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AssigneeNova Biomedical Corporation
InventorsXiaohua Cai, Handani Winarta, Andy Vo, Chung Chang Young
Estimating the term…
A disposable electrode strip for testing a fluid sample including a laminated strip with a first and second end, a vent, an open path for receiving a fluid sample of less than one microliter beginning from the first end and connecting to the vent, a working electrode, a reference electrode and a pseudo-working electrode embedded in the laminated strip within the open path and proximate to the first end, a reagent matrix coextensive within the open path and covering the three electrodes, and conductive contacts located at the second end of the laminated strip.
A disposable electrode strip for testing a fluid sample comprising:
A disposable electrode strip for detecting or measuring the concentration of an analyte in a fluid sample, said electrode strip comprising:
A method of making a disposable biosensor comprising:
A method of making multiple, disposable sensors wherein each sensor has at least a working electrode, a reference electrode, a pseudo-working electrode, and a reagent matrix, wherein said reagent matrix contains an enzyme capable of catalyzing a reaction involving a substrate for the enzyme, said working electrode and said reference electrode being disposed in a fluid sample channel for measuring a fluid sample, said method comprising:
A laminated biosensor strip comprising:
Dependencies are inferred from the claim text.
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Measuring or testing processes involving enzymes, nucleic acids or microorganisms ; Compositions therefor; Processes of preparing such…
Amperometric enzyme electrodes for analytes in body fluids, e.g. glucose in blood: test elements therefor, i.e. disposable laminated substrates…
Measuring or testing processes involving enzymes, nucleic acids or microorganisms
Investigating or analysing materials by determining their chemical or physical properties
Term end not estimated
1. Field of the Invention
The present invention relates generally to electrochemical sensors that can be used for the quantification of a specific component or analyte in a liquid sample. Particularly, this invention relates to a new and improved electrochemical sensor and to a new and improved method of fabricating electrochemical sensors. More particularly, this invention relates to a disposable electrochemical sensor that is inexpensive to manufacture. Even more particularly, this invention relates to a disposable electrochemical sensor that gives accurate readings and requires only about 0.2 microliter of fluid sample. Still even more particularly, this invention relates to disposable electrochemical sensors which are used for performing electrochemical assays for the accurate determination of analytes in physiological fluids.
2. Description of the Prior Art
FIG. 1 is a perspective view of the present invention showing the open end, the vent and the electrical contact points of the laminated body.
FIG. 2 is an exploded, perspective view of the present invention showing the various layers of the laminated body.
FIG. 3 is a cross-sectional view of the present invention of FIG. 1
The preferred embodiment of the present invention is illustrated in FIGS. 1-4. FIG. 1 shows a sensor 10 of the present invention. Sensor 10 has a laminated body 100, a fluid sampling end 110, an electrical contact end 120, and a vent opening 42. Fluid sampling end 110 includes a sample fluid channel 112 between a sampling end aperture 114 and vent opening 42. Sampling end 110 also includes an inlet notch 44. Electrical contact end 120 has three discreet conductive contacts 122,123 and 124.
Referring now to FIG. 2, laminated body 100 is composed of a base insulating layer 20, a middle layer 30, and a top layer 40. All layers are made of a dielectric material, preferably plastic. Examples of a preferred dielectric material are polyvinyl chloride, polycarbonate, polysulfone, nylon, polyurethane, cellulose nitrate, cellulose propionate, cellulose acetate, cellulose acetate butyrate, polyester, acrylic and polystyrene. Base insulating layer 20 has a conductive layer 21 on which is delineated a first conductive conduit 22, a second conductive conduit 23 and a third conductive conduit 24. Conductive conduits 22, 23 and 24 may be formed by scribing or scoring the conductive layer 21 as illustrated in FIG. 2 and shown as scribe line 27 and 28 or by silk-screening the conductive conduits 22, 23 and 24 onto base layer 20. Scribing or scoring of conductive layer 21 may be done by mechanically scribing the conductive layer 21 sufficiently to create the three independent conductive conduits 22, 23 and 24. The preferred scribing or scoring method of the present invention is done by using a carbon dioxide (CO2) laser, a YAG laser or an eximer laser. An additional scoring line 29 (enlarged and not to scale; for illustrative purposes only) may be made, but is not necessary to the functionality of sensor 10, along the outer edge of base layer 20 in order to avoid potential static problems which could give rise to a noisy signal. Conductive layer 21 may be made of any electrically conductive material, preferably gold or tin oxide/gold. A useable material for base layer 20 is a tin oxide/gold polyester film (Cat. No. FM-1) or a gold polyester film (Cat. No. FM-2) sold by Courtaulds Performance Films, Canoga Park, Calif.
Middle layer 30 has a U-shaped channel cutout 32 located at middle layer sensor end 31. The U-shaped cutout can be made by using a laser or diecut. The length of channel cutout 32 is such that when middle layer 30 is layered on top of base layer 20, electrode areas W, R and W0 are within the space defined by channel cutout 32. The thickness of middle layer 30 was found to be critical for the volume of the capillary channel and for the speed of the sample fluid flow into sample fluid channel 112, which is filled by capillary action of the sample fluid. Channel cutout 32 holds the reagent matrix 50, more clearly shown in FIG. 3, forming the working electrode, the reference electrode and the pseudo-working electrode. Typically, the reagent matrix 50 must be loaded with a redox mediator to make the reference electrode function. If R is not loaded with a redox reagent or mediator, working electrode W and W0 will not work. Electrode areas W, W0 and R are loaded preferably with the same chemical reagent. The reagents preferably contain an oxidized form of a redox mediator, a stabilizer, a binder, a surfactant, a buffer, and an enzyme. Typically, the redox mediator may be at least one of ferrocene, potassium ferricyanide, other ferrocene derivatives, or other organic and inorganic redox mediators. The preferred stabilizer is polyethylene glycol, the preferred binder is methyl cellulose, the preferred surfactant is t-octylphenoxypolyethoxyethanol, and the preferred buffer is a citrate buffer. The enzyme is capable of catalyzing a reaction involving a substrate for the enzyme or a substrate catalytically reactive with an enzyme and a mediator capable of transferring electrons transferred between the enzyme-catalyzed reaction and the working electrode to create a current representative of the activity of the enzyme or substrate and representative of the compound. The enzyme could be glucose oxidase, lactate oxidase, cholesterol oxidase and creatinine amidohydrolase.