EP1805496A1

EP1805496A1 - A sample lifting tape and a method for forensic sampling of surfaces

Info

Publication number: EP1805496A1
Application number: EP05789699A
Authority: EP
Inventors: Angela Forensic Alliance Limited Gallop; Tiernan Forensic Alliance Limited Coyle; David Raybone
Original assignee: FORENSIC ALLIANCE Ltd
Current assignee: LGC Ltd
Priority date: 2004-10-07
Filing date: 2005-10-07
Publication date: 2007-07-11
Also published as: WO2006038023A1; GB0422302D0

Abstract

A method for the collection of a sample from an area, for example for forensic examination, comprises the steps of applying to the area a collection sheet (1) with an adhesive collecting surface (4) so that the adhesive collecting surface collects a sample (5) from the area, and subsequently covering the adhesive collecting surface with a backing medium (8) which is attached to the collection sheet so as to protect the collected sample. To reduce the risk of contamination, the collection sheet is provided with a border region (7) around the adhesive-collecting surface, the border region being non-adhesive during sample collection. This may be achieved by having a masking sheet over the adhesive surface of the collection sheet (1), divided into a border portion (2) and a central portion (3). Before use, the central portion (3) is removed to expose the adhesive collection surface (4). Once sample collection has been completed, the border portion (2) is removed, exposing the adhesive border region. The backing medium (8) can then be adhered to the sample collection and border regions.

Description

A SAMPLE LIFTING TAPE AND A METHOD FOR FORENSIC SAMPLING OF SURFACES

This invention relates to the collection of samples, particularly but not exclusively for forensic analysis.

A number of techniques are well known for the recovery of trace evidence samples. Reference is made for example to " Trace Evidence Recovery Guidelines", Forensic Science Communications 1,(3)1999; "Forensic Examination of Fibres" (Second Edition), James Robertson and Michael Grieve Ch 5. p 94 - p 100, published by Taylor and Francis; and "The Manual of Best Practice for the Forensic Examination of Fibres", p208-p212, trie European Fibre Group 2001. These known techniques include but are not limited to; scraping, picking, combing, clipping, vacuum lifting and tape lifting. Tape lifting using an adhesive pressure sensitive tape is a particularly convenient and common technique that has been in use for many years. It was first proposed by Frei - Sulzer in 1951 ("Die Sicherung van Mikrospuren mit Klebeband " , Kriminalistik, 10/51 190- 194). In Europe, tape lifting is the technique recommended as first choice for the recovery of textile contact traces. In practice the tape is applied, by pressing or rolling, to the article from which the evidence is to be collected and on removal of the tape, loosely adhering trace evidence such, as hairs, fibres and other materials remain bound to the tape. The tape and recovered sample material is then temporarily fixed to a transparent backing medium, such, as an acetate or plastic sheet or even a glass slide, to protect the evidence from contamination, to facilitate transportation and to allow microscopic examination of the gathered materials. The materials of interest can be subsequently recovered, for example by softening or dissolving the adhesive in a suitable solvent. A variety of commercially available lifting tapes are known and they are supplied either in roll or strip form. Examples include: Fingerprint Lifting Tape from www.crimescene.com; Remco (TM) Fingerprint Lifting Tape from Arrowhead

Forensic Products Lenexa KS 66214; and Faurot (TM) Fingerprint Lifting Tape from Faurotlnc. Product differentiation is achieved by means of varying the adhesive type for example to achieve improved lifting of powders for dusted prints and varying tape material for improved tear resistance. GB2386084-A describes an adhesive tape strip system for collection of environmental samples, in particular moulds, including a window for enhanced location and viewing and an adhesive free tab for enhanced handling. GB2253337-A describes a pick up implement with a stack of individually separable adhesive sheets.

When collecting, transporting and examining forensic evidence it is of critical importance to minimise all potential sources of contamination, ether real or perceived as these would render useless any findings as they may lead to erroneous court verdicts, collapsed trials and resultant wastage of valuable police resources. The present invention is concerned with reducing the risk of such contamination.

Viewed from one aspect the present invention a method for the collection of a sample from an area using a collection sheet with an adherent collecting surface, comprising the steps of applying the collection sheet to the area so that the adherent collecting surface collects a sample from the area, and subsequently covering the adherent collecting surface with a backing medium which is attached to the collection sheet so as to protect the collected sample, characterised in that the collection sheet is provided -with a border region comprising an adherent border surface around a major part of the adherent collecting surface, the adherent border surface being provided initially with a removable border masking layer which renders the border region non-adherent during sample collection, wherein after sample collection the border masking layer is removed prior to attachment of the backing medium to the collecting surface and the adherent border surface.

Viewed from another aspect of the invention, there is provided a collection sheet for the collection of a s ample, the collection sheet having an adherent collecting surface to which the sample will be adhered, the adherent collecting surface being provided with a collecting surface masking layer which is to be removed prior to sample collection, characterised in that the collection sheet is provided with a border region comprising an adherent border surface around a major part of the adherent collecting surface, the adherent border surface being provided with a removable border masking layer which is separate from the collecting surface masking layer, so that in use the border masking layer will render the border region non-adherent during sample collection and after sample collection the border masking layer can be removed prior to attachment of a backing medium to the collecting surface and the adherent border surface.

