Centrifuge

Abstract

A centrifuge comprises a rotating chamber containing a compressible container for the liquid to be centrifuged. The centrifuge also includes means to compress the container to transfer liquid from the container during centrifugation. The compressing means is also capable of compressing one or more further compressible containers to transfer liquid therefrom to the first-mentioned compressible container. The compressing means is preferably a diaphragm member which is urged by centrifugal force against a compressible container. In one application, the container is filled with blood to be centrifuged and, after the serum is separated, a valve is opened permitting the diaphragm to compress the container to transfer the serum to a further container. The valve is then closed and speed reduced until the diaphragm returns to its rest position causing compression of a still further container provided with wash water. A valve is then opened to permit transfer of some or all of the wash water into the first-mentioned container and the device may then be braked to cause the water to mix with the blood cells therein. The washed blood cells are then centrifuged and the water transferred to the water container or yet a still further container by the actuation of an appropriate valve similarly as in the case of transferring the serum. The washing operation is repeated if desired until all of the wash water has been utilized.

Description

BACKGROUND OF THE INVENTION

The invention relates to a centrifuge and particularly to a centrifuge suitable for the treatment of blood.

In the treatment of blood the problem often arises of separating blood corpuscles from serum or replacing the serum by some other liquid. In the latter case a careful washing of the blood corpuscles may become necessary so as to remove as completely as possible the blood serum from the same.

It is known that blood can be treated in a cylindrical centrifugal rotor in which is arranged an equally cylindrical filter, the blood being on the inside (centrally) around the filter wall and the washing liquor being outside the same in the rotor chamber. During centrifuging, the liquid flows towards the center and the blood corpuscles are maintained in suspension by suitable adjustment of the centrifugal force in relation to the flow of the washing liquor. This device is bulky and clumsy and relatively complicated, which renders it difficult to maintain sterility. The device is also expensive.

It is an object of the present invention to provide a centrifuge which is free of the disadvantages mentioned above. It is a further object to provide a simple and inexpensive centrifuge allowing separation of blood during centrifuging while maintaining sterile conditions.

BRIEF SUMMARY OF THE INVENTION

The foregoing and other objects which will become apparent to those having ordinary skill in the art are achieved according to the present invention by providing a centrifuge comprising a rotor, a chamber mounted for rotation with the rotor, a compressible container located in said chamber, passage means in fluid communication with said chamber, valve means for controlling fluid flow through said passage means, and means for compressing said flexible container to decrease the volume thereof.

DETAILED DESCRIPTION

There follows a detailed description of a preferred embodiment of the invention, together with accompanying drawings. However, it is to be understood that the detailed description and accompanying drawings are provided solely for the purpose of illustrating a preferred embodiment and that the invention is capable of numerous modifications and variations apparent to those skilled in the art without departing from the spirit and scope of the invention.

FIG. 1 is a radial elevation section along line I in FIG. 2 through the top portion of a centrifuge according to the invention;

FIG. 2 is a schematic perspective view of the central portion of the centrifuge of FIG. 1 showing the course of conduits;

FIG. 3 is a schematic expanded perspective view showing connections between containers provided in the centrifuge of FIG. 1; and

FIG. 4 is a diagram illustrating the control of fluid flow between the containers.

FIG. 1 is a radial section of a centrifuge according to the invention to which correspond similar sections at 120.degree. and 240.degree. distance, as can be seen in FIG. 2. On the central portion 1 of the centrifuge rotor is fitted a bottom disc 2 and on this an outer ring 3, which has inside it three rectangular threads with three entrances. A top disc 4 is fixed on a threaded inner ring 5, whose threads match those of the outer ring 3. The outer volume of the centrifuge formed in this manner is divided into two chambers by a control device 6. This has a rigid conical partition wall 7 which is penetrated by an opening 8. On both sides of the partition wall 7 are situated clamped rubber diaphragms 9 and 10 and the diaphragm 10 is reinforced on the underside by a further rubber diaphragm 11 vulcanized to it which is heavy and has a high specific gravity. The diaphragms 9 and 10 are strongly biassed, so that they are urged to be curved downards under their own stress as shown in FIG. 1. Enclosed between the diaphragms 9 and 10 is a cavity 12 containing a displacement liquid having a volume equal to the liquid quantity which will be conveyed to or from the blood being centrifuged as will be explained below. Details concerning a suitable control device are described in U.S. application Ser. No. 61,573, filed Aug. 6, 1970, entitled "Rotating Sensitive Pumping Device," herein incorporated by reference. The control device can be raised and lowered within the centrifuge rotor through the presence on it of three plugs 13 which fit into the threads of the ring 3 and can so be adjusted up and down by twisting.

