GB2227559A

GB2227559A - Biological or chemical test sticks

Info

Publication number: GB2227559A
Application number: GB8829356A
Authority: GB
Inventors: Ernest Brian Hayes
Original assignee: Cigarette Components Ltd
Current assignee: Cigarette Components Ltd
Priority date: 1988-12-16
Filing date: 1988-12-16
Publication date: 1990-08-01
Anticipated expiration: 2008-12-16
Also published as: GB8829356D0; GB2227559B

Abstract

Stick has a core comprising (a) a liquid-permeable core member at one end in longitudinal alignment with (b) a liquid- impermeable core member, and around the core a sleeve comprising (c) a liquid-permeable layer in communication with the liquid-permeable core member and carrying at least one reagent and (d) an outer liquid-impermeable layer through which visible reaction products of said reagent(s) will show.

Description

TEST DEVICE This invention relates to a device of the type for testing a fluid by formation of visible reaction product due to interaction between the fluid or a species therein and reagent carried by the device.

The invention provides, in one preferred class of embodiment, a biological or chemical test stick of this type having a (preferably substantially eylindrical) sor comprising (a) a liquid-permeable core member (e.g. plug, rod or tube) at one end in longitudinal alignment with [b] a liquid-impermeable ochre member (e.g. plug, rod or tube), and around the core a sleeve comprising [c] a liquid-permeable layer in communication with the liquid-permeable core member and carrying at least one reagent and [d] an outer liquid-impermeable (and e.g. transparent or translucent) layer through which visible reaction product of reagent(s) and test fluid or species therein will show.

In use the end [a] can be inserted into a fluid to be tested, the liquid-permeable core member acting as a wick and transferring liquid to the surrounding liquid-permeable layer [c]; the liquid permeates layer [c] and encounters the reagent(s) carried thereby to give through layer [d) a visible indication of the condition (e.g. pH) of the liquid or of the presence and/or concentration of a targeted species in the liquid.

The liquid-permeable layer (c) may carry one or more diagnostic or other reagents. The or each such reagent will usually be confined to one or more restricted zones of (c3, e.g. to a circumferential ring or rings; where a plurality of reagents is employed, they may be in separate zones, or two or more may be present in the same zone; the or each reagent zone on layer (c] will preferably be over the liquid-impermeable core member (b).

The core and sleeve of a said preferred stick according to the invention will usually be co-terminous, but liquid-permeable core member (a], or this rod or plug (a] and liquid-permeable layer c of the sleeve, might protrude at one end.

The liquid-permeable core member [a] could for example be of gathered creped paper, cotton wool, or filamentary tow; the material might be bonded to itself so as to form a rod or plug or tube which is coherent and dimensionally stable in the absence of a wrapper, it could be pre-formed with its own wrapper (which would of course be such - e.g. of liquid-permeable material and/or perforate etc. - as to permit liquid communication between the interior and surrounding sleeve layer [c)), or could be held in rod or plug form by the said sleeve.

The liquid-impermeable core member tb] could for example be of closed-cell plastics foam. It will usually be inherently dimensionally stable without a wrapper, but as with ta] it could be pre-formed with its own wrapper or held in shape by the said sleeve.

The liquid-permeable layer tc] of the sleeve may for example be of filter paper or chromatography paper. A transparent or translucent sleeve layer td] may for example be of clear plastics film, e.g. of polyester or polyethylene.

Layers [c] and [d] may be pre-laminated before application around the core; layer Ic3 might instead be a coating applied to layer (d] before application of the composite sleeve around the core.

A said preferred test stick according to the invention can be made continuously by continuously forming and advancing longitudinally a core of alternating member [a] and [b], concurrently and continuously longitudinally advancing the sleeve and applying it around the core (e.g. by means of a garniture), and cutting the resulting continuously produced composite stick into finite lengths. In a modification the core is first wrapped in sleeve layer [c], and sleeve layer [d] is subsequently applied (e.g. by wrapping in similar manner or by extrusion) before the composite is cut into finite lengths.

Test sticks according to the invention can be used for a wide variety of diagnostic/chemical/clinical tests, according to the nature of reagent(s) employed with layer [c].

Thus indicators may be used as reagent to provide a stick for pH testing; or the stick may be used for pregnancy testing, layer [c] carrying appropriate antibodies as reagent for interaction with hormones in urine.

Various modifications of the above-described preferred stick are possible. Thus all of the core may be liquid-permeable, though preferably with a portion [b] which is less so than portion [a]; where all of the core is liquid-permeable, a downstream portion preferably has a liquid-impermeable surface or wrap within sleeve [c]. In another variation, liquid-permeable core portion [a] is omitted, so that the test liquid is taken up solely and directly by sleeve layer [c]; in this case the core portion [b] could be permeable or impermeable, though in the former case it preferably has an impermeable skin or wrap. In another variation, the whole of the core is liquid-impermeable; in this case sleeve layer (d] will preferably be perforate or apertured at one end to allow easier access of test liquid to the sleeve layer [c] - this being a feature which could be employed in all described embodiments.

Accordingly, in a broad aspect, the invention provides a biological and/or chemical test stick having a (preferably substantially cylindrical) core and around the core a sleeve comprising [i] a liquid-permeable layer carrying at least one reagent and [ii] an outer liquid-impermeable layer through which visible reaction product of said reagent(s) will show, layer ti] being exposable to contact with a fluid to be tested. The core is usually of circular section.

Claims

CLAIMS:

1. A biological and/or chemical test stick having a core and around the core a sleeve comprising (i] a liquid-impermeable layer carrying at least one reagent and [ii] an outer liquid-permeable layer through which visible reaction product of said reagent(s) will show, layer [i] being exposable to contact with a fluid to be tested.

2. A biological and/or chemical test stick having a core comprising [aj a liquid-permeable core member at one end in longitudinal alignment with [b] a liquid-impermeable core member, and around the core a sleeve co.mprising [cj a liquid-permeable layer in communication with the liquid-permeable core member and carrying at least one reagent and [d] an outer liquid-impermeable layer through which visible reaction products of said reagent(s) will show.

2. A biological and/or chemical test stick having a core comprising [a] a liquid-permeable core member at one end in longitudinal alignnent with [b] a liquid-impermeable core member, and around the core a sleeve comprising [c] a liquid-permeable layer in communication with the liquid-permeable core member and carrying at least one reagent and [d) an outer liquid-impermeable layer through which visible reaction products of said reagent(s) will show. Amendments to the claims have been filed as follows 1.A biological and/or chemical test stick having a core and around the core a sleeve ocnnprising [I) a liquid-permeable layer carrying at least one reagent and [ii) an outer liquid-impermeable layer through which visible reaction product of said reagent(s) will show, layer [i] being exposable to contact with a fluid to be tested.