Automatic handling of sample cups closed with a screwable cap

The invention concerns a sample cup according to the preamble of claim 1.

The invention further concerns an apparatus according to the preamble of claim 2.

The invention further concerns a method according to the preamble of claim 3.

The invention concerns in particular a sample cup, an apparatus, and a method of the above mentioned types which are suitable in particular for isolating a nucleic acid sample from cell material.

Such sample cups have to be hermetically closed preferably with a screwable cap in order to ensure that the sample contained therein cannot be contaminated by external agents and also in order to protect laboratory staff from the risk of being contaminated by a pathological sample which may be contained in the sample cup. This applies in general to sample cups used for clinical chemistry tests, and in particular to sample cups used in methods for isolating a nucleic acid sample from cell material.

According to the prior art the cap of such a sample cup has to be removed and replaced manually with great care in order to allow pipetting operations, e.g. for transferring a portion of a biological sample contained in a primary sample tube can be pipetted into the sample cup, e.g. before a method for isolating a nucleic acid sample from cell material is carried out on a sample contained in a sample cup, or for transferring a nucleic acid sample isolated by such a method into the sample cup.

The above mentioned manual removal and replacement of the screwable cap of sample cups is a handling which is time consuming and which is not compatible with the increasing need for automatic handling of sample cups in modern automatic sample cup handling apparatuses. There is therefore a need to automatize the removal and replacement of the screwable caps.

There is moreover a need to transport individual sample cups closed with their respective screwable cap to different positions within the sample cup handling apparatus, e.g. in order to perform different steps of a method for isolating a nucleic acid sample from cell material.

US Patent number US-A-5826400 discloses an apparatus and a method for bottle capping, a plurality of bottles with petaloid lobes on the bottom of the bottles being seated in nests with fingers inserted between the petaloid lobes of the bottles to prevent rotation of the bottle during rotation of the capping head when the caps are successively engaged and applied to the threaded necks of the bottles.

UK Patent Application GB2187720A describes a method and an apparatus for automatic capping or uncapping screw closures onto or from containers. The containers are received in recesses around the periphery of a rotatable table. The recesses are vertically aligned with capping heads which move with the table. Rotation of the capping head whilst engaged with the closure causes to screw the closure onto the neck of the container. Part of the inner surface of the recesses is provided with a series of teeth angled backwardly in relation to the direction of rotation, the teeth frictionally engaging with the surface of the bottle neck as to resist rotation during capping.

European Patent Application EP-A-676643 describes a system using several vessels which are closed by individual caps. This known system comprises means for automatically opening and closing the vessels by automatically removing and replacing the individual caps. In this known system each cap has a lower part which tightly fits into the open upper end of a vessel, and an upper part which has a cylindrical cavity for receiving an opening tool. The tool for automatically removing the caps is matched to the shape of the upper part of the cap. This tool has the shape of a tapered plug which has a removal ring which has to be pressed into the upper part of the cap over a corresponding resistance of the cap. When the tapered plug is withdraem the removal ring acts as a resistance. Since the pressure of the cap on the inner wall of the reaction vessel is smaller than the resistance of the ring with the cap, the cap is removed from the reaction vessel. In the known system described by European Patent Application EP-A-676643 a vessel can be closed again by means of the same cap or of a new cap. For this purpose, the same plug used for removal of the cap is used for holding the cap and inserting the lower part of the cap into the vessel. After this the removal plug is removed and the cap remains on the vessel. This known system cannot be used when the caps are screwable caps, i.e. when the caps and the vessels are connected with each other by a screw connection. There is therefore a need for a sample cup adapted for being closed by a screwable cap and for means for opening and closing such a sample cup by automatically removing and replacing the screwable caps.

French Patent FR-A-2129254 describes an arrangement wherein jaws 17 grasp and held a screwable closure 15 and a container 11 is held by a rotatable gripper 13. Container has in its upper part a screw thread for connecting it to screwable closure 15. In order to connect screwable closure 15 to container 11, screwable closure 15 is held by jaws 17 and container 11 is held and rotated by gripper 13.

A first aim of the invention is therefore to provide a sample cup which is suitable for satisfying the above mentioned needs in the most simple and therefore less expensive way.

A second aim of the invention is to provide an apparatus and a method which are suitable for satisfying the above mentioned needs in the most simple and therefore less expensive way.

According to a first aspect of the invention the aims of the invention are attained with a sample cup according to claim 1.

According to a second aspect of the invention the aims of the invention are attained with an apparatus according to claim 2.

According to a third aspect of the invention the aims of the invention are attained with a method according to claim 3.

