Stacker for laboratory plates

Abstract

A stacker for laboratory plates (e.g. multiwell plates), the stacker comprising: a first side wall connected to a second side wall, the first side wall having an outer surface and an inner surface, the second side wall having an outer surface and an inner surface, the inner surface of the first side wall opposing the inner surface of the second side wall; and a plurality of rails disposed on the inner surface of the first side wall and an opposing plurality of rails disposed on the inner surface of the second side wall, forming a plurality of pairs of opposing rails; wherein each pair of opposing rails is arranged to slidingly receive a respective laboratory plate in use, through an opening in the front of the stacker, between the first and second side walls; and wherein at least one rail of each pair of opposing rails comprises means for engaging with the respective laboratory plate as it is slid towards the rear of the stacker.

Description

[0001] STACKER FOR LABORATORY PLATES

[0002] FIELD OF THE INVENTION

[0003] This invention relates to a stacker for laboratory plates. Expressed differently, the invention relates to a rack structure that enables laboratory plates to be stacked, one above another. The invention is particularly applicable, but by no means limited, for use in supporting multiwell plates (also known as microplates, microtiter plates, or microwell plates), such as, for example, 6-, 12-, 24-, 48-, 96-, 384- or 1536-well plates. The invention is particularly suited, but by no means limited, for stacking such plates above one another within a biosafety cabinet (also known as a biological safety cabinet or a microbiological safety cabinet), for example when fumigating the plates within the cabinet, or when autoclaving the plates.

[0004] BACKGROUND TO THE INVENTION

[0005] Multiwell plates are in widespread use in research and analytical laboratories in the life sciences and pharmaceutical fields, e.g. for performing tests or other procedures on biological, biochemical, pathological or pharmaceutical samples. As those skilled in the art will appreciate, a multiwell plate is a flat plate with multiple “wells” that are used as small sample tubes. Multiwell plates are available in a range of formats, for example incorporating 6, 12, 24, 48, 96, 384 or 1536 wells, typically arranged in a 2:3 rectangular matrix, with each well typically able to hold a volume of liquid ranging from tens of nanolitres to several millilitres. A typical 96-well plate, to which the present invention is suited, is illustrated in Figure 6. However, the present invention is by no means limited for use with 96-well plates, and may for example be used in respect of 6-, 12-, 24-, 48-, 384- or 1536-well plates instead, or a combination of such plates.

[0006] When performing certain tests or procedures it can be desirable to stack multiwell plates one above another, for example when the available space on which to place the plates (e.g. on a laboratory bench or in a biosafety cabinet or autoclave) is limited. For example, a plurality of multiwell plates may be stacked in a biosafety cabinet in order to fumigate the plates (to disinfect or sterilise the plates), or in abiosafety cabinet or incubator to allow samples to develop or reactions to take place in a controlled environment over a period of time. However, preexisting stands for supporting multiwell plates in a stacked arrangement have been found to be unreliable, since plates can accidentally be knocked off the stands, or may tip over or fall over. The risk of plates being accidentally knocked off a stand may be increased if a researcher or technician is interacting with the plates using gloves -for example within a so-called “Class III” gas-tight cabinet, in which gloves are integrated within the front of the cabinet to isolate the researcher or technician from the interior of the cabinet. There is therefore a desire to provide a structure that is capable of securely supporting a plurality of multiwell plates in a stacked arrangement, thereby reducing the likelihood of the plates being accidentally knocked over, tipping over or falling over during use.

[0007] There is also a desire to enable multiwell plates to be fumigated or autoclaved effectively, e.g. within a fumigation chamber, autoclave or biosafety cabinet, when the plates are in a stacked arrangement. In particular, there is a desire for the fumigant, or steam in an autoclave, to be able to flow around stacked plates easily and enter the wells of the stacked plates - in particular, without the wells of a first plate being blocked by the base of a second plate that is on top of the first plate within a stack. Similar considerations apply if, for a certain test, it is desired to expose the contents of the wells to a particular gas that is introduced into the cabinet, e.g. in order to investigate possible reactions between the contents of the wells and the introduced gas.

