Chemical signal-impermeable mask

• US 6,201,979 B1
• Filed: 03/13/2000
• Issued: 03/13/2001
• Est. Priority Date: 09/12/1995
• Status: Expired due to Term

• Current Assignee: Animas Technologies LLC (Johnson & Johnson)
• Original Assignee: Cygnus, Inc. (Johnson & Johnson)
• Inventors: Kurnik, Ronald T., Tamada, Janet, Tierney, Michael
• Primary Examiner(s): NASSER, ROBERT L
• Application Number:
  US09/523,826
• Time in Patent Office: 365 Days
• Field of Search: 600/345-350, 600/362, 600/365, 600/382, 600/307, 600/309, 600/386, 600/361, 600/395-397, 604/20
• US Class Current: 600/345
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• CPC Class Codes: A61N 1/30 Apparatus for iontophoresis, i.e. transfer of media in ionic state by an electromotoric force into the body, or cataphoresis
• CPC Class Codes: C12Q 1/001 Enzyme electrodes
• CPC Class Codes: C12Q 1/002 Electrode membranes
• CPC Class Codes: C12Q 1/006 for glucose

Abstract

A chemical signal-impermeable mask is positioned in the electrolyte flow such that the mask is between a source of chemical signal and a working electrode which senses the chemical signal transported from the source (e.g., by diffusion). The configuration of the mask is such that the mask prevents substantially all chemical signal transport from the chemical signal source having a radial vector component relative to a plane of the mask and the catalytic face of the working electrode, thus allowing primarily only chemical signal transport that is substantially perpendicular to the place of the mask and the catalytic surface of the working electrode. By reducing or eliminating chemical signal radial transport toward the working electrode, the mask thus significantly reduces or eliminates edge effects. By substantially reducing edge effects created by radial transport of chemical signal, it is possible to obtain a more accurate measurement of the amount (e.g., concentration) of chemical signal that is transported from a given area of source material.

Claims

1. A method of measuring an amount or concentration of a compound present in a mammalian subject, comprising the steps of:

contacting a surface of the mammalian subject with a sensor assembly comprising;

a) an ionically conductive material comprising first and second faces;

b) a working electrode comprising a catalytic surface, said catalytic surface in contact with said first face of the ionically conductive material, said contact defining a target area;

c) a mask characterized by being substantially impermeable to the compound or a related chemical signal, the mask being positioned on the second face of the ionically conductive material, wherein the assembly is positioned so that the mask is between the ionically conductive material and the surface of the subject, such that the compound or related chemical signal transported through a plane of the mask, through the ionically conductive material, and toward the target area is substantially only that compound or related chemical signal transported in a direction substantially perpendicular to the target area;

transporting the compound or related chemical signal through the surface of the mammalian subject, through the plane of the mask, and through the ionically conductive material to the target area;

monitoring an electrical signal which is generated at the catalytic surface of the working electrode by catalytic conversion of the compound or related chemical signal into the electric signal, wherein the electrical signal generated at the working electrode over a given period of time is correlated with the amount or concentration of compound present in the mammalian subject.

2. The method of claim 1, wherein the assembly further comprises:

d) an electroosmotic electrode in contact with the ionically conductive material and said transporting is accomplished by applying an electrical current to the electroosmotic electrode.

3. The method of claim 2, wherein the compound comprises glucose, the ionically conductive material is a hydrogel, said hydrogel comprising a hydrophilic polymer, an electrolyte, water, and glucose oxidase, and the catalytic surface of the working electrode comprises a material selected from the group consisting of carbon, platinum, palladium, nickel, oxides thereof, and dioxides thereof.

4. The method of claim 1, wherein the compound is glucose.

5. The method of claim 1, wherein the ionically conductive material is a hydrogel.

6. The method of claim 5, wherein the hydrogel comprises, a hydrophilic polymer, an electrolyte, and water.

7. The method of claim 5, wherein the hydrogel further comprises glucose oxidase.

8. The method of claim 1, wherein the catalytic surface of the working electrode comprises a material selected from the group consisting of carbon, platinum, palladium, nickel, oxides thereof, and dioxides thereof.

9. The method of claim 1, wherein the compound comprises glucose, the ionically conductive material is a hydrogel, said hydrogel comprising a hydrophilic polymer, an electrolyte, water, and glucose oxidase, and the catalytic surface of the working electrode comprises a material selected from the group consisting of carbon, platinum, palladium, nickel, oxides thereof, and dioxides thereof.

10. The method of claim 3, wherein the mammalian subject is a human.

11. The method of claim 1, wherein the mammalian subject is a human.

12. The method of claim 1, wherein the ionically conductive material comprises glucose oxidase.

14. The method of claim 12, wherein the mammalian subject is a human.

15. The method of claim 12, wherein the ionically conductive material is a hydrogel.

16. The method of claim 12, wherein the catalytic surface of the working electrode comprises a material selected from the group consisting of carbon, platinum, palladium, nickel, oxides thereof, and dioxides thereof.

13. A method of measuring a glucose amount or concentration in a mammalian subject, comprising:

contacting a surface of the mammalian subject with a sensor assembly comprising;

a) an ionically conductive material comprising a hydrophilic polymer, an electrolyte, water, and glucose oxidase, wherein (i) said ionically conductive material comprises first and second faces, and (ii) the glucose oxidase is capable of converting glucose to gluconic acid and hydrogen peroxide;

b) a working electrode comprising a catalytic surface, said catalytic surface in contact with said first face of the ionically conductive material, said contact defining a target area;

c) an electroosmotic electrode in contact with said first face of the ionically conductive material

d) a mask characterized by being substantially impermeable to the glucose or a related chemical signal, the mask being positioned on the second face of the ionically conductive material, wherein the assembly is positioned so that the mask is between the ionically conductive material and the surface of the subject, such that the glucose or related chemical signal transported through a plane of the mask, through the ionically conductive material, and toward the target area is substantially only that compound or related chemical signal transported in a direction substantially perpendicular to the target area;

transporting the compound or related chemical signal through the surface of the mammalian subject, through the plane of the mask, and through the ionically conductive material to the target area, wherein said transporting is accomplished by applying an electrical current to the electroosmotic electrode;

monitoring an electrical signal which is generated at the catalytic surface of the working electrode by catalytic conversion of the hydrogen peroxide into the electric signal, wherein the electrical signal generated at the working electrode over a given period of time is correlated with the amount or concentration of glucose present in the mammalian subject.