The main advantage of the sample cup, apparatus and method according to the invention is that they provide very simple and relatively inexpensive means for automatically opening, closing and transporting sample cups.

Exemplified embodiments of apparatus, method and sample cup according to the invention are described below with reference to the accompanying drawings wherein: <ul id="ul0001" list-style="none"><li>Fig. 1 shows a perspective view of a transportable gripper 11 which is an essential part of an apparatus according to the invention.</li><li>Fig. 2 shows an exploded view of the gripper 11 in Fig. 1.</li><li>Fig. 3 is a cross-sectional view of the gripper tool 21 of gripper 11 in Figures 1 and 2.</li><li>Fig. 4 is a perspective view of a sample cup 31 according to the invention.</li><li>Fig. 5 is a side view of sample cup 31 in Fig. 4.</li><li>Fig. 6 is a cross-sectional view of sample cup 31 along A-A in Fig. 5.</li><li>Fig. 7 is a plan view of sample cup 31 in Fig. 4.</li><li>Fig. 8 is a perspective view of a sample cup holder 41 holding a plurality of sample cups.</li><li>Figures 9 to 16 illustrate schematically various steps of methods of handling sample cups according to the invention.</li></ul>

An apparatus according to the invention comprises a transportable and rotatable the gripper 11 of the type described hereinafter with reference to Figures 1 to 3. Transport of gripper 11 is carried out e.g. by an X-Y-Z transport system which enables movement of gripper 11 in 3 directions which are normal to each other. Rotation of the gripper is carried out by suitable controlled motor means associated to the latter transport system. The controlled motor means are such that rotation of gripper 11 and thereby of gripper tool 21 is possible in both angular senses, clockwise or in the opposite sense. The controlled motor means include means for measuring variations of the amount of electrical energy associated to rotational movement of the gripper tool. In this way the apparatus is able to detect different states of its operation, e.g. when the gripper tool has engaged the recess of the cap 34 and force should be applied to unscrew cap 34 and remove it from sample cap 31.

Gripper 11 comprises a housing 12 having a top wall and a. side wall which has elongated openings 13 and 13 a (not shown) located on diametrically opposite sides of the side wall of housing 12, a first spring 14, and a gripper tool 21 which has a cylindrical upper part 16 which has a cavity 15 and a bottom wall connected to a shaft 25 which extends along the rotation axis of the cylindrical upper part 16 and has a lower end 24.

Pin shaped projections 17 and 17 a radially extend in opposite directions from the side wall of cylindrical upper part 16. Shaft 25 has at its lower end pin shaped projections 22, 23 which radially extend in opposite directions.

An annular disk 19 is free to glide along shaft 25 between the bottom wall of cylindrical upper part 16 and pin shaped projections 22, 23. Disk 19 is however pressed against projections 22, 23 by a second spring 18 arranged with respect to shaft 25 as shown by Fig. 2.

In the assembled state of gripper 11 shown by Fig. 1, spring 14 and cylindrical part 16 are so arranged within housing 12 that pin shaped projections 17 and 17 a pass through respective openings 13, 13 a of housing 12, and spring 14 transmits force exerted on it by housing 12 to cylindrical upper part 16. In this way depending on the magnitude of the force applied, cylindrical upper part 16 can move within housing 12 within limits defined by the length of openings 13, 13 a.

From figures 1-4 and the above description it can be appreciated that when gripper 11 is rotated, gripper tool 21 rotates with it.

In addition to the above described parts of gripper 11, Figures 1 and 2 show a cap 34 of a sample cup according to the invention.

As shown by Fig. 1, when gripper tool 21 of gripper 11 holds cap 34 spring 18 presses disk 19 against the top of cap 34, a part of which is held between disk 19 and projections 22, 23 of gripper tool 21, and the projections 22, 23 at the lower end of gripper tool 21 are engaged with recesses 35, 36 of cap 34. In Fig 1 only recess 35 and projection 22 are shown.

Figures 4 to 7 show in more detail a sample cup 31 according to the invention. Such a sample cup 31 comprises a removable screwable cap 34 which has a recess located in the top and central part of the cap. This recess comprises a slot 37 which extends along the length axis of the sample cup 31 and which ends in two annular channel segments 35, 36 which extend in opposite angular directions with respect to the length axis of the sample cup 31. Sample cup 31 has an outer wall 32 which has a zone 33 the shape of which is adapted to cooperate with the shape of a corresponding zone of the inner surface of a chamber of a sample cup holder in order to prevent rotation of the sample cup 31 when the lower part thereof is inserted in that chamber.

