Apparatus and methods for analyzing fluid variables

Abstract

Methods and devices for analyzing fluid variables. The devices analyze fluid variables by measuring cessation of fluid flow through the medium or a change in flow rate due to an inherent property of the fluid variable, or due to a modification of the fluid variable as the fluid migrates through the medium; or by measuring relative rates of capillary flow down two or more arms of a common element of porous media in some alternatives, converging in which at least one of the arms has been modified by the addition of flow-modifying agents which affect the flow rate in response to the concentration of the analyte; or by detecting changes in the rate of the capillary flow of the sample fluid along a path through an element of porous media, or through multiple elements of porous media.

1 . (canceled) 
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . (canceled) 
     
     
         5 . (canceled) 
     
     
         6 . (canceled) 
     
     
         7 . (canceled) 
     
     
         8 . (canceled) 
     
     
         9 . (canceled) 
     
     
         10 . A device for determining the amount or concentration of an analyte in a fluid, comprising:
 a curvilinear medium defining a closed fluid path encircling an open space;   wherein the medium is configured to receive a fluid sample at one defined position on the medium.   
     
     
         11 . A device as in  claim 10 , further comprising a housing that at least partially contains the curvilinear medium, and further comprising:
 a first layer above the medium; and   a second layer below the medium, wherein the first and second layers contain the medium therebetween.   
     
     
         12 . A device as in  claim 10 , further comprising:
 a well for receiving an amount of fluid; and   a capillary reservoir that provides a fluid pathway connecting the well and the one defined position on the medium via a vertical separator.   
     
     
         13 . A device as in any of  claims 10 , further comprising a graduated scale configured to provide an indication as to a position in the curvilinear medium fluid path at which two fluids flowing in opposite directions from the one defined position converge in the medium. 
     
     
         14 . A method for assessing coagulation of a fluid, comprising:
 applying the fluid to a medium; and   determining if flow of the fluid in the medium ceased or substantially slowed with time without saturating the medium; wherein:   the medium and/or the fluid has been modified such that flow of the fluid in the medium will cease or substantially slow without saturating the medium if the fluid has the ability to coagulate; and   cessation or substantial slowing of the fluid flow is indicative of the ability of the fluid to coagulate.   
     
     
         15 . The method of  claim 14 , wherein the fluid is whole blood or plasma. 
     
     
         16 . A method for determining coagulation time of a fluid, comprising:
 applying the fluid to a medium comprising converging flow paths, wherein the fluid flows into each of the converging flow paths;   determining the point of convergence of the fluid fronts in the flow paths; and   determining the coagulation time of the fluid based on the point of convergence;   wherein:   one of the flow paths has been modified such that flow of the fluid in the modified flow path changes in proportion to the ability of the fluid to coagulate;   one of the flow paths has not been modified; and   the point of convergence of the fluid fronts in the converging flow paths is indicative of the ability of the fluid to coagulate.   
     
     
         17 . The method of  claim 16 , wherein the fluid is whole blood or plasma. 
     
     
         18 . The device of any of  claim 10 , wherein the curvilinear medium is in the shape of a racetrack with rectangular sides flanked by curved ends. 
     
     
         19 . The method of  claim 16 , wherein the medium is in the shape of one or more of an oval and a racetrack. 
     
     
         20 . (canceled) 
     
     
         21 . The method of  claim 16 , wherein the point of convergence is along one or both of a curved portion and a linear portion of the curvilinear medium. 
     
     
         22 . (canceled)