WO2024194624A1

WO2024194624A1 - Sample swabs and method of production

Info

Publication number: WO2024194624A1
Application number: PCT/GB2024/050739
Authority: WO
Inventors: Alastair Beadle
Original assignee: Smiths Detection-Watford Limited
Priority date: 2023-03-20
Filing date: 2024-03-19
Publication date: 2024-09-26

Abstract

- 20 - ABSTRACT Sample swabs and methods for producing sample swabs for collecting samples for delivery to a detector are provided. A method of producing a sample swab for collecting samples for delivery to a detector comprises providing a swab substrate in the form of a sheet, and stamping the swab substrate in a press comprising surface projections to form one or more ridges in a sample collection region of the swab substrate, wherein the one or more ridges project from the surface of the sheet by more than 0.1mm and no more than 1.0mm.

Description

Sample swabs and method of production

The present disclosure relates to sample swabs and methods for producing sample swabs for collecting samples for delivery to a detector. In particular, the present disclosure relates to sample swabs and methods for producing sample swabs where the sample swabs are formed by stamping a swab substrate to provide surface projections.

Sample swabs are used for sample collection for trace analyte detectors in order to deliver samples from a subject, such as a surface to be analysed, to the inlet of a detector. Sample collection efficiency is important in such applications in order to ensure that trace substances, such as explosives or narcotics, can be detected. It is therefore desired to enhance the collection efficiency of such sample collection swabs.

In addition, as a result of the use of such swabs in detecting only trace amounts of collected substances, sample collection swabs are typically single-use to avoid contamination and false positives. Sample swabs must therefore be suitable for efficient mass production in order to provide for practical and economical production of such swabs.

Aspects and embodiments of the present disclosure aim to address the above technical problems.

Summary

Embodiments of the disclosure relate to sample swabs and methods for producing sample swabs for collecting samples for delivery to a detector.

While trace detectors such as ion mobility spectrometers, mass spectrometers and the like are configured to detect very low concentrations of substances of interest, such trace detection is also dependent upon delivery of a reliable sample to the detector. Thus, sample collection efficiency when using a swab to collect samples is of importance in providing a reliable detection system. Swabs for sample collection may suitably comprise a substrate that is contacted with a surface to collect trace amounts of substances of interest present on the surface. Such swabs can be provided with adhesive or other chemical coatings on the swab to enhance collection efficiency generally and/or to provide specific chemical compatibility with targeted trace materials. However, post-processing of swabs in this way can require complex additional processes that can add significant cost to the production process when performed on a large scale, and can be difficult to scale up to large quantities efficiently for mass production.

Embodiments of the present disclosure aim to address such problems by providing methods for producing sample swabs to improved collection efficiency that can be readily scaled up for efficient mass production.

Aspects of the disclosure are set out in the independent claims and optional features are set out in the dependent claims. Aspects of the disclosure may be provided in conjunction with each other, and features of one aspect may be applied to other aspects.

In an aspect there is provided a method of producing a sample swab for collecting samples for delivery to a detector, the method comprising: providing a swab substrate in the form of a sheet; and stamping the swab substrate in a press comprising surface projections to form one or more ridges in a sample collection region of the swab substrate, wherein the one or more ridges project from the surface of the sheet by more than 0.1 mm and no more than 1.0mm.

By using a press to deform a sheet of a swab substrate, the method may be applied efficiently on a large scale to produce swabs having ridges on the surface of the swab substrate. Ridges formed by the stamping step may suitably be formed so as to project more than 0.1 mm from the surface of the swab substrate. In this way, ridges may be formed that can aid in the collection of a material of interest onto the swab in an efficient manner, for example compared with surface coating and chemical treatments. The use of a press to stamp the swabs and provide the one or more ridges can allow for the process to be conducted at scale in an efficient and consistent manner. The swab substrate is suitably in the form of a sheet, The sheet for the swab substrate may be provided in any suitable form for use in the present process. The swab substrate may suitably be used in a form from which a sheet material may be provided. For example, the swab substrate material may be provided in the form of a roll of sheet material, or the sheet-form swab substrate may be a sheet material provided from an extrusion process and/or a sheet rolling process such as calendering.

