US3838809A - Automatic serum preparation station - Google Patents

Abstract

A centrifuge apparatus for centrifugally separating the lighter components of a sample mixture from its heavier components is disclosed. The apparatus includes a centrifuge drum having vertically aligned separation and aspiration chambers separated by a common wall having valve means therein for connecting the two chambers. The separation chamber has a truncated conical side wall with a larger diameter trap portion located at the base thereof. A motor is included for spinning the centrifuge drum to force the heavier components into the transportation while the lighter components are forced up the conical side wall. A trigger mechanism opens the valve means to pass the lighter components through the common wall into the aspiration chamber while the centrifuge drum is spinning, closing the valve means when the rate at which the centrifuge drum is spinning falls below a desired level. An automatic sample loading mechanism is also provided which utilizes centrifugal forces to load a sample into the separation chamber of the centrifuge drum.

Description

United States Patent 1 Williams [76] Inventor: Melvin Williams, 840 Elmwood,

Evanston, 111. 60202 [22] Filed: Apr. 16, 1973 [21] Appl. No.: 351,631

[52] US. Cl 233/24, 233/25, 233/26,

[51] Int. Cl B04b 9/02 [58] Field of Search 233/23 R, 24, 25, 26, 27, 233/28, 14 R; 23/259 [56] References Cited UNITED STATES PATENTS 2,822,127 2/1958 Sinn 233/25 X 3,737,096 6/1973 Jones et al. 233/14 R [4 1 Oct. 1, 1974 Primary Examiner-George H. Krizmanich Attorney, Agent, or Firm-Merriam, Marshall, Shapiro & Klose [5 7 ABSTRACT components into the transportation while the lighter components are forced up the conical side wall. A

trigger mechanism opens the valve means to pass the lighter components through the common wall into the aspiration chamber while the centrifuge drum is spinning, closing the valve means when the rate at which the centrifuge drum is spinning falls below a desired level. An automatic sample loading mechanism is also provided which utilizes centrifugal forces to load a sample into the separation chamber of the centrifuge drum.

2 Claims, 4 Drawing Figures ASPIRATE AUTOMATIC SERUM PREPARATION STATION BACKGROUND OF THE INVENTION The present invention relates generally to centrifugal separation of liquids and more particularly to an apparatus for automatically separating the serum, or plasma, from a whole blood sample for subsequent biochemical analysis.

Reference may be made to the following U.S. pa-

tents: U.S. Pat. Nos. 3,586,484; 3,439,871; 3,228,595; 3,211,368; 3,190,547; 3,161,593; 3,129,175; 2,948,462; 2,940,662; 2,906,453; 2,906,452;

2,906,451; 2,906,450; 2,822,315; 2,822,126; 621,706; 436,419; 360,342 and 241,172.

The modern medical research and diagnosic tech niques in use today commonly rely on the analysis of blood samples. Whole blood, however, comprises a variety of immiscible components (e.g., the red cells, the white cells and the platelets) suspended in a colloidal serum, or plasma. Often, however, the analysis must be performed solely on the plasma so that the immiscible components are not present to alter or mask the characteristics to be observed.

In spite of the advent in recent years of many automatic and semiautomatic clinical chemistry analyzers, blood processing techniques have remained unchanged and time consuming. The present centrifugal separation technique commonly used for processing whole blood to serum or plasma (heparinized serum) requires the following steps:

1. Collecting a whole blood sample in a test tube;

2. removing the stopper from the test tube;

3. rimming the specimen with a stirring rod;

4. balancing the test tube (geometrically and symmetrically) in a centrifuge;

5. centrifuging the test tube for 10 minutes at a relative centrifugal force (RCF) of 850 to 1,000;

6. decanting or aspirating the serum into a serum container; and

7. transporting the serum to an analyzer station.

While this technique is commonly used to process blood samples, it requires approximately 30 minutes to process a single sample. Thus, this technique is illsuited for use in modern automated laboratories capable of analyzing up to 120 blood samples per hour.

Batch centrifuging has been utilized to process a plurality of blood samples simultaneously. However,

successive batches may not contain the same number of samples, and accordingly, the centrifuge should be rebalanced after each batch to prevent vibrations which might damage the centrifuge. Moreover, the

batch size (i.e., the number of samples in a batch) is limited because the plasma should be decanted or aspirated as soon as possible after the centrifuge is stopped, or the immiscible components will re-diffuse into the plasma.

Accordingly, complex mechanical devices have been devised to automatically separate the serum or plasma from whole blood. However, the systems heretofore devised liave generally been so mechanically complex and expensive that their use has been limited.

