Devices and methods for testing analytes

Abstract

A method and device are provided for measuring a level of a clinically relevant analyte (such as glucose) in a fluid (such as blood). The device includes a flow path for conducting said fluid through the device; a detection chamber arranged on said flow path; and detector means arranged to detect analyte levels in the fluid in said chamber, wherein: said detection chamber contains a predetermined amount of an analyte such that that analyte mixes with fluid in the detection chamber to form, at the detector means, a calibration sample of the fluid at a time after the arrival of the fluid in said detection chamber, and said detector means is arranged to detect a first analyte level of an unadulterated sample of the fluid at a first time which is before the formation of said calibration sample and to detect a second analyte level of said calibration sample at a second time which is after the formation of said calibration sample.

1 .- 50 . (canceled) 
     
     
         51 . A device for measuring a level of a clinically relevant analyte in a fluid, including:
 a flow path for conducting said fluid through the device;   a detection chamber arranged on said flow path; and   detector means arranged to detect analyte levels in the fluid in said chamber, wherein:   said detection chamber contains a predetermined amount of an analyte such that that analyte mixes with fluid in the detection chamber to form, at the detector means, a calibration sample of the fluid at a time after the arrival of the fluid in said detection chamber, and   said detector means is arranged to detect a first analyte level of an unadulterated sample of the fluid at a first time which is before the formation of said calibration sample and to detect a second analyte level of said calibration sample at a second time which is after the formation of said calibration sample.   
     
     
         52 . A device according to  claim 51  wherein the analyte in said predetermined amount is the same as said clinically relevant analyte. 
     
     
         53 . A device according to  claim 51  wherein said device has a single detector means. 
     
     
         54 . A device according to  claim 51  wherein said device has a single flow path. 
     
     
         55 . A device according to  claim 51  wherein said predetermined amount of analyte is located at a position within the detection chamber remote from the position of the detector means. 
     
     
         56 . A device according to  claim 51  wherein said predetermined amount of analyte is located on a substrate at a predetermined position in relation to the position of the detector means. 
     
     
         57 . A device according to  claim 56  wherein the flow path and detection chamber are formed by a plurality of structural components and said substrate forms part of at least one of said structural components. 
     
     
         58 . A device according to  claim 56  where the predetermined location of the analyte is within an area on said substrate which has a different surface energy to other areas on the same substrate, and the substrate on which the predetermined amount of analyte is located is generally hydrophobic and the formulation containing the predetermined amount of analyte provides a surface which is more hydrophilic than the substrate and which facilitates capillary fill of the flow path and detection chamber. 
     
     
         59 . A device according to  claim 56  where the predetermined location of the analyte is within an area on said substrate which has a different surface energy to other areas on the same substrate, and wherein the substrate on which the predetermined amount of analyte is located is generally hydrophobic and is covered by a layer of hydrophilic material which forms a wall of the flow path. 
     
     
         60 . A device according to  claim 51  wherein the predetermined amount of analyte is contained within a formulation containing a thickening agent. 
     
     
         61 . A device according to  claim 51  wherein the predetermined amount of analyte is positioned in a line across the width of the flow path or detection chamber in a direction orthogonal to the direction of flow through the flow path or into the detection chamber. 
     
     
         62 . A device according to  claim 51  wherein the detector includes a working electrode and said predetermined amount of analyte and the working electrode of the detector are located on opposing surfaces of the detection chamber. 
     
     
         63 . A device according to  claim 62  wherein at least part of said predetermined amount of analyte is located directly opposite at least part of said working electrode. 
     
     
         64 . A device for measuring clinically relevant analyte according to  claim 51  wherein the device includes at least 2 detector means, wherein a first detector means is optimised for measuring the clinically relevant analyte, and a second detector means is optimised for measuring a non-analyte-dependent signal, such that the non-analyte-dependent signal can be used to obtain information about the analyte level measured by the first of said detector means. 
     
     
         65 . A device according to  claim 64  wherein the second detector means is arranged to detect a quantity related to the diffusivity of the clinically relevant analyte. 
     
     
         66 . A device according to  claim 65  wherein the first detector means includes a redox mediator and the second detector means does not include said redox mediator, and wherein the detector means are arranged such that the measurement of the non-analyte-dependent signal is made before said redox mediator is able to diffuse to the second detector means. 
     
     
         67 . A method for testing, in a portable device, a level of a clinically relevant analyte in a fluid, the method including the steps of:
 guiding a sample of the fluid to a detection chamber containing a known amount of an analyte;   measuring an analyte level in an unadulterated sample of the fluid at a first predetermined time after the arrival of the fluid in said detection chamber;   measuring an analyte level in a calibration sample of the fluid which has mixed with said known amount of said analyte at a second predetermined time after the arrival of the fluid in said detection chamber, being later than said first predetermined time; and   adjusting the analyte level measured in said unadulterated sample using the analyte level measured in said calibration sample.   
     
     
         68 . A method according to  claim 67  wherein said analyte in said known amount of analyte is the same as said clinically relevant analyte. 
     
     
         69 . A method according to  claim 67  wherein the step of adjusting uses the rate of diffusion or the time taken to detect the effects of the mixing of the predetermined amount of analyte, or a combination thereof, to adjust the analyte level measured in said unadulterated sample. 
     
     
         70 . A method according to  claim 67  further including the steps of: storing a record of said non-analyte specific information; updating said record after subsequent measurements; and determining a deviation from said record in a subsequent measurement; and, optionally, if said deviation is greater than a predetermined amount, alerting the user.