We have found that despite the widespread use of adhesive tapes there are lirnitations with the known approaches when applied to evidence recovery. In the prior art the adhesive layer on the tape extends fully over the surface of the tape used for sample collection in an uninterrupted fashion to the edge of the tape, as in a typical painter's masking tape, or roll of office tape. In GB 2253337 -A there is provided a tab or finger lift area but otherwise the adhesive layer on the tape extends fully over the surface of the tape, to the edge of the tape. We have found that the technique is potentially prone to cross-contamination from false evidence which may become attached to exposed adhesive, particularly on the edge of the tape strip or roll, either in storage or transport of the tape, or even at the time of evidence collection. The latter can potentially be a serious problem. For example, when examining a suspect vehicle for trace contact fibres to determine occupancy positions it is imperative that trace fibres from one seat are not transferred by the act of examination to the cabin air where they could become attached to any traces of exposed adhesive on tapes used to extract evidence from another seat.

The present invention provides a system, for evidence collection that can reduce or overcome the potential risk of cross -contamination from materials picked up on the edges of known tapes. At the point of evidence collection, there is provided a border region with no exposed adhesive between the adhesive section where evidence is collected and the outer edges of the sheet where potential contamination may occur. In addition the current approach is prone to wastage and potential loss of evidence as the tape strip may fold onto itself or become attached to other objects such as tiie operative's gloves, during evidence gathering, prior to sample fixing. In some situations where evidence is limited to a few fibres on a small surface, it is imperative to eliminate completely any wastage and potential losses. The present invention reduces the likelihood of the sheet becoming adhered to itself or to other objects, and the non-adherent border region facilitates handling by an operative.

A further problem with existing systems is that when a conventional tape is attached to an acetate backing sheet or the like, to seal in the evidence, there is a requirement to seal the edges of the tape to the acetate by fixing applying additional clear tape around the evidence collection strip. This is required because the tape may lose some of its adhesive quality when collecting the evidence so there is a risk that the edges will lift off the acetate at some later time and contamination or evidence loss may occur. The taping down of the edges is very time consuming and irritating to a scene of crime officer wearing gloves, for example. A preferred embodiment of the present invention avoids the need for an additional step to seal the edges of the sheet.

Thus, whilst the border region in a system in accordance -with another aspect of the invention may be non-adherent throughout use, in this preferred embodiment the border region comprises an adherent layer which is provided with a masking layer during the collection of a sample. Once sample collection is completed, the masking layer is removed and a clean border region of fresh adherent surface is exposed for the backing medium to be adhered to. Even if an edge should start to lift, it is only the protective border region and not the evidence region that is affected. This embodiment of the invention thus removes the requirement for the additional sealing of the edges of the sample collection sheet. The adherent surface of the border region may terminate at a distance from the edge of the sheet.

The adherent collecting surface requires protection before use, and one of the first steps when using the sheet will be to expose the collecting surface. In one embodiment, the collection sheet could be part of a continuous roll, in the nature of adhesive tape. In that case, the adherent collecting surface could be protected by being on the inner surface and contacting the non -adherent outer surface of an underlying part of the roll. However, in some embodiments of the invention and whether or not the sheet is provided part of a continuous roll or for example as a discrete item, the sheet is provided with a removable masking Layer adhered temporarily to the adherent collecting surface. This is removed prior to the collection of samples. As noted above, in accordance with another aspect of the invention the border region could be completely non-adherent or have an adherent surface which is covered with a border region removable masking layer adhered temporarily to the adherent surface. This border region masking layer remains in place during sample collection, but is then removed so that the ^"backing medium can be adhered to the sheet across the adherent collecting surface and the border region. The masking layers for the collecting surface and the border region could be of the same material or of different materials. In some embodiments they are of the sam& material for ease of manufacture, and the portions for the collecting surface and the border region are separated by e.g. a cut or score line so that they can be removed separately.

The expression "sheet" encompasses a range of structures but the sheet will normally be reasonably flexible and relatively thin, and may be transparent. It may be of a plastics or other synthetic material. In general, the sheet may be of a similar material to known tapes as discussed above. For example, the sheet may be designed so that the adherent collecting surface, which may be an adhesive surface applied "to a substrate, will dissolve easily in water or a suitable solvent.

The sheet may be of any size and shape, and could be square, rectangular, circular, or any other regular or irregular shape. It may be elongate and in the form, of a strip or tape. The sheet may be provided as a discrete item, or may for exanipLe be detachable from a planar element comprising a number of the sheets or, as not&d above, may be detachable from a roll. In the case of a continuous roll, perforations or the like may be provided for ease of use when detaching individual sheets.

