Assay Device Having Multiple Reagent Cells

Abstract

An assay device includes: a liquid sample zone; a reagent zone downstream and in fluid communication with the sample zone. The reagent zone includes at least two reagent cells containing a reagent material and arranged in the reagent zone such that each reagent cell experiences substantially the same flow conditions of sample from the sample zone. The reagent cells divide the sample flow from the sample zone into multiple flow streams. Also includes are: one or more flow control elements disposed downstream from the reagent zone which combine the multiple flow streams into fewer flow streams; a detection zone in fluid communication with the reagent zone; and a wicking zone in fluid communication with the detection zone having a capacity to receive liquid sample flowing from the detection zone. The sample addition zone, the detection zone and the wicking zone define a fluid flow path.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This patent application claims priority to U.S. Provisional Application No. 61 / 588,738, filed Jan. 20, 2012, the disclosure of which is incorporated by reference in its entirety.FIELD OF THE INVENTION[0002]The present invention relates to the field of diagnostic assays, and in particular to lateral flow assays where an analyte to be detected is present in a biological sample.BACKGROUND[0003]Diagnostic assays are widespread and central for the diagnosis, treatment and management of many diseases. Different types of diagnostic assays have been developed over the years in order to simplify the detection of various analytes in clinical samples such as blood, serum, plasma, urine, saliva, tissue biopsies, stool, sputum, skin or throat swabs and tissue samples or processed tissue samples. These assays are frequently expected to give a fast and reliable result, while being easy to use and inexpensive to manufacture. Understandably it is difficul...

AI Technical Summary

Benefits of technology

[0019]According to another aspect of the invention, there has been provided a method of controlling the flow around the reagent zone in an assay device. The method includes: providing a liquid sample zone; providing a reagent zone upstream and in fluid communication with the sample zone comprising at least two reagent cells arranged in the reagent zone such that each reagent cell experiences substantially the same flow conditions of sample from the sample zone, wherein the reagent cells divide the sample flow from the sample zone into multiple flow streams; providing one or more flow control elements disposed upstream from the reagent zone, arranged to provide channel gates having a width narrower than the reagent cells and which are adapted to constrict the flow from the sample leaving the sample zone; providing one or more flow control elements disposed downstream from the reagent zone which combine the multiple flow streams into fewer flow streams; providing a detection zone in fluid communication with the reagent zone; providing a wicking zone in fluid communication with the capture zone having a capacity to receive liquid sample flowing from the capture zone, wherein the sample zone, the detection zone and the wicking zone define a fluid flow path; adding sample to the sample zone; flowing the sample from the sample zone through the upstream flow channel gates which increase the velocity of the flow; flowing the sample past the reagent zone, whereby the flow has an increased velocity next to the reagent boundary compared to the flow at a distance from the reagent boundary, resulting in a more complete dissolution of the reagent zone; flowing the sample past the downstream flow channel gates, which increases the velocity of the flow and results in a wider reagent plume flowing through the detection zone, as compared to a reagent plume generated by a single reagent cell.

Problems solved by technology

Understandably it is difficult to meet all these requirements in one and the same assay.

In practice, many assays are limited by their speed.

One drawback with such known assay devices such as those described above, is that the dissolved conjugate stream in the reaction zone is often narrower than the read window of the instrument, which may negatively impact assay sensitivity and variability.

If the channel is made wider than the read window, although the dissolved reagent width may match the read window size, the fluid sample outside the read window contributes no signal and is wasted.

Another drawback is that the dissolved reagent is not adequately mixed with the sample by the time it reaches the reaction zone, with the result being a lower signal in the middle of the reaction zone because dissolved reagent has local higher concentration and needs to diffuse to mix with sample further away from the reagent, and to bind with the analyte, and hence less signal being read by the read window of the instrument.

However, it has been found that reducing the sample size and dimensions of the device provides inadequate conjugate in the detection zone and accordingly less signal that can be read by the instrument.

The inadequate conjugate in the detection zone is believed to be due to reduced sample size and inefficient use of the sample in the device, amongst other conditions.

Another drawback of reducing dimensions is that the width of the detection zone will also be reduced, again making less signal available that can be read by the instrument.

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