Imperforate bowl: centrifugal separators – Including plurality of miniature bowls distrubuted about... – Having bowls – or holders therefor – pivotaby attached to...
Reexamination Certificate
2000-03-24
2001-05-22
Cooley, Charles E. (Department: 1723)
Imperforate bowl: centrifugal separators
Including plurality of miniature bowls distrubuted about...
Having bowls, or holders therefor, pivotaby attached to...
C494S037000
Reexamination Certificate
active
06234948
ABSTRACT:
TECHNICAL FIELD
The present invention refers to phase separation in liquids. More particularly the present invention relates to methods and devices for centrifugation of blood to achieve phase separation.
BACKGROUND ART
There have been developed various combined separation systems for rapid phase separation. Certain attempts have been made to make use of the so called “Boycott” effect, which requires inclination of the tube walls at a certain angle to the vector of the centrifugation force in order to make the phase separation more efficient. An example of a system employing the Boycott effect is described in the article “Automated Centrifuge Technology”—Laboratory Automation News—vol. 1 No. Oct. 4, 1996. The device described in this article employs switchable cam-like mechanism for displacement the tube during centrifugation.
There are known also other centrifugation assemblies utilizing the Boycott effect, e.g. as disclosed in U.S. Pat. No. 5,584,790 assigned to Beckman Instruments Inc.. This assembly employs a spring-loaded linkage system for inclination holders carrying the tubes and thus to misalign the tubes with the vector of the centrifugation force.
The other example of a centrifugation assembly employing the Boycott effect can be found in U.S. Pat. No. 5,588,946 assigned to Johnson & Johnson Clinical Diagnostics, Inc. In this assembly a patient sample tube is spun while non-aligned with the centrifugation force to allow phase separation and then while aligned to allow any gel present between the separated phases to seal.
Unfortunately the constructions of the above assemblies are not suitable for implementation in a conventional swing-out bucket centrifuge in which a large number of tubes should be rotated. Furthermore the assemblies mentioned above are not capable of developing sufficient phase separation in large number of sample tubes.
DISCLOSURE OF THE INVENTION
This invention relates to an assembly and a method for rapid phase separation in liquids in general and for blood phase separation in particular. The invention can be implemented either in ordinary swing-out rotor centrifuges, in high-speed centrifuges and in Automatic Laboratory Systems.
The method of the present invention comprises spinning the tubes with blood samples while they are inclined to make use of the Boycott effect for more rapid phase separation. In the second stage of separation the tubes spin while their longitudinal axes are aligned with the direction of the centrifugation force to allow reliable gel seal.
In accordance with the method of the invention the position of the common centre of gravity of the holders and of the tubes placed therein is varied during the separation process. The first position of the common center of gravity is above the pivoting axis of each holder. By virtue of this provision the centrifugal force can not pivot the holders with tubes in ordinary horizontal position. The degree of inclination of the holders is maintained by a stopping means having various construction as it will be disclosed further. The stopping means can be individual for each holder or common for all holders. The stopping means can be formed integrally with the holder or with the centrifuge rotor or with the other parts of the centrifuge. The common stopping means may be placed in the middle of the rotor. The collapsible and revolving stopping means also can be used and are operated electromagnetically or manually.
After completing the first stage of the separation accompanied by the Boycott effect the common center of gravity is displaced in the second position, i.e. under the pivoting axis of the holder. During the second stage the centrifugal force urges the holders with tubes to pivot into horizontal position in which they could have been aligned with the vector of the centrifugation force and thus the complete gel seal can take place. The stopping means does not prevent this pivoting movement. In the end of the second stage the centrifuge is stopped and the holders and tubes return back into the initial position.
According to the present invention in the beginning of centrifugation the common center of gravity of the holders, including tubes, specimens and gel is above the pivoting axis of the holder. After performing the first stage of separation accompanied by the Boycott effect the common gravity center is displaced below the pivoting axis.
According to the alternative method of the present invention in the beginning of centrifugation the common center of gravity of the holders, including tubes, specimens and gel is below the pivoting axis of the holder. After performing the first stage of separation accompanied by the Boycott effect the common gravity center is displaced below its first position.
The holders may include displacement means to vary the location of the gravity center during centrifugation. Various embodiments of the centrifugation assembly of the present invention are summarized below.
In the first embodiment the assembly comprises:
a rotor with a holding means for carrying at least one tube, said tube containing a blood sample and a gel separator, said holding means being pivotable with respect to the rotor, the position of the common center of gravity of the holders and of the tubes placed therein is varied during the separation process,
a means for rotation the rotor about a rotor axis to produce a centrifugal force having its vector radiating from the rotor axis, said centrifugal force is capable:
a) to induce phase separation due to the Boycott effect when the tube is pivoted in the first position in which the tube walls are inclined with respect to the vector of the centrifugal force and
b) to allow complete gel seal when the tube is pivoted in the second position in which the tube walls are aligned with the vector of the centrifugal force,
a displacing means for displacing the common center of gravity of the holding means together with the tube carried thereby from a first location situated above the pivoting axis into a second location situated below the pivoting axis,
a stopping means for maintaining a degree of inclination of the tube when it is pivoted in the said first position.
The assembly may comprise a swing-out bucket centrifuge, while said rotor carries a yoke for mounting the holding means thereon and said holding means comprises at least one bucket preferably equipped with an adapter for inserting the tube there into, said bucket is mounted on the yoke with possibility for swinging with respect to the yoke.
The centrifugation assembly may comprise also a high-speed centrifuge.
The centrifugation assembly may comprise a displacing means formed as a closed cylindrical container, said container being insertable within the holder, said container being filled with a fluid capable to flow from one extremity of the container to the opposite extremity thereof, said fluid being selected from the group comprising viscous liquids, suspensions, loose particles or their combination.
The said container may be formed with a narrowing central portion. The container may be provided with a partition and channels, said partition is fixedly secured in the middle part of the container.
The container may comprise a spring loaded piston movable along the container and a spherical valve, said valve is fixedly secured opposite to the piston in the middle part of the container, said valve has through going channels for flowing the fluid there through.
The container may comprise a free mass placed therein with the possibility to move along the container, the outside diameter of the mass is less than the inside diameter of the container and there is provided a gap there between, said gap is sufficient for flowing the fluid there through.
The mass may be provided with a valve and with through going channels, said channels are closed from one side of the mass by a valve and are open from the opposite side of the mass, said container having a spring means urging the mass to return from the lowermost extremity of the container to the uppermost extremity thereof, said container has
Cooley Charles E.
Freiburger Thomas M.
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