Particularly in the case of an elongate sheet which is detached from a roll, it may be practical to have the border region only along the two longer sides of the sheet as that will assist in manufacture. However the border region may extend along at least one, and preferably both, of the other two sides also. Thus, in general, whilst the border region may extend around all or substantially all of the adherent collecting surface, it may be acceptable for it to extend only around the major part of the periphery of the adherent collecting surface, for example at least 75% of the periphery. Functionally, sufficient of the periphery of the adherent collecting surface should be provided with the border region to provide a significant reduction in the> risk of cross contamination, and the extent of the periphery of the collecting surface that needs to provided with the border region may depend on a number of factors such as shape, size and the particular purpose for which the sheet is used. For example, if contamination is not a serious issue in a particular application, then a reduced extent of border region protection may be adequate and may provide the other advantages of the invention as referred to above. Preferably, the border region extends outwardly from the periphery of the adherent collecting surface for at least about 5 mm, preferably at least about 10 mm and for example in the range of about 10 mm to about 20 mm. In general it is unlikely that the border region would extend beyond about 30 mm. Functionally, for forensic investigations, it is necessary to consider a lateral extent for the border region which is of the same magnitude as a piece of fibre evidence from e.g. clothing. Below the 5 mm range there may be a risk that a stray contaminant fibre could get attached to the border region and span the region from the edge of the sheet to the evidence collection region. In this situation it would be difficult to determine if the fibre was genuinely from the evidence or from a contaminant fibre. Above about a 20 mm to 30 mm border region, the overall size of the sheet gets quite large if there is to be a reasonable size of collecting surface, the volume of material used in manufacture becomes excessive, and yet there is no appreciable benefit in terms of improved cross contamination risk reduction. The border region may be of constant or varying width. In the case of an elongate sheet, the border region could for example be of one width along the sides and of another, smaller or larger, across the ends.

As regards the size of the sheet, this can generally be comparable to existing products, possibly with the dimensions increased somewhat to accommodate the border region whilst retaining the same collecting area. A typical size used could be a strip of about 170 mm x 50 mm. The likely extremes would be a footprint sized lifting sheet that could be up to about 400 mm x 300 mm (total dimensions including borders) down to a "credit card" sized sheet (useful for police scene of crime officers when gathering evidence at e.g. point of entry) at about 75 mm to 100 mm in one dimension and about 45 to 75 mm in the other, and typically about 85 mm x 54 mm (total dimensions including borders). One possible configuration is a circular sheet, of about 15 mm diameter with a concentrically arranged sample collecting surface of about 5 mm diameter. This sheet would have use when collecting evidence from specific detailed regions using e.g. forceps or the tip of a knife. The border region would approach its smallest dimension limit but preferably it would still be about 5 mm or more. In general, the minimum usable sample collecting surface area may be about 15 to 20 mm , and the maximum may be 0.35 m . For general use, typical areas may be in the range of 30 cm² to 100 cm². In the case of an elongate sheet, in the nature of a strip, the strip width may be in the range of about 25 mm to 100 mm, with typical widths being about 37.5 mm, 50 mm, and 75 mm. Lengths of such strips could be in the range of 50 mm to 200 mm, and for example 150 mm to 180 mm.

The adherent collection surface may be provided by adhesive covering all or part of the collection surface. The adhesive may be patterned, confined to specific shaped zones and may comprise multiple adhesive types to facilitate specific types of sample lift. Where the border region is adherent and covered by a masking layer at the time of sample collection, the adherent border region may be provided by adhesive covering all or part of the border region and the adhesive may be patterned or confined to specific shaped zones of the border region.

The border region with no exposed adhesive at the time of sample collection may extend fully to the sheet edge or part way to the sheet edge. Thus, moving from the edge of the sheet to the centre, the outermost peripheral region of the sheet could be plain, then there could be a border region with a masking layer which is left in place during sample collection, and then the adherent sample collecting surface which is initially covered by a masking layer which is removed for sample collection.

A plurality of squares or other regular shapes formed by e.g. a grid may be marked onto the sheet in the collection area in order to provide improved spatial definition for identification and subsequent retrieval of recovered samples. In addition, the grid may be marked with a grid reference to further aid in improved location and subsequent retrieval of evidence.

Operating instructions may be printed on the masking layer used on the sheet, such as backing paper. Where masking layers are used, the central section of sheet is revealed first for sample collection and the border region is revealed subsequently prior to fixing, stage one instructions may be printed on the central piece of masking layer such as backing paper and stage two instructions may be printed on the backing paper covering the border region. The back face of the sheet will generally be free of adhesive and may have a region that facilitates the recording of data specific to the evidence collection. For example this may include, but is not limited to, time, date, location, reference number and so forth which can be written in this region. Additionally or alternatively, the backing medium to protect the samples after collection may have a region that facilitates the recording of data specific to the evidence collection, and for example this may include, but is not limited to, time, date, location, reference number and so forth.

