US3850369A

US3850369A - Centrifuge for preparing platelet rich plasma

Info

Publication number: US3850369A
Application number: US00339403A
Authority: US
Inventors: B Bull; O Proni; L Melnick
Original assignee: Coulter Electronics Inc
Current assignee: Coulter Electronics Inc
Priority date: 1973-03-08
Filing date: 1973-03-08
Publication date: 1974-11-26
Anticipated expiration: 1991-11-26
Also published as: GB1449362A; CA992933A; IT1051572B; FR2220314B1; DE2410720A1; JPS49120267A; FR2220314A1; NL7402862A

Abstract

A centrifuge for production of platelet rich plasma by accelerated sedimentation of whole blood. The centrifuge is adapted to apply greater than gravity force laterally, that is, approximately perpendicular, to the long axis of a thin cylindrical container partially filled with whole blood. The centrifuge includes cam actuated timer means cyclically operating a centrifuge head in which the cylindrical containers are held. Drive means are provided to rotate the head and said timer means includes means controlling the coupling of said drive means with said head whereby said head is driven for a predetermined duration, the drive means deenergized and the head is uncoupled therefrom to a free rotational state during which a gradual slowdown is effected to permit the vertically oriented column of blood to return from the side of the container to the bottom smoothly and with mixing within the plasma and cell layers but not between the two layers. Also provided are alarm means for indicating the expiration of a predetermined time during which the head is at rest so as to enable the operator to be certain sufficient time has elapsed to accomplish the required degree of sedimentation.

Description

United States Patent [191 Bull et al.

[4 1 Nov. 26, 1974 CENTRIFUGE FOR PREPARING PLATELET RlCH PLASMA [75] Inventors: Brian S. Bull, Loma Linda, Calif; Oscar Proni, Hollywood; Loran V. Melnick, Miami, both of Fla.

[73] Assignee: Coulter Electronics, Inc., Hialeah,

Fla.

[22] Filed: Mar. 8, 1973 [21] Appl. No.: 339,403

Primary ExaminerGeorge H. Krizmanich Attorney, Agent, or Firm-Silverman & Cass, Ltd.

[57] ABSTRACT A centrifuge for production of platelet rich plasma by accelerated sedimentation of whole blood. The centrifuge is adapted to apply greater than gravity force laterally, that is, approximately perpendicular, to the long axis of a thin cylindrical container partially filled with whole blood. The centrifuge includes cam actuated timer means cyclically operating a centrifuge head in which the cylindrical containers are held. Drive means are provided to rotate the head and said timer means includes means controlling the coupling of said drive means with said head whereby said head is driven for a predetermined duration, the drive means deenergized and the head is uncoupled therefrom to a free rotational state during which a gradual slowdown is effected to permit the vertically oriented column of blood to return from the side of the container to the bottom smoothly and with mixing within the plasma and cell layers but not between the two layers. Also provided are alarm means for indicating the expiration of a predetermined time during which the head is at rest so as to enable the operator to be certain sufficient time has elapsed to accomplish the required degree of sedimentation.

10 Claims, 9 Drawing Figures PAIENIE HEW 2 51974 sum 30F 53 CENTRIFUGE FOR PREPARING PLATELET RICH PLASMA FIELD OF THE INVENTION This invention relates generally to centrifugal separation of whole blood fractions and more particularly, concerns the provision of an improved centrifuge apparatus for rapid production of platelet rich plasma from whole blood samples.

CROSS REFERENCE TO RELATED APPLICATIONS The centrifugal augmentation of rouleaux formation of whole blood is discussed and apparatus provided in co-pending US. Pat. Applications Ser. Nos. 191,886 and 191,768, both filed on Oct. 22, 1971 and assigned to assignee of this application.

BACKGROUND OF THE INVENTION The enumeration of platelets in a specified quantity of whole blood, usually a cubic millimeter, is a clinical procedure, the result of which is of great diagnostic utility. A common method for counting platelets employs dilution of a whole blood sample with diluents which lyse or destroy the red cell component, permitting microscopic enumeration of the remaining platelets. Electronic particle counters, which have a substantially lower coefficient of variation than visual counting methods have been employed in platelet counting methodology, the coefficient of variation being about 4 percent compared with about 16 percent for conventional manual counting procedures. Further, less time is required for performance of the enumeration.

