Electrochemical test strip with an integrated micro-needle and associated methods

• US 20030150745A1
• Filed: 08/23/2002
• Published: 08/14/2003
• Est. Priority Date: 12/13/2000
• Status: Active Grant

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: Lifescan Incorporated (Duv Holding Corporation)
• Inventors: Teodorczyk, Maria, Leong, Koon-wah, Olson, Lorin P., Yuzhakov, Vadim V., McAllister, Devin, Kiser, Ernest J.
• Granted Patent: US 7,144,495 B2
• Time in Patent Office: Days
• US Class Current: 205/775
• CPC Class Codes: A61B 10/0045 Devices for taking samples of body liquids devices for taking blood samples A61B5/15
• CPC Class Codes: A61B 5/150022 for capillary blood or interstitial fluid
• CPC Class Codes: A61B 5/150358 Strips for collecting blood, e.g. absorbent optical reagent test strips G01N21/8483; chemical reagent test strips G01N33/4875, G01N33/52
• CPC Class Codes: A61B 5/150419 comprising means for capillary action
• CPC Class Codes: A61B 5/150435 Specific design of proximal end
• CPC Class Codes: A61B 5/150511 Details of construction of shaft
• CPC Class Codes: B01L 2300/0672 Integrated piercing tool
• CPC Class Codes: B01L 2300/0825 Test strips
• CPC Class Codes: B01L 2400/0406 capillary forces
• CPC Class Codes: B01L 3/5027 by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip B01L3/5023 takes precedence; micromixers B01F33/30; microreactors for synthesis B01J19/0093; microcapillary devices in general B81B1/00
• CPC Class Codes: B01L 3/502715 characterised by interfacing components, e.g. fluidic, electrical, optical or mechanical interfaces
• CPC Class Codes: G01N 11/00 Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
• CPC Class Codes: G01N 2011/0066 electrical properties
• CPC Class Codes: G01N 27/307 Disposable laminated or multilayered electrodes G01N27/3272 takes precedence
• CPC Class Codes: G01N 33/4905 Determining clotting time of blood by chemical methods G01N33/86, C12Q1/54
• CPC Class Codes: G01N 33/491 by separating the blood components G01N15/05 takes precedence
• CPC Class Codes: G01N 33/5438 Electrodes
• CPC Class Codes: G01N 33/86 involving blood coagulating time or factors, or their receptors

Abstract

Methods and devices for electrochemically detecting a change in the viscosity of a fluid are provided. In the subject methods, a fluid sample (e.g., a whole blood sample) is introduced into an electrochemical test strip'"'"'s electrochemical cell using a micro-needle integrated into one of oppositely spaced apart working and reference electrodes. An electric potential is applied to the electrochemical cell to first achieve a steady state cell current. A decrease in the steady state cell current is then detected and related to a change in viscosity of the sample. In many embodiments, the sample is blood and the change in viscosity is related to the onset of coagulation in the blood sample, and often the PT of the blood sample. An electrochemical test strip includes an electrochemical cell and an integrated micro-needle. The electrochemical cell includes oppositely spaced apart working and reference electrodes and a reagent mixture (e.g., a redox couple and a coagulation catalyzing agent). The micro-needle is integrated into one of the working and reference electrodes of the electrochemical cell.

Claims

1. A method for detecting a change in the viscosity of a fluid sample, said method comprising:

(a) introducing a sample into an electrochemical cell comprising oppositely spaced apart working and reference electrodes, wherein one of the working and reference electrodes includes an integrated micro-needle for obtaining the sample from a user;

(b) applying an electric potential to said electrochemical cell to produce a steady state current between said oppositely spaced apart working and reference electrodes;

(c) detecting a change in said steady state current; and

(d) relating said change in steady state current to a change in viscosity of said fluid sample.

2. The method of claim 1, wherein the introducing step includes introducing the sample through a capillary channel integrated into the micro-needle and electrochemical cell.

3. The method of claim 1, wherein the introducing step introduces a sample in the range of 100 nano-liters to 150 nano-liters in volume.

4. The method of claim 1, wherein said fluid sample is a physiological sample.

5. The method of claim 4, wherein said physiological sample is blood.

6. The method of claim 5, wherein said method further comprises relating said change in viscosity to the prothrombin time (PT) of said blood.

7. The method of claim 1, wherein said electrochemical cell comprises a redox couple.

8. A method for detecting the onset of coagulation of a blood sample, said method comprising:

(a) introducing said blood sample into an electrochemical cell comprising;

(i) oppositely spaced apart working and reference electrodes; and

(ii) a reagent mixture comprising a redox couple;

wherein one of the working and reference electrodes includes an integrated micro-needle for obtaining the blood sample from a user;

(b) applying an electric potential to said electrochemical cell to produce a steady state current between said oppositely spaced apart working and reference electrodes;

(c) detecting a change in said steady state current; and

(d) relating said change in steady state current to the onset of coagulation in said blood sample.

9. The method of claim 8, wherein said change is a decrease.

10. The method of claim 8, wherein said reagent comprises a coagulation catalyzing agent.

11. The method of claim 10, wherein said coagulation catalyzing agent comprises thromboplastin.

12. The method of claim 10, wherein said method further comprises relating said onset of coagulation to the prothrombin time of said blood sample.

13. An electrochemical test strip comprising:

an electrochemical cell comprising;

(a) oppositely spaced apart working and reference electrodes; and

(b) a reagent mixture comprising;

(i) a redox couple; and

(ii) a coagulation catalyzing agent, and

a micro-needle integrated into one of the working and reference electrodes.

14. The electrochemical test strip of claim 13, wherein said oppositely spaced working and reference electrodes are separated by a distance ranging from 50 μ

m to 500 μ

m.

15. The electrochemical test strip of claim 14, wherein said coagulation catalyzing agent comprises thromboplastin.

16. The electrochemical test strip of claim 13, wherein said redox couple comprises a ferricyanide and ferrocyanide.

17. The electrochemical test strip of claim 13 further including a capillary channel adapted to convey a fluid sample from the micro-needle to the electrochemical cell.

18. The electrochemical test strip of claim 13, wherein the micro-needle is adapted for obtaining a whole blood sample from a user.