Additional tabs may be used to assist in the removal of the masking layer, from the adherent surfaces. The tabs may be attached to or be constructed as part of a central portion of the masking layer and/or the border region of the masking layer. Tabs are particularly useful when the operative is wearing protective gloves. A transparent protective backing medium such as a sheet may be pre- attached to the collection sheet. The attachment may be by a perforated strip to allow ease of detachment of the transparent backing sheet from the collection sheet prior to evidence collection if this is desired. This embodiment may be preferred in some situations and in all cases will ensure that a transparent backing sheet is available for every collection sheet.

As noted above, sheets may be portions of tape supplied in continuous roll form. There may be no requirement for a central strip of masking paper or the like covering the evidence collection adhesive. In roll form the tape may be manufactured in a clean environment and the subsequent rolling may serve to protect the evidence collection region from contamination until the time of usage. In roll form, backing paper or.. the like acting as a mask for the border region may be in strip form. At least two masking strips may run the length of the tape and may extend to the edge of the tape or may be recessed from the edge. The masking strips cover a clean strip of adhesive which may or may not fully cover the border regions under the masking strips. Where the masking strips are recessed from the edges of the tape, the regions between the edges of the tape and the masking strips may or may not contain adhesive, and where adhesive is present it may cover part or all of the region. In roll form, the tape may also be supplied without the requirement for the central strip of protective backing paper or the strips of backing paper protecting the border region. In this arrangement, at least two strips of clean adhesive free tape may run the length of the tape, adjacent to the evidence collection adhesive, and may extend to the edge of the tape or may be recessed from the edge of the tape. Where the strips are recessed from the edge of the tape the region between the edge of the tape and the strips may or may not contain adhesive.

A collection sheet, transparent backing sheet or adhesive may be optically modified to assist in recognition of the collected sample. This may include, but is not limited to, modification with one or more optical filters, dyes, colorants or polarizers which may assist recognition following subsequent irradiation with various light sources. Analysis may include but is not limited to reflected light, absorbed light, scattered light, and fluorescence. Part of the sheet and / or transparent backing sheet and/or adhesive may be modified and part left unmodified. A collection sheet, transparent backing sheet or adhesive may be chemically or biologically impregnated to assist in recognition of the collected sample. This may include, but is not limited to, impregnation with enhancement agents such as

Luminol to provide information on blood traces that would be invisible to the naked eye. It may also include substances to trap or improve the stability of biological and or general volatile materials so as to preserve for example a perfume sample associated with the evidence at the time of collection. The tape may have multiple additives and impregnations hi distinct regions and may be partially or wholly covered with additives and impregnations.

A collection sheet, transparent backing sheet or adhesive may be formulated to have specific porosity to enable for example thermally assisted removal of trapped volatile species for analysis without the requirement to separate the tape from the backing sheet.

A collection sheet, transparent backing sheet or adhesive may be formulated to have specific solubility to assist hi their removal.

Embodiments of the invention may be used in conjunction with automated or semi-automated evidence recognition systems, including but not limited to fibre identification systems based on colour recognition and fluorescence. In such cases, in addition to the optical, chemical or biological types of modification mentioned above, the collection sheet and backing sheet type and shape may be modified to facilitate compatibility with the equipment used.

Embodiments of the invention may also be used in conjunction with other automated or semi-automated sampling and recording technology, which may include, but is not limited to, temperature, time, humidity, and global positioning equipment to enable more detailed information about the evidence collection point to be coded onto the tape or backing sheet. This may include, but is not limited to, printed labels, stamps, bar codes, or encoded chips.

It will be appreciated that collection sheets in accordance with the invention may be produced in any shape, size or specific aspect ratio and that tape material and adhesive type or multiple adhesives may be chosen to facilitate a specific type of evidence lift For example a sample recovered from a wet irregular shaped object outdoors may require a different size of tape, tape material, and adhesive to sample recovered from a soft, dry, smooth object indoors. In addition to hairs, fibres, and other solid materials, the collection sheets are suitable for the collection and subsequent analysis of bodily fluids including, but not limited to, blood, saliva and semen.

It will be appreciated that the invention has applications beyond the forensic usage described and could be applied in any instance where a loosely bound substance is required to be removed from a surface while minimising contamination risk from adjacent or airborne substances, for example in lifting mould or spore samples in environmental monitoring applications or in removing particulate, dust or other material from a surface in quality control applications.

The invention may be viewed from a number of different aspects, and different embodiments of the invention may be expressed in different ways. Thus, for example, viewed from one aspect there is provided a collection sheet of flexible sheet material for use in the collection of a sample for analysis, the collection sheet having a collection side provided with an adhesive layer which is covered by a removable masking layer which is removed to expose the adhesive layer when a sample is to be collected, characterised in that the masking layer is divided into a central portion which covers a central sample collecting region of the adhesive layer and which is removed to expose the sample collecting region when a sample is to be collected, and a border portion which covers a border region of the adhesive layer extending around the sample collecting region, the border portion of the masking layer remaining in place when a sample is to be collected and being removable after sample collection so that a protective backing medium can be adhered to the both the sample collecting region and the border region of the adhesive layer.

