Patent Application
20150141233
The present invention relates to an adapter for a centrifuge vessel.
Centrifuge vessels, for example, centrifuge bottles, are special containers which comprise a vessel body and either a sealable or a non-sealable opening and which are adapted for use in a centrifuge for the purpose of accommodating and separating samples. In a centrifuge, substance mixtures are separated by implementation of high acceleration forces. To this end, a mixture to be separated is placed in a centrifuge vessel, which is then driven so as to rotate in such a manner that centrifugal forces occur within the centrifuge vessel to cause separating processes to take place. By this means, individual liquids may be separated from each other or solid particles from a liquid. On account of the high acceleration values, very high forces act on the centrifuge vessel and its contents, so that the centrifuge vessels must show a high degree of mechanical stability or must be stabilized.
There are various types of centrifuge vessels, for which reason adapters are used to fit the different geometries of centrifuge vessels to a centrifuge holding means. The centrifuge vessels are accommodated in the centrifuge adapter and the adapter is mounted on the centrifuge rotor's holding means, which is driven so as to rotate during a centrifuging operation.
It is desirable for the walls of the centrifuge vessels used for the accommodation of samples to be as thin as possible for reasons of weight and the reduction of overall costs. This, however, results in a loss of stability of the centrifuge vessel—often to such an extent that they are no longer self-supporting. The same problem occurs with respect to sample bags as used, for example, for centrifuging blood. In the case of such centrifuge vessels, the adapters themselves will also serve to support the vessels so as to maintain their shape.
Furthermore, increasingly larger centrifuge vessels are being used for the purpose of achieving more efficient centrifugation. Every centrifuging operation is set to a predetermined time limit, so that centrifuge vessels of the largest possible capacity are used to save batch time and reduce overall costs. Due to the high acceleration forces that occur during centrifugation, however, enormous forces are liberated, which act on both the centrifuge vessel and on the adapter. As a result, the centrifuge vessel and the adapter may be deformed to such an extent that they can hardly or not at all be separated from each other. Furthermore, there is the possibility of an increased risk of injury occurring during removal of the centrifuge vessel, since the centrifuge vessel and the adapter will have become firmly wedged together to render them less readily separable. There is also the added possibility of the deformed centrifuge vessel being no longer reusable, which increases the costs of the process of centrifugation. Due to the above risks, centrifuge vessels of a larger volume are usually restricted as to acceleration, which, however, is concomitant with a reduction in separation efficiency.
Thus, it is the object of the present invention to avoid problems incurred in the prior art and to provide an adapter for a centrifuge vessel which can withstand high acceleration values during centrifugation and which is also capable of stabilizing centrifuge vessels having comparatively thin walls and from which the centrifuge vessel can nevertheless be readily removed following a centrifuging operation.
In its broadest aspect, the present invention therefore relates to an adapter for a centrifuge vessel, which adapter comprises a shell-like base body formed as a single piece and delimiting a cavity provided to accept the centrifuge vessel, and also comprising a base region and an adjoining side-wall region, the top edge of which defines the opening edge of the cavity, said side-wall region comprising at least one expansion joint that allows the side-wall region to be expanded from a starting position to an expanded position by means of an applied force such that the length of the opening edge is larger in the expanded position than in the starting position. The adapter is made of a plastics material adapted to cause the side-wall region to return automatically to the starting position upon removal of said force. A return to the starting position may also be understood to involve recoiling to an extent that the outer diameter of the basic adapter body will differ in the recoiled position from the original outer diameter at the same location by an amount of up to ±10%, preferably by a maximum of ±5%, more preferably by not more than ±2%, and very preferably by a maximum of ±1%.
On the one hand, the design of the adapter according to the present invention allows for easy removal of a centrifuge vessel, in a very simple manner, in that the opening edge of the cavity accommodating the centrifuge vessel is expanded by the application of a force. This is only possible due to the provision of an expansion joint in the side-wall region of the adapter and due to the adapter itself being of a plastics material having elastic properties enabling it to return to its starting position. The combination of said properties allows for an increase in the length of the opening edge without it being necessary to provide the adapter with any folding or opening devices.
