Devices and methods relating to electrochemical biosensors

Abstract

A system for testing for analytes in a sample of biological fluid includes a test strip that defines a cavity for receiving the sample. At least two sets of electrodes are adjacent the sample cavity, including one for measuring one property of the sample, and another for measuring one or more other properties of the sample, such as temperature and/or the presence or magnitude of confounding variables. The measurements are combined to yield the desired result. At least one set of working and counter electrodes each have a plurality of elongated “fingers” interdigitated with those of the other electrode in the set. The gaps between fingers can be quite small, so that the two electrode sets together can operate in a small measurement volume of sample. Additional electrodes can be included that measure the presence or sufficiency of the sample, and additional traces on the strip can act as configuration identifiers.

What is claimed is: 
     
         1 . A test strip, comprising:
 a first sensor adapted to test a sample of a bodily fluid in a first measurement region of a sample cavity; and   a second sensor adapted to test the same sample within a second measurement region of the sample cavity;   wherein the first measurement region and second measurement region total at most about 240 nL.   
     
     
         2 . The test strip of  claim 1 , wherein the total measurement volume is at most about 200 nL. 
     
     
         3 . The test strip of  claim 1 , wherein the total measurement volume is at most about 90 nL. 
     
     
         4 . The test strip of  claim 1 , wherein the total measurement volume is at most about 80 nL. 
     
     
         5 . The test strip of  claim 1 , wherein the total measurement volume is at most about 65 nL. 
     
     
         6 . The test strip of  claim 1 , wherein:
 the first sensor comprises a working electrode and a counter electrode; and   the second sensor comprises a single lead.   
     
     
         7 . The test strip of  claim 1 , wherein:
 the first sensor comprises a first working electrode and a first counter electrode; and   the second sensor comprises a second working electrode and a second counter electrode.   
     
     
         8 . The test strip of  claim 7 , wherein the second working electrode and the second counter electrode are interdigitated arrays of conductive fingers, each finger being substantially rectangular in shape and having a width between about 5 μm and about 50 μm. 
     
     
         9 . A method of measuring concentration of an analyte in a sample of bodily fluid, comprising:
 obtaining a first response to an application of a first electrical signal to the sample;   obtaining a second response to an application of a second electrical signal to the sample; and   using the first response and the second response to derive a measurement of the concentration of the analyte in the sample.   
     
     
         10 . The method of  claim 9 , wherein the obtaining steps are performed in overlapping periods of time. 
     
     
         11 . The method of  claim 9 , wherein:
 the first electrical signal is applied through a first electrode pair in electrical contact with the sample;   the second electrical signal is applied through a second electrode pair in electrical contact with the sample; and   the volume of the sample is less than about 240 nL.   
     
     
         12 . The method of  claim 11 , wherein the volume of the sample is less than about 200 nL. 
     
     
         13 . The method of  claim 11 , wherein the volume of the sample is less than about 90 nL. 
     
     
         14 . The method of  claim 11 , wherein the volume of the sample is less than about 80 nL. 
     
     
         15 . The method of  claim 11 , wherein the volume of the sample is less than about 65 nL. 
     
     
         16 . The method of  claim 9 , further comprising:
 before the obtaining steps, detecting the sufficiency of the volume of the sample.   
     
     
         17 . The method of  claim 16 , wherein the detecting is performed using at least a third electrode. 
     
     
         18 . The method of  claim 17 , wherein the detecting is performed using a third electrode pair.