In the space between the bottom disc 2 and the control device 6 are three compressible containers 14, 15, 16. A compressible blood container 17 is arranged between the top disc 4 and the control device 6. The container 17 is covered by a conforming plastic disc 18 with a number of ridges 19. The compressible containers are annular in shape and conveniently made of polyethylene or other plastic film inert to blood. Details of a preferred bag are disclosed in U.S. application Ser. No. 61,574, filed Aug. 6, 1970 titled "Container for Blood" herein incorporated by reference.

A screen 20 surrounds a narrower part of the central portion 1 of the centrifuge rotor. A slot 21 is provided in screen 20 through which flexible tubes 14', 15', 16' connected to the containers 14, 15, 16 are introduced into the space between rotor 1 and the screen 20. Each tube 14', 15', 16' connects its respective container with container 17 and each is provided with a valve 14", 15", and 16" to control the flow of fluid between container 17 and each container 14, 15, and 16.

Valve 16" is visible in FIG. 1 and comprises an electro magnet 22 which acts on a valve arm 23, which forms a loop in which is inserted the line 16', so that the line is closed when the magnet is activated. Electromagnet 22 is actuated by electrical leads 22' in a conventional manner. When current is broken, line 16' is free, and the release of the line can be assisted by a spring 22". These details are conventional and can obviously be varied in a number of different ways.

FIG. 4 shows schematically how a program register 24 is arranged for the control of the operation of the centrifuge 25 through lines to the valves 14", 15", 16" and to a brake 26, which may be any suitable electrically controlled brake. It should be noted that the valves 14", 15", 16" are opened when the magnets are currentless.

The separation of blood plasma from blood corpuscles and washing of the latter takes place in the following manner:

It is assumed that the centrifuge is intended for five washings of a quantity of blood, for example 250 ml. Container 14 is filled with 5 .times. 250 = 1,250 ml of washing liquor. Containers 15 and 16 are empty. Containers 14, 15, and 16 are placed in the lower chamber of the centrifuge on the bottom disc 2, as can be seen in FIG. 1. The three connecting lines or flexible tubes are placed around the central portion 1, as shown in FIG. 2 and clamped tight at the valve devices 14", 15", 16".

Control device 6 is now threaded in until practically all the air has been driven out from the lower centrifuge space. Control device 6 has then reached its bottom position, and the displacement fluid (250 ml) in cavity 12 is below partition wall 7. Owing to the substantial diaphragm stress it is not possible by hand to press the displacement fluid up through the opening 8. Control device 6 is locked in this position by any suitable known device, for example, a locking screw, which is not shown in the drawings.

Subsequently, the blood container 17 and the disc 18 are inserted, whereupon the three connecting lines to container 17 are joined together with three lines from the containers 14, 15, 16 as shown in FIG. 3. The top disc 4 of the centrifugal rotor with ring 5 is screwed down into position as shown and locked in a suitable manner.

The centrifuge can now be started, and approximately three minutes after it has reached the steady state with approximately 1,000 g in the periphery, the blood corpuscles have been packed together and the plasma, which constitutes approximately half the volume, can be conveyed to empty container 16. Through the program register 24 valve 16" is opened. Thus, a connection is established between the top and bottom space of the centrifuge. The heavy diaphragm 10, whose centrifugal force is greater than the diaphragm stresses, drives the displacement fluid through the opening 8. Through this, a corresponding amount of plasma is driven from container 17 into container 16. When the conveying has been completed, the program register closes valve 16" and opens valve 14", so that a connection is established between the containers 17 and 14. At the same time the rotational speed of the centrifuge is lowered to a low value such that the stresses in the rubber diaphragm become substantially greater than the centrifugal force of the heavy diaphragm. Therefore, a pumping action in the opposite direction sets in, and container 17 is filled up again with 250 ml washing liquor from container 14 owing to the displacement fluid being driven down again through the opening 8. When container 17 is filled, valve 14" is closed and the rotational speed of rotor 1 is increased. When the operating speed has been attained, the motor is stopped and the centrifuge is quickly braked by the brake 26 but the liquid in the blood container 17 continues to rotate. The container, which is flexible, has in the meantime engaged projections 19 which through this provide a stirring action in container 17 such that an effective mixing of the blood corpuscles with the washing liquor is obtained.