There is, furthermore, no need for any closing or holding devices for keeping the adapter in its starting position without expansion of the opening edge. Recoiling from the expanded position to the starting position takes place solely on account of the recoiling force embodied in the adapter due to its design as a single piece and to the material thereof. This has the added advantage of the possibility of holding the centrifuge vessel securely inside the adapter, while it is stabilized at all times due to the adapter being in the non-expanded starting position as long as that the opening edge is not specifically expanded by application of force. The length of the opening edge in the starting position is appropriately selected such that the top edge of the side-wall region delimiting the cavity in the starting position is closely adjacent to the centrifuge vessel. This, in combination with the shell-like structure of the basic adapter body formed as a single piece, the cavity of which is adapted to the outer shape of the accommodating centrifuge vessel in a manner known per se, results in perfect support of the accommodated vessel, even when said vessel is of only very small wall thickness. Even when exposed to high centrifugal forces, for example, forces ranging from 5,000 to 10,000 g, the elastic properties of the adapter allow for adaptation thereof to the centrifuge vessel contained therein and also to a holding device, for example, a centrifuge cup or swinging bucket or the like, accommodating the adapter and serving to attach it to the centrifuge rotor. The holding device further stabilizes the outer circumference of the adapter during the centrifuging operation and thus prevents excessive expansion of the adapter. Due to its elastic properties, however, the adapter is able to adapt its outer circumference to the contact surface of the holding device and can thus be supported thereby.
There is, furthermore, no need to trigger any holding mechanisms for the purpose of removing the centrifuge vessel from the adapter. No tools are required, since the user can, for example, both expand the adapter and remove the centrifuge vessel by hand. This is readily possible even in the event of the centrifuge vessel becoming deformed during centrifugation, though such deformation will be relatively slight due to the flexibility and the absorptive properties of the adapter. Because of the elastic properties of the adapter and the presence of the expansion joint, excessive force is not necessary in order to facilitate bending of the adapter away from the centrifuge vessel and to ease it open for the purpose of effecting unhindered separation of the centrifuge vessel from the adapter and removing it therefrom. Thus, the risk of incurring damage to the centrifuge vessel and/or to the adapter, or of the user being injured is therefore extremely low. Consequently, the adapter and centrifuge vessel have an increased lifespan. Due to the high level of support, even large and/or thin-walled centrifuge vessels having, for example, a capacity of up to 3000 ml, can be used at high rotational speeds. The throughput and separation efficiency are thus improved.
Within the scope of the present invention, an expansion joint is defined as being any kind of recess in the material of the side-wall region that enables movement of segments of the side-wall region relatively to one another. The expansion joint is preferably configured as a recess, more particularly, as a slit traversing the thickness of the wall. It is also possible for multiple recesses to be combined to form an expansion joint. In one possible embodiment, the expansion joint is a recess, more particularly, a straight slit, extending from the top edge of the side-wall region toward the base region. The expansion joint thus divides the side-wall region into two segments capable of being separated from each other, starting at the top edge delimiting the cavity and thereby increasing the length of the opening edge. The length of the opening edge is measured along the inner edge of the side-wall region immediately adjacent to the cavity, wherein in an expanded state the shortest distance between the endpoints of the inner edge separated by the expansion joint is taken into account. Said two endpoints are positioned closer to one another in the starting position than in the expanded position. The expansion joint appropriately extends downwardly from the opening edge toward the base region of the adapter to such an extent that the sections of the side-wall region can be moved sufficiently far from each other to enable easy removal of the centrifuge vessel from the adapter. The expansion joint preferably extends into the edge of the base region of the adapter. This is advantageous, because, on the one hand, the long expansion joint allows for easy expansion of the adapter and, on the other hand, the bend between the base region and the side-wall region of the adapter provides increased tension when expanded and thus an increased force for effecting recoiling to the starting position.
