Electrochemical Biosensor

Abstract

According to one embodiment of the present invention, an electrochemical sensor ( 10 ) for detecting the concentration of analyte in a fluid test sample is disclosed. The sensor ( 10 ) includes a counter electrode having a high-resistance portion for use in detecting whether a predetermined amount of sample has been received by the test sensor.

1 . (canceled) 
     
     
         2 - 35 . (canceled) 
     
     
         36 . An electrochemical sensor for detecting the concentration of an analyte in a fluid test sample, the sensor comprising:
 a flow path receiving the fluid test sample;   a first lead and a second lead each adapted to be electrically coupled with a current detector;   a working electrode disposed along the flow path, the working electrode being in electrical communication with the first lead;   a counter electrode in electrical communication with the second lead, the counter electrode having a low-resistance portion and a high-resistance portion, the low-resistance portion of the counter electrode being disposed along the flow path downstream from the working electrode, the high-resistance portion of the counter electrode being disposed along the flow path upstream from the working electrode;   a resistor electrically coupled between the high-resistance portion of the counter electrode and the second lead; and   a reagent disposed on the working electrode, the reagent being adapted to react with the analyte to produce electrons that are transferred to the working electrode;   wherein a current profile is produced in response to a voltage profile applied by a detector to the first and second leads when the fluid test sample is received, and the presence of an underfill condition is detected based on the produced current profile by the detector.   
     
     
         37 . The electrochemical sensor of  claim 36 , wherein the reagent is further disposed over the low-resistance portion of the counter electrode. 
     
     
         38 . The electrochemical sensor of  claim 37 , wherein the reagent is also further disposed over the high-resistance portion of the counter electrode. 
     
     
         39 . The electrochemical sensor of  claim 36 , wherein the flow path is a capillary space formed with a lid and a base, the capillary space having an opening configured to receive the fluid test sample. 
     
     
         40 . The electrochemical sensor of  claim 39 , wherein the lid includes a concave portion to assist in forming the capillary space. 
     
     
         41 . The electrochemical sensor of  claim 36 , wherein the working electrode, the counter electrode, and the resistor are formed by the same type of manufacturing process. 
     
     
         42 . The electrochemical sensor of  claim 41 , wherein the type of manufacturing process is a screen-printing process. 
     
     
         43 . The electrochemical sensor of  claim 36 , wherein the reagent and the resistor are formed by the same type of manufacturing process. 
     
     
         44 . The electrochemical sensor of  claim 43 , wherein the type of manufacturing process is a screen printing process. 
     
     
         45 . The electrochemical sensor of  claim 36 , wherein the resistor has a resistance of about 50 kΩ to about 500 kΩ. 
     
     
         46 . The electrochemical sensor of  claim 36 , wherein electrical communication occurs between only the high-resistance portion of the counter electrode and the working electrode when a less than predetermined volume of fluid sample is received by the flow path and wherein electrical communication occurs between the low-resistance portion of the counter electrode and the working electrode when at least a predetermined volume of fluid sample is received by the flow path. 
     
     
         47 . The electrochemical sensor of  claim 36 , wherein the current profile has a decay-type shape. 
     
     
         48 . The electrochemical sensor of  claim 36 , wherein a decay factor is calculated from two current values from the current profile and wherein detecting the presence of the underfill condition includes comparing the decay factor with a pre-determined lower limit. 
     
     
         49 . The electrochemical sensor of  claim 36 , wherein the voltage profile has a first and a second voltage level. 
     
     
         50 . The electrochemical sensor of  claim 36 , wherein the current detector generates an under-filled error signal when the presence of an underfill condition is detected. 
     
     
         51 . An electrochemical system for determining whether an appropriate amount of a fluid test sample is collected for detection of the concentration of an analyte in the fluid sample, the sensor system comprising:
 a testing device including a current detector; and   a sensor including:
 a flow path receiving the fluid test sample; 
 a first lead and a second lead each adapted to be electrically coupled with the current detector; 
 a working electrode disposed along the flow path, the working electrode being in electrical communication with the first lead; 
 a counter electrode in electrical communication with the second lead, the counter electrode having a low-resistance portion and a high-resistance portion, the low-resistance portion of the counter electrode being disposed along the flow path downstream from the working electrode, the high-resistance portion of the counter electrode being disposed along the flow path upstream from the working electrode; 
 a resistor electrically coupled between the high-resistance portion of the counter electrode and the second lead; and 
 a reagent disposed on the working electrode, the reagent being adapted to react with the analyte in the fluid sample to produce electrons that are transferred to the working electrode; 
   wherein a first current profile is produced in response to a first voltage profile applied by the detector to the first and second leads when a fluid test sample is received in the sensor, and the presence of an underfill condition is detected by the testing device based on the produced current profile.   
     
     
         52 . The system of  claim 51 , wherein the testing device generates an under-filled error signal when the presence of an underfill condition is detected. 
     
     
         53 . The system of  claim 51 , wherein a second current profile is produced in response to a second voltage profile applied by the detector to the first and second leads, the second current profile produced at a different time than the first current profile. 
     
     
         54 . The system of  claim 51 , wherein a decay factor is calculated from two current values from the current profile and wherein detecting the presence of the underfill condition includes comparing the decay factor with a pre-determined lower limit.