25 are described in U.S. Pat. Nos. 3,864,089, 3,873,217, 4,035,156, 4,225,558, 4,279,862 and 4,689,203.
sirable if the rotors were of unitary construction with SAMPLE METERING PORT FOR ANALYTICAL no separable or movable parts.
ROTOR HAVING OVERFLOW CHAMBER 2. Description of the Background Art
U.S. Pat. No. 4,284,602 describes a centrifugal rotor This patent application is a continuation-in-part of 5 which measures a predetermined amount of fluid by application Ser. No. 07/532,524 filed Jun. 4, 1990 now filling a measuring chamber with fluid under centrifugal U.S. Pat. No. 5,061,381 issued Oct. 29, 1991, the full force to a certain level, wherein an overflow passage disclosure of which is incorporated herein by reference. allows excess fluid to flow to an outlet. U.S. Pat. No.
4,876,203 describes a centrifugal rotor which measures BACKGROUND OF THE INVENTION J0 a predetermined quantity of fluid by filling a calibrated 1. Field of the Invention cell through a capillary duct from a storage chamber,
The present invention relates generally to apparatus *e excess fluid flowing from the calibrated cell through and methods for separating cellular material from bio- » second capillary duct to an overflow chamber. U.S logical fluids and, more particularly, to the design and Pat. No- 3,901,658 describes a centrifugal rotor which use of a centrifugal rotor which is capable of separating 15 measures predetermined volumes of blood by filling a plasma from a measured volume of whole blood and plurality of measuring chambers with blood under cenoptionally distributing the plasma to a plurality of test trifugal force' *•* excess blood .flowm8 .mt0TM wells within the rotor flow passageway when a certain centripetal level is
Blood tests frequently require that potentially-inter- reached U.S. Pat. No. 3,899,296 describes a centrifugal fering cellular components of the blood be separated 20 rotor wluch measures, a discrete volume of blood by from the blood plasma prior to testing of the plasma. It fflhng » passageway with blood under centrifugal force, is also frequently desirable to divide the separated blood therein «cess blood flows into an overflow chamber,
plasma into a plurality of discrete aliquots so that a **« 8 bal1 fcheck * ^d to„"?^the m * °f l,he faS" ;,„•,„ - .„»; „ „„„,„. „„,. „Jf„TM^j „„ sageway after it has been filled. Other centrifugal rotors
variety of tests or assays may be performed on the „ _f aj„^a ;„ Ttc n- i a^nao far* 117
blood. Such separation and division steps have heretofore been typically performed by centrifugation to separate the blood plasma from the cellular components, SUMMARY OF THE INVENTION followed by manual or Automated pipetting ofthe blood According t0 the present inve„tion, an improved plasma into separate test wells. Such procedures are 3Q ^a,^ roKtor of metering a discrete q^ntity labor intensive and time-consuming and various auto- of fluid rises £rotor ^ havi a le a lica. mated systems and methods have been proposed for ^ ^ which a flujd , whole Wood providing multiple aliquots of plasma suitable for test- can ^ mtroduced without prior measurement by the mg in a more efficient manner. human operator Connected to the sample application
Of particular interest to the present invention are 35 are a metering chamber and an overflow chamber,
centrifugal rotors which have been modified both to ^ configured t0 permit a capillary flow of fluid from
separate plasma from whole blood and to distribute the the appncation p^. By configuring the cham
separated plasma into separate test wells. The use of ^rs t0 provide a higher flow rate of fluid from the
such rotors can provide a plurality of discrete plasma appiication port into the metering chamber than
volumes which may be tested or evaluated, all present 40 from the sample ... port into the overflow
within the centrifugal rotor, greatly enhancing the effi- chamber, the metering chamber will preferentially be
ciency of automated testing procedures. fiUed. Alternatively, flow into the overflow chamber
Although a significant improvement over prior man- Can be initially blocked, e.g., by preventing venting of
ual or partly manual procedures, previous modified the overflow chamber, to permit complete filling of the
centrifugal rotors have suffered from a number of defi- 45 metering chamber prior to flow of excess fluid into the
ciencies. Such rotors have frequently required the appli- overflow chamber.
cation of relatively large volumes of whole blood in in a flrst exemplary embodiment, the portion of the order to achieve the desired separation and distribution. metering chamber which connects to the sample appliMoreover, such rotors have frequently utilized complex cation port is of larger cross-sectional flow area than the designs which are difficult and costly to manufacture. 50 cross-sectional flow area of the region connecting the Often, the rotors require various separable parts or overflow chamber to the sample application port, causcomponents which are brought together or separated at ing fluid to flow more rapidly into the metering chamdifferent points in the centrifugation procedure. Previ- ber than into the overflow chamber Thus, the metering ous centrifugal rotors have often required the user to chamber will fill entirely with fluid and excess will manually measure a volume of sample prior to applying 55 continue to flow into the overflow chamber. In a seethe sample to the rotor. The need to manually measure ond exemplary embodiment, a vent is provided in each the sample volume can significantly decrease the effi- of the overflow chamber and the metering chamber, ciency of an otherwise automated process. When fluid is introduced into the sample application For these reasons, it would be desirable to provide port, the vent in the metering chamber is open, while improved centrifugal rotors and methods suitable for 60 the vent in the overflow chamber is closed, causing the separating blood into plasma and cellular components fluid to flow only into the metering chamber. Once the and for further distributing the separated plasma into a metering chamber is filled, the vent in the overflow plurality of discrete test wells within the rotors. The chamber is opened, causing any remaining fluid in the rotors and methods should be capable of metering pre- sample application port to flow into the overflow chamcise quantities of blood without requiring the user to 65 ber.
premeasure the volume being applied to the rotor. The In a specific aspect of the present invention, the me
rotor design should be simple and amenable to low-cost tering chamber is provided with an indicator which
manufacturing procedures, and it would be further de- indicates that the metering chamber is filled with fluid.