In an alternative embodiment, the expansion joint comprises an indenture extending from the top edge to an upper side-wall region of the adapter. Additionally, there is at least one recess extending to the side of the indenture and displaced therefrom toward the base region in such a way that a web-like region is formed between the indenture and the recess. Upon expansion of the adapter, said bar-like region can lift horizontally and thus cause an enlargement of the opening edge. The recess may preferably be configured so as to be bow-shaped, where the term “bow-shaped” includes not only rounded but also angular shapes. The bow-shaped recess is preferably disposed below the indenture in such a manner that the latter is positioned approximately centrally above the bow. This results in a bowed or angular bar-like region between the indenture and the recess that may be twisted into a horizontal direction, thus resulting in expansion of the opening edge. In one development, the bow-shaped recess can join a slit-like recess extending toward the base region, resulting in a basically forked or Y-shaped expansion joint. The latter further facilitates expanding of the side-wall region and thus simplifies removal of the centrifuge vessel from the adapter.
Instead of a bow-shaped recess, recesses may be provided on each side of the indenture. Such recesses may extend parallel to or at an angle to either each other and/or to the indenture. In either case, bar-like regions are created, effecting expansion of the opening edge by means of twisting. Again, the recesses are preferably slit-like, but other shapes are permitted as long as the adapter's stability is sufficiently maintained. The indentures can be of any shape, for example, slit-like or wedge-shaped. Their length depends on the extent of expansion of the opening edge to be achieved.
Although a single expansion joint in the side-wall region of the adapter may be sufficient for the purpose of achieving the object of the present invention, it is preferable to provide more than one expansion joint, since this eases handling of the adapter. For example, two to four expansion joints, preferably evenly spaced, are provided in the peripheral direction of the side-wall region. These expansion joints may be of the same or of different type. The expansion joints separate the side-wall region of the adapter into a number of segments, preferably of the same type, that are, however, all part of the single-piece basic adapter body and are connected thereto via the base region.
The base region and the side-wall region of the adapter are disposed at an angle to each other. A rounded transition region is preferably located between them. The curve of the transition region may contribute to an increase in recoiling force, by means of which the side-wall region moves back to the starting position from the expanded position, as adopted contrarily to said curvature. Furthermore, in the event of a side-wall segment being pulled outwardly and simultaneously flattened contrarily to said curvature, tension is built up in this area toward the perimeter of the shell-like basic adapter body due to the curvature of the side-wall region.
Reinforcing ribs may be provided on the exterior surface of the base body for the purpose of stiffening the adapter and simultaneously increasing the recoiling properties. These ribs preferably extend from the side-wall region via the transition region to the base region. A further advantage of the ribs is the reduced contact area of the adapter against the holding means accommodating the adapter. The ribs can easily adapt to the contact area of the holding device and can be readily detached therefrom. Since the reinforcing ribs are also of a flexible material forming part of the single-piece basic adapter body, they are able to provide a mechanical damping effect which makes them capable of absorbing additional forces during the centrifuging process. It is also possible for the ribs to define an external geometry of the adapter. In this regard, the shape of the centrifuge vessel—and, thus, the shape of the adapter cavity accommodating said vessel—may differ from the outer shape of the adapter. Whereas, for example, the cavity may accommodate a centrifuge vessel of a circular or oval cross-section, the centrifuge holding means may have an angular basic shape, reproduced by the reinforcing ribs. To this end, a number of reinforcing ribs may be disposed in particular in the corner regions of the receptacle.
In order to remove the adapter and to expand it very easily, at least one handle protrusion, for example, in the form of a pin, is suitably provided in a top marginal region of the base body. This facilitates opening of any partial segment of the side wall and the removal of the centrifuge vessel from the adapter cavity. The handle protrusion may be integrally joined to the base body or connected thereto as a separate piece. The former option is preferred.