Viewed from another aspect, there is provided a method of collecting a sample for analysis using a collection sheet of flexible sheet material, the collection sheet having a collection side provided with an adhesive layer which is covered by a removable masking layer which is removed to expose the adhesive layer when a sample is to be collected, characterised in that the masking layer is divided into a central portion which covers a central sample collecting region of the adhesive layer and which is removed to expose the sample collecting region so that the sample can be collected, and a border portion which covers a border region of the adhesive layer extending around the sample collecting region, the border portion of the masking layer remaining in place when a sample is to be collected and being removed after sample collection, a backing medium then being adhered to the both the sample collecting region and the border region of the adhesive layer.

Viewed from another aspect there is provided a roll of flexible tape with an adhesive surface, from which portions can be detached to expose the adhesive surface, characterised in that a pair of longitudinally extending, detachable masking strips define border regions on either side of a central region of adhesive, so that when a portion is detached from the tape the central region is exposed and is bounded by the border regions which remain masked until the masking strips are removed. Viewed from another aspect, there is provided a method of collecting a sample for analysis using a roll of flexible tape with an adhesive surface, in which a portion of tape is detached to expose the adhesive surface, the adhesive surface is used to collect a sample, and a backing medium is attached to the tape portion to protect the sample, characterised in that a pair of longitudinally extending, detachable masking strips define border regions on either side of a central region of adhesive, so that when the portion is detached from the tape the central region of adhesive is exposed and is bounded by the border regions which remain masked, and in that the central region is used to collect the sample, the masking strips are subsequently removed, and the backing medium is attached to the central region and the border regions.

Viewed from another aspect the invention provides a roll of flexible tape with an adhesive surface, from which roll portions of tape can be detached to expose the adhesive surface for use in the collection of a sample, characterised in that a pair of longitudinally extending, non adhesive border regions are provided on either side of a central region of adhesive, so that when a portion is detached from the tape the central region is exposed and is bounded by the border regions which remain masked.

Viewed from another aspect, the invention provides a method of collecting a sample for analysis using a roll of flexible tape with an adhesive surface, in which a portion of tape is detached to expose the adhesive surface, the adhesive surface is used to collect a sample, and a backing medium is attached to the tape portion to protect the sample, characterised in that a pair of longitudinally extending, detachable masking strips define border regions on either side of a central region of adhesive, so that when the portion is detached from the tape the central region of adhesive is exposed and is bounded by the border regions which remain masked, and hi that the central region is used to collect the sample, the masking strips are subsequently removed, and the backing medium is attached to the central region and the border regions.

Viewed from another aspect, the invention provides a method for the collection of a sample from an area, comprising the steps of applying to the area a flexible collection sheet with an adherent collecting surface so that the adherent collecting surface collects a sample from the area, and subsequently covering the adherent collecting surface with a backing medium which is attached to the collection sheet so as to protect the collected sample, characterised in that the collection sheet is provided with a border region extending substantially completely around the adherent collecting surface, the border region being non-adherent during s ampl e collection.

Viewed from another aspect, the invention provides a flexible collection sheet for the collection of a sample, the collection sheet having an adherent collecting surface to which the sample will be adhered, characterised in that a border region extends substantially completely around the adherent collecting surface, the border region being adapted to be non-adherent during sample collection.

In general, other aspects of the invention provide a method for the collection of a sample from an area, comprising the steps of applying to the area a collection sheet with an adherent collecting surface so that the adherent collecting surface collects a sample from the area, and subsequently covering the adherent collecting surface with a backing medium which is attached to the collection sheet so as to protect the collected sample, characterised in that the collection sheet is provided with a border region around the adherent collecting surface, the border region being non-adherent during sample collection, or collection sheet for the collection of a sample, the collection sheet having an adherent collecting surface to which the sample will be adhered, and a border region around the adherent collecting surface, the border region being adapted to be non-adherent during sample collection, wherein the collection sheet includes any of the novel features of the embodiments described, or discussed above, in any operable combination.

Some embodiments of the invention will now be described by way of example, and with reference to the accompanying drawings, in which:

Figures 1 (a) to 1 (e) shows the stages involved in the use of a collection sheet in accordance with the invention, in the form of a tape;

Figures 2 (a) and (b) show the use of a collection tape with an added grid for improved spatial resolution of sample evidence;

Figures 3 (a) and (b) respectively show a sheet and a strip defining individual collection tapes; Figure 4 shows a collection tape with operating instructions printed on the protective masking layers;

Figure 5 shows a collection tape with an additional region for recording data;

Figure 6 shows a collection tape with peel off -strips or tabs to assist in removal of the protective masking layers; Figure 7 shows the tape strip supplied with a pre-attached but detachable backing sheet; Figure 8 shows a section of strip from a roll, defining individual collection tapes without the requirement for a centre section of protective masking layer;

Figure 9 shows a section of strip from a roll, defining individual collection tapes, where a masked border region comprises two strips of protective masking layer running the length of the tape;

Figure 10 shows a section of strip from a roll, defining individual collection tapes, where no protective masking layer is required to create the border region; and

