Biosensor and method

• US 7,547,383 B2
• Filed: 06/04/2004
• Issued: 06/16/2009
• Est. Priority Date: 07/31/2001
• Status: Active Grant

• Current Assignee: Nova Biomedical Corporation (Nova Chemicals)
• Original Assignee: Nova Biomedical Corporation (Nova Chemicals)
• Inventors: Young, Chung Chang, Cai, Xiaohua, Winarta, Handani
• Primary Examiner(s): Olsen; Kaj K
• Application Number:
  US10/861,670
• Publication Number:
  US 20040217019A1
• Time in Patent Office: 1,838 Days
• Field of Search: 20440301-40304, 204/403.12, 205/777.5, 205/778, 205/792, 427/125
• US Class Current: 205/777.5
• CPC Class Codes: C12Q 1/004 mediator-assisted
• CPC Class Codes: C12Q 1/006 for glucose
• CPC Class Codes: C12Q 1/26 involving oxidoreductase
• CPC Class Codes: C12Q 1/28 involving peroxidase
• CPC Class Codes: C12Q 1/34 involving hydrolase
• CPC Class Codes: Y10T 29/49002 Electrical device making

Abstract

An improved biosensor having at least a first working electrode and a first electrode material disposed on the first working electrode. The first electrode material is a mixture made by combining at least one enzyme where the at least one enzyme is a capable of reacting with the analyte to be measured, a redox mediator capable of reacting with a product of an enzymatic reaction or a series of enzymatic reactions involving the at least one enzyme, a peroxidase capable of catalyzing a reaction involving the redox mediator where the redox mediator is oxidized, a binder and a surfactant.

Claims

1. A method of using an electrode strip for determining the concentration of creatinine, said method comprising:

obtaining an electrode strip comprising a first working electrode with a reagent matrix capable of measuring creatine in a liquid sample, a second working electrode with a reagent matrix capable of measuring creatine and creatinine in said liquid sample and a reference electrode wherein said reagent matrix of said first working electrode and said second working electrode are water-soluble and contain a peroxidase enzyme;

disposing a fluid sample over said first working electrode, said second working electrode and said reference electrode of said electrode strip;

applying a potential of 0.0V or less between said reference electrode and said first working electrode;

measuring a first current generated between said first working electrode and said reference electrode and correlating said first current to a concentration of said creatine in said fluid sample;

applying a potential between said reference electrode and said second working electrode;

measuring a second current generated between said second working electrode and said reference electrode;

subtracting said first current from said second current and obtaining a current difference whereby said current difference is representative of the concentration of creatinine in said fluid sample.

2. The method of claim 1 wherein said method further includes triggering said current measuring step when said fluid sample contacts said first working electrode, said second working electrode and said reference electrode creating said first current and said second current.

3. The method of claim 2 wherein said method further includes reading a current value for each of said first current and said second current at about a time where said current values for each of said first current and said second current reach a steady-state.

4. The method of claim 3 wherein said reading is taken at about 20 seconds after said current measuring step is triggered.

5. The method of claim 1 further comprising:

measuring a resistance value of said liquid sample between said reference electrode and one of said first working electrode and said second working electrode;

applying said resistance value to a first equation and determining the hematocrit level of said liquid sample; and

calculating a corrected concentration of said analyte using a hematocrit equation to correct for the presence of hematocrit in said liquid sample.

6. A method of making a creatinine sensor comprising:

obtaining a base strip of an insulating material, said base strip having a first end and a second end;

disposing three conductive conduits between said first end and said second end;

disposing a first middle layer of insulating material over said base strip, said first middle layer having three cutouts wherein each cutout exposes an electrode portion of each of said three conductive conduits wherein said three cutouts are spaced from said first end of said base strip, and wherein said first middle layer is sized to expose a contact portion of each of said three conductive conduits for a distance from said second end of said base strip;

