27. A method of fabricating an electrochemical biosensor, comprising the steps of:

forming a layer of electrically conductive wires on a substrate by screen printing which then is dried between 40°

C. and 120°

C.;

forming an electrode layer on top of said layer of electrically conductive wires by screen printing and drying said substrate between 40°

C. and 120°

C.;

forming a middle insulating layer with a slot formed therein above said electrode layer, wherein a working electrode, a reference electrode and an auxiliary electrode are confined within said slot and the opposite ends of said electrodes are exposed to make contact with a measuring device;

applying an active reaction layer on said slot;

adhering an upper cover formed with an opening therein above said middle insulating layer, wherein said opening is positioned at one end of said slot; and

applying a surface layer above said upper cover,

wherein said opening defines a closed chamber within said upper cover above and in communication with one end of said slot said slot defining a capillary inflow channel such that a sample of substance in said closed chamber can be rapidly introduced into and fill said electrode layer by capillary action upon contact of the substance with a front tip of said capillary inflow channel and said sample is configured by said slot not to go from said chamber beyond said capillary inflow channel.

28. The method of claim 27, wherein said middle insulating layer is formed on top of said electrode layer by screen printing.

29. The method of claim 27, wherein said slot is a T-shaped slot and the transverse opening of said T-shaped slot forms two air vents on opposite sides of said biosensor.

30. The method of claim 27, wherein said middle insulating layer is formed on top of said electrode layer by adhesion.