The swab substrate may be made from any suitable sheet material. In preferred embodiments, the swab substrate may comprise a woven or non-woven sheet material. Any materials may be used to form the woven or non-woven sheet material, including cellulose-based materials (e.g. paper), polymer fibers (e.g. PTFE, polyamide such as aramid polymers), glass fibres, natural fibres such as cotton. For example, the swab substrate may comprise or consist essentially of any one of paper, a polymeric material, glass fibres or a mixture thereof. Preferably the swab substrate comprises or consists essentially of paper or an aramid polymer, for example a meta-aramid polymer such as Nomex (RTM). The swab material may suitably be processed, for example calendered, to provide the swab substrate in the form of a sheet.

The swab substrate comprises one or more ridges in a sample collection region, wherein the one or more ridges project from the surface of the sheet of the swab substrate. The projection of the one or more ridges (at their peak) from the surface of the sheet may suitably define the perpendicular projection of the swab surface from the plane containing the non-deformed portion of the swab substrate (i.e. the portion pressed between portions of the press surface having no surface projections). For example, the projection of the one or more ridges from the surface of the sheet may suitably define the perpendicular projection of the swab surface from the remainder of the undeformed swab surface when the undeformed portions define a substantially flat plane. In addition, the pressing step may in some cases comprise providing projections from the plane of the swab substrate in both directions, and therefore the projection from the surface of the sheet of the swab substrate of more than 0.1 mm and no more than 1.0mm as described herein, may be considered the thickness of the swab from the peak of a ridge on one side of the substrate to a peak on the opposite side of the swab substrate. The one or more ridges project from the surface of the sheet by more than 0.1 mm and no more than 1.0mm. Surface ridges greater than 0.1mm can provide a surface texture on the swab to allow for improved sample collection from a surface against which the swab is contacted, whilst also allowing for economical production of the swab. Large surface ridges, for example greater than 1.0mm, may be more easily deformed by use of the swab for sampling, and excessive deformation of the swab during stamping may weaken the swab material and lead to undesired breakage during use.

The one or more ridges may suitably project from the surface of the swab substrate sheet by 0.2mm or more, for example by 0.3mm or more. Similarly, the one or more ridges may project from the surface of the sheet by no more than 0.8mm, for example by no more than 0.6mm. In embodiments, the one or more ridges may project from the surface of the swab substrate sheet by at least 0.5mm, for example at least 0.7mm.

It will be appreciated that the size of the surface ridges may suitably be determined based on the size of the projections on the surface of the press that is used. In addition, the height of ridges on the swab may also suitably be measured, for example by microscopy such as optical microscopy, or any other suitable method known in the art.

The thickness of the swab substrate sheet may suitably be in the range of from 0.02mm to 2.0mm, for example from 0.04mm to 1.0mm, for example from 0.05mm to 0.5mm and may for example have a thickness of no more than 0.3mm, for example no more than 0.2mm. It will be appreciated that the thickness of the swab substrate may be varied depending on the particular material being used. For example, a paper swab substrate may in some embodiments have a thickness of from 0.02mm to 0.1mm, for example from 0.04mm to 0.08mm, and an aramid polymer swab may in some embodiments have a thickness of from 0.06mm to 0.14mm, for example from 0.08mm to 0.12mm.