[0008] SUMMARY OF THE INVENTION

[0009] Aspects and embodiments of the present invention are set out in the appended claims. Optional features are set out in the dependent claims.

[0010] According to a first aspect of the invention there is provided a stacker for laboratory plates (e.g. multiwell plates), the stacker comprising: a first side wall connected to a second side wall, the first side wall having an outer surface and an inner surface, the second side wall having an outer surface and an inner surface, the inner surfaceof the first side wall opposing the inner surface of the second side wall; and a plurality of rails disposed on the inner surface of the first side wall and an opposing plurality of rails disposed on the inner surface of the second side wall, forming a plurality of pairs of opposing rails; wherein each pair of opposing rails is arranged to slidingly receive a respective laboratory plate in use, through an opening in the front of the stacker, between the first and second side walls; and wherein at least one rail of each pair of opposing rails comprises means for engaging with the respective laboratory plate as it is slid towards the rear of the stacker. By virtue of these features, the stacker is capable of securely supporting a plurality of laboratory plates in a stacked arrangement, thereby reducing the likelihood of the plates being accidentally knocked over, tipped over or falling over during use.

[0011] The terms “rail” and “rails” as used herein should be interpreted broadly, to encompass any suitable surfaces disposed on the inner surfaces of the first and second side walls, on which a laboratory plate may be slid into the stacker.

[0012] Preferably each rail of each pair of opposing rails comprises respective means for engaging with a laboratory plate.

[0013] Preferably said means for engaging comprises a ramp disposed on the respective rail, the ramp being located towards the rear of the stacker, the ramp having an inclined surface facing the front of the stacker and a vertical (or substantially vertical) surface facing the rear of the stacker. Advantageously, such a ramp is able to engage with the hollow underside of a commonly-available multiwell plate or the like, by the plate latching over the vertical surface of the ramp.

[0014] Preferably the width of the ramp is less than the width of the respective rail, thereby providing a gap between the ramp and the side wall on which the rail is disposed.

[0015] Preferably at least some of the rails are inclined downwards, from the front of the stacker towards the rear of the stacker, to prevent the plates from accidentallysliding out of the front. The inclined rails may be inclined downwards at an angle of approximately 1°, for example.

[0016] Optionally the vertical position of the end of each inclined rail nearest to the front of the stacker is substantially level with the top of the ramp disposed on the rail.

[0017] Advantageously the first side wall and the second side wall may each incorporate a respective coupling means configured to enable the first side wall of a first stacker to be coupled to the second side wall of a second stacker.

[0018] For example, the coupling means of the first side wall may comprise a dovetail groove and the coupling means of the second side wall may comprise a corresponding dovetail protrusion.

[0019] Optionally the dovetail groove and the dovetail protrusion extend vertically.

[0020] Alternatively, or in addition, the coupling means of the first side wall and the coupling means of the second side wall may comprise embedded magnets, for example.

[0021] Preferably the stacker incorporates multiple apertures to aid the flow of a fumigant, steam or another gas into, through and out of the stacker, and around the plates therein, in use.

[0022] Preferably the first side wall and the second side wall incorporate a plurality of apertures.

[0023] Preferably the stacker further comprises a base, the base extending between the first side wall and the second side wall. Preferably the base incorporates one or more apertures.

[0024] Preferably the base further comprises a plurality of feet, which may optionally be domed.Preferably the stacker further comprises a top, the top extending between the first side wall and the second side wall. Preferably the top incorporates one or more apertures.

[0025] Advantageously, to facilitate stacking of the present stackers on one another, the top may further incorporate a plurality of recesses, wherein the positions of the recesses correspond with the positions of the feet, the recesses and the feet being configured to enable a first stacker to locate on top of a second stacker, with the feet of the first stacker locating in the recesses of the second stacker.

[0026] Preferably the recesses are shallower than the depth of the feet, such that, when a first stacker is located on top of a second stacker, a gap is formed between the base of the first stacker and the top of the second stacker, thereby aiding the flow of a fumigant, steam or another gas between the stackers.

[0027] Preferably the stacker further comprises a rear wall. Preferably the rear wall incorporates one or more apertures. Preferably each rail extends rearwardly to meet the rear wall.