Such electronic particle counting methods require prior separation of whole blood into platelet rich plasma and a sediment consisting of red and white blood cells. As commonly performed, the technique requires sedimentation of a specimen of anticoagulated blood, withdrawal of a specific quantity of the supernatant plasma, high dilution in the region of 13000, followed by actual counting. The processes employed in sedimentation of the whole blood sample conventionally in common are time consuming, requiring at least ten minutes and sometimes as long as thirty minutes per sample. Further, filling the small bore plastic tubes ordinarily employed to provide microliter samples, requires considerable manual dexterity.

As reported by Brian S. Bull in American Journal of Clinical Pathology, Volume 54, Number 5, November 1970, pages 707-710; it is known to perform the separation of platelet rich plasma from whole blood by augmentation of rouleaux formation followed by a period of normal sedimentation. Rouleaux may be described as red cell agglomerates or stacks. One method employs anticoagulated blood collected in a X 75 mm test tube to be centrifuged at 40 times G for 25 seconds with the test tube held vertically so that the amount of sample in the tube does not change the effective rotation radius of the supernatant plasma. This short spin or rotation produces rouleaux and is followed by a 1 to 2 minute period of gravity or G sedimentation to produce a column of plasma in which there is no layering of platelets.

A small table top centrifuge has been modified to permit this procedure with the governor thereof adjusted so that the centrifuge rotates at approximately 1,000 rpm.

Test tubes 12 X mm are inserted into the head and fixed in a vertical position so as to function as holders for the smaller bore, 10 X 75 mm sample containing tubes.

Centrifugation at low gravity force is known as an alternative method of specimen preparation involving the use of a large angle head centrifuge for this purpose. Attempts to reproduce this approach using a small centrifuge have not been successful. The platelet rich plasma produced in the small angle head centrifuge shows marked overall loss of platelets into the erythrocyte column as well as layering of platelets immediately over the buffy coat. This unequal distribution of platelets in the plasma column results in platelet counts that vary from normal to as much as 40 percent low depending on the height at which the plasma column is sampled. Plasma prepared in a swinging bucket, tabletop centrifuge shows far less layering and samples recovered from the upper third of the plasma column provide counts that compare favorably with those in plasma separated from the same blood sample by normal sedimentation methods. Because the centrifugal force on the plasma column varies appreciably with the amount of blood in the sample tube, great care has to be exercised to provide identical amounts of blood in all tubes. This requirement plus the possibility of taking the sample at too great a depth from the plasma column makes the method unsatisfactory as a routine clinical procedure.

It would be advantageous to provide a centrifuge apparatus which is particularly adapted to the production of platelet rich plasma by centrifugal augmentation of sedimentation. This requires a relatively simple structure having timing means particularly adapted for requirements of the desired method of centrifugal augmentation, and which is reliable, repetitive and economical.

SUMMARY OF THE INVENTION A centrifuge device for obtaining platelet rich plasma from whole blood samples is provided comprising a centrifuge head and a motor, the centrifuge head carrying multiple sample tubes in holders arranged to orient the samples substantially parallel to the rotational axis of the centrifuge head, the sample containers being inclined inwardly toward the rotational axis of the centrifuge head at an angle between 70 and to the vertical so as to render closure of the tube unnecessary. Transfer means are connected between the motor and the centrifuge head for effecting rotation of the same sufficient to exert greater than gravity force laterally to the long axis of said sample containers. Means are provided for effecting gradual slow down of the centrifuge head after the motor has been deenergized. Timing means are provided operable upon the motor and transfer means for operating the centrifuge head in timed cycles. Alarm means also operated by said timing means are provided for permitting ready ascertainment of the completion and/or non-completion of the sedimentation process.

The timing means provided includes plural switch means, cam means arranged to operate the plural switch means in a predetermined cycle, means for stopping the driven rotation of the centrifuge head substantially instantly with the deenergization of the motor.

and means for effecting the gradual slowdown of the centrifuge head subsequent to deenergization of said motor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the centrifuge device constructed in accordance with the invention.

FIG. 2 is a partially exploded perspective view of the centrifuge device illustrated in FIG. 1, the cover removed to show interior construction.

FIG. 3 is a top plan view section taken along lines 3-3 of FIG. 2.