Figures 11 (a) to (c) show the stages involved in the use of a further collection sheet in accordance with, the invention. With reference to figure 1 (a) there is shown a collection sheet in the form of an elongate, rectangular tape 1 of thin, flexible plastics material, with an adhesive layer on one of its surfaces. This layer is covered by two protective masking layer portions of a suitable backing paper, namely masking portion 2 covering a border region and masking portion 3 covering a central rectangular collection region. As shown in Figure 1 (b), for use in collecting samples the masking portion 3 is removed to reveal a central adhesive collection surface 4 for evidence collection, bounded by a border region still protected by masking portion 2. In the next stage, as shown in Figure 1 (c) evidence 5 is collected on the collection surface 4 by pressing the tape 1 onto the article from which the evidence sample is to be collected. It will be appreciated that the evidence 5 is separated from the tape edge 6 by the border region which is still covered by protective masking portion 2, thus eliminating cross contamination and improving operator handling. After sample collection, as shown in Figure 1 (d) the masking portion 2 of backing paper can then be removed from the border region to reveal a clean border region 7 of exposed adhesive covered tape. In this embodiment the adhesive border region 7 terminates before the edge 6 of the tape, although it could extend to th.e edge 6. The tape is then fixed to a suitable transparent backing sheet 8, covering and protecting the collected samples, as shown in Figure 1 (e).

Figure 2 (a) shows an alternative embodiment of collection tape I¹. This generally similar to the first embodiment, with a masking portion 2' covering a border region, and as shown in Figure 2 (a) the central masking portion removed to reveal the adhesive collection surface 4'. In this embodiment a grid 9 of square cells is defined by perpendicular intersecting lines to provide improved spatial definition for identification and subsequent retrieval of recovered evidence. In addition, the grid may be marked with a grid reference to further aid in improved location and subsequent retrieval of evidence. In other embodiments, the collecting surface may be marked to define cells which are oblong or have other regular shapes. As shown in Figure 2 (b) a cell 10 contains a specific piece of evidence 11 which can be differentiated from other samples that may be on the collection surface by reference to its location in cell 10. Figure 2 (b) also shows that the border masking paper has been removed to reveal the adhesive border region 7, and that the tape V has been attached to a backing sheet 8" which covers and is adhered to the sample collection area 4' and the border region T. In this embodiment the adhesive border region T extends to edge 6' of the sheet.

Figure 3 (a) shows a section of an alternative embodiment, in which a sheet

12 defines a number of collection tapes 1 of the type illustrated in Figure 1, although they could be in accordance with other embodiments, separated by perforated lines

13 so that individual tapes can be torn off. Figure 3 (b) shows a section of an alternative embodiment in which a strip 14 from a roll defines a number of collection tapes 1 of the type illustrated in Figure 1, although they could be in accordance with other embodiments, separated by perforated lines 15 so that individual tapes can be torn off.

Figure 4 shows a collection tape 1 of the type illustrated in Figure 1, although it could be in accordance with other embodiments, with operating instructions 16 and 17 printed on the masking paper of the tape. The tape can be supplied as individual items, or in extended sheet or roll form as in Figures 3 (a) and (b), or in other pre- formed detachable forms. The particular embodiment shown illustrates two-stage instructions, stage one instructions 16 being printed on the central piece of masking paper 3 which is removed first, and stage two instructions 17 being printed on the masking paper 2 covering the border region which is removed second. Figure 4 also shows the border region masking paper 2 with additional score lines 50, dividing it into sections for ease of removal. Dividing the border region masking layer into sections can be applied to other embodiments also and the score lines can be in any convenient position. Figure 5 shows an alternative embodiment in which a collection tape 18, similar to that of any of the preceding embodiments, is provided with a region 19 for recording details of the sample collected and any other information required. In this embodiment the back face of the tape has the region 19. This facilitates the recording of data specific to the evidence collection, and for example this may include, but is not limited to, time, date, location and reference number. The tape can be supplied as individual items, or in extended sheet or roll form as in Figures 3 (a) and (b), or in other pre-formed detachable forms. The tape is shown after use, with the backing sheet 8 applied to the front face of the tape 18. Figure 6 shows an alternative embodiment of collection, tape 20, which is generally similar to that of any of the preceding embodiments but is provided with additional tabs 21 and 22 to assist in the removal of the masking paper from the adhesive tape. In this embodiment, tab 21 is attached to or is integral with the central strip of masking paper 23, and tab 22 is attached to or is integral Λvith the border region of masking paper 24. This is particularly useful when the operative is wearing protective gloves. Again, the tape can be supplied as individual items, or in extended sheet or roll form as in Figures 3 (a) and (b), or in other pre- formed detachable forms.

Figure 7 shows a further embodiment in which a transparent backing strip 25 is pre-attached to a collecting tape 1 of the type illustrated in Figure 1, although it could be in accordance with other embodiments. The attachment may be by a perforated strip 26 to allow ease of detachment of the transparent backing strip 25 from the tape strip 1 prior to evidence collection if this is desired. This embodiment may be preferred in some situations and in all cases will ensure that a transparent backing strip is available for every tape strip.

