Analyte sensor and a method for producing an analyte sensor
A fully or partially implantable analyte sensor for continuously monitoring analyte concentration in a body fluid has a substrate with a first surface configured to face towards the body fluid. The sensor has a working electrode and an interferent electrode. The interferent electrode and the working electrode are electrically separated layers located adjacently on the first surface. The sensor has a further electrode, the further electrode being a counter electrode, a reference electrode or a counter/reference electrode. The working electrode and the interferent electrode each have a layer of a conductive material. The working electrode has an enzyme whereas the interferent electrode is devoid of enzyme. A method for producing the fully or partially implantable analyte sensor for continuously monitoring analyte concentration in a body fluid is also disclosed.
1 . A fully or partially implantable analyte sensor for continuously monitoring analyte concentration in a body fluid, the sensor comprising:
a substrate having a first surface configured to face towards the body fluid;
a working electrode;
an interferent electrode, wherein the interferent electrode and the working electrode are electrically separated layers and are located adjacently on the first surface; and
a further electrode selected from the group consisting of a counter electrode, a reference electrode and a counter/reference electrode;
wherein (i) the working electrode and the interferent electrode each have a layer of a conductive material, (ii) the working electrode further comprises at least one enzyme, and (iii) the interferent electrode is devoid of enzyme; and
further wherein the working electrode is substantially surrounded by the interferent electrode.
2 . The analyte sensor according to claim 1 , wherein the substrate has a second surface facing away from the first surface, wherein the further electrode is located on the second surface of the substrate.
3 . The analyte sensor according to claim 1 , further comprising a diffusion limiting membrane covering at least the working electrode.
4 . The analyte sensor according to claim 3 , wherein the diffusion limiting membrane covers both the working electrode and the interferent electrode.
5 . The analyte sensor according to claim 3 , wherein a thickness of the diffusion limiting membrane exceeds a diameter of the working electrode.
6 . The analyte sensor according to claim 5 , wherein the thickness of the diffusion limiting membrane is in the range of 20 μm to 50 μm.
7 . The analyte sensor according to claim 3 , wherein the working electrode and the interferent electrode are separated from each other by a distance in the range of 0.5 to 2.0 of the thickness of the diffusion limiting membrane.
8 . The analyte sensor according to claim 1 , wherein the interferent electrode is operable at the same potential applied to the working electrode.
9 . The analyte sensor according to claim 1 , wherein the analyte comprises glucose and the enzyme is at least one of glucose oxidase or glucose dehydrogenase.
10 . A method for producing a fully or partially implantable analyte sensor for continuously monitoring analyte concentration in a body fluid, the method comprising:
a) applying a layer of a conductive material to a first surface of a substrate, the first surface being configured to face towards a body fluid, wherein the layer is applied so that two electrically separated layers located adjacent to one another are obtained in a first portion of the first surface and a second portion of the first surface, respectively;
b) applying onto the conductive material a layer of a composition comprising an enzyme such that a working electrode is formed on the first portion covered by the composition and an interferent electrode is formed on the second portion and the interferent electrode is devoid of the composition, wherein the working electrode is substantially surrounded by the interferent electrode; and
c) forming on the substrate at least one further electrode selected from the group consisting of a counter electrode, a reference electrode and a counter/reference electrode.
11 . The method according to claim 10 , wherein step a) comprises:
applying a first individual layer of the conductive material onto the first portion and a second individual layer of the conductive material onto the second portion such that the first portion and the second portion are electrically separated from each other; or
applying the layer of the conductive material onto the first surface and removing the conductive material between the first portion and the second portion.
12 . The method according to claim 10 , wherein step b) comprises:
further applying onto the conductive material the layer of the composition on the first portion in a manner that the conductive material on the second portion is maintained devoid of the composition comprising the enzyme; or
further applying onto the conductive material the layer of the composition comprising the enzyme onto the conductive material, subsequently removing the composition comprising the enzyme from the second portion and maintaining the composition comprising the enzyme on the first portion.
13 . The method according to claim 10 , wherein step c) comprises applying a second layer of the conductive material to a second surface of the substrate, the second surface facing away from the first surface.
14 . The analyte sensor according to claim 1 , wherein interferents are reduced or eliminated by the interferent electrode, whereby the current from the interferent electrode is not subtracted from the current of the working electrode to obtain a precise glucose measurement.
15 . The analyte sensor according to claim 1 , wherein the interferent electrode surrounds the working electrode.