FIG. 4 is a sectional view of the centrifuge taken along lines 4-4 of FIG. 3 in the direction indicated.

FIG. 5 is a sectional view of the centrifuge taken along lines 55 of FIG. 3 in the direction indicated.

FIG. 6 is an enlarged detail of the spinner arrangement utilized in the centrifuge of FIG. 1 illustrated in vertical sectional representation.

FIG. 7 is a sectional view taken along lines 7--7 of FIG. 6, in the direction indicated.

FIG. 8 is a fragmentary perspective view of the centrifuge head and spinner arrangement illustrating the operation of the clutch means provided in accordance with the invention.

FIG. 9 is a schematic representation of the electrical circuit utilized to operate the centrifuge of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT The centrifuge apparatus provided by the invention for production of platelet rich plasma from whole blood particularly is adapted for the performance of a method for such plasma production which capitalizes upon the fact that whole blood, if permitted to stand in a vertically oriented container such as a test tube, will separate into two layers. The upper layer comprises a layer of platelet rich plasma containing some of the white cells present in the original sample. The lower layer is a layer of red cells in stacked formations known to the art as rouleaux which contain the re mainder of the white cells and a small amount of the plasma of the original whole blood sample.

Three phases are known to occur during the sedimentation of whole blood. The first is characterized as the rouleaux formation. This phase occupies the first few minutes subsequent to filling the container with sample. Following this first phase, the phase of maximum sedimentation occurs, wherein after about three to five minutes, the red cell rouleaux reach the maximum velocity of fall. When whole blood enters this last mentioned phase, the separation process and hence the production of platelet rich plasma per unit time is optimal. If it is possible to augment rouleaux formation and subsequently allow a period of sedimentation, then adequate platelet rich plasma to permit platelet counting can be produced rapidly. A method of rouleaux augmentation involves the application of greater than gravity force laterally to a long thin container vertically arranged and partially filled with whole blood.

According to the invention, there is a provided a centrifuge capable of delivering a force in the range of G. for a period of less than one minute in duration in a lateral direction relative to a long thin container which is only partially filled with whole blood. The laterally applied force acts to pack the red cells into rouleaux and to express from between the rouleaux a certain amount of platelet rich plasma, the amount varying with the hematocrit of the whole'blood sample under test. Subsequent to the formation of rouleaux, the centrifugal force is lessened gradually so that the substantially vertical oriented layers of platelet rich plasma and the red cells are permitted to slide down to the bottom of the test tube where minimal mixing occurs. but with out disruption of the rouleaux. The centrifuge. in accordance with the invention, provides for a period of rest so that normal sedimentation under I G. force is permitted, which in general will produce adequate platelet rich plasma within a shortlength of time subsequent to the augmentation of the rouleaux formation.

Generally, the red cell sedimentation has been accelerated by the greater of the gravity force applied during the initial phases of sedimentation in order to decrease the time required to form red cell rouleaux. Subsequently, the blood sample is remixed gently to obviate any inequality or layering of platelets within the plasma layer and is permitted then to sediment. Since the blood is now in a state where platelet rich plasma will be produced with a maximum efficiency, a brief period sometimes less than two minutes is all that is required to produce adequate platelet rich plasma for counting purposes.

Referring now to the drawings, in FIG. 1 there is illustrated a centrifuge device constructed in accordance with the invention and generally designated by reference character 10. The centrifuge device 10 includes a centrifuge head assembly 12 mounted for rotation at high speed, housing 14 containing drive means for the centrifuge head assembly, timer means and the other operating components of the centrifuge 10.

The centrifuge head assembly includes a centrifuge head formed of a pair of

discs

16 and 18 coaxially mounted to a central shaft 20 in spaced apart relation. A plurality of top opening cylindrical tube holders 22 are secured to the lower disc 18 symmetrically about the circumference thereof. Each tube holder 22 has a protrusion 24 axially depending from the bottom wall 26 thereof so as to be received tightly in suitable openings 28 formed in the disc 18. (FIG. 8) Each holder 22 includes an interior groove 30 in which an O-ring gasket 32 is seated. The upper disc 16 has passageways 34 formed therein about the circumference thereof. Each of the passageways 34 is arranged for alignment with a respective holder 22, with its center offset inwardly relative to the axis of the matching holder 22. The openings 28 have a diameter sufficient to accommodate loosely small test tubes 36 which are seated in the tube holders 22, the O-ring gasket 32 engaging the tubes 36 close to the bottom ends thereof. Tubes 36 are adapted to be partially filled with anticoagulated whole blood sample.