Figure 8 shows a further embodiment, in some respects similar to that of Figure 3 (b), in which a strip 27 from a roll defines a number of collection tapes 28 of the general type illustrated in Figure 1, separated by optional perforated lines 29 for ease of use when individual tapes are torn off. The tapes 28 do not require the central strip of protective backing paper 3 and the central adhesive collection region 30 is exposed once the strip is unrolled. However backing paper 31 is provided for the adhesive border region. In roll form the product may be manufactured in a clean environment and the subsequent rolling may serve to protect the evidence collection regions 30 from contamination.

Figure 9 shows a further embodiment in which a strip 32 from a roll defines a number of collection tapes 33, separated by optional perforated lines 34 for ease of use when individual tapes are torn off. In this embodiment also there is no requirement for a central strip of protective masking paper to cover the cerxtral collection surface 35. Masking paper protecting the border region is in the form of two spaced, parallel longitudinally extending strips 36 going the length of the strip 32 of tapes, although they could be interrupted at intervals, such as at the perforations. The strips 36 in this embodiment are recessed from the edges of the strip 32 so that there are regions 37 of adhesive-free material outside the adhesive border regions covered by the masking strips 36. These adhesive border regions may be fully or partially provided with adhesive. It would be possible for the regions 37 outside the masking strips 36 to be provided with adhesive, as the masking strips 36 will prevent contamination during sample collection . In a modification of this embodiment, the masking paper strips 36 and the adhesive border regions could extend to the edges of the strip 32.

Figure 10 shows a further embodiment in which a strip 38 from a roll defines a number of collection tapes 39, separated by optional-perforated lines 40 for ease of use when individual tapes are torn off. In this embodiment also there is no requirement for a central strip of protective backing paper to cover the central collection surface 41. Furthermore, there is no need for strips of backing paper to protect the border region. In this embodiment, the border region is defined by spaced, parallel strips 42 of clean adhesive free tape which run the length of the tape and extend to the edge of the tape. However, the border strips 42 could be iecessed from the edge, in the manner of the border strips in the embodiment of Figure 9. Where the strips 42 are recessed from the edge of the tape the region between the edge of the tape and the strips 42 may or may not contain adhesive.

It will be appreciated that in the embodiments of Figures 9 and 10, the border region comprises two longitudinally extending strips and does not include transverse strip portions. However, transverse portions of adhesive free sheet, or of adhesive sheet covered with masking paper, could be provided at one or both ends of the individual tapes 33 or 39.

Figures 11 (a) to 11 (c) show a modification of the embodiment of Figures 1 (a) to 1 (e) but which is also applicable to other embodiments. In this embodiment, as shown in Figure 11 (a) a collection tape 43 has an adhesive layer covered by masking paper, with a central masking portion 44 and a border masking portion 45. The central masking portion 44 covers an adhesive collection surface 46 for evidence collection which does not fully extend to the area protected by the masking portion 44. Similarly, the adhesive on the border region of tape 47 under the border masking portion 45 does not fully cover the area protected by the border masking portion 45. Figure 11 (b) shows the arrangement when the central masking portion 44 has been removed so that evidence collection can take place. An additional adhesive free border 48 is formed between the evidence collection surface 46 and the border masking portion 45. In this condition, evidence collection can be carried out in the normal way. Once evidence collection has been completed, the border masking portion 45 is removed and the situation is as shown in Figure 11 (c). The adhesive border region 47 has been exposed, and the adhesive free border 48 has expanded somewhat. In this condition, a backing sheet may be applied to the tape in the manner described with reference to other embodiments. As in various other embodiments, the adhesive on the outer border region 47 of the tape 43 may or may not extend fully to the edge of the tape 43.

In practice many combinations of adhesive tape and backing sheets may be used to construct products in accordance with the embodiments of the invention. However it has been established that the range of 'Self Laminating Cards' manufactured by 3L Office Products (www.3L.dk) have particularly suitable adhesive properties for abroad range of forensic lifting applications and as such they represent a convenient starting material to fabricate the tapes. A convenient tape size for recovery of fibre based trace evidence comprises an evidence collection window of 170 mm by 50 mm, with a border region in the range of 10 mm to 30 mm. Tapes of this size can be conveniently fabricated from A4 sized self laminating cards such as those manufactured by 3L Office Products, product code 11051.

Claims

1. A method for the collection of a sample from an area using a collection sheet with an adherent collecting surface, comprising the steps of applying the collection sheet to the area so that the adherent collecting surface collects a sample from the area, and subsequently covering the adherent collecting surface with a backing medium which is attached to the collection sheet so as to protect the collected sample, characterised in that the collection sheet is provided with a border region comprising an adherent border surface around a major part of the adherent collecting surface, the adherent border surface being provided initially with a removable border masking layer which renders the border region non -adherent during sample collection, wherein after sample collection the border masking layer is removed prior to attachment of the backing medium to the collecting surface and the adherent border surface.

