Devices comprising multiple capillary inducing surfaces

Abstract

Assay device structures for a device where fluid flows from a one region to another. The device structures comprising one or more capillarity-inducing structures; where the capillarity-inducing structure induces capillary force along an axis that is essentially perpendicular to the axis along which capillary force induced in another region of the device.

Description

RELATED PATENT APPLICATIONS [0001] This application is a continuation of, and claims priority from, U.S. patent application Ser. No. 09 / 612,815, filed on Jul. 10, 2000 and U.S. patent application Ser. No. 08 / 749,702, filed on Nov. 15, 1996. The content of both applications are hereby incorporated herein by reference.FIELD OF THE INVENTION [0002] This application concerns capillarity, also referred to as capillary action or capillary force. In a particular embodiment, the invention concerns an assay device that comprises multiple capillary force-inducing surfaces having distinct positional orientations. BACKGROUND ART [0003] With the advent of field-based testing and point of care testing in hospitals, it has become increasingly important to develop diagnostic products which are simple, rapid and convenient for use. In these contexts, results are generally needed rapidly, with a minimum of time given to the performance of a test. Providing an assay result in minutes allows prompt act...

AI Technical Summary

Benefits of technology

[0038] Disclosed herein for the first time in the art are assay device structures that accomplish the objectives of permitting a compact assay device configuration together with enhanced assay volumes. When conducting an assay in laboratory or non-laboratory settings, it is frequently desired that only a small amount of sample to be assayed be provided, compact devices are well suited to this aspect. Additionally, devices comprising microcapillaries are generally preferred because they are readily manipulated and they provide for enhanced reaction kinetics. It is advantageous for the device to be approximately the size of a human hand. This size facilitates manipulation of the device, making it easier for the individual conducting the assay to place any assay reactants into the device. Additionally, devices which are readily held in the human hand are of a size that facilitates packing, shipping and storage of the devices.

[0066] In the embodiment of FIG. 7, the distance between the lid and the base of this region was 12 microns; this was the distance believed to induce the effective capillarity of this region. Each structure in the embodiment depicted in FIG. 7 was 10 microns high. The 2 micron distance between the top of a hexagonal structure and the lid merely filled with liquid, then ceased to impact the effective capillarity of the region. The hexagonal structures served to decrease the surface tension of a fluid flow front, whereby the fluid flow front was essentially perpendicular to lateral walls.

Problems solved by technology

Additionally, non-laboratory settings often lack the same level of access to assay equipment or reagents found in laboratories.

A problem with the use of capillarity as a means to achieve proximal-to-distal movement through a device concerns the fluid volume required to perform an assay, i.e., the “assay volume.” An assay result is often achieved only when the sample has traveled through the device.

However, in order to achieve sufficient distal capillarity in a compact device, dimensions in the distal areas are often extremely minute.

If sample and non-sample fluids must be accommodated distally, devices with sufficient capillarity and the requisite capacity have highly impractical configurations for laboratory or field settings.

If a capillary in a distal region is made larger to accommodate an assay volume (a reaction volume and other needed volumes), the drop in capillarity in that region often impairs fluid flow into the region.

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