The ratio of the projection of the one or more ridges to the swab thickness may suitably be from 0.2 to 50, for example from 1 to 10, for example from 2 to 6. In some preferred embodiments, the size of the surface projection of the one or more ridges is at least equal to the thickness of the swab, for example the surface projection of the one or more ridges may preferably be greater than the thickness of the swab. The swab substrate may have ridges formed by deformation of the swab substrate throughout its cross-section. For example, the swab substrate sheet may be defined by a plane and the ridges comprise deformation of the plane from the undeformed portions, for example the flat portions of the swab. Thus, in preferred embodiments, the one or more ridges may correspond to indentations on the opposite surface of the swab substrate, for example where the swab has a substantially uniform thickness and/or wherein the ridges are formed by deformation of the swab substrate material throughout its thickness. In particular, the one or more ridges may correspond to indentations on the opposite surface of the swab substrate when the swab thickness is smaller than the ridge projection height from the surface of the swab. In other embodiments, the ridges formed on the swab may project from one face of the swab substrate, for example where the swab substrate is thick compared to the ridge projection from the surface then the ridges may be formed without deformation of the side of the swab substrate opposite to that on which the ridges are provided.

The method comprises stamping the swab substrate in a press comprising surface projections to form ridges on the swab. Stamping the swab substrate in a press suitably comprises applying pressure to the swab substrate sheet between two surfaces, where at least one of the surfaces may be shaped so as to deform the swab substrate to provide ridges, for example both surfaces of the press that contact opposing faces of the swab substrate may suitably be shaped for stamping the swab substrate. For example, the press may comprise two surfaces having corresponding surface profiles so that projections from one face match indents in the opposing face of the press. Thus, the press may comprise first and second plates comprising surface projections and corresponding surface indentations, respectively, where the swab substrate is pressed between the first and second plates. The stamping step may comprise forming cuts through the sheet of the swab substrate adjacent at least a portion of the one or more ridges, for example so that a cut edge of the swab substrate forms a peak of a corresponding ridge.

The press used in the present process may suitably comprise a die, such as forming die.

The press can be configured in any suitable way to provide ridges corresponding to a desired ridge configuration on the swab substrate. The press may comprise an embossing die comprising projections on one surface of the press and corresponding indentations on the opposing surface. Where cuts through the swab substrate material are desired, the press may comprise a die configured to cut the sheet of the swab substrate and to cause the material adjacent to the cut to form a ridge that projects from the swab surface. A press configured to cause cuts in the swab substrate may also suitably be configured for the formation of uncut ridges, for example embossed portions of the swab substrate.

The press may take any suitable form, and may for example comprise two surfaces between which the swab substrate sheet is pressed, each surface provided by a substantially flat plate, a curved surface of a roller, or a combination thereof (for example one flat surface and one roller.

In embodiments, a plurality of sample swabs may suitably be produced by the same stamping step. For example, the stamping may comprise providing a plurality of separate sample collection areas, each comprising ridges as defined herein, on the same sample substrate sheet. The stamping step may also comprise cutting the swab substrate sheet to separate the plurality of sample collection areas and form a plurality of sample swabs. This may be achieved, for example, by use of a die configured to cut the swab substrate around predefined boundaries between each of the swabs present on a sheet of swab substrate. Within each cutting portion of such a die, the press or die may suitably be configured to provide stamped ridges in a sample collection region of each separate swab. In this way, multiple swabs may be stamped and separated from each other in a single step.

The one or more ridges formed by the stamping step may have any suitable dimensions or shape in terms of their arrangement on the surface of the swab, for example their location and dimensions within the plane of the swab substrate. For example the ridges may be provided in the form of lines on the swab substrate, which may include straight lines and/or curved lines. The ridges may form closed shapes on the surface of the swab, for example circular ridges or any other shape, and/or the ridges may comprise one or more lines that do not form a closed shape. It will be appreciated that where ridges adjacent to cuts in the swab substrate are present, such ridges will not typically be arranged to form closed shapes as this would cut off the material inside the closed shape from the remainder of the swab substrate. Thus, where a plurality of ridges comprise adjacent cuts in the swab substrate, such ridges may be arranged so as to not intersect (however such ridges may be arranged to intersect with ridges that do not comprise cuts). In embodiments, the one or more ridges may include points rather than lines, so as to form generally conical or hemispherical protrusions on the swab substrate.

