Sample Metering Device and Assay Device with Integrated Sample Dilution

Abstract

In one embodiment, the invention is to a sample metering device, comprising a sample holding chamber oriented between a sample entry port and a sample extraction unit, wherein a portion of said extraction unit defines a metered volume of a sample. A diluent may be transported over and/or through the extraction unit to form a diluted sample for sample analysis. In another embodiment, the invention is to an apparatus and method for rapid determination of analytes in liquid samples by various assays including immunoassays incorporating a sample dilution feature, capable of being used in the point-of-care diagnostic field is provided. The devices and methods of the invention preferably are well-suited for high range sample dilution.

What is claimed is: 
     
         1 . A method of performing an assay for an analyte in a sample, said method comprising the steps of:
 introducing a sample into a sample chamber of a cartridge, wherein the sample chamber terminates in a sample extraction unit;   loading said extraction unit with said sample;   washing a portion of said sample from the extraction unit using a volume of diluent from a diluent conduit to form a diluted sample; and   analyzing said diluted sample for an analyte.   
     
     
         2 . The method of  claim 1 , wherein the volume of diluent is a metered volume of diluent. 
     
     
         3 . The method of  claim 1 , further comprising:
 transporting said diluted sample to a sensor; and   performing an analyte assay at said sensor.   
     
     
         4 . The method of  claim 1 , wherein the diluted sample has a dilution ratio of from about 50:1 to about 50,000:1 (v/v diluent:sample). 
     
     
         5 . The method of  claim 1 , wherein the sample extraction unit comprises a wicking material configured to extract a portion of the sample into the diluent at a dilution ratio of 50:1 v/v diluent:sample or greater. 
     
     
         6 . The method of  claim 1 , wherein the loading step comprises wicking said sample into said extraction unit. 
     
     
         7 . The method of  claim 6 , wherein the diluted sample has a dilution ratio of 50:1 v/v diluent:sample or greater. 
     
     
         8 . The method of  claim 6 , wherein said extraction unit comprises a porous hydrophilic material. 
     
     
         9 . The method of  claim 1 , wherein said extraction unit comprises nitrocellulose. 
     
     
         10 . The method of  claim 1 , wherein said extraction unit comprises cotton fiber. 
     
     
         11 . The method of  claim 1 , wherein said extraction unit comprises paper. 
     
     
         12 . The method of  claim 1 , wherein said extraction unit comprises a transverse filter material. 
     
     
         13 . The method of  claim 1 , wherein said extraction unit comprises a lysing agent. 
     
     
         14 . The method of  claim 13 , wherein said extraction unit comprises sodium deoxycholate or saponin. 
     
     
         15 . The method of  claim 2 , wherein a distal portion of said extraction unit defines a metered volume of said sample.