Heated electrochemical cell

Abstract

The invention provides a method for determining the concentration of an analyte in a sample comprising the steps of heating the sample and measuring the concentration of the analyte or the concentration of a species representative thereof in the sample at a predetermined point on a reaction profile by means that are substantially independent of temperature. Also provided is an electrochemical cell comprising a spacer pierced by an aperture which defines a cell wall, a first metal electrode on one side of the spacer extending over one side of the aperture, a second metal electrode on the other side of the spacer extending over the side of the aperture opposite the first electrode, means for admitting a sample to the cell volume defined between the electrodes and the cell wall, and means for heating a sample contained within the cell.

What is claimed is:  
     
         1 . A method of heating an electrochemical cell, the electrochemical cell comprising a spacer pierced by an aperture which defines a cell wall, a first metal electrode on one side of the spacer extending over one side of the aperture, a second metal electrode on the other side of the spacer extending over the side of the aperture opposite the first electrode, an ingress for admitting a sample to a cell volume defined between the electrodes and the cell wall, and a resistive element for heating a sample contained within the cell, the method comprising: 
 applying a potential across the resistive element to generate an amount of heat;    interrupting a potential across the resistive element; and    applying a potential between the first electrode and the second electrode to perform an electrochemical assay of an analyte.    
     
     
         2 . The method according to  claim 1 , wherein a potential across the resistive element is maintained during the assay of the analyte at an initial level or at a lower level sufficient to substantially maintain a sample temperature.  
     
     
         3 . The method according to  claim 1 , wherein a current flowing through the resistive element is monitored and the potential automatically adjusted so as to maintain a power output.  
     
     
         4 . The method according to  claim 3 , wherein the power output is adjusted on a basis of an ambient temperature measured by a separate sensor.  
     
     
         5 . The method according to  claim 1 , wherein the electrochemical cell further comprises means of measuring a concentration of the analyte or a concentration of a species representative of the analyte in a sample at a predetermined point on a reaction profile by means that are substantially independent of a temperature of the sample in the electrochemical cell.  
     
     
         6 . The method according to  claim 1 , wherein the electrochemical cell further comprises a mediator, wherein the mediator comprises a species representative of a concentration of the analyte.  
     
     
         7 . The method according to  claim 6 , wherein the mediator is an enzyme mediator.  
     
     
         8 . The method according to  claim 1 , wherein the step of applying a potential across the resistive element to generate an amount of heat raises an analyte temperature by from 5 to 15° C.  
     
     
         9 . The method according to  claim 1 , wherein the step of applying a potential across the resistive element to generate an amount of heat raises an analyte temperature to a final temperature within a period of 2 to 10 seconds.  
     
     
         10 . The method according to  claim 1 , wherein the step of applying a potential across the resistive element to generate an amount of heat raises an analyte temperature to a peak temperature within 2 to 5 seconds.  
     
     
         11 . The method according to  claim 1 , wherein the electrochemical cell comprises a glucose sensor.  
     
     
         12 . The method according to  claim 1 , wherein the electrochemical cell comprises a glucose sensor capable of measuring a concentration of glucose in a blood sample.  
     
     
         13 . The method according to  claim 1 , wherein the electrochemical cell comprises an enzyme.  
     
     
         14 . The method according to  claim 13 , wherein the enzyme comprises glucose dehydrogenase.  
     
     
         15 . The method according to  claim 14 , wherein the electrochemical cell further comprises an oxidizing mediator.  
     
     
         16 . The method according to  claim 15 , wherein the oxidizing mediator comprises ferricyanide.  
     
     
         17 . The method according to  claim 1 , wherein the electrochemical cell comprises means for applying a potential to the resistive element that is capable of measuring a current flowing through the resistive element and automatically adjusting the potential so as to maintain a power output.  
     
     
         18 . The method according to  claim 17 , wherein the power output is capable of being adjusted on a basis of an ambient temperature measured by a separate sensor.  
     
     
         19 . The method according to  claim 1 , wherein the analyte comprises glucose.