Dual electrode system for a continuous analyte sensor

Abstract

Disclosed herein are systems and methods for a continuous analyte sensor, such as a continuous glucose sensor. One such system utilizes first and second working electrodes to measure analyte or non-analyte related signal, both of which electrode include an interference domain.

What is claimed is: 
     
       1. A continuous glucose monitoring system configured for measuring glucose concentration in a host, the system comprising:
 a continuous glucose sensor comprising a first working electrode disposed beneath an active enzymatic portion of a membrane system and configured to generate a first signal, and a second working electrode disposed beneath an inactive-enzymatic or a non-enzymatic portion of the membrane system and configured to generate a second signal, wherein the membrane system is configured to substantially reduce interfering species from reaching the first working electrode and the second working electrode; and 
 electronics configured to process the first signal and the second signal to produce a glucose signal that is substantially without signal contribution from interfering species, and to monitor the second signal for a change in amplitude above a threshold. 
 
     
     
       2. The system of  claim 1 , wherein the membrane system comprises an interference domain. 
     
     
       3. A method for providing a substantially noise-free glucose signal for a glucose sensor implanted in a host, the method comprising:
 providing a glucose sensor, the glucose sensor comprising a first working electrode disposed beneath an active enzymatic portion of a membrane system, and a second working electrode disposed beneath an inactive-enzymatic or a non-enzymatic portion of the membrane system, wherein the membrane system is configured to substantially reduce one or more interfering species from reaching the first working electrode and the second working electrode; 
 generating a first signal associated with the first working electrode; 
 generating a second signal associated with the second working electrode; 
 processing the first signal and the second signal to produce a glucose signal that is substantially without signal contribution from interfering species; and 
 monitoring the second signal for a change in amplitude above a threshold. 
 
     
     
       4. The method of  claim 3 , further comprising requesting an external reference value when the change is above the threshold. 
     
     
       5. The method of  claim 3 , further comprising not calibrating the glucose signal when the change is above the threshold. 
     
     
       6. The method of  claim 3 , further comprising determining an instability of the glucose signal when the change is above the threshold. 
     
     
       7. The system method of  claim 6 , further comprising controlling a display of the glucose signal based on the determined instability. 
     
     
       8. The system of claim 2, wherein the interference domain comprises a cellulosic derivative.  
     
     
       9. The system of claim 8, wherein the cellulosic derivative comprises at least at least one of cellulose acetate and cellulose acetate butyrate.  
     
     
       10. The system of claim 8, wherein the cellulosic derivative comprises a blend from about 1.5 parts to about 60 parts of cellulose acetate butyrate to one part of cellulose acetate.  
     
     
       11. The system of claim 8, wherein the cellulosic derivative comprises a cellulose acetate with a molecular weight of about 30,000 daltons to about 100,000 daltons.  
     
     
       12. The system of claim 8, wherein the interference domain is configured to substantially block passage therethrough of at least one interferent selected from the group consisting of acetaminophen, ascorbic acid, dopamine, ibuprofen, salicylic acid, tolbutamide, tetracycline, creatinine, uric acid, ephedrine, L-dopa, methyl dopa and tolazamide.  
     
     
       13. The system of claim 8, wherein the interference domain is configured to substantially block acetaminophen passage therethrough, wherein an eqivalent glucose signal response of the acetaminophen is less than about 30 mg/dl.  
     
     
       14. The method of claim 3, wherein the membrane system comprises an interference domain comprising a cellulosic derivative.  
     
     
       15. The method of claim 14, wherein the cellulosic derivative comprises at least at least one of cellulose acetate and cellulose acetate butyrate.  
     
     
       16. The method of claim 14, wherein the cellulosic derivative comprises a blend from about 1.5 parts to about 60 parts of cellulose acetate butyrate to one part of cellulose acetate.  
     
     
       17. The method of claim 14, wherein the cellulosic derivative comprises a cellulose acetate with a molecular weight of about 30,000 daltons to about 100,000 daltons.  
     
     
       18. The method of claim 14, wherein the interference domain is configured to substantially block passage therethrough of at least one interferent selected from the group consisting of acetaminophen, ascorbic acid, dopamine, ibuprofen, salicylic acid, tolbutamide, tetracycline, creatinine, uric acid, ephedrine, L-dopa, methyl dopa and tolazamide.  
     
     
       19. The method of claim 14, wherein the interference domain is configured to substantially block acetaminophen passage therethrough, wherein an equivalent glucose signal response of the acetaminophen is less than about 30 mg/dl.