When the

discs

16 and 18 are assembled to the shaft 20, the openings 28 are aligned with the open ends of the tube holders 22, so that when the test tubes 36 are passed through openings 28 with their closed bottom ends seated in tube holders 22, the vertical axis of each of the tubes 36 is inclined at an angle of between inward toward the rotational axis of the centrifuge head assembly 12 so as to render closure of the sample tubes unnecessary as will be described hereinafter.

The housing 14 is formed of a U-shaped cover 40 having a top panel 42 and a pair of opposite side panels 44. A front panel 46 is provided with

suitable openings

48,50,52 and S4 to provide for passage of operating levers 56,58 and 60 and a window for a pilot or indicating lamp 62. Lever 56 operates an on-off switch to momentarily initially energize the timer means, lever 58 operates an on-off switch to energize the buzzer circuit and lever 60 operates an on-off switch controlling the power to the centrifuge device 10. The purpose of indicating lamp 62 shall be discussed hereinafter.

Within the housing and secured thereto are a pair of

platforms

64 and 66. Platform 64 includes an upstanding front wall 70 and upstanding rear wall or panel 72. The upper platform 66 includes a pair of right angle flanges or lugs 74 at the front comers thereof and an upstanding rear flange 76. The platform 66 is secured to the front wall 70 by suitable fastening means such as screws 78. The platform 66 has a rear extension 80 arranged to be fastened by suitable bolt means 82 to the right angle inwardly extending lug 84 at the upper edge of rear panel 72. The upper platform 66 also referred to as an upper chassis 66 carries on the top surface thereof, the timing means and primary switch means associated therewith, as well as means for transferring rotary motion from the motor to the centrifuge head assembly 12. The motors operating the drive and the timing means respectively are secured to the undersurface of the platform 66 by suitable fastening means such as including nut and bolt means 86 and nut and bolt means 86'. The lower chassis or platform 64 has mounted thereto, the master switch means 88 and alarm means, here in the form of buzzer means 90. The electrical connection to the line is made at socket 92 which is mounted to the rear panel 72 of lower chassis 64 while the operating on-off switches are arranged mounted to the front wall of chassis 64. A notch 94 is provided opening to one edge of the platform 66 to permit passage of necessary electrical leads between the

platforms

66 and 64.

The drive means for centrifuge device comprises a dc. drive motor 96 which has a driven shaft 98. Driven shaft 98 carries drive pulley 100 having circumferential groove 102. A support bracket 104 is mounted to the platform 66. The bracket 104 includes a horizontally disposed flange 106, the flange having a passage 108 to accommodate driven shaft 112 therethrough. Driven pulley wheel 114 is mounted on shaft 112 between the flange 106 and the platform 66 and includes a depending conical bearing 116 coaxially arranged on the undersurface thereof, and a mounting center post 118. Cylindrical tubular collar 120 is secured to bracket flange 106 through passage 108 with integral flange 122 thereof seated upon the undersurface of said flange 106. Collar 120 functions as journal means for the shaft 112. The driven pulley wheel 114 carries circumferential groove 115 which is aligned horizontally with groove 102 of pulley 100. An endless belt 124 drivingly links the drive pulley 100 with the driven pulley 114 by virtue of seating within

grooves

102 and 115.

The timer means provided by the invention for operating the centrifuge device 10 in accordance with a predetermined timed cycle, comprises a cam member 126, a timer motor 128, including gear reduction means 130, contact switches 132, 134 and 136 operating master switch means 88 and the buzzer means 90.

Contact switch 132 includes contact arm 138 having a rolling contact member 140 engaged on the outer circumferential edge of the central circular cam 142 of cam member 126. Contact switch 132 normally is closed and controls the operation of the drive motor 96. Circular cam 142 has a notch 143, including drop- ,off 145 and inclined surface 147.

Contact switch 134 functions as the timer motor control and includes a switch arm 144 having a roller contact in engagement with one corner 148 of the lower cam block 150 of cam 126. Closure of switch 134 deenergizes the timer motor 128.

