Fluent material handling – with receiver or receiver coacting mea – Plural filling means – For plural receivers simultaneously filled
Reexamination Certificate
2001-11-30
2003-06-10
Douglas, Steven O. (Department: 3751)
Fluent material handling, with receiver or receiver coacting mea
Plural filling means
For plural receivers simultaneously filled
C141S130000, C422S091000, C422S105000, C073S864140
Reexamination Certificate
active
06575209
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a proportioning head and specifically concerns the field of automatic proportioners. Automatic proportioners are known which have a proportioning head with a multitude of tiny steel cannulae in a matrix array which permits to simultaneously proportion a multitude of various liquid samples into the receptacles of microtitration plates. Proportioning heads are known which have 384 steel cannulae which are adopted to be introduced into the receptacles of 384-receptacles microtitration plates from above. The steel cannulae are connected to one or more displacement devices at top in order to draw in or expel a liquid through a lower cannulea aperture by displacing an air column. The proportioning head is disposed on a reception unit and this one is disposed on a shifting device which make possible shifting in the X, Y, and Z directions to introduce the steel cannulae into the receptacles of a microtitration plate for the reception or delivery of samples, to pull them out therefrom, and to shift them sideward for the transfer of samples into another microtitration plate.
2. Description of the Prior Act
The proportioning heads which are known are problematic because they involve hazards of substance entrainment and contamination. They require thorough cleaning for re-use. However, it is opportune to reuse them because the proportioning heads involve very large expenditure and are costly because of the steel cannulae.
EP 0 206 945 relates to an apparatus for adapting multi-way pipetting stations to different geometries (dimensions or arrangements) of receptacles. To this end, an overall number of pipette tips are disposed in a matrix and the deformable pipette tips can be moved by means of a perforated plate in a cross direction in such a way that if they are deflected they can be aligned with a geometry of receptacles which differs from the one in case of non-deflection.
WO 95/21696 shows pipette tips in a tip holder, which can be stripped from a tip carrier.
EP 0 743 749 A1 shows arrays of pipette tips in carrier plates which can be inserted into each other to allow space-saving accommodation.
Therefore, it is the object of the invention to provide a proportioning head which has a reduced risk of entrainment and contamination while involving less expenditure.
SUMMARY OF THE INVENTION
The object of the invention is achieved by providing a proportioning head having
a head plate,
a multiplicity of pipette tips in plastic in a matrix array the tip apertures of which are disposed below the head plate and which are mounted at top of the head plate wherein the upper apertures of the pipette tips are accessible from the upper surface of the head plate, and
a centering plate which has a multiplicity of centering holes in the same matrix array as have the pipette tips the inner diameter of which is tailored to the outer diameters of entering portions of the pipette tips disposed below the head plate in such a way that the centering plate is adapted to be pushed onto the centering portions while aligning the centering portions of the pipette tips.
The fact that the proportioning head is fitted with pipette tips in plastic considerably reduces its expenditure as compared to the known proportioning heads so that it can be used as a disposable which is thrown away after use. The manufacturer can deliver the proportioning head in a cleanliness which is such as to make it usable without any pre-treatment. It may be thrown away without any after-treatment after use. A proportioning head having pipette tips in plastic which have dimensions as are required for insertion into the receptacles of microtitration plates can only be produced at a dimensional stability which is critical for an insertion of the pipette tips into the receptacles of a higher-density microtitration plate which has a larger number of receptacles. Therefor, the proportioning head comprises a centering plate which, when in an operational position, uses its centering holes to align the pipette tips, on their centering portions, onto the matrix array of the centering holes that corresponds to the matrix array of pipette tips in the head plate. As a result, the pipette tips with their tip apertures are readily adapted to be inserted into the receptacles of a higher-density microtitration plate that have the same matrix array as have the centering holes and pipette tips in the head plate.
The centering plate, if used for lower-density microtitration plates, particularly microtitration plates having 384 receptacles, generally need not be in its operational position in which centering holes align the pipette tips at their centering portions. For this application case, it is possible to remove the centering plate or to displace it towards the head plate to such an extent that the pipette tips are lowerable approximately up to the bottom of the receptacles of microtitration plates, which makes it possible to completely receive the liquid contained in the receptacles. In contrast, for use in higher-density microtitration plates, particularly microtitration plates having 1536 receptacles, the centering plate is preferably placed in its operational position so that correct alignment of the tip apertures onto the receptacle apertures which are far smaller is achieved. At this point, it is unharmful for a mere delivery of liquid if the centering plate, when in its operational position is at a smaller spacing above the tip apertures because it is sufficient for delivery to bring the tip apertures closer to the apertures of the microtitration plate receptacles or, what is better, to slightly immerse them in these. For instance, the proportioning head may be fitted with 384 pipette tips, which makes it possible to receive or deliver liquid form or into all of the receptacles in a single step for 384-receptacle microtitration plates and at least to deliver liquid into all of the receptacles in four steps for 1536-receptacle microtitration plates.
The proportioning head may be employed on automatic proportioners in lieu of a conventional proportioning head having steel cannulae. Basically, it is possible to design the head plate and/or centering plate as separable components which can even be left permanently on automatic proportioners as they are under a low risk of contamination and can be cleaned more easily than can pipette tips. Basically, it is possible to manufacture the head plate and/or centering plate form metal, glass or another material. In such an aspect, the pipette tips may be adapted to be exchangeably connected to the head plate and to be brought together with the centering plate only in an application case. However, it is preferred that the head plate and/or the centering plate be of a plastic as well. This makes it possible to design the head plate and/or centering plate as a part of a disposable, which can reduce the expenditure for an exchange and can even further diminish the risk of entrainment and contamination.
An automatic proportioner can be provided with a reception unit which is adapted to receiving such a disposable. The pipette tips can be connected to the at least one displacement device of the automatic proportioner via pin-shaped or conical members which are sealingly seated at the inner edge of upper apertures of the pipette tips or of mounting holes of the head plate in which the pipette tips are sealingly seated at the circumference.
The inner diameters of the centering holes have preferably been chosen to be slightly larger than the outer diameters of the centering portions where the differences in diameter are determined by the accuracy which is required for aligning the tip apertures on the receptacles of the microtitration plate. Preferably, the centering portions are substantially cylindrical shank portions or slightly conical shank portions of the pipette tips. In the latter case, the inner diameters of the centering apertures require to be tailored to the maximum outer diameters of the centering portions.
According to an advan
Douglas Steven O.
Eppendorf AG
Sidley Austin Brown & Wood LLP
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