An essential feature of an apparatus according to the invention is that it comprises a rotatable gripper tool 21 which is configured and dimensioned to enter and engage with a recess 35, 36 of said cap 34 to form a connection which can be locked by rotating the gripper tool 21 in a first sense with respect to said sample cup 31 and which can be unlocked by rotating the gripper tool 21 with respect to said sample cup 31 in a second sense opposite to the first.

In a preferred embodiment now described with reference to Fig. 8 an apparatus according to the invention is used to handle a plurality of sample cups 51-69 each of which is inserted in one of a corresponding plurality of chambers of a sample cup holder 41 which has e.g. the shape shown by Fig. 8. For proper operation according to the invention the inner surface of each of said chambers has to have a zone the shape of which is apt to cooperate with zone 33 of the outer wall of sample cup 31 in such a way that when such a sample cup is inserted in one of the chambers of sample cup holder 41, sample cup 31 is held stationary by said chamber and is not free to rotate around its length axis.

As can be appreciated from Fig. 8 the sample cups schematically shown therein are of the type described above with reference to Figures 4 to 7. Each of the sample cups 51-69 shown in Fig. 8 is closed with a removable screwable cap and the lower part of which is inserted in one of said chambers of the sample cup holder 41. The outer wall of each of said cups 51-69 has a zone which cooperates with a corresponding zone of the inner surface of the chamber of the sample cup holder 41 to prevent rotation of the sample cup 51-69 inserted in said chamber. The screwable cap of each of sample cups 51-69 has a recess located in the top and central part of the cap, said recess comprising a slot which extends along the length axis of the sample cup and which ends in two annular channel segments which extend in opposite angular directions with respect to the length axis of the sample cup.

An apparatus according to the invention for the above mentioned use with reference to Fig. 8 comprises a gripper of the type described above with reference to Figures 1-3, that is a gripper like gripper 11 movable in three orthogonal directions by a transport device. Such a gripper comprises a rotatable gripper tool which has an end part having a shape and dimensions which match the shape and dimensions of the recess of the cap of each sample cup in such a way that the end part of the gripper tool can enter through the slot of the cap's recess and by rotation enter into and engage the annular channel segments of said recess. The transport device for moving the latter gripper is suitable for moving it in said three orthogonal directions, and for positioning and rotating the gripper tool of the gripper of a predetermined angle within the recess of the cap of each of the sample cups 51-69.

A method for holding and transporting sample cups 31 closed with a screwable cap 34 with an apparatus according to the invention in a system wherein portions of biological samples contained in primary sample tubes have to be automatically pipetted into and from said sample cups is now described with reference to Figures 9 to 12. Such a method comprises transporting a sample cup 31 by means of a transportable and rotatable gripper which includes a gripper tool 21 apt to enter a recess 35, 36, 37 of said cap 34, said transporting being effected by positioning said gripper tool 21 in said recess 35, 36, 37; by rotating said gripper tool 21 within said recess 35, 36, 37 with respect to said sample cup 31 until it engages and locks into said recess 35, 36, 37; and by transporting the gripper tool and thereby the sample cup 31 from a first position to a second position.

In order to position gripper tool in the recess of cap 34, gripper tool 21 is lowered by the transport means (see Fig. 9) until it contacts the upper surface of cap 34. When that contact is established gripper tool 21 is rotated by the above mentioned controlled motor means while the transport means still exert a gentle downwards force on gripper tool 21. In this way, when the angular position of projections 22, 23 of gripper tool 21 coincides with the angular position of slot 37 of cap 34, the latter projections enter slot 37 and upon further rotation projections 22, 23 engage with annular channel segments 35, 36 of cap 34 (see Fig. 10), and in this way establish a locked connection between gripper tool 21 and cap 34, and thereby between gripper tool 21 and sample cup 31. Figures 11 and 12 illustrate upward and downward transport of sample cup 31 by means of gripper tool 21.

A method for removing the screwable sample cap 34 of a sample cup 31 with an apparatus according to the invention is now described with reference to Figure 13. Such a method comprises positioning said gripper tool 21 in said recess 35, 36, 37 and rotating said gripper tool 21 within said recess 35, 36, 37 in a first sense with respect to said sample cup 31, thereby unscrewing the cap 34 and removing it from the sample cup 31.

A method for replacing, i.e. for screwing a screwable sample cap 34 on a sample cup 31 with an apparatus according to the invention is now described with reference to Figures 14 and 15. Such a method comprises positioning said gripper tool 21 in said recess 35, 36, 37 and rotating said gripper tool 21 within said recess 35, 36, 37 in a second sense with respect to said sample cup 31, said second sense being opposite to said first sense, thereby screwing the cap 34 and replacing it on the sample cup 31.

Figure 16 illustrates how cap 34 and thereby sample cup 31 is released from gripper tool 21.