Switch 136 controls the operation of the buzzer means 90. Switch 136 includes a switch arm 152 having a roller 154 disposed in the path of corner 156 of the upper cam block 158 of cam member 126. Block 158 is of generally rectangular configuration, but has a diagonal side surface 160, one comer 156 of which is arranged to intercept the roller 154 causing the switch am 152 to close switch 136. Closure of the switch 136 energizes the buzzer means 90.

According to the invention, spinner means 162 are provided to mount the driven shaft 112 to the centrifuge head assembly. Spinner means 162 comprises a cylindrical hub 164 having an axial bore 166 of diameter selected to enable telescopic engagement, frictionally, with the driven shaft 112, suitable means such as Allen nuts being utilized to maintain the assembly and yet permit selective disengagement when desired. A pair of spaced like

circular discs

168 and 170 are arranged coaxially at one end of the hub 164, flush with one end of said hub 164. A pair each of

pins

172 and 174 are fastened between the

discs

168 and 170. Pins 172 are disposed diametrically opposite each other along a line taken through the rotational axis of hub 164. Pins 174 likewise are disposed diametrically opposite one another along a line also intersecting the axis of said hub 164. In this manner a pin 172 is associated with a pin 174 in pairs on opposite sides of the hub 164, each of said

pins

172 and 174 being spaced inwardly of the circumferential edges of the matched

discs

168 and 170.

Band springs 176 each having a loop 178 at one end thereof are joumalled for free rotation on pins 172 and between the hub 164 and the pins 174. The springs 176 accordingly can move between the shaft 164 and the pins 174 so that the free ends 180 are movable to a position outwardly extending from' the circumferential edge of the

spinner discs

168 and 170 and each hearing at its approximate midportion against a respective pin 174. On rotation of the spinner means 162 in the direction of the arrow 182, the springs 176 are forced outward from the spinner 162 to their broken line position shown in FIG. 7.

The lower disc 18 carries a pair of diametrically spaced depending pins 184, which are arranged so as to intercept and engage the springs 176 when the springs 176 are in their outwardly extending or broken line position on initiation of rotation of the spinner means 162 whereby to drive the centrifuge head assembly. The lower disc 18 of the centrifuge head 12 also carries an axial socket 186 opening downwardly. Ball bearing assembly 188 is mounted tightly within said socket 186 which assembly 188 includes a central passage 190 capable of receiving the hub 164 of spinner means 162 so that the centrifuge head 12 is rotatable freely on hub 164 of the spinner means 162.

As earlier stated, spinner means 162 is fastened securely to the driven shaft 112 and rotates therewith. On

rotation of the spinner means 162, in the direction of arrow 182 the springs 176 are directed outwardly of hub 164 by centrifugal force so as to intercept the depending pins 184, driving the centrifuge head assembly 12. When the rotation of the driven shaft 112 is stopped, rotation of spinner means 162 ceases. However, the rotation of the centrifuge head assembly 12 does not stop, since it is freely rotatable on hub 164 by virtue of bearing means 186. The pins 184 simply continue to rotate engaging the springs 176 and causing same to be driven inward toward the hub 164. The centrifuge head assembly therefore is permitted gradually to slow down until it is at rest.

In operation of the centrifuge apparatus in accordance with the desired method, the blood samples are introduced into the test tubes 36 partially to fill same. The tubes then are deposited each in a respective one of openings 34 to seat in respective holders 22. Because the openings 34 are off-set inwardly of the axis of rotation of head assembly 12 as compared with the position of the matching holder 22, the test tubes are inclined with their upper ends inwardly directed toward the axis of rotation of the centrifuge head assembly 12, closure of the upper ends of the tubes 36 is not required and spillage will not occur. The centrifuge head assembly is rotated to apply about 35 G force laterally to the long axis of tubes 36. The time period duration for application of such high 6 force is less than one minute, preferably from 10 to 15 seconds. As will be seen in the foregoing table, the total elapsed time of the procedure is about 300 seconds.

The operation of the centrifuge apparatus 10 now will be described with reference to the foregoing table and the circuitry illustrated in FIG. 9.