The brake is now released and the centrifuge is re-started. Approximately 3 minutes after the steady state has been attained, the blood corpuscles have again been packed together and the liquor can be tapped. This is done by opening valve 15", so that the consumed washing liquor is conveyed to the container 15 in the same manner as described above for the transport of plasma to container 16. The washing process is repeated five times whereupon the centrifuge is stopped.

The result is that the blood corpuscles have been thoroughly washed and a minimum of washing liquor remains in the blood container 17. The plasma has been conveyed to the plasma container 16 and the washing liquor to the discharge container 14. The displacement fluid which at the beginning was in the lower part of control device 16 is now in the top part thereof and the bottom part is consequently exposed to a substantial overpressure caused by the diaphragm stresses. After the stop screws have been loosened, the top part 4, 5 is screwed off. The blood container 17 is detached from the connecting lines and the plastic disc 18 is taken off. The connecting tube of the discharge container 15 is connected up to a discharge and the valve 15" is opened. As a result, 250 ml consumed washing liquor runs off, so that the displacement fluid drops down into the bottom part. The overpressure in the bottom part disappears, and the centrifuge can be dismantled.

It will be apparent that without any other change of the centrifuge than coupling to a different program and a different content in the container 17, it may also be used for washing out protecting agent from frozen blood and conversion of the blood to a condition suitable for transfusion.

According to the modified embodiment, the function of control device 6 may be exercised by means of a pressure variation across the control device brought about, for example, by sealing off of the chamber where the blood container is situated and supply of the pumping pressure to that chamber via a rotating coupling.

Such a centrifuge operates in the same manner as the one described above, except that at least one of the chambers of the centrifuge must be in airtight separation from the atmosphere environment as well as from the other chamber. The pumping action from the one chamber to the other chamber is not obtained through variation of speed, but through variation of the air pressure in the airtight chamber surrounding the containers. The amount of liquid which is transported is determined in this variant by the pressure set up when, at a certain speed, equilibrium can permanently be made to prevail at a certain level, through the application of a certain external overpressure.

Centrifuges in accordance with the invention are intended in the first place to be used for the treatment of one blood unit at a time, but it will be apparent that it is quite possible to stack on the same axle a number of compressible containers.

Claims

What is claimed is:

1. A centrifuge comprising:

a rotor;

a first chamber mounted for rotation with said rotor;

a first compressible container located in said chamber;

a second chamber mounted for rotation with said rotor;

at least one further compressible container located in said second chamber;

passage means placing said first compressible container in fluid communication with said further compressible container;

valve means for controlling the flow of fluid through said passage means;

a first diaphragm for compressing said one flexible container in said one chamber;

a second diaphragm spaced from said first diaphragm and including a cavity therebetween;

said cavity between said diaphragms being filled with a displacement fluid; and

said flexible diaphragms being inclined with respect to the axis of rotation of said rotor such that, at a certain rotational speed, said diaphragms are urged from a rest position to a high speed position compressing said one compressible container.

2. A centrifuge according to claim 1 wherein said cavity includes a rigid wall positioned between said diaphragms, said wall including an opening therethrough for the passage of said displacement fluid.

3. A centrifuge according to claim 2 wherein said diaphragms are downwardly curved in said rest position and upwardly curved in said high speed position.

4. A centrifuge according to claim 1 including a plurality of further compressible containers each in fluid communication with said first compressible container through said passage means, said valve means controlling the fluid flow between said first compressible container and each of said further compressible containers.

5. A centrifuge according to claim 4 wherein said plurality of further compressible containers are located in said second chamber.

6. A centrifuge according to claim 5 wherein said first container includes a liquid to be centrifuged, and said further compressible containers comprise a container for receiving a phase separated from the centrifugal liquid, a container for wash liquid to be introduced into said first container after separation of said phase, and a container for receiving wash liquid from said first container, said centrifuge including means for arresting motion of said first chamber whereby said wash liquid is mixed with the phase in said first container.