Preferably, the one or more ridges are formed in a symmetrical pattern on the swab. For example, the sample collection region may comprise one or more ridges arranged in a symmetrical pattern. The symmetric pattern may have any desired level of symmetry. For example, the symmetric pattern may have at least 2-fold symmetry, for example at least 3-fold symmetry, such as at least 4-fold symmetry or higher such as at least 6 fold symmetry. A symmetric pattern may include all of the ridges formed on the swab or only some of the ridges. For example, a swab may be formed having a mixture of different patterns having different degrees of symmetry. In some embodiments, the ridges may comprise a combination of (i) ridges comprising cuts through the swab material and (ii) ridges without cuts, where (i) and (ii) together form a symmetric pattern, or each individually form separate patterns, one or both of which may be symmetric and may have different degrees of symmetry. A symmetric arrangement of ridges on the swab can help to reduce anisotropy in relation to sample collection efficiency. For example, because a user may not always wipe the swab against a surface to be sampled in the same direction, or in the direction intended according to the swab design, providing symmetry in the sample collection region can aid in effective and consistent sample collection.

The method may comprise applying a coating configured to enhance sample collection efficiency to at least the sample collection region of the swab substrate. For example, an adhesive coating may be applied to the swab substrate, which may be applied to the entire swab surface or may be applied only in a sample collection region. The coating may comprise any suitable coating material and is suitably a non-volatile coating that does not result in out-gassing or decomposition of the coating when heated, for example to desorb collected sample for analysis by a detector. The coating may suitably comprise a non-volatile polymeric coating. In embodiments, the coating comprises polyisobutylene.

A coating may be applied to the swab substrate before or after the stamping step. In embodiments, the coating is applied before the stamping step, which can avoid the coating covering ridges formed on the swab substrate. The ridges may therefore be formed by both deformation of the swab substrate material as well as the material coated on the swab substrate. In other embodiments, the coating may be applied after the stamping step, and may be applied so as to retain the surface profile of the ridges, for example the coating may be applied in a thin layer relative to the size of the ridges. For example, the thickness of the coating may be less than the size of the ridges, for example the projection of the ridges before coating may be at least 2 times the thickness of the coating, for example at least 5 times the thickness of the coating.

The stamping step may further comprise stamping ridges into the swab substrate outside of the sample collection region. For example, additional ridges may be applied to the swab to provide increased rigidity to the swab to aid in inserting the swab into a detector. Further ridges may be stamped into the swab to provide visual markers such as identification numbers or to add a manufacturers name or logo. Advantageously, this may be performed at the same time as providing ridges for enhanced sample collection as described previously.

The present method provides a sample swab for collecting samples for delivery to a detector. The detector may be any suitable detector that is able to obtain samples for analysis from a sample collection swab and may comprise a trace analyte detector. For example, the detector may comprise an ion mobility spectrometer (IMS), a mass spectrometer (MS), a chromatography apparatus such as a gas chromatography (GC) apparatus or a liquid chromatography apparatus such as a HPLC apparatus, or a combination thereof such as an I MS-MS or a GC-MS. Delivery of a sample from the sample swab to the detector may suitably be by heating the swab to desorb a sample of interest collected on the swab for analysis. The formation of ridges provided by the swab material itself can be beneficial in that this can avoid the need for the use of adhesive coatings that may release interferent substances when heated in this way. The provision of the ridges on the swab to provide a sample collection region may be such that the sample collection region is configured, for example by its size and/or shape, to match with the inlet of a detector that draws in vapourised sample, which may, for example, enhance extraction of materials of interest collected on the swab into the inlet. The sample collection region may have a size and/or shape configured to match a heater that is operable to desorb sample from the swab, for example a heater at the inlet of a detector.