After the partially filled test tubes 36 have been introduced into the head 12 the power lever and the buzzer lever 58 are depressed closing switches 200 and 202 respectively. The start lever 56 then is depressed momentarily closing switch 204, energizing the timer motor 128 causing the cam 126 to rotate in the direction of the arrow 127. With the momentary closure of switch 204, the spinner drive motor 96 is energized by closure of normally open switch 206. The energization of spinner motor 96 causes the drive pulley 100 to rotate, said rotation being transmitted simultaneously by belt 124 to the driven pulley 114, driving the spinner shaft 112 to rotate the spinner means 162. Rotation of the spinner means 162 directs the springs 176 outwardly intercepting the posts 184 of the centrifuge head assembly 12 causing same to rotate.

1n the meantime, rotation of the cam 126 causes the switch 132 to be open by the dropping of roller from the circumferential edge of the circular cam 142 at drop-off 145. Opening of switch 132 continues the spinner motor operation until the cam member 126 has rotated sufficiently so that the roller 140 of spring arm 138 has moved along inclined surface 147 to place the circumferential edge 142 in contact with the roller 140 of spring arm 138, closing switch 132 and deenergizing the spinner motor 96.

When the spinner motor 96 is deenergized. the pulley 100 ceases its rotation and, because of the linkage by belt 124, the cessation is transmitted immediately to driven pulley 114 so that rotation of the spinner means 162 ceases. However, the centrifuge head assembly 12 continues to rotate freely at a gradually diminishing rate until rotation ceases.

ln the meantime, the cam member 126 continues to rotate. After an elapsed time required for the centrifuge head assembly 12 gradually to come to rest. the corner 156 of cam block 158 intercepts the buzzer switch 136 to close same causing the buyer to operate for a short period of time. Now the operator is alerted to the fact that the natural sedimentation stage is soon to be completed. After a short time lapse, one corner of block 150 intercepts the roller 146 of switch arm 144 closing switch 134, thereby deenergizing the timer motor 128 and, at the same time, comer 156 passes roller 154 to release arm 152 opening switch 136 to deenergize the buzzer means 90. The natural sedimentation has been completed at this time and the test tubes 36 may be removed and the supernatant platelet rich plasma siphoned or otherwise removed by conventional means.

The centrifugation can be varied simply by varying the length of the inclined surface 147 of notch 143 in the circular cam 142. The duration of the gradual slow down and rest period required to assure sufficient time for natural sedimentation to follow the period of augmentation of rouleaux formation can be varied simply by varying the circumference of said portion 142 and the location and dimensions of cam block 150. The timing is controlled by the cam member 126 with the

cams

142, 150 and 158 operating upon their

respective switches

132, 134 and 136 as described. The transmission of driven rotation from the spinner to the centrifuge head assembly 12 is accomplished by means of the springs 176 engaging the posts 184, so long as the spinner means 162 rotates. When rotation ceases the springs are forced out of their driving intercepting condition by continued rotation of the centrifuge head as sembly freely.

The pins 174 limit outward movement of the springs 176 and, also function to provide a stop against which the springs 176 can bear so that when the pins 176 engage the posts 184, the posts are driven with the rotation of the spinner means 162. The use of a pair of springs 176 permits balancing of the loads placed upon springs 176 and reduces the shock produced by the engagement of the springs 176 with the posts or pins 184 on initiation of rotation of said spinner means 162.

Indicator lamp 62 is provided connected across the timer motor 128 and is energized so long as said timer motor is energized. While the indicator lamp 62 is energized, the sedimentation process is incomplete. When extinguished at the terminus of the cycle by operation of switch 134, settling has been completed, the tubes 38 removed and the platelet rich plasma decanted.

As can be noted from the description hereinabove, the centrifuge device 10 is a relatively economical assembly of readily available components with equally economic timing means provided. The assembly is compact and highly suitable for the production of a platelet rich plasma fraction from whole blood samples in accordance with the desired method of augmenting rouleaux formation at its inception by centrifugation, that is the application of high G force laterally to vertically arranged columns of the whole blood sample. The test tubes 36 which hold the sample are passed through openings 34 and seated in holders 22. On the driven rotation of the centrifuge head assembly and for a considerable duration of the free rotation of said head assembly, the plasma and red cell layers will be held against the outwardly facing inner wall of the respective test tube 36 is a desired vertically oriented arrangement except for their inclination at angles between 70 and 90 from vertical, directed inwardly, their upper ends pointing toward the rotational axis of the centrifuge head assembly 12 so that spillage is avoided.

