Method and apparatus for assay of electrochemical properties

Abstract

A method for monitoring a select analyte in a sample in an electrochemical system. The method includes applying to the electrochemical system a time-varying potential superimposed on a DC potential to generate a signal; and discerning from the signal a contribution from the select analyte by resolving an estimation equation based on a Faradaic signal component and a nonfaradaic signal component.

1 - 10 . (canceled) 
     
     
         11 . A method of determining a plurality of environmental factors in an electrochemcial system containing a liquid sample, wherein the electrochemical system comprises an electrode having a surface, and the surface includes a contact portion and a non-contact portion, wherein the contact portion is in electrolytic contact with the sample and the non-contract portion of the electrode is not in contact with the sample, the method comprising:
 applying a time-varying potential stimulus to the system to generate a signal;   measuring the signal;   computing at least one parameter of all or some portion of the signal; and   determining values of the plurality of environmental factors by resolving an estimation equation based on the at least one parameter, wherein the surface area corresponds to the contact portion.   
     
     
         12 . The method of  claim 11 , wherein the at least one parameter contains capacitive information about the electrochemical system. 
     
     
         13 . The method of  claim 11 , wherein the effective electrode area is determined by resolving the equation based on the at least one parameter. 
     
     
         14 . The method of  claim 11 , wherein the area of the electrode is determined by resolving the estimation equation based on the at least one parameter. 
     
     
         15 . The method of  claim 11 , wherein the electrode has a quantity of fouling, and the fouling is determined by resolving the estimation equation based on the at least one parameter. 
     
     
         16 . The method of  claim 11 , wherein the time-varying potential is a DC bias potential with a sinusoidal potential superimposed. 
     
     
         17 . The method of  claim 16 , wherein the DC bias is approximately 0 volts. 
     
     
         18 . The method of  claim 16 , wherein the estimation equation extracts capacitive information from the signal. 
     
     
         19 . The method of  claim 16 , wherein the sinusoidal potential has less than approximately 50 mV peak-to-peak amplitude. 
     
     
         20 . The method of  claim 12 , wherein the capacitive information is based on an imaginary component of a complex immittance of the electrochemical system. 
     
     
         21 . The method of  claim 12 , wherein the time-varying potential has an amplitude, and the capacitive information is based on the amplitude. 
     
     
         22 . The method of  claim 12 , wherein the capacitive information is based on a rate of decay of the signal. 
     
     
         23 . The method of  claim 12 , wherein the capacitive information is based on a rate of rise of the signal. 
     
     
         24 . The method of  claim 11 , wherein the electrochemical system includes a select analyte in the sample, wherein a volume of the sample is determined. 
     
     
         25 . The method of  claim 11 , wherein the electrochemical system includes a select analyte in the sample, and the select analyte is glucose. 
     
     
         26 . The method of  claim 11 , wherein the electrochemical system includes a select analyte in the sample, and the select analyte is a carbohydrate. 
     
     
         27 . The method of  claim 11 , wherein the electrochemical system includes a select analyte in a sample, and the select analyte is a mediator species. 
     
     
         28 . The method of  claim 27 , wherein the mediator species is a ferrocene/ferrocenium couple. 
     
     
         29 . The method of  claim 27 , wherein the mediator species is a ferrocyanide/ferricyanide couple. 
     
     
         30 . A method of determining a volume of a sample present in an electrochemical system, wherein the electrochemical system comprises an electrode and an effective electrode area is an area of the electrode that is in contact with the liquid sample, the method comprising:
 applying a potential stimulus to the system to generate a signal;   measuring the signal;   computing at least one parameter of all or some portion of the generated signal; and   determining a surface area of the contact portion by resolving an estimation equation based on the at least one parameter, wherein the surface area corresponds to the contact portion of the electrode.