2. A method as claimed in claim 1, characterised in that the border region extends completely around the collecting surface.

3. A method as claimed in claim 1 or 2, characterised in that the collection sheet is flexible.

4. A method as claimed in claim 1, 2 or 3, characterised in that the adherent collecting surface is provided initially with a removable collecting surface masking layer which is removed prior to sample collection.

5. A method as claimed in claim 1, 2 or 3, characterised in that prior to use the collection sheet is detached from a continuous roll of collection sheets and in that the adherent collecting surface of each sheet is masked by a portion of another sheet in the roll.

6. A method as claimed in any preceding claim, characterised in that the collection sheet is rectangular.

7. A method as claimed in any preceding claim, characterised in that the border region is at least 5 mm wide.

8. A method as claimed in any preceding claim, characterised in that the border region is no more than 30 mm wide.

9. A method as claimed in claim 8, characterised in that the border region is between 10 mm and 20 mm wide.

10. A method as claimed in any preceding claim, characterised in that the sample is evidence for forensic analysis.

11. A collection sheet for the collection of a sample, the collection sheet having an adherent collecting surface to which the sample will be adhered, the adherent collecting surface being provided with a collecting surface masking layer which is to be removed prior to sample collection, characterised in that the collection sheet is provided with a border region comprising an adherent border surface around a major part of the adherent collecting surface, the adherent border surface being provided with a removable border masking layer which is separate from the collecting surface masking layer, so that in use the border masking layer will render the border region non-adherent during sample collection and after sample collection the border masking layer can be removed prior to attachment of a backing medium to the collecting surface and the adherent border surface.

12. A collection sheet as claimed in claim 11, characterised in that the border region extends completely around the collecting surface.

13. A collection sheet as claimed in claim 11 or 12, characterised in that the collection sheet is flexible.

14. A collection sheet as claimed in claim 11, 12 or 13, characterised in that the collection sheet is rectangular.

15. A collection sheet as claimed in any of claims 11 to 14, characterised in that the border region is at least 5 mm wide.

16. A collection sheet as claimed in any of claims 11 to 15, characterised in that the border region is no more than 30 mm wide.

17. A collection sheet as claimed in claim 16, characterised in that the border region is between 10 mm and 20 mm wide.

18. A collection sheet as claimed in any of claims 11 to 17, characterised in that the collection sheet has a collection side provided with an adhesive layer covered by a removable masking sheet, the masking sheet being divided into a central portion which covers a central sample collecting region of the adhesive layer and which is removed to expose the sample collecting region when a sample is to be collected, and a border portion which covers a border region of the adhesive layer extending around the sample collecting region.

19. A collection sheet as claimed in claim 18, characterised in that the central portion and the border portion of the masking layer are separated by a cut or score line.

20. A collection sheet as claimed in claim 18 or 19, characterised in that between the sample collecting region and the border region of the adhesive layer, there is provided a zone of the collection sheet with no adhesive.

21. A collection sheet as claimed in claim 18, 19 or 20, characterised in that between the border region of the adhesive layer and the outer edge of the collection sheet, there is provided a zone of the collection sheet with no adhesive.

22. A collection sheet as claimed in any of claims 11 to 21, characterised in that the border masking layer is divided into sections.

23. A roll of flexible tape with an adhesive surface, from which roll portions of tape can be detached to expose the adhesive surface for use in the collection of a sample, characterised in that a pair of longitudinally extending, non adhesive border regions are provided on either side of a central region of adhesive, so that when a portion is detached from the tape the central region is exposed and is bounded by the border regions which remain masked.

24. A roll of flexible tape as claimed in claim 25, characterised in that the non adhesive border regions are defined by detachable masking strips over the adhesive surface.

25. A roll of flexible tape as claimed in claim 25, characterised in that the non adhesive border regions are regions in which there is no adhesive.

26. A method of collecting a sample for analysis using a roll of flexible tape with an adhesive surface, in which a portion of tape is detached to expose the adhesive surface, the adhesive surface is used to collect a sample, and a backing medium is attached to the tape portion to protect the sample, characterised in that a pair of longitudinally extending, detachable masking strips define border regions on either side of a central region of adhesive, so that when the portion is detached from the tape the central region of adhesive is exposed and is bounded by. the border regions which remain masked, and in that the central region is used to collect the sample, the masking strips are subsequently removed, and the backing medium is attached to the central region and the border regions.

27. A method for the collection of a sample from an area, comprising the steps of applying to the area a flexible collection sheet with an adherent collecting surface so that the adherent collecting surface collects a sample from the area, and subsequently covering the adherent collecting surface with a backing medium which is attached to the collection sheet so as to protect the collected sample, characterised in that the collection sheet is provided with a border region extending substantially completely around the adherent collecting surface, the border region being non¬ adherent during sample collection.

28. A flexible collection sheet for the collection of a sample, the collection sheet having an adherent collecting surface to which the sample will be adhered, characterised in that a border region extends substantially completely around the adherent collecting surface, the border region being adapted to be non-adherent during sample collection.