In embodiments, the stamping step can provide a boundary ridge to provide a user with a guide as to where the sample collection region is located on the swab, without the need for other visual markings that could add cost and complexity to the process or may introduce additional contaminants that may interfere with subsequent trace detection. Thus, in embodiments one or more boundary ridges are formed on the swab substrate, the one or more boundary ridges defining, for example surrounding, the sample collection region (e.g. surrounding the ridges formed in the sample collection region). The one or more boundary ridges may project from the surface of the swab substrate sheet more than the one or more ridges in the sample collection region so as to provide a visual guide of the sample collection region and/or to retain and aid in the concentration of sample in the sample collection region.

The boundary ridge and the sample collection region may be configured to correspond to the inlet of a detector, for example the boundary ridge may be sized to correspond to an inlet of a detector or to a heater at an inlet of a detector. In this way, the sample collection may be easily concentrated by a user in a region of the swab from which a sample can be efficiently transferred to the detector. By creating one or more boundary ridges during the stamping step as described, this may also be achieved without adding significant processing complexity as this can be performed at the same time as stamping the one or more ridges onto the swab in the sample collection region.

A further aspect provides a sample swab comprising a swab substrate in the form of a sheet, wherein the sample swab comprises one or more ridges projecting from the surface of the sheet in a sample collection region, the ridges projecting above the surface of the swab by more than 0.1 mm and no more than 1.0mm. It will be understood that the sample swab may be substantially as defined elsewhere herein and may suitably be a swab prepared by any of the methods defined herein.

For example, the one or more ridges may project from the surface of the sheet by 0.2mm or more, for example by 0.3mm or more. Similarly, the one or more ridges may project from the surface of the sheet by no more than 0.8mm, for example by no more than 0.6mm. In embodiments, the one or more ridges may project from the surface of the swab substrate sheet by at least 0.5mm, for example at least 0.7mm.

The one or more ridges may correspond to indentations on the opposite surface of the swab substrate as described elsewhere herein, for example such that the ridges are formed by deformation of the plane of the swab substrate sheet rather than only singlesurface deformation.

The swab may comprise cuts through the sheet of the swab substrate adjacent at least a portion of the one or more ridges as described elsewhere herein, for example so that a cut edge of the swab substrate forms a peak of an adjacent ridge.

The one or more ridges may be arranged in a symmetrical pattern in the sample collection region as described elsewhere herein.

The swab may comprise one or more boundary ridges defining the sample collection region, for example surrounding, the sample collection region, as described elsewhere herein. For example, the one or more boundary ridges may project from the surface of the sheet more than the one or more ridges in the sample collection region.

As described elsewhere herein, the swab may comprise a coating configured to enhance sample collection efficiency on at least the sample collection region of the swab substrate, for example a polyisobutylene coating.

As described, the swab substrate may suitably comprise a woven or non-woven sheet material, for example the swab substrate may comprise paper, a polymeric material or glass fibres, preferably paper or an aramid polymer.

A further aspect provides a system comprising one or more sample swabs as defined herein, and a detector, for example wherein the size and/or shape of the sample collection region of the sample swab and/or the size and/or shape of the sample swab are configured to correspond with an inlet of the detector configured to receive the swab.

Brief Description of Figures

Examples of the disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figures 1A to 1C show a schematic illustration of a stamping process to form ridges on a swab;

Figures 2A to 2E show a schematic illustration of a stamping process to form ridges and cuts on a swab;

Figures 3A to 3C show a schematic illustration of an arrangement of ridges and/or cuts on the surface of a swab; and

Figures 4A to 4C show a schematic illustration of a boundary ridge surrounding a sample collection region of a swab.

In the drawings like reference numerals are used to indicate like elements.

The present disclosure relates to sample swabs and methods for producing sample swabs for collecting samples for delivery to a detector.

Figures 1A, 1 B and 1C illustrate the production of a sample swab 106 by stamping a swab substrate 100 with a press.

