Passive sample detection to initiate timing of an assay

Abstract

The present invention provides methods and systems for passively and automatically detecting the presence of a sample (the “sample detection phase”) upon application of the sample to a biosensor, identifying the sample detection time and then initiating the measurement of a targeted characteristic, e.g., the concentration of one or more analytes, of the sample (the “measurement phase”), immediately upon sample detection. The subject methods and systems do not employ or involve the application of an electrical signal from an external source to the electrochemical cell for purposes of performing the sample detection phase and are, thus, less complicated and involve fewer steps and components.

1 - 25 . (canceled)  
     
     
         26 . A method for determining the presence of a sample within an electrochemical cell comprising two electrodes defining an electrochemical cell, said method comprising the steps of: 
 providing a signal producing system within said electrochemical cell wherein the concentration of said signal producing system deposited on one electrode is greater than the concentration of said signal producing system deposited on the other electrode;    applying said sample to said electrochemical cell in the absence of an external signal applied to said electrochemical cell;    producing a potential difference within said electrochemical cell without applying an external signal to the electrochemical cell; and    monitoring said potential difference.    
     
     
         27 . The method of  claim 26  wherein said signal producing system comprises an enzyme component and a mediator component, wherein said step of producing a potential difference comprises dissolving said enzyme component and said mediator component within said sample wherein a substance is released from said signal producing system in a concentration sufficient to generate a potential difference between electrodes without application of an external potential source.  
     
     
         28 . The method of  claim 27  wherein said mediator component is reducible/oxidizable in said sample and said substance is oxidized/reduced therefrom.  
     
     
         29 . The method of  claim 27  wherein said mediator component is ferricyanide and said substance is ferrocyanide.  
     
     
         30 . The method of  claim 27  wherein said enzyme component is selected to target glucose within said sample and comprises one of the group consisting of glucose oxidase and glucose dehydrogenases.  
     
     
         31 . The method of  claim 26  said step of monitoring is performed until said potential difference reaches a predetermined value.  
     
     
         32 . The method of claim  1  wherein said signal producing system is deposited on only one of said electrodes.