Chemistry: molecular biology and microbiology – Apparatus – Including measuring or testing
Reexamination Certificate
1999-12-01
2001-06-26
Redding, David A. (Department: 1744)
Chemistry: molecular biology and microbiology
Apparatus
Including measuring or testing
C435S305300, C422S105000
Reexamination Certificate
active
06251662
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a sealing mat for multiwell laboratory plates. The invention also relates to a lid for a multiwell laboratory plate which includes a sealing mat and to a method of sealing a multiwell laboratory plate using those things.
BACKGROUND TO THE INVENTION
Multiwell plates are used extensively in molecular biology laboratories and elsewhere. One such use is in Polymerase Chain Reaction (PCR) experiments where, once filled or part filled with reagents, the plates are often sealed prior to further processing.
Multiwell plates now come in a variety of formats. 96 wells, in a 12×8 array, is one standard but now a 384 well format is becoming increasingly common. Forming a cheap, re-usable seal on these 384 plates presents a real problem.
There are a number of known ways of achieving such seals. For example, a foil or plastic film may be applied across the entire upper surface of the plate. Thus heat sealable aluminium foils or adhesive plastic films are commercially available. Once applied, these films provide an efficient, gas and liquid tight seal but are tiresome to apply and remove. Access to each well can only be obtained by piercing the film or by peeling the film off by hand or with a foil stripper. Consequently, this type of seal is not re-usable, and is not suitable for robotic application or removal.
Alternatively, a seal may be achieved by placing a relatively heavy, flexible rubber mat over the entire surface of the plate. The weight of the mat and any plates stacked on top of the mat keep the seal in place. It is important that the mat does not slide over the top of the plate in order to avoid cross-contamination. In the case of 96 well plates, this is achieved by having 96 raised pimples or “dimples” on the surface of the mat in an array which matches exactly the array of wells. Each dimple is sized and shaped to sit firmly into a well. Once in place, no lateral movement of the mat is possible because the perimeter of each dimple fits snugly within its respective well.
This arrangement is not applicable to the 384 well version because the wells are much smaller in diameter. Each dimple would need to be so small in profile that it becomes very difficult to align the mat with the wells. Even if the mat can be aligned, there is an increased tendency for the mat to slide across the top face of the wells because each dimple is correspondingly smaller than in the 96 well version.
As a further alternative, sealing caps can be applied, either in strips or as an array of 96. These sealing caps consist of individual, circular cylindrical walled caps with a pierceable lid. They fit snugly into the internal bore of each plate and each cap normally has an outer lip, which prevents it entering into the well beyond a certain point.
These caps are time-consuming to apply and require a good deal of manual dexterity on the part of the technician. Furthermore, sealing caps would be practically impossible to fit to 384 well plates, and, in any event, cannot be inserted or removed robotically.
It is therefore an objective of the present invention to overcome some or all of these disadvantages and provide an improved, re-usable sealing means applicable to all multiwell plates.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a plate sealing means or cover suitable for use with multiwell plates of the type in question said sealing means comprising:
(i) a resilient sealing mat having a flat or even surface substantially free from dimples; and
(ii) engagement means adapted to co-operate with at least two opposing edges of the plate and adapted to retain the sealing mat in a substantially fixed position with respect to the plate. By providing some means of engaging the mat with the side of the multiwell plate it is no longer necessary to use dimples as locators.
Preferably, the engagement means comprises a lid adapted to fit over the plate, said lid comprising a substantially flat top with depending edges, the sealing mat being located on the underside of the lid top, being the side in contact with the plate when the sealing means is in use. This provides the advantage that a multiwell laboratory plate can be quickly and effectively sealed by placing the lid onto the plate. Also, the lid can quickly and easily be removed and can be re-used. It is not necessary to accurately position any projections on the mat into wells on the multiwell plate because the mat is smooth on the surface which contacts the multiwell plate.
Preferably, the lid is substantially rigid.
In a particularly preferred embodiment, the lid further comprises locators on its uppermost-in-use surface, said locators being adapted to locate with the underside of a second plate such that the plates will stack securely one on top of each other.
Preferably, the edge of the lid incorporates apertures corresponding with holes in the plate, said holes being provided to facilitate robotic plate positioning and removal from a thermal cycle block. Robotic operation is particularly important when large numbers of plates have to be handled. The plates must still be capable of robotic manipulation even when the lids are in place.
In an alternative embodiment, the engagement means comprises a series of lugs projecting from the sealing mat and adapted to engage with holes in the plate, said holes being provided to facilitate robotic plate positioning and removal from a thermal cycler block.
Preferably the lugs are resiliently flexible.
Preferably the lugs project outwardly from the edges of the mat in the plane of the mat.
In a particularly preferred embodiment the sealing mat and the lugs are of unitary construction.
Preferably the sealing mat is made from neoprene or silicone rubber.
In order that the invention may be better understood, preferred embodiments will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:
FIG. 1
illustrates a plan view from above of a lid for a multiwell plate according to a first embodiment of the invention;
FIG. 2A
shows a cross-section along line A—A of
FIG. 1
;
FIG. 2B
is an enlargement of a detail in
FIG. 2A
;
FIG. 3
shows a plan view from below of the lid of
FIG. 1
;
FIG. 4A
shows a cross-sectional view along line B—B of
FIG. 1
;
FIG. 4B
is an enlargement of a detail in
FIG. 4A
;
FIGS. 5A
,
5
B and
5
C illustrate plan, side and end elevations of a sealing mat according to a second aspect of the invention;
FIGS. 6A
,
6
B and
6
C illustrate plan, side and end elevations of a lug from
FIG. 5
;
FIG. 7A
shows diagrammatically the location of robotic arm locator holes;
FIG. 7B
shows how the lugs of this embodiment flex over to locate in the robotic arm locator holes.
REFERENCES:
patent: 5342581 (1994-08-01), Sanadi
patent: 5516490 (1996-05-01), Sanadi
patent: 5741463 (1998-04-01), Sanadi
patent: 5856176 (1999-01-01), Mathus et al.
patent: 0388159 (1990-03-01), None
patent: 0747476 (1996-04-01), None
patent: 9302290 (1993-11-01), None
patent: 9503364 (1995-03-01), None
patent: 9607921 (1996-05-01), None
Advanced Biotechnologies Limited
Galgano & Burke
Redding David A.
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