As shown in Figure 1A, a swab substrate 100 in the form of a sheet is provided between a first die 110 and a second die 120 of a press. While the press is shown as using first and second flat dies 110/120 (and 210/220 in Figure 2), it will be appreciated that any suitable configuration could be used, such as two roller dies or a combination of a roller die and a flat die. The first die 110 comprises surface projections 112 configured to deform the swab substrate 100 when the swab substrate is pressed between the first and second dies 110/120. The second die 120 comprises surface indentations 122, which correspond to the projections 112 so that the projections 112 deform and push the swab substrate 100 into the indentations 122 when the press is operated. The deformation of the swab substrate 100 is shown in Figure 1 B, in which stamping the swab substrate 100 in the press has formed ridges 102 that project from the surface 103 of the swab substrate sheet 100.

Figure 1C shows a sample swab 106 formed by stamping the swab substrate 100 in the press. The sample swab 106 comprises ridges 102 that project a height h from the surface 103 of the sample substrate sheet 100. While not labelled in Figures 1A and 1 B, it will be appreciated that the height h also corresponds to the height of the surface projections 112 and the depth of the indentations 122. Figure 1C also shows that the ridges 102 correspond to indentations 104 on the opposite surface 105 of the swab substrate sheet 100. As can be seen in Figures 1A to 1C, the ridges 102 on the swab 106 are formed by deformation of the plane defined by the swab substrate 100.

Figures 2A to 2C illustrate an example of forming ridges on the swab substrate together with cuts of the swab substrate. As shown in Figure 2A, a swab substrate 200 is provided between a first die 210 and a second die 220 of a press. The first die 210 comprises surface projections 212 configured to deform and to cut the swab substrate 200 when the swab substrate is pressed between the first and second dies 210/220. The second die 220 comprises surface indentations 222, which correspond to the projections 212 so that the projections 212 deform and push the swab substrate 200 into the indentations 222 to cut the swab substrate 200 when the press is operated. The deformation of the swab substrate 200 is shown in Figure 2B, in which stamping the swab substrate 200 in the press has formed ridges 202 that project from the surface 203 of the swab substrate sheet 200.

Figure 2C shows a sample swab 206 formed by stamping the swab substrate 200 in the press. The sample swab 206 comprises ridges 202 that project a height h from the surface 203 of the sample substrate sheet 200. While not labelled in Figures 2A and 2B, it will be appreciated that the height h also corresponds to the height of the surface projections 212 and the depth of the indentations 222. Figure 1C also shows that the ridges 202 correspond to indentations 204 on the opposite surface 205 of the swab substrate sheet 200. As can be seen in Figures 2B and 2C, the ridges 202 on the swab 206 are formed by cutting the swab substrate 200 to provide a cut edge 208a/208b of the swab substrate 200. As can be seen in Figure 2C, the ridges 202 are formed adjacent a cut edge 208. A peak of the ridge 202 may be formed by a cut edge 208b of the swab substrate 200 that is pushed away from the surface 203 of the swab substrate 200. The other edge of the cut 208a remaining in the undeformed plane of the swab substrate 200. It will be appreciated that Figure 2 shows a cross sectional view of the press and the swab 206, and that the ridge 202 may suitably form a peak at height h and reduce in height in the dimension orthogonal to the cross-section shown in Figure 2C. Thus, in three dimensions the ridges 202 may be of a generally half-conical, hemispherical, half- pyramidal or any other form. Figures 2D and 2E show example projections along the direction A-B shown in Figure 2C and illustrate the possible cross-section of ridges 202 formed by cutting the swab substrate 200 and stamping ridges 202 adjacent the cuts. Figures 2D and 2E show the profile of the cut edge 208b that forms a ridge 202, and it will be appreciated that the triangular and generally hemispherical profiles shown in Figures 2D and 2E, respectively, are merely exemplary and any profile may be formed, depending on the form of the projections 212 and indentations 222 of the press.