[0028] Optionally the rear wall incorporates one or more magnets, by means of which the stacker may be magnetically attached to a metal wall of a cabinet in which the stacker is located in use, to stabilise the stacker.

[0029] Optionally the rear wall incorporates coupling means configured to enable the rear wall of a first stacker to be coupled to the rear wall of a second stacker, in a back-to-back configuration. Such coupling means may comprise one or more magnets embedded within the rear wall.

[0030] In certain embodiments the stacker may be formed of a plastics material. In other embodiments the stacker may be formed of metal.BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Embodiments of the invention will now be described, by way of example only, and with reference to the drawings in which:

[0032] Figure 1 is a perspective view of a stacker for laboratory plates, the stacker having a plurality of pairs of opposing rails, with each pair of opposing rails having means (here in the form of ramps on the rails) for engaging a respective laboratory plate as it is slid along the rails towards the rear of the stacker;

[0033] Figure 2 is a plan view of the stacker of Figure 1 from above;

[0034] Figure 3 is a front view of the stacker of Figure 1 ;

[0035] Figure 4 is a perspective cross-sectional view through the stacker of Figure 1, showing the inner surface of a side wall with a plurality of rails thereon, with each rail having a plate-engaging ramp thereon;

[0036] Figure 5 is a side view of the stacker of Figure 1 , showing the internal rails with broken lines and illustrating that each rail is inclined downwards, from the front of the stacker towards the rear of the stacker;

[0037] Figure 6 illustrates the stacker of Figure 1 in use, with a plurality of multiwell plates stacked therein, and another multiwell plate alongside; and

[0038] Figure 7 is a side view of the stacker of Figure 6, showing the internal rails with broken lines, as in Figure 5.

[0039] In the figures, like elements are indicated by like reference numerals throughout.

[0040] DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0041] The present embodiments represent the best ways known to the Applicant of putting the invention into practice. However, they are not the only ways in which this can be achieved.

[0042] With reference to Figures 1 to 7, the present work provides a stacker 10 (which may also be referred to as a rack structure) that is capable of securely supporting a plurality of multiwell plates 80 in a stacked arrangement, and which also allows a fumigant, steam or another gas to flow around the plates easily and enter the wells of the stacked plates. The stacker 10 is preferably made of a plastics material thatis suitable for autoclaving, e.g. formed by injection moulding or 3D printing. Alternatively the stacker 10 may be made of a suitable autoclavable metal, for instance.

[0043] Figure 6 shows an example stacker 10 in use, holding five 96-well multiwell plates 80, one above another, with gaps between the plates 80 to allow a fumigant, steam or another gas to readily flow around the plates and into the wells. However, the present invention is by no means limited for use with 96-well plates, and may for example be used in respect of 6-, 12-, 24-, 48-, 384- or 1536-well plates instead, or a mixture of such plates within a single stacker. Multiwell plates, when viewed from above, typically have a standard size of 128mm by 85mm, although deviations from this are possible. Accordingly, the present stacker 10 is typically sized to accommodate plates that are 128mm by 85mm in size, with a degree of tolerance to accommodate variations in plate size, e.g. due to manufacturing tolerances or to cater for plates from different manufacturers. However, in other examples, the present stacker 10 may be sized to accommodate significantly different sizes of laboratory plates. Indeed, it should be appreciated that the present stacker 10 is not limited for use with multiwell plates. Other laboratory plates or trays (e.g. as may support petri dishes or other items of laboratory equipment) may be used instead of, or together with, multiwell plates, within the stacker 10.

[0044] Thus, in general terms, and with reference for example to Figure 1 , the present work provides a stacker 10 for laboratory plates. The stacker 10 comprises a first side wall 40 connected to a second side wall 50. The first side wall 40 has an outer (i.e. outwardly facing) surface and an inner (i.e. inwardly facing) surface. Likewise, the second side wall 50 has an outer surface and an inner surface. The inner surface of the first side wall 40 opposes (i.e. faces towards) the inner surface of the second side wall 50.

[0045] In the illustrated example, the stacker 10 further comprises a base 30 and a top 20, which both extend between the first side wall 40 and the second side wall 50, thereby connecting the first and second side walls together. However, in alternativeexamples the first and second side walls 40, 50 may be connected together in other ways, e.g. by struts, rods or other members extending between the first and second side walls 40, 50.

