Liquid transfer devices

Details Liquid transfer devices Liquid transfer devices

1990-10-29

1993-03-30

Housel, James C.

Chemical apparatus and process disinfecting, deodorizing, preser

Control element responsive to a sensed operating condition

422103, 422 58, 436169, 436170, G01N 3000

Patent

active

051981939

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

There is considerable commercial interest in simple analytical devices, usually of disposable, one-time use form, intended for extra-laboratory usage to conduct biochemical diagnostic assays. Ideally such devices should be operable in a satisfactory manner by lay persons, but this is not as yet normally the case in practice. Many of the currently available devices in fact involve complex manual procedures, with a common feature of such procedures being a requirement to effect a timed sequence of reagent additions to an analyte.


SUMMARY OF THE INVENTION

An object of the present invention is to improve this situation and, to this end, there is provided a liquid transfer device comprising two channels leading from a pair of respective channel ends to a common site and operable to deliver liquid to said site in sequentially timed manner following simultaneous application of such liquid to said channel ends.
In application to an analytical device, the site to which liquid is to be delivered will typically be one at which analysis is to be effected following deposition there of a sample to be tested in respect of an analyte of interest. Correspondingly the liquid to be delivered by each channel will typically comprise an individual reagent or a diluent, with the relevant channel usually bearing a reagent to be entrained by diluent flow in the latter case. The reagent and/or diluent for delivery can emanate from one or more reservoirs associated with or incorporated in the device. Similarly the device can be associated with or incorporate one or more reservoirs for the purposes of drainage of waste liquid.
The proposed device will, of course, involve liquid flow along its channels and this can involve two basically different forms of flow. One such form is that resulting from predominantly capillary action and this will normally involve the use of porous material to define a related channel. Alternatively, capillary flow can involve channel definition by impermeable material in tubular, canal and other formations. The other form of flow is that resulting from predominantly gravitational or pressure forces and this is referred to hereinafter where appropriate as non-capillary flow. Non-capillary flow will normally involve channels defined by impermeable material in tubular, canal and other formations but, alternatively, can involve porous material. In both cases the impermeable material and porous material can be combined to form channels. Also, the two forms of flow are not mutually exclusively applicable to a given channel but can, if desired, be deployed in successive longitudinal portions of the same channel.
Operation of the proposed device to deliver liquid in sequentially timed manner inherently involves delay of the liquid flow along one channel relative to the other and various mechanisms are contemplated for this purpose. These mechanisms fall into two basic categories respectively involving differential flow path lengths and flow rates, and mechanisms of each category are applicable to each form of liquid flow. For example, the transit time of a capillary liquid flow along a path will clearly vary with path length when the path is that of a porous material channel of given uniform cross section, and the same is true for a non-capillary flow along a path extending upwardly through a hollow formation of similarly uniform cross section to be filled by the flow before continuance of the latter. Correspondingly the rates of such flows can be differentiated by variation of the cross sections of the respective channels.
A preferred form of flow rate delay mechanism for use in connection with capillary flow involves the provision of one channel of porous material in a compacted form expansible upon hydration to bridge, directly or indirectly, a subsequent gap in such channel.
As with the liquid flow forms, these delay mechanisms and their categories are not exclusively applicable to a single channel.
In addition to the delivery at a common site of liquids in sequentially timed ma

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