SUMMARY OF THE INVENTION According to the present invention, there is provided a centrifuge apparatus for centrifugally separating a sample mixture into its lighter and heavier components. The apparatus comprises a centrifugal drum having a separation chamber and an aspiration chamber positioned directly thereabove, the chambers being separated by a common wall having valve means connecting the separation chamber and the aspiration chamber. The separation chamber has a truncated conical side wall with a larger diameter trap portion located at the base thereof. A motor is provided for spinning the centrifuge drum to force the heavier components into the trap portion while the lighter components are forced up the conical side wall. A trigger mechanism opens the valve means to pass the lighter components through the common wall while the centrifuge drum is spinning. closing the valve means when the rate at which the centrifuge drum is spinning falls below a desired level.

The centrifuge apparatus further includes an automatic sample loading mechanism for loading a sample into the separation chamber of the centrifuge drum through an aperture in its bottom end. The automatic sample loading mechanism comprises a sample cup having an open top end corresponding to the aperture in the centrifuge drum for containing the sample to be loaded into the drum. A transport means selectively moves the centrifuge drum and the sample cup into juxtaposition during loading so that the open top end of the sample cup is coincident with the aperture in the bottom end of the centrifuge drum. When the sample cup is rotated by thespinning centrifuge drum, the sample flows from the sample cup into the centrifuge drum.

In accordance with one embodiment of the invention, a plurality of samples are simultaneously centrifugally separated into their components by an automatic centrifuging apparatus comprising a plurality of centrifuge units, each unit comprising a centrifugedrum and a motor for spinning the drum. Loading means are pro vided for sequentially loading'each of the drums with one of the samples and brake means for braking the drum to a stop after the sample therein has been centrifugally separated. One of the components is removed from the drum by an aspiration means, and the drum is then washed by wash means to remove any remaining sample from the drum. The centrifuge drum is then rinsed by rinse means and dried by a drying means. Means are provided for sequentially advancing each of the centrifuge units past the loading means, the brake means, the aspiration means, the wash means, the rinse means and the drying means to simultaneously process a plurality of samples.

BRIEF DESCRIPTION OF THE DRAWINGS The features of this invention which are believed to be novel are set forth with particularity in the appended claims. The invention together with its further objects and advantages thereof, may be best understood, however, by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements in the several figures and in which:

FIG. 1 is a perspective view of a centrifuge unit in accordance with a referred embodiment of the invention;

FIG. 2 is a sectional view of the centrifuge unit taken along lines 2-2 of FIG. 1 illustrating a method of loading a sample into the centrifuge drum of the centrifuge unit;

FIG. 3 is a detailed sectional view of the centrifuge drum taken along lines 2-2 of FIG. 1; and

FIG. 4 is a schematic representation of an automatic serum preparation apparatus utilizing a plurality of the centrifuge units shown in FIG. 1.

PREFERRED EMBODIMENT OF THE INVENTION In accordance with one embodiment of the present invention, the centrifuge unit shown in FIG. 1 includes a centrifuge drum for centrifuging whole blood to obtain plasma samples for biochemical analysis.

More particularly, thedrum 10 is mounted on a shaft 11, coincident with its longitudinal axis, and rotated at high speeds by ahydraulic motor 12 to centrifuge the blood sample, separating the packed red cells from the plasma.

A sample loading mechanism is positioned directly below thedrum 10 for automatically loading the whole blood into thedrum 10 for subsequent centrifugal separation. The loading mechanism comprises a substantiallycylindrical cup 13 removably mounted on ahorizontal plate 14 by means of ashaft 15 on the bottom ofcup 13 which is insertable into an aperture inplate 14. Further, an arrangement comprising several ball bearings (not shown) mounted in anannular sleeve 16 is interposed betweenplate 14 and the bottom ofcup 13. Accordingly,cup 13 is free to spin about its longitudinal axis (i.e., shaft 15). Moreover, the longitudinal axis ofcup 13 is aligned with the rotational axis (i.e., shaft 11) ofcentrifuge drum 10.

A pair ofair cylinders 17, positioned at opposite ends ofplate 14, are effective to vertically repositionplate 14 relative to the bottom ofcentrifuge drum 10 whenever compressed air is introduced, or released as the case may be, into the cylinders throughtubing 18. Consequently,cup 13 can be moved along its longitudinal axis until its open top end is coincident, or in juxtaposition, with a corresponding aperture 19 (not shown) in the bottom end of centrifuge drum l0.