[0046] As shown in Figures 3 to 5, in the illustrated example the base 30 is provided with a plurality of feet 34, to raise the base 30 off the surface on which it is placed. The feet 34 may also have a gripping function, to prevent the stacker 10 from sliding on the surface on which it is placed.

[0047] Referring back to Figure 1, for example, the front 60 of the stacker 10 has an opening 62 through which the laboratory plates 80 may be introduced (and subsequently removed) in use.

[0048] In the illustrated example, the stacker 10 also has a rear wall 70.

[0049] For supporting the laboratory plates, a plurality of rails 46, 49 are disposed on the inner surface of the first side wall 40, and an opposing plurality of rails 56, 59 are disposed on the inner surface of the second side wall 50, forming a plurality of pairs of opposing rails (46, 56; 49, 59). The rails may also be considered to be runners. As shown in Figures 1, 3 and 4, the illustrated example of the stacker 10 has five pairs of opposing rails (46, 56; 49, 59), in order to accommodate five laboratory plates 80 in use, although in other examples different numbers of pairs of opposing rails may be provided, to accommodate correspondingly different numbers of plates. Moreover, in further examples the vertical spacing of the rails may be different to that illustrated (and may or may not be equally spaced), to cater for different depths of plates.

[0050] Each rail extends rearwardly to meet the rear wall 70 of the stacker. With the exception of the lowermost rails 49, 59, the other rails 46, 56 project inwardly from the side walls 40, 50. The lowermost rails 49, 59 are formed in the internal comers between the base 30 and the side walls 40, 50.The base 30 incorporates a central recessed region 36 that is lower than the lowermost rails 49, 59, to aid the flow of a fumigant, steam or another gas under the lowermost plate (as supported on rails 49, 59) in use.

[0051] Each pair of opposing rails (46, 56; 49, 59) is arranged to slidingly receive a respective laboratory plate 80. In use, such a plate 80 is inserted through the opening 62 in the front 60 of the stacker, between the first and second side walls 40, 50, and is slid rearwardly along a respective pair of rails, towards the rear wall 70.

[0052] To securely retain each laboratory plate 80, at least one rail of each pair of opposing rails (46, 56; 49, 59) comprises means for engaging with the laboratory plate 80 as it approaches the rear wall 70 of the stacker. In the illustrated example, each rail of each pair of opposing rails (46, 56; 49, 59) comprises respective means for engaging with such a plate, although in principle only one rail of each pair need be provided with such means.

[0053] In the illustrated example, the means for engaging comprises a ramp formed on each rail 46, 49, 56, 59. With particular reference to Figures 3 and 4, rails 46, 49 are provided with ramps 48, and rails 56, 59 are provided with ramps 58. As shown in Figure 4, each ramp 48, 58 is located near to the rear 70 of the stacker. Each ramp 48, 50 has an inclined surface facing the front 60 of the stacker, and a vertical (or substantially vertical) surface facing the rear 70 of the stacker.

[0054] As those skilled in the art will appreciate, and with reference at this juncture to Figure 6, multiwell plates 80 have an upper surface 82 in which the wells 84 are formed, and a rim 86. As shown, the rim 86 may incorporate or more corner notches 87 as reference points for determining the correct orientation of the plate. The underside 88 of the plate, within the rim 86, is hollow.

[0055] Referring back to Figures 1 and 4, for example, when a user slides a plate 80 into the stacker 10 the plate 80 engages with the ramps 58 (or 48) by means of the rear-facing part of the rim 86 of the plate 80 sliding up the inclined front-facing surface of the ramp 58, and then dropping down or latching over the vertical rear-facing surface of the ramp 58. Thus, the ramp 58 engages into the hollow underside 88 of the plate 80.

