Surgery – Diagnostic testing – Liquid collection
Reexamination Certificate
1998-05-13
2001-06-05
Hindenburg, Max (Department: 3736)
Surgery
Diagnostic testing
Liquid collection
Reexamination Certificate
active
06241689
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to apparatus for use in collecting liquid samples, in particular biological samples, e.g. blood or saliva. Such apparatus is useful in collecting samples for use in diagnostic tests, and the invention also provides a kit for use in such tests.
Increasingly, use is being made of rapid diagnostic tests, both for use at home by a patient or for use by doctors in their surgeries. These tests have been made available through the use of diagnostic test devices and/or kits which provide everything needed to collect a sample and to perform the diagnostic test thereon. This enables many such tests to be performed more rapidly with less fuss and inconvenience. One example of such a test is the HELISAL™ test used to diagnose infection by
H. pylori
using a sample of blood.
Of course, such tests, and the test devices/kits provided to perform them, must be capable of providing the required level of accuracy that hospital laboratories can achieve, or at least a level of accuracy approaching that of hospital laboratories. In addition, it is often the case that the sample size required for the test fall within a particular range. For home use, and even for use by a doctor in the surgery, accurate measurement of sample volume may present problems. In addition, handling of samples which may represent a “biohazard” can be difficult. Thus, what is required is some form of apparatus which will allow collection of a sample in the right volume range, while at the same time minimising the risk of contact with the sample by the user.
In general, at present, samples are first collected and then transferred to a means, be it a device or the like or a simple test strip, where the test is performed. For example, to perform a test on a sample of blood, the person performing the test might prick the subject's finger and then use a simple capillary to draw up a sample of blood. This sample would then be transferred to the device or test strip for the reaction to occur. Clearly, it would be better if one could provide a sample collection apparatus which would accurately take up a “fixed” volume of sample and which would then release the sample in such a way that the sample is made available accurately and quickly every time, thus ensuring accurate and repeatable results.
SUMMARY OF THE INVENTION
We have now devised such an apparatus. This is simple to use, can be adapted easily to collect different types of sample as well as different sample sizes and which also minimises the risk of user contact with the sample, particularly when transferring the sample to a device designed to perform a diagnostic test on the sample. In particular, the apparatus is designed to connect with a device or housing which incorporates an analyte detection means. The connection of the two parts ensures that the sample is accurately presented each time a test is performed such that the sample can be quickly and accurately transferred to the detection means.
Thus, in a first aspect, the present invention provides sample collection apparatus adapted to interconnect with a device or housing which incorporates analyte detection means, wherein upon interconnection with said device or housing the sample is presented such that at least a part of any sample in the apparatus will be transferred to the device or housing from the apparatus. Suitably, the apparatus comprises a first portion adapted to be held by the user while collecting the sample, and a second portion comprising sample collection means.
The apparatus could be designed to simply be pushed together with the device or housing incorporating the analyte detection means. However, in one embodiment, the apparatus further comprises alignment means adapted to ensure correct presentation of the sample collection apparatus upon interconnection with the device or housing. One example of such alignment means would be guide rails, or projections designed to align with recesses formed in the device or housing. Furthermore, the alignment means could itself act as interconnection means.
In one preferred embodiment, which is particularly suited to collecting blood samples, the sample collection means comprises at least two members adapted to receive a sample volume therebetween upon bringing the members into contact with a liquid. In particular, the apparatus will work by taking up the sample by capillary action, simply by bringing the members into contact with the sample. Preferably, the members are elongate and could, for instance, be formed by plates, or could form a comb arrangement. In another arrangement there could be provided a two-dimensional arrangement of members with spaces therebetween. The apparatus can easily be adapted to collect particular volumes of sample, simply by means of altering the volume of the spaces between the members. Preferred embodiments include four, five or six elongate members in a comb arrangement providing three, four or five spaces therebetween, respectively, to receive the sample volume.
The exact nature and arrangement of the members is not critical. However, clearly, one would not construct the members of a hydrophilic material. Also, the spacing between the members should be such that the sample will be taken up and held between the members. If the spacing is too great, this will not occur. The essential feature which the arrangement must possess is the ability to both present the liquid sample accurately and allow it to be released quickly and reliably. One example of how this can be achieved would be by having an arrangement of the collection means such that contact over a substantial proportion of its surface area with part of the device or housing was achieved upon interconnection. For example, one arrangement would provide for contact of the sample collection means with a test strip, usually formed of porous material, or with an intermediate member, formed of porous material and designed to take up the sample and transfer it to where the reaction is to be performed, upon interconnection.
It may also be advantageous to coat the sample collector with a substance such as heparin to reduce or eliminate blood clotting.
In an alternative preferred embodiment, which would be particularly suited to collecting saliva samples, the sample collection means is formed from a body of absorbent material. An example of a suitable material is absorbent material comprising one or more sintered polymers. Useful polymers include plastics, such as sintered polyethylene (PE).
This material is bio-compatible, does not fragment, break, deform, etc., and is also able rapidly and consistently to absorb liquid. In addition, it has a controlled pore size, and in this way the material can be formed such that it will readily transfer/give up absorbed material to “downstream” components in any diagnostic kit. Pore size can be controlled in a number of ways. Firstly, polymer powders of different mean particle sizes can be used. If a polymer powder is not available which has exactly the required pore size, then a powder with a larger mean pore size can simply be ground to the desired particle size. Polymer powders having a mean particle size within the range 20-500 microns are particularly useful.
Another way of controlling particle size is by adjustment of the packing of the polymer powders in the mould before sintering. However, using this method, it is only possible to alter pore size to a smaller degree.
To ensure good uptake of a hydrophilic liquid like saliva, relatively hydrophilic polymers can be used. However, relatively non-hydrophilic polymers can be treated to increase their hydrophilicity. Such treatment can be carried out either before or after the sintering process. Examples of such treatment include treatment with a surface-active/wetting agent, e.g. Sodium Dodecyl Sulphate (SDS) or more preferably a biocompatible agent such as Crodasinic LS
30
, (Sodium Lauroyl Sarcosinate) chemical, electrical or radiation treatment, thereby modifying the surface of the material.
To produce such an absorbent material
Chard Michael John
Goodwin Philip Robert
Sams Bernard
Smith Christopher John
Woolston Robert
Hindenburg Max
Pennie & Edmonds LLP
Provalis UK Limited
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