Operationally, the blood sample is initially placed incup 13 for subsequent loading into thecentrifuge drum 10. The automatic loading feature of the present invention may be more readily understood by reference now to FIG. 2. Once the sample is placed therein,cup 13 is repositioned so that its open end is in juxtaposition with theaperture 19 in the bottom ofdrum 10. The top edge ofcup 13 is beveled to fit the correspondingly beveled edge ofaperture 19. Consequently, when the centrifuge drum is rotated while in juxtaposition withcup 13, thecup 13 is also rotated. A pair of alignment bars 20 (FIG. I) extend from base 21 and pass through corresponding apertures inplate 14 to prevent twisting.

When the drum l0 and thecup 13 are rotated at high speed about their common axis, the blood sample is subjected to powerful centrifugal forces which displace the blood, pressing it against the cylindrical wall of cup l3. Consequently, the blood is also subjected to lateral forces'resulting from the pressure developed between the blood sample and the wall. Accordingly, the sample, in effect,flows up the cylindrical wall and into thecentrifuge drum 10. Thus, whendrum 10 reaches a certain rotational speed, the entire sample, for all practical purposes, is loaded therein. While still spinning, thecup 13 is then dropped away fromaperture 14 by the loading mechansim. Becausedrum 10 is still spinning, however, the blood sample is pressed against the drums interior wall so that it can not escape throughaperture 19.

The interior features of thecentrifuge drum 10 are shown in FIG. 3. There, it may be seen that thecentrifuge drum 10 is divided into a pair of adjacent chambers, a separation chamber identified generally at 22 and an aspiration chamber identified generally at 23, separated by acommon wall 24. In addition toaperture 19 in the bottom ofseparation chamber 22, asimilar aperture 25 is provided in the top end of the aspiration, or pick-up,chamber 23. Thus, the shaft 11 is passed throughaperture 25 and is attached to the center ofcommon wall 24 by asuitable fastening arrangement 26.

The interior wall 27 ofseparation chamber 22 comprises three essentially distinct sections: 270 defining a truncated conical portion while 27b and 27c define a larger diameter trap portion, identified generally at 28, located at its base. During loading, the blood is initially forced into thetrap portion 28 where the heavier immisciblecellular components 29 are trapped. Even when the volume of blood loaded into theseparation chamber 22 exceeds the volume oftrap portion 28, the packed red cells are captured in thetrap 28 while the lighter plasma forms adistinct layer 30 interior to the packed red cells. By loading a precise amount of blood into theseparation chamber 22, it is insured the volume oftrap 28 is sufficient to contain the entire volume of packed red cells in the sample. Consequently, the same lateral forces resulting from centrifugation that were utilized to load the sample into theseparation chamber 22 will prevail to force the plasma up theconical wall portion 27a toward theaspiration chamber 23.

As previously mentioned, theseparation chamber 22 and theaspiration chamber 23 are separated by acommon wall 24. However, avalve orifice 31 is provided inwall 24 to connect the two chambers at a point near the juncture of theconical wall portion 27a and thecommon wall 24. During centrifuging, therefore, the plasma is forced into theaspiration chamber 23 while the heavy blood cells are retained in thetrap portion 28. At all other times, theorifice 31 is closed by avalve plug 32 insertable therein. Thus, if thecentrifuge drum 10 is stopped, the plasma cannot flow back into theseparation chamber 22 throughorifice 31.

More particularly, at a predetermined time during centrifuging, a trigger mechanism, comprising air cylin- -der 33,bar 34, and L-shaped rod 35 (FIG. 1) combine to remove theplug 32 from theorifice 31. In operation, theair cylinder 33, controlled by an influx of compressed air, forces bar 34 downward. The L-shapedrod 35, which passes through aguide slot 36 in thecommon wall 24, in turn, is effective to disengage theplug 32. Subsequently, when the trigger mechanism (i.e., air cylinder 33) is released just prior to the end of centrifuging, aspring 37 on shaft 1 l forces thebar 34 upward so that plug 32 seals theorifice 31, permanently separating the plasma from the packed red cells. Accordingly, when thecentrifuge drum 10 stops spinning, the plasma may be manually or automatically aspirated from the pick-upchamber 23 through theaperture 25. Abarrier 38 is also provided to contain the plasma within a limited area of the base ofaspiration chamber 23 after thedrum 10 stops spinning so that the plasma may be more easily aspirated.

The centrifuge unit of the present invention is especially well suited for adaptation to provide an automatic serum preparation apparatus, such as that shown schematically in FIG. 4. That is, because each centrifuge unit is virtually independent of the other units, several units may be combined to provide an automatic serum preparation unit for simultaneously processing several blood samples.