[0056] It may be noted from Figure 4 that the width of each ramp 58 is less than the width of the respective rail 56, 59 on which the ramp 58 is formed, thereby providing a gap 57 between the ramp 58 and the side wall 50 on which the rail is disposed. As the rear-facing part of the rim 86 latches over the vertical rear-facing surface of the ramp 58, a side-facing part of the rim 86 locates into the gap 57 between the ramp 58 and the side wall 50. The same happens with the ramps 48 on the opposing rails 46, 49 on the other side wall 40. Accordingly, when the plate 80 is fully inserted into the stacker 10 and the rim 86 of the plate is engaged around the ramps 48, 58, the rim 86 of the plate rests flatly and evenly on the rails.

[0057] The present ramps 48, 58 also act as an aid for blind or partially sighted users to know when the plates are properly located within the stacker.

[0058] It will be appreciated that laboratory plates other than multiwell plates may also be provided with a hollow underside suitable for engaging with the present ramps.

[0059] To remove a plate 80 from the stacker 10, the user lifts the plate 80 sufficiently to disengage the underside of the plate 80 from the ramps 48, 58, thereby enabling the plate to be retracted out through the opening 62 in the front 60 of the stacker.

[0060] Referring now to Figure 5, in the present example at least some of the rails 46, 56 are inclined slightly downwards, from the front 60 of the stacker towards the rear 70 of the stacker, to prevent the plates 80 from accidentally sliding out of the opening 62 in the front 60. In the present example, the rails 46, 56 that project inwardly from the side walls 40, 50 (i.e. the rails other than the lowermost rails 49, 59) are inclined in such a manner, whereas the lowermost rails 49, 59 are not inclined. However, inalternative examples the lowermost rails 49, 59 may also be inclined. In yet other examples, none of the rails 46, 49, 56, 59 may be inclined.

[0061] In more detail, in the present example the rails 46, 56 are inclined downwards at an angle of approximately 1° from the horizontal. In Figure 5, the horizontal is indicated by the broken line A-B, and the downward inclination of the rails below the horizontal is denoted by angle a. The angle a may be 0.7°, 0.8°, 0.9°, 1°, 1.1°, 1.2° or 1.3°, for example. It may also be noted from Figure 5 that the vertical position of the end of each inclined rail 46, 56 nearest to the front 60 of the stacker is substantially level with the top of the ramp 48, 58 disposed on the rail, as indicated by the horizontal broken line A-B.

[0062] Apertures to aid the flow of a fumigant, steam or another gas

[0063] The present stacker 10 incorporates multiple apertures to aid the flow of a fumigant, steam or another gas into, through and out of the stacker, and around the plates 80 therein, in use.

[0064] More particularly, referring for example to Figure 1, in the illustrated example the first side wall 40 incorporates a plurality of apertures 42, and the second side wall 50 incorporates a plurality of apertures 52, through which a fumigant, steam or another gas may pass into and out of the stacker 10 and flow around the plates 80 therein. In the present example the apertures 42, 52 on each side wall are arranged in an array, with each row of apertures corresponding to the vertical position of a respective plate 80 in use, as shown in Figure 7. The columns of apertures 42, 52 are aligned with the dovetail regions 44, 54 (which are discussed in greater detail below) and on either side of the dovetail regions 44, 54.

[0065] Also to aid the flow of a fumigant, steam or another gas into and out of the stacker and around the plates 80 therein, in the illustrated example the base 30 incorporates a single large aperture 32, although in alternative examples the base 30 may incorporate a plurality of smaller apertures instead. The flow of a fumigant, steam or another gas into the stacker from underneath is also aided by the feet 34, whichraise the base 30 off the surface of the cabinet, and by the central recessed region 36 within the base 30, which facilitates flow around the underside of the lowermost plate 80 within the stacker.

[0066] For similar reasons, in the illustrated example the top 20 incorporates a single large aperture 22, although in alternative examples the top 20 may incorporate a plurality of smaller apertures instead. Preferably the aperture 22 in the top 20 corresponds in shape and position to the aperture 32 in the base 30, thereby aiding the flow of a fumigant, steam or another gas between vertically-stacked stackers 10. (The ability to stack the present stackers on top of one another is described in more detail below.)

[0067] Again, for similar reasons, in the illustrated example the rear wall 70 incorporates a single large aperture 72, although in alternative examples the rear wall 70 may incorporate a plurality of smaller apertures instead. The aperture 72 in the rear wall is smaller than the opening 62 in the front 60. The regions of the rear wall 70 to the sides of the aperture 72, where the rails 46, 49, 56, 59 meet the rear wall, prevent the plates 80 from sliding out the back of the stacker.

