Portable Diagnostic Device and Method for Determining Temporal Variations in Concentrations

Abstract

A rapid assay concentration device. In one form, the device includes a substrate and a plurality of elongated membranes on the substrate. At least one capture zone is formed in each membrane. Each capture zone is responsive to the presence of a target chemical in the fluid. Capture zones on different membranes have different threshold levels of response to the chemical. In a method for monitoring temporal changes of analyte levels in a source multiple test devices are provided, with each device including a plurality of regions. Each region is responsive at a different sensitivity level to indicate presence of the analyte. A source sample is brought into contact with a first of the test devices to determine whether the source contains a level of analyte sufficient to induce a response thereto in one or more of the test unit regions. A different sample from the source is brought into contact with a second of the test devices to determine whether the source contains a level of analyte sufficient to induce a response thereto in one or more regions of the second test device.

1 . A portable diagnostic test kit comprising a plurality of identical portable test units which each provide for quantitation of hCG concentration and determining whether a sample contains hCG within one of several different ranges, thereby enabling a user to compare a change in analyte concentration over time based on multiple samples taken from a source on different days. 
     
     
         2 . The test kit of  claim 1  wherein each test unit comprises:
 a substrate;   a plurality regions each chemically responsive to the presence of hCG in a different range; and   a plurality of lanes each coupled to receive a portion of the sample from one of the regions and indicate when at least a minimum concentration of hCG is present in the region by generating a visually discernable signal in response thereto.   
     
     
         3 . The test kit of  claim 1  wherein each test unit comprises:
 a substrate   a plurality of elongate membranes, of the type which exhibit capillary flow of fluid from the sample therethrough, positioned on the substrate; and   at least one capture zone formed in each membrane, each said one capture zone responsive to a presence of hCG in the fluid and entering said one zone, capture zones on different membranes having different threshold levels of response to hCG concentration.   
     
     
         4 . The test kit of  claim 1  wherein each test unit comprises
 a substrate; and   an elongate test membrane having multiple spaced-apart capture zones formed thereon, each positioned to provide a different sensitivity response to the presence of hCG in the source.   
     
     
         5 . The test kit of  claim 1  comprising at least three test units designed to collectively provide a set of at least three possible outcomes when hCG concentration is monitored over multiple days, the outcomes including multiple levels of response, each corresponding to a different concentration range, including:
 a level one response indicative of hCG concentration in a first range;   a level two response indicative of hCG concentration in a second range in which hCG concentration is higher than a concentration in the first range; and   a level three response indicative of a hCG concentration in a third range in which hCG concentration is higher than a concentration in the second range.   
     
     
         6 . The test kit of  claim 5  wherein the test units are designed to also provide a level four response indicative of a hCG concentration in a fourth range in which hCG concentration is higher than a concentration in the third range. 
     
     
         7 . The test kit of  claim 5  wherein the test units are designed to also provide:
 a level four response indicative of a hCG concentration in a fourth range in which hCG concentration is higher than a concentration in the third range; and   a negative response indicating absence of hCG concentration in any of the multiple levels of response.   
     
     
         8 . The test kit of  claim 5  wherein the test units are designed to also provide a negative response indicating absence of hCG concentration in any of the multiple levels of response. 
     
     
         9 . The test kit of  claim 1  wherein the plurality of identical portable test units each provide for quantitation by provision of a visibly discernable signal from one or more regions on each test unit and the units are designed to enable monitoring temporal changes of hCG levels in the source by:
 on a first occasion bringing a first urine sample from the source into contact with a first of the test units to determine whether the source contains a level of analyte sufficient to induce a response thereto in one or more of the test unit regions;   subsequently, on a second occasion, bringing a second and different urine sample from the same source into contact with a second of the test units to determine whether the source subsequently and on the second occasion contains a level of analyte sufficient to induce a response thereto in one or more regions of the second test device, wherein responses induced in the second test unit relative to the first test unit provide information about temporal change in hCG concentration.   
     
     
         10 . The test kit of  claim 9  wherein the test kit further enables monitoring by subsequently, on a third occasion, bringing a third urine sample, different from the first and second urine samples, but from the same source, into contact with a third of the test units to determine whether the source subsequently and on the third occasion contains a level of analyte sufficient to induce a response thereto in one or more regions of the third test device, wherein responses induced in the third test unit relative to the first test unit provide information about temporal change in hCG concentration.