As shown in FIG. 4, a number of centrifuge units (i.e., 18) are mounted on a conveyor such ascircular plate 39 approximately 16 inches in diameter. Theplate 39, in turn, is sequentially rotated at a predetermined rate to various positions, or stations, by a step ping motor 40. Atinput station 41, acentrifuge unit 42 is centered over an automatic loading mechanism so that the cup containing the whole blood can be raised into juxtaposition with the centrifuge drum. Subsequently, the centrifuge motor spins the drum and the cup in the manner previously described, causing the sample to be loaded into the drum. Once the whole blood is loaded, the cup is dropped away, and the stepping motor 40 advances theplate 39, movingcentrifuge unit 42 to the next station- Accordingly, blood samples can be introduced into successive centrifuge units atasingle input station 41 by loading the sample into a unit and advancing theplate 39 so that the loaded unit is replaced by an empty unit.

As thecentrifuge 42 is advanced, the plasma and packed red cells are separated, and the plasma is isolated in the aspiration chamber of the drum. Subsequently, thecentrifuge unit 42 reachesbrake stop station 43 where the spinning drum is stopped. The stepping motor 40 next advances theunit 42 to theaspirate station 44 where aspiration of the plasma may be manually or automatically accomplished. Thecentrifuge unit 42 is then moved to the wash"station 45 where a soap solution is sprayed into both chambers of the drums, cleaning both of all traces of the blood sample. In turn, theunit 42 is advanced to the rinsestation 46 where both chambers are thoroughly rinsed, and finally, it is stepped through two successivedry stations 47 and 48 where the centrifuge drum is dried. After completion of this sequence, thecentrifuge unit 42, as well as successive centrifuge units, is ready to centrifuge a new sample; and thus, when it once again reachesinput station 41, it is loaded with a new blood sample.

Accordingly, there has been shown an automatic loading centrifuge unit which is adaptable for use in a batch processing automatic serum preparation arrangement. Because the plasma, or serum, is automatically separated from the whole blood and isolated in a pick-up chamber where the packed red cells cannot recombine with the plasma. there is less urgency for removing the plasma from the centrifuge. Further, less care need be taken in aspirating the plasma since only the plasma is separated into the pick-up chamber. if that were not the case, as in prior art systems, care would have to be exercised to insure that the end of the aspirating needle is not inserted too deeply into the plasma layer, aspirating the immiscible components as well as the plasma. Finally, the units relatively simple design maintains the cost of each unit at a minimal level, making it extremely attractive for use in hospitals and research laboratories.

While a particular embodiment of the present invention has been shown and described, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the invention in its broader aspects. Accordingly, the aim in the appended claims is to cover all such changes and modifications as may fall within. the true spirit and scope of the invention.

I claim:

1. An automatic centrifuging apparatus for simultaneously centrifuging a plurality of samples into their components, the apparatus comprising:

a plurality of centrifuge units, each unit comprising a centrifuge drum and a motor for spinning the drum;

loading means for sequentially loading each of the drums with one of the samples;

brake means for braking the drum after the sample therein has been centrifugally separated; aspiration means for removing one of the components from the centrifuge drum;

wash means for washing the centrifuge drum to remove any remaining sample tlherefrom;

rinse means for rinsing the centrifuge drum;

drying means for drying the centrifuge drum; and,

means for sequentially advancing each of the centrifuge units past the loading means, the brake means, the aspiration means, the wash means, the rinse means and the drying means to simultaneously process a plurality of the samples.

2. An automatic centrifuging apparatus in accordance with claim 1 wherein the means comprises a stepping motor driving a conveyor, the plurality of centrifuge units being mounted on the conveyor and sequentially advanced by the stepping motor.

Claims (2)

1. An automatic centrifuging apparatus for simultaneously centrifuging a plurality of samples into their components, the apparatus comprising: a plurality of centrifuge units, each unit comprising a centrifuge drum and a motor for spinning the drum; loading means for sequentially loading each of the drums with one of the samples; brake means for braking the drum after the sample therein has been centrifugally separated; aspiration means for removing one of the components from the centrifuge drum; wash means for washing the centrifuge drum to remove any remaining sample therefrom; rinse means for rinsing the centrifuge drum; drying means for drying the centrifuge drum; and, means for sequentially advancing each of the centrifuge units past the loading means, the brake means, the aspiration means, the wash means, the rinse means and the drying means to simultaneously process a plurality of the samples.

2. An automatic centrifuging apparatus in accordance with claim 1 wherein the means comprises a stepping motor driving a conveyor, the plurality of centrifuge units being mounted on the conveyor and Sequentially advanced by the stepping motor.

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