disposing a first reagent material on one of said three cutouts forming a first working electrode, a second reagent material on a second of said three cutouts forming a second working electrode and a reference material on a third of said three cutouts forming a reference electrode, wherein said first reagent material is made from mixing in water first and second enzymes wherein one of said first and second enzymes is a substrate of creatine, a redox mediator capable of reacting with a product of an enzymatic reaction involving said first and second enzymes, a peroxidase capable of catalyzing a reaction involving said redox mediator and said product wherein said redox mediator is oxidized, and said second reagent material is made from mixing in water said first and second enzyme, a third enzyme that is a substrate of creatinine, said redox mediator capable of reacting with a product of an enzymatic reaction involving said first and second enzymes and said third enzyme, said peroxidase capable of catalyzing a reaction involving said redox mediator and said product wherein said redox mediator is oxidized;

solidifying said first reagent material and said second reagent material by removing a predefined quantity of said water from said first reagent material and said second reagent material;

overlaying a second middle layer of insulating material over and coextensive with said first middle layer, said second middle layer having an elongated cutout portion where said elongated cutout portion exposes said three cutouts of said first middle layer; and

disposing a top layer of insulating material over and coextensive with said second middle layer, said top layer having a vent opening wherein said vent opening exposes a portion of said elongated cutout portion furthest from said first end of said base strip.

7. The method of claim 6 further comprising drying said first reagent material and said second reagent material at a predetermined temperature and for a predetermined length of time sufficient to allow said first reagent material, said second reagent material and said reference reagent material to solidify and adhere to each of said electrode portions of said three conductive paths.

8. A method of making multiple, disposable creatinine sensors comprising:

obtaining a base strip of an insulating material having a layer of conductive material disposed thereon, said base strip having a first edge and a second edge;

scribing in said conductive material a plurality of lines in a repetitive pattern wherein said plurality of lines contain a repetitive pattern forming three conductive paths in each of said repetitive pattern;

disposing a first middle layer of insulating material over said base strip, said first middle layer having a repetitive pattern of three cutouts wherein each cutout of each of said repetitive pattern exposes an electrode portion of each of said three conductive paths of each repetitive pattern wherein said repetitive pattern of said three cutouts are spaced from said first edge of said base strip, and wherein said first middle layer is sized to expose a contact portion of each of said three conductive paths of each repetitive pattern for a distance from said second edge of said base strip;

disposing a first reagent material on one of said three cutouts of each repetitive pattern forming a first working electrode, a second reagent material on a second of said three cutouts of each repetitive pattern forming a second working electrode and a reference material on a third of said three cutouts of each repetitive pattern forming a reference electrode, wherein said reference reagent material is made from a mixture of components in water comprising a redox mediator, said first reagent material is made from a mixture of components in water, said components being first and second enzymes, a redox mediator capable of reacting with a product of an enzymatic reaction involving said first and second enzymes, a peroxidase capable of catalyzing a reaction involving said redox mediator and said product wherein said redox mediator is oxidized, and said second reagent material is made from a mixture of components in water, said components being said first and second enzymes, a third enzyme that is a substrate of creatinine, said redox mediator capable of reacting with a product of an enzymatic reaction involving said first and second enzymes and said third enzyme, said peroxidase capable of catalyzing a reaction involving said redox mediator and said product wherein said redox mediator is oxidized;

drying said first reagent material, said second reagent material and said reference reagent material;

overlaying a second middle layer of insulating material over and coextensive with said first middle layer, said second middle layer having a plurality of elongated cutout portions in a repetitive pattern wherein each of said elongated cutout portions exposes a corresponding repetitive pattern of said three cutouts of said first middle layer;

disposing a top layer of insulating material over and coextensive with said second middle layer, said top layer having a plurality of vent openings in a repetitive pattern wherein each of said vent openings exposes a portion of a corresponding repetitive pattern of said elongated cutout portion furthest from said first edge of said base strip; and

separating each of said repetitive pattern forming one of each of said disposable sensors.

9. The method of claim 8 further comprising drying said first reagent material, said second reagent material and said reference reagent material at a predetermined temperature and for a predetermined length of time sufficient to allow said first reagent material, said second reagent material and said reference reagent material to solidify and adhere to each of said electrode portion of each of said repetitive pattern of said three conductive paths.

10. The method of claim 9 further comprising cutting along said first edge of each of said sensors and transverse to said sensors a predetermined distance creating a sample inlet port.