Low oxygen in vivo analyte sensor
The present invention relates generally to systems and methods for measuring an analyte in a host. More particularly, the present invention relates to systems and methods for transcutaneous and subcutaneous measurement of glucose in a host.
1. A wholly implantable analyte sensor system comprising:
a wholly implantable body comprising an electrode configured to measure a glucose level in a host;
a membrane disposed over the electrode and configured to limit transport of glucose to the electrode;
a layer comprising an enzyme to catalyze a reaction of glucose and oxygen as a co-reactant; and
a sensor electronics unit operably connected to the electrode and configured to measure a current produced by the electrode, wherein the sensor electronics unit is configured to measure glucose concentration with substantial linearity at glucose concentrations of up to about 400 mg/dL at an oxygen concentration of less than about 0.6 mg/L,
wherein the sensor system is configured to have, in operation, a sensitivity of from about 1 pA/mg/dL to about 100 pA/mg/dL.
2. The wholly implantable analyte sensor system of claim 1 , wherein the sensor electronics unit is configured to directly measure the current produced by the electrode.
3. The wholly implantable analyte sensor system of claim 1 , further comprising a biointerface membrane configured to support tissue ingrowth.
4. The wholly implantable analyte sensor system of claim 1 , further comprising an analog-to-digital converter configured to translate the current into a digital signal.
5. The wholly implantable analyte sensor system of claim 1 , wherein the electrode comprises an exposed electroactive working electrode surface with a surface area of from about 0.00002 in 2 to about 0.0079 in 2 .
6. The wholly implantable analyte sensor system of claim 1 , wherein the membrane comprises a resistance domain configured to have a permeability ratio of at least about 50:1 of glucose to an interferant.
7. The wholly implantable analyte sensor system of claim 1 , wherein the membrane comprises a resistance domain configured to have a permeability ratio of at least about 200:1 of glucose to an interferant.
8. The wholly implantable analyte sensor system of claim 1 , wherein the sensor system is configured to have, in operation, a sensitivity of from about 5 pA/mg/dL to about 25 pA/mg/dL.
9. The wholly implantable analyte sensor system of claim 1 , wherein the sensor system is configured to have, in operation, a sensitivity of from about 3.5 to about 7.5 pA/mg/dL.