[0068] The large apertures 62 and 72 also facilitate handling of the stacker 10, e.g. by users of limited manual dexterity.

[0069] Coupling and stacking options

[0070] A number of options will now be described for enabling multiple stackers 10 to be connected together or stacked on top of one another, e.g. to enable the stackers 10 to be packed efficiently within a cabinet or autoclave.

[0071] To enable side-by-side connection of the stackers 10, the first side wall 40 and the second side wall 50 may each incorporate a respective coupling means configured to enable the first side wall 40 of a first stacker to be coupled to the second side wall 50 of a second stacker. In the illustrated example, e.g. as shown in Figure 1, the coupling means of the first side wall 40 comprises a dovetail groove 44 and thecoupling means of the second side wall comprises a corresponding (complementary) dovetail protrusion 54. The dovetail protrusion 54 of a second stacker can be slotted into the dovetail groove 44 of a first stacker, to connect the two stackers together. By continuing this process with further stackers, a longer row of connected stackers may be formed. In turn, this adds stability to the stackers, further reducing the likelihood of the plates falling or tipping over.

[0072] In the illustrated example the dovetail protrusion 54 and the dovetail groove 44 are oriented vertically, although an alternative example may be realised in which the dovetail protrusion and corresponding dovetail groove are oriented horizontally, for instance.

[0073] In other examples, other means for connecting stackers side-by-side may be realised. For instance, magnets may be embedded in the side walls 40, 50, the magnets being positioned to generate magnetic attraction between adjacent stackers as they brought alongside one another. Such magnets may be instead of, or in addition to, the aforementioned dovetail protrusion and dovetail groove.

[0074] Similarly, to enable back-to-back connection of the stackers, the rear wall 70 may incorporate coupling means configured to enable the rear wall of a first stacker to be coupled to the rear wall of a second stacker. For instance, the coupling means may comprise one or more magnets embedded within the rear wall 70, the magnets being positioned to generate magnetic attraction between adjacent stackers as they brought against one another, back-to-back. Such magnets may also be used to magnetically fasten a stacker against a metal cabinet wall, enhancing the stability of the stacker and its contents. By being embedded within the rear wall 70, such magnets are not prone to rusting when the stacker 10 is cleaned.

[0075] To enable stackers to be stacked on top of one another, in the illustrated example the top 20 further incorporates a plurality of recesses 24. The positions of the recesses 24 correspond with the positions of the feet 34. The recesses 24 and the feet 34 are configured to enable a first stacker to locate on top of a second stacker,with the feet 34 of the first stacker locating in the recesses 24 of the second stacker. Preferably the recesses 24 are shallower than the depth of the feet 34, such that, when a first stacker is located on top of a second stacker, a gap is formed between the base 30 of the first stacker and the top 20 of the second stacker. By providing such a gap between vertically-stacked stackers, this further aids the flow of a fumigant, steam or another gas into and out of the stackers and around the plates 80 therein.

[0076] In the present example the feet 34 are domed, to reduce the degree of contact between vertically-stacked stackers (whilst also saving the material used) and further aiding the flow of a fumigant, steam or another gas into and out of the stackers and around the plates 80 therein.

[0077] From the above discussion, it will be appreciated that the present stackers save space and increase safety without affecting the quality of the experimental work performed using the plates.

[0078] Modifications and alternatives

[0079] Detailed embodiments and some possible alternatives have been described above. As those skilled in the art will appreciate, a number of modifications and further alternatives can be made to the above embodiments whilst still benefiting from the inventions embodied therein.

[0080] The concepts presented above may be employed separately from one another, or in any feasible combination. For example, the concept of the inclined rails may be employed without the rails comprising means for engaging the plates. Similarly, the apertures for aiding the flow of a fumigant, steam or another gas into and out of the stackers and around the plates therein may be employed without the rails comprising means for engaging the plates.

