Analyte test strip with improved reagent deposition
An analyte, system, strip and method are described. In one example, an analyte test strip is provided that includes a substrate, electrically conductive material and an isolated portion of the electrically conductive material. The substrate has a generally planar surface that extends from a first end to a second end. The electrically conductive material is disposed on the generally planar surface to define a plurality of electrodes spaced apart from each other. The isolated portion of the electrically conductive material is disposed between at least two electrodes so that the isolated portion is not in electrical communication with the plurality of electrodes.
1. An analyte test strip comprising:
a substrate having a generally planar surface that extends from a first end to a second end;
an electrically conductive material disposed on the generally planar surface to define a plurality of electrodes spaced apart from each other;
an electrically isolated island portion of the electrically conductive material disposed between at least two of the plurality of electrodes; and
a reagent layer at least partially covering the plurality of electrodes and the electrically isolated island portion.
2. The test strip of claim 1 , in which the width of the electrically isolated island portion is from about 120 microns to about 200 microns.
3. The test strip of claim 1 , in which the distance between one of the plurality of electrodes and the electrically isolated island portion and the distance between the electrically isolated island portion and another of the plurality of electrodes is from about 2 microns to about 50 microns.
4. The test strip of claim 1 , further including another electrically isolated island portion of electrically conductive material distal to both the first end and one of the plurality of electrodes and configured such that capillary action is assisted during filling of the test strip with a fluid sample deposited on the test strip.
5. The test strip of claim 1 , in which the plurality of electrodes and the electrically isolated island portion of electrically conductive material is coated with a hydrophilic material.
6. A test strip for measuring a concentration of an analyte in a fluid sample, the test strip comprising:
a substrate;
a reference electrode disposed on the substrate;
a first working electrode disposed on the substrate proximate the reference electrode;
a second working electrode disposed on the substrate proximate the first working electrode;
a first electrically isolated island portion of electrically conductive material located proximal to one of the first and second working electrodes and distal to the reference electrode; and
a reagent layer at least partially covering the reference electrode, the first working electrode, the second working electrode and the electrically isolated island portion.
7. The test strip of claim 6 , wherein the first electrically isolated island portion comprises a substantially triangular shape portion.
8. The test strip of claim 6 , further comprising a vent opening through the electrically isolated island portion of electrically conductive material and through the substrate.
9. The test strip of claim 6 , in which a width of the electrically isolated island portion is from about 120 microns to about 200 microns.
10. The test strip of claim 6 , in which the distance between the reference electrode and the first electrically isolated island portion and the distance between the first electrically isolated island portion and the working electrode is from about 2 microns to about 50 microns.
11. The test strip of claim 6 , further including a second electrically isolated island portion of electrically conductive material and wherein the first electrically isolated island portion is between the reference electrode and the first working electrode and the second electrically isolated island portion is between the first working electrode and the second working electrode, and in which the reference electrode, the first working electrode, the second working electrode,the first electrically isolated island portion and the second electrically isolated island portion are coated with a hydrophilic material.
12. The test strip of claim 11 , in which the hydrophilic material comprises 2-mercaptoethanesulfonic acid sodium salt.
13. A method of making an analyte test strip, the method comprising:
depositing a layer of a conductive material on a substrate;
removing selective portions of the layer of conductive material to define a plurality of electrodes and at least one electrically isolated island portion of the conductive material separated from any of the plurality electrodes at a distance of less than about 50 microns to electrically isolate the at least one electrically isolated island portion from the electrodes; and
depositing a reagent layer at least partially covering the plurality of electrodes and the at least one electrically isolated island portion.
14. The method of claim 13 , in which the removing comprises broad field laser ablating the layer of conductive material over a duration of less than 100 nanoseconds.
15. The method of claim 13 , further comprising coating the plurality of electrodes and the at least one electrically isolated island portion with a layer of material to render such surfaces hydrophilic.
16. The method of claim 13 , further comprising attaching a cover layer to the layer of conductive material.
17. The method of claim 16 , further comprising forming a chamber defined by a surface of the reagent layer, a wall of the cover layer and a top cover over the chamber.
18. The method of claim 17 , in which the removing step removes less than 10% of the layer of conductive material to form the plurality of electrodes and the at least one electrically isolated island portion.
19. The method of claim 18 , further comprising puncturing an orifice through the substrate and the layer of conductive material.