It will be appreciated that Figures 1A to 1C and 2A to 2E are merely illustrative and that many variations of the process shown may be envisaged. For example, while in Figures 1 and 2 the formation of two ridges 102/202 on the swab 106/206 are shown, it will be appreciated that this is merely exemplary and that any number of or configuration of ridges may be formed by the methods of the present disclosure. Similarly, while Figures 1 and 2 show the swab substrate as wider than press, this is merely illustrative and the swab substrate may suitably have a surface area relative to the press so as to be covered by the press surfaces during pressing.

Figure 3 shows views of an arrangement of ridges on a swab as viewed from above, i.e. along the direction A-C shown in Figure 2C (though it will be appreciated that the arrangement shown in Figure 3 do not necessarily correspond to the swab shown in Figure 2C). Figure 3A shows an arrangement of ridges 302a on the surface of a swab substrate 300. The ridges may, for example, be formed as shown in Figures 1A to 1C. The arrangement in Figure 3A is made up of connected hexagons of ridges 302a and shows 6-fold symmetry. The symmetrical nature of the arrangement can aid in ensuring that sample collection is efficient and consistent independent of which direction the swab is wiped against a surface. This use of symmetry can help to eliminate user error in collecting samples to provide improved reliability, for example as compared to where a swab has a specific directionality for optimal swabbing (which may not be followed consistently by users). It will be appreciated that hexagonal shapes and 6-fold symmetry is merely one example and other arrangements may be used.

Figure 3B shows an alternative arrangement in which a plurality of ridges 302b are formed adjacent to a cut in the swab substrate 300, for example as shown in Figures 2A to 2C. As will be appreciated, where ridges comprising a cut in the swab substrate are used, the ridges are suitably separated so as to maintain the integrity of the swab substrate 300. While the arrangement in Figure 3B only shows 2-fold symmetry, it will be appreciated that higher levels of symmetry may also be used.

As shown in Figure 3C, an arrangement may be provided having a combination of ridges without cuts (302a) and ridges with cuts (302b). As can be seen, the arrangement comprises (in addition to cut ridges 302b at the centre of each hexagon) a symmetric hexagonal arrangement of ridges 302a and 302b similar to that shown in Figure 3A, but comprising a combination of cut ridges 302b and uncut ridges 302a. The combination of cut and uncut ridges permits cut ridges to be used whilst also permitting a more complex and interconnected arrangement of ridges to be used (without compromising the structural integrity of the swab by using intersecting cut ridges 302b).

It will also be appreciated that while Figures 3A to 3B show arrangements made using straight lines, more complex arrangements and/or arrangements including curved lines are also envisaged. Figures 4A to 4C show examples of sample collections regions comprising ridges 402, together with a boundary ridge 404. As can be seen in Figure 4A, the boundary ridge 404 may project further from the surface of the swab substrate than the ridges 402 such that the boundary ridge 404 is more prominent and provides a visual aid as to where the sample collection region is located on the swab. This may aid a user in concentrating sample collection in the sample collection region, which may correspond in size and/or shape to an inlet and/or a heater of a detector to maximise delivery of collected samples to the detector. As shown in Figure 4B, the boundary ridge 404 may surround the ridges 402 that are provided in the sample collection region of the swab. Figure 4C shows an example of a rectangular sample swab 406, having a sample collection region comprising ridges 402 and a boundary ridge 404 according to Figure 4B.

In general, apparatus features described herein may be provided as method features, and vice versa.

It should also be appreciated that particular combinations of the various features described and defined in any aspects of the invention can be implemented and/or supplied and/or used independently. Other examples and variations will be apparent to the skilled addressee in the context of the present disclosure.

Claims

CLAIMS:

1. A method of producing a sample swab for collecting samples for delivery to a detector, the method comprising: providing a swab substrate in the form of a sheet; and stamping the swab substrate in a press comprising surface projections to form one or more ridges in a sample collection region of the swab substrate, wherein the one or more ridges project from the surface of the sheet by more than 0.1 mm and no more than 1.0mm.