It is feasible to utilize holders 22 and openings 34 of diametric dimensions sufficient to receive test tubes of slightly larger diameter than tubes 36. Thus, tubes 12 X 75 mm may be set on the head 12 while the tubes 36, being X 75 mm may be seated within the larger tubes. Also, it is likewise feasible to construct the shaft so that the disc 16 is seated thereon closer to disc 18. In such instance, the openings 34 are spaced closer to the circumferential edge of the disc 16 so as to maintain the desired inclination of the tubes 36 at the lower position of disc 16 relative to disc 18. In the lower position, an effective guage or measure thus is provided to aid the operator in visibly determining and maintaining the level to which the tubes 36 can be filled without exceeding the level which could result in spillage during centrifugation, notwithstanding the angle of inclination.

We claim:

1. A centrifuge device comprising a centrifuge head mounted for rotation, sample holder means arranged on said centrifuge head for receiving at least one elongate sample container on the circumference of said centrifuge head, each sample container having an open end and being oriented on said centrifuge head with its open end closer to the rotational axis of said centrifuge head and such that the long axis of said container intersects a plane normal to said rotational axis at an angle between approximately 70 and 90, drive means including a drive motor, for rotating said centrifuge head, timing means operative on said drive means for rotating said centrifuge head in timed cycles and said drive means including spinner means coaxially mounting said centrifuge head to enable free rotation of said centrifuge head, said spinner means having engaging means mounted thereon and said centrifuge head having depending post means arranged to be engaged by said engaging means to drive said centrifuge head only when the spinner means is rotated and to be released therefrom when rotation of said spinner means ceases, means to effect cessation of rotation of said spinner means immediately upon de-energization of said drive motor whereby to permit free rotation of said centrifuge head on a gradually diminishing rate to assume a rest condition.

2. The centrifuge device as claimed in claim 1 in which said means to effect cessation of rotation of said spinner means comprises, first pulley means coupled to said drive motor and arranged to be driven thereby. second pulley means coupled to said spinner means.

means for transmitting rotational drive between said first and second pulley means to enable said pulleys to operate substantially simultaneously whereby said spinner means stops substantially instantaneously with deenergization of said drive motor.

3. A centrifuge device comprising a centrifuge head mounted for rotation, sample holder means arranged on said centrifuge head for receiving at least one elongate sample container on the circumference of said centrifuge head, each sample container having an open end and being oriented on said centrifuge head with its open end closer to the rotational axis of said centrifuge head and such that the long axis of said centrifuge head and such that the long axis of said container intersects a plane normal to said rotational axis at an angle be tween approximately and drive means including a drive motor, for rotating said centrifuge head, timing means operative on said drive means for rotating said centrifuge head in timed cycles and means for enabling gradual diminishing of the rotation of said centrifuge head to a rest condition upon deenergization of said motor, said drive means includes spinner means arranged to drive said centrifuge head. first pulley means coupled to said drive motor and arranged to be driven thereby, second pulley means coupled to said spinner means, means for transmitting rotational drive between said first and second pulley means to enable said pulleys to operate substantially simultaneously whereby said spinner means stops substantially instantaneously with deenergization of said drive motor, and said spinner means includes spring means mounted for rotation therewith to place end portions thereof extending outwardly of said spinner means on rotation thereof, and said centrifuge head includes depending posts arranged in the rotational path of said spring means whereby to be drivingly engaged thereby on rotation of said spinner means, said spring means capable of being driven by said depending posts inwardly out of said intercepting path with said depending posts when said spinner means ceases rotation, thereby permitting said centrifuge head gradually to diminish its rotation to assume a rest condition on deenergization of said drive motor.

4. The centrifuge device as claimed in claim 1 in which said timing means includes a timer motor, first switch means operative on said drive motor, second switch means operative on said timer motor and cam means coupled to said timer motor and operative successively on said first and second switch means whereby to energize said drive motor for a predetermined time duration thereafter to deenergize said drive motor and thereafter to deenergize said timer motor.

5. The centrifuge device as claimed in claim 4; and alarm means for indicating an elapsed time duration, third switch means operative to energize said alarm means immediately subsequent to expiration of said elapsed time duration and said cam means also being coupled to said third switch means to operate same on expiration of said time duration.

