Subcutaneous Glucose Electrode
A small diameter flexible electrode designed for subcutaneous in vivo amperometric monitoring of glucose is described. The electrode is designed to allow “one-point” in vivo calibration, i.e., to have zero output current at zero glucose concentration, even in the presence of other electroreactive species of serum or blood. The electrode is preferably three or four-layered, with the layers serially deposited within a recess upon the tip of a polyamide insulated gold wire. A first glucose concentration-to-current transducing layer is overcoated with an electrically insulating and glucose flux limiting layer (second layer) on which, optionally, an immobilized interference-eliminating horseradish peroxidase based film is deposited (third layer). An outer (fourth) layer is biocompatible.
1 . A glucose monitoring device having a stacked construction comprising a first electrode, a second electrode, a glucose-responsive enzyme, and a substrate, wherein the first and second electrodes, and the substrate are positioned in a stacked construction, and further, wherein at least a portion of the device is configured for positioning below a skin surface.
2 . The device of claim 1 further wherein the enzyme is a wired enzyme.
3 . The device of claim 2 wherein the enzyme is adjacent at least one of the first and second electrodes.
4 . The device of claim 1 comprising a membrane.
5 . The device of claim 4 wherein the membrane is formed in situ.
6 . The device of claim 5 , wherein the membrane is a mass transport limiting membrane.
7 . The device of claim 1 wherein the device includes a part that is connectable to a device to receive glucose data from the glucose monitoring device when connected.
8 . The device of claim 1 wherein the first and the second electrodes include a working electrode, and a reference electrode or a reference/counter electrode, respectively.
9 . The device of claim 1 including a third electrode.
10 . The device of claim 9 wherein the first electrode, the second electrode and the third electrode include a working electrode, a reference electrode, and a counter electrode.
11 . The device of claim 9 wherein the device includes two working electrodes.
12 . A transcutaneous sensor, comprising:
a first layer;
a first conducting layer at least a portion of which is positioned in contact with at least a first portion of the first layer;
a second layer having a first surface and a second surface, at least a portion of the first surface positioned in contact with at least a first portion of the first conducting layer; and
a second conducting layer at least a portion of which is positioned in contact with at least a portion of the second surface of the second layer.
13 . The sensor of claim 12 wherein the first and the second layers include nonconducting material.
14 . The sensor of claim 12 wherein at least one of the conducting layers includes a working electrode.
15 . The sensor of claim 12 wherein the second layer is substantially disposed between the first conducting layer and the second conducting layer.
16 . The sensor of claim 12 comprising an analyte responsive enzyme.
17 . The sensor of claim 16 , wherein the enzyme is a wired enzyme.
18 . The sensor of claim 12 , comprising a redox compound.
19 . The sensor of claim 18 , wherein the redox compound includes a redox polymer.
20 . The sensor of claim 18 , comprising a mass transport limiting layer.
21 . The sensor of claim 12 , wherein at least another portion of the first conducting layer is in fluid contact with an analyte of a patient.
22 . The sensor of claim 12 , wherein the device comprises a portion connectable to a device for measurement of the signal generated by the sensor.