2. A method according to claim 1 , wherein the one or more ridges project from the surface of the sheet by 0.2mm or more, for example by 0.3mm or more.

3. A method according to claim 1 or claim 2, wherein the one or more ridges project from the surface of the sheet by no more than 0.8mm, for example by no more than 0.6mm.

4. A method according to any one of the preceding claims, wherein the one or more ridges correspond to indentations on the opposite surface of the swab substrate.

5. A method according to any one of the preceding claims, wherein said stamping comprises forming cuts through the sheet of the swab substrate adjacent at least a portion of the one or more ridges, for example so that a cut edge of the swab substrate forms a peak of a corresponding ridge.

6. A method according to any one of the preceding claims, wherein the one or more ridges are formed in a symmetrical pattern in the sample collection region.

7. A method according to any one of the preceding claims, wherein one or more boundary ridges are formed on the swab substrate, the one or more boundary ridges defining, for example surrounding, the sample collection region.

8. A method according to claim 7, wherein the one or more boundary ridges project from the surface of the sheet more than the one or more ridges in the sample collection region.

9. A method according to any one of the preceding claims, wherein said stamping comprises providing a plurality of separate sample collection areas on the same sample substrate sheet.

10. A method according to claim 9, wherein the stamping step comprises cutting the swab substrate sheet to separate the plurality of sample collection areas and form a plurality of sample swabs.

11. A method according to any one of the preceding claims, wherein the press comprises first and second plates comprising surface projections and corresponding surface indentations, respectively.

12. A method according to any one of the preceding claims, wherein the press comprises two surfaces between which the swab substrate sheet is pressed, each surface provided by a substantially flat plate or a curved surface of a roller.

13. A method according to any one of the preceding claims, further comprising applying a coating configured to enhance sample collection efficiency to at least the sample collection region of the swab substrate, for example a polyisobutylene coating.

14. A method according to claim 13, wherein the coating is applied before the stamping step.

15. The method of any one of the preceding claims, wherein the swab substrate comprises a woven or non-woven sheet material.

16. The method of claim 15, wherein the swab substrate comprises paper, a polymeric material or glass fibres, preferably paper or an aramid polymer.

17. A sample swab comprising a swab substrate in the form of a sheet, wherein the sample swab comprises one or more ridges projecting from the surface of the sheet in a sample collection region, the ridges projecting above the surface of the swab by more than 0.1 mm and no more than 1.0mm.

18. A swab according to claim 17, wherein the one or more ridges project from the surface of the sheet by 0.2mm or more, for example by 0.3mm or more.

19. A swab according to claim 17 or claim 18, wherein the one or more ridges correspond to indentations on the opposite surface of the swab substrate.

20. A swab according to any one of claims 17 to 19, comprising cuts through the sheet of the swab substrate adjacent at least a portion of the one or more ridges, for example so that a cut edge of the swab substrate forms a peak of an adjacent ridge.

21. A swab according to any one of claims 17 to 20, wherein the one or more ridges are arranged in a symmetrical pattern in the sample collection region.

22. A swab according to any one of claims 17 to 21 , comprising one or more boundary ridges defining the sample collection region, for example surrounding, the sample collection region.

23. A swab according to claim 22, wherein the one or more boundary ridges project from the surface of the sheet more than the one or more ridges in the sample collection region.

24. A swab according to any one of claims 17 to 23, comprising a coating configured to enhance sample collection efficiency on at least the sample collection region of the swab substrate, for example a polyisobutylene coating.

25. The swab of any one of claims 17 to 24, wherein the swab substrate comprises a woven or non-woven sheet material.

26. The swab of claim 25, wherein the swab substrate comprises paper, a polymeric material or glass fibres, preferably paper or an aramid polymer.

27. The swab of claim 17, wherein the sample swab is prepared by the method of any one of claims 1 to 16.