Claims

CLAIMS1. A stacker for laboratory plates, the stacker comprising:a first side wall connected to a second side wall, the first side wall having an outer surface and an inner surface, the second side wall having an outer surface and an inner surface, the inner surface of the first side wall opposing the inner surface of the second side wall; anda plurality of rails disposed on the inner surface of the first side wall and an opposing plurality of rails disposed on the inner surface of the second side wall, forming a plurality of pairs of opposing rails;wherein each pair of opposing rails is arranged to slidingly receive a respective laboratory plate in use, through an opening in the front of the stacker, between the first and second side walls; andwherein at least one rail of each pair of opposing rails comprises means for engaging with the respective laboratory plate as it is slid towards the rear of the stacker.

2. The stacker according to claim 1 , wherein each rail of each pair of opposing rails comprises respective means for engaging with a laboratory plate.

3. The stacker according to claim 1 or claim 2, wherein said means for engaging comprises a ramp disposed on the respective rail, the ramp being located towards the rear of the stacker, the ramp having an inclined surface facing the front of the stacker and a vertical or substantially vertical surface facing the rear of the stacker.

4. The stacker according to claim 3, wherein the width of the ramp is less than the width of the respective rail, thereby providing a gap between the ramp and the side wall on which the rail is disposed.

5. The stacker according to any preceding claim, wherein at least some of the rails are inclined downwards, from the front of the stacker towards the rear of the stacker.

6. The stacker according to claim 5, wherein the inclined rails are inclined downwards at an angle of approximately 1 °.

7. The stacker according to claim 5 or claim 6 when dependent on claim 3 or claim 4, wherein the vertical position of the end of each inclined rail nearest to the front of the stacker is substantially level with the top of the ramp disposed on the rail.

8. The stacker according to any preceding claim, wherein the first side wall and the second side wall each incorporate a respective coupling means configured to enable the first side wall of a first stacker to be coupled to the second side wall of a second stacker.

9. The stacker according to claim 8, wherein the coupling means of the first side wall comprises a dovetail groove and the coupling means of the second side wall comprises a corresponding dovetail protrusion.

10. The stacker according to claim 9, wherein the dovetail groove and the dovetail protrusion extend vertically.

11. The stacker according to any of claims 8 to 10, wherein the coupling means of the first side wall and the coupling means of the second side wall comprise embedded magnets.

12. The stacker according to any preceding claim, wherein the first side wall and the second side wall incorporate a plurality of apertures.

13. The stacker according to any preceding claim, further comprising a base, the base extending between the first side wall and the second side wall.1714. The stacker according to claim 13, wherein the base incorporates one or more apertures.

15. The stacker according to claim 13 or claim 14, wherein the base further comprises a plurality of feet.

16. The stacker according to claim 15, wherein the feet are domed.

17. The stacker according to any preceding claim, further comprising a top, the top extending between the first side wall and the second side wall.

18. The stacker according to claim 17, wherein the top incorporates one or more apertures.

19. The stacker according to claim 17 or claim 18 when dependent on claim 15 or claim 16, wherein the top further incorporates a plurality of recesses, and wherein the positions of the recesses correspond with the positions of the feet, the recesses and the feet being configured to enable a first stacker to locate on top of a second stacker, with the feet of the first stacker locating in the recesses of the second stacker.

20. The stacker according to claim 19, wherein the recesses are shallower than the depth of the feet, such that, when a first stacker is located on top of a second stacker, a gap is formed between the base of the first stacker and the top of the second stacker.

21. The stacker according to any preceding claim, further comprising a rear wall.

22. The stacker according to claim 21 , wherein the rear wall incorporates one or more apertures.1823. The stacker according to claim 21 or claim 22, wherein each rail extends rearwardly to meet the rear wall.

24. The stacker according to any of claims 21 to 23, wherein the rear wall incorporates one or more magnets.

25. The stacker according to any of claims 21 to 24, wherein the rear wall incorporates coupling means configured to enable the rear wall of a first stacker to be coupled to the rear wall of a second stacker.

26. The stacker according to claim 25 when dependent on claim 24, wherein the coupling means comprises one or more magnets embedded within the rear wall.

27. The stacker according to any preceding claim, being formed of a plastics material.

28. The stacker according to any of claims 1 to 26, being formed of metal.

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