6. The centrifuge device as claimed in claim 5 in which said alarm means comprises audible buzzer means.

7. The centrifuge device as claimed in claim 5 and indicator lamp means operable until the expiration of said elasped time duration and coupled to said third switch means for deenergization on closing of said third switch means.

about 35 G to each sample container in a direction traversely of the long axis of said container for a time period duration less than one minute.

10. The centrifuge device as claimed in claim 1 in which the sample container is adapted to be filled partially with whole blood.

Claims

1. A centrifuge device comprising a centrifuge head mounted for rotation, sample holder means arranged on said centrifuge head for receiving at least one elongate sample container on the circumference of said centrifuge head, each sample container having an open end and being oriented on said centrifuge head with its open end closer to the rotational axis of said centrifuge head and such that the long axis of said container intersects a plane normal to said rotational axis at an angle between approximately 70* and 90*, drive means including a drive motor, for rotating said centrifuge head, timing means operative on said drive means for rotating said centrifuge head in timed cycles and said drive means including spinner means coaxially mounting said centrifuge head to enable free rotation of said centrifuge head, said spinner means having engaging means mounted thereon and said centrifuge head having depending post means arranged to be engaged by said engaging means to drive said centrifuge head only when the spinner means is rotated and to be released therefrom when rotation of said spinner means ceases, means to effect cessation of rotation of said spinner means immediately upon de-energization of said drive motor whereby to permit free rotation of said centrifuge head on a gradually diminishing rate to assume a rEst condition.

2. The centrifuge device as claimed in claim 1 in which said means to effect cessation of rotation of said spinner means comprises, first pulley means coupled to said drive motor and arranged to be driven thereby, second pulley means coupled to said spinner means, means for transmitting rotational drive between said first and second pulley means to enable said pulleys to operate substantially simultaneously whereby said spinner means stops substantially instantaneously with deenergization of said drive motor.

3. A centrifuge device comprising a centrifuge head mounted for rotation, sample holder means arranged on said centrifuge head for receiving at least one elongate sample container on the circumference of said centrifuge head, each sample container having an open end and being oriented on said centrifuge head with its open end closer to the rotational axis of said centrifuge head and such that the long axis of said centrifuge head and such that the long axis of said container intersects a plane normal to said rotational axis at an angle between approximately 70* and 90*, drive means including a drive motor, for rotating said centrifuge head, timing means operative on said drive means for rotating said centrifuge head in timed cycles and means for enabling gradual diminishing of the rotation of said centrifuge head to a rest condition upon deenergization of said motor, said drive means includes spinner means arranged to drive said centrifuge head, first pulley means coupled to said drive motor and arranged to be driven thereby, second pulley means coupled to said spinner means, means for transmitting rotational drive between said first and second pulley means to enable said pulleys to operate substantially simultaneously whereby said spinner means stops substantially instantaneously with deenergization of said drive motor, and said spinner means includes spring means mounted for rotation therewith to place end portions thereof extending outwardly of said spinner means on rotation thereof, and said centrifuge head includes depending posts arranged in the rotational path of said spring means whereby to be drivingly engaged thereby on rotation of said spinner means, said spring means capable of being driven by said depending posts inwardly out of said intercepting path with said depending posts when said spinner means ceases rotation, thereby permitting said centrifuge head gradually to diminish its rotation to assume a rest condition on deenergization of said drive motor.

5. The centrifuge device as claimed in claim 4 and alarm means for indicating an elapsed time duration, third switch means operative to energize said alarm means immediately subsequent to expiration of said elapsed time duration and said cam means also being coupled to said third switch means to operate same on expiration of said time duration.

7. The centrifuge device as claimed in claim 5 and indicator lamp means operable until the expiration of said elapsed time duration and coupled to said third switch means for deenergization on closing of said third switch means.

8. The centrifuge device as claimed in claim 6 and indicator lamp means energized until the expiration of said elapsed time duration and coupled to said third switch means for deenergization on closing of said third switch means.

9. The centrifuge device as claimed in claim 1 in which said drive means operates To rotate said centrifuge head sufficiently to apply a centrifugal force of about 35 G to each sample container in a direction traversely of the long axis of said container for a time period duration less than one minute.