To ensure the recoiling properties, the basic adapter body is appropriately of a flexible, more particularly, elastomeric, plastics material. This can be basically any suitable plastics material which has the stiffness required to accommodate a centrifuge vessel disposed in the cavity in the starting position and to keep it stable, but which is sufficiently mechanically flexible in order to be bent into the expanded position for the purpose of removing the vessel and to subsequently recoil to the starting position upon removal of such an expanding force. The precise mechanical properties, for example, shape retention and elasticity, are, for example, dependent on the dimensions of the adapter and on the type and size of the centrifuge vessel to be accommodated therein. Self-supporting centrifuge vessels require less support from the adapter than non-self-supporting centrifuge vessels of reduced wall thickness, for example, blood bags. Furthermore, plastics materials adequately resistant to chemicals are preferred, in case they come into contact with leaky samples. Thermally resistant plastics materials that can be used both in cooled centrifuges and at elevated outside temperatures are also advantageous. Injection-moldable plastics materials are preferably used, as these are particularly suitable for the manufacture of the single-piece basic adapter body. In the event of the entire adapter being made as a single piece, as is preferred, it appropriately consists entirely of injection-molded plastics material and is manufactured by means of injection-molding. In this regard, the elastomeric plastics materials are all plastics materials capable of elastic deformation, namely homopolymers, copolymers, and polymer blends, with or without fillers, i.e. minerals or fibers. They particularly include thermoplastic elastomers. Specific examples of suitable and preferred plastics materials are polyolefins, more particularly, polypropylenes, or polyamides. Blends or copolymers of such plastics materials may also be used.
The present invention is explained in greater detail below with reference to exemplary embodiments. However, the present invention is not restricted to these exemplary embodiments, and other combinations and applications are therefore possible. In the following diagrammatic drawings, in which like parts are identified by like reference numerals:
Pin-like protrusions 17 are integrally connected to the rest of the adapter on two opposing segments 16 in the top marginal region 18 of the side-wall region 13. By means of said protrusions, it is possible to pull the segments 16 outwardly so as to increase the length of the opening edge defined by the top edge 15 and also to enlarge the opening cross-section of the cavity 11.
Reinforcing ribs 19 are formed on the outer surface of the adapter. These extend from the top marginal region 18 along the side-wall region 13 via the transition region 123 down into the base region 12 and serve to stiffen the adapter. Additionally, they facilitate fabrication of the adapter by injection molding, improve the adaptability of the adapter to the contact area of the centrifuge holding means 60, and facilitate the removal of the adapter therefrom.
The adapter 10 is formed as a single piece and is made of an elastomeric plastics material, for example, polypropylene or polyamide, preferably fiber-reinforced polyamide by, for example, injection molding. The plastics material is flexible such that the four segments 16 are moveable relatively to each other for the purpose of accommodating the centrifuge vessel 30 (see
The adapters shown in
Other embodiments of an adapter are conceivable, for example, adapters for various sizes and geometries of centrifuge vessels and also adapters for various types of centrifuges and their centrifuge holders. Typical centrifuge vessels have capacities of from, say, 100 ml to 3000 ml.
While the present invention has been illustrated by description of various embodiments and while those embodiments have been described in considerable detail, it is not the intention of Applicants to restrict or in any way limit the scope of the appended claims to such details. Additional advantages and modifications will readily appear to those skilled in the art. The present invention in its broader aspects is therefore not limited to the specific details and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of Applicant's invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2012 013 641.2 | Jul 2012 | DE | national |
This application is a submission under 35 U.S.C. §371 of International Application No. PCT/EP2013/002011, filed Jul. 8, 2013, which claims priority to German Application No. 10 2012 013 641.2, filed Jul. 9, 2012, the disclosures of which are hereby expressly incorporated by reference herein in their entireties.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2013/002011 | 7/8/2013 | WO | 00 |
