CA1074275A - Device for use in the centrifugal separation of components of a liquid - Google Patents
Device for use in the centrifugal separation of components of a liquidInfo
- Publication number
- CA1074275A CA1074275A CA298,331A CA298331A CA1074275A CA 1074275 A CA1074275 A CA 1074275A CA 298331 A CA298331 A CA 298331A CA 1074275 A CA1074275 A CA 1074275A
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- Canada
- Prior art keywords
- separator
- tube
- connector
- separator element
- separator tube
- Prior art date
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- Investigating Or Analysing Biological Materials (AREA)
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Abstract
ABSTRACT
A device for the centrifugal separation of a liquid having at least two components is disclosed. The device comprises a separator tube, and a separator element having a specific gravity between those of the components to be separated.
The separator tube is formed of plastics material and the separator element comprises a cylindrical member which has an external diameter effectively equal to the internal diameter of the tube and which is movable into the tube under sliding friction with the inner face of the tube.
A device for the centrifugal separation of a liquid having at least two components is disclosed. The device comprises a separator tube, and a separator element having a specific gravity between those of the components to be separated.
The separator tube is formed of plastics material and the separator element comprises a cylindrical member which has an external diameter effectively equal to the internal diameter of the tube and which is movable into the tube under sliding friction with the inner face of the tube.
Description
~ his invention relates to a device for use in the centri~ugal separation of components of a liquid.
So that the components of a liquid, e.g. bloodt of different specific gravities ~ay be separated by centrifuging, and that subsequent re~i~ing of the components may be prevented, use has been ~ade until now o~ glass vessels containing a plug consisting of an elastomeric material and dispiaceable by centrifugal force, the diameter of the plug being greater than that of the glass vessel. Separator elements of this nature, such as disclosed in U.S. Patent No. 3,508,653, have the disadvantage that they must be produced to very close tolerances to secure an effective seal, with these instru-ments, the frictional forces can be so great that no sepa-ration or only poor separation ~ay occur. Centrifuging containers are also ~nown from ~E-OS 2,535,580, where a sepa-rator element is located in the separator tube, the specific gravity of the element being between those of the co~onents rhich are to be separated, and the external diameter being considerably smaller than the internal diameter of the tube;
in this case, sealing is intended to be established by an elastic disc or wash~r bearing against the side of the vessel and operating as a filter. With such separator tubes, con-siderable remixing of substances dissolved in the one phase, such as potassium ions or enzymes such as ~D~ ay be caused b~ diffusion throu~h the filter, so that the vessels are un-suitable for protracted storage or for transporting after centrifuging. An analoOous device is known, moreover, from DE-OS 2,2l~3,569, for maintaining the separation of heavier .
,, ~
- . . . .
.
'' ' . ' . ' ~ . ' ' - . . : .
. . : , : ., -: . :: ~ :: . : : .
and lighter phases of a 1lquid, wherein a cylindrical coil having a central axial opening carries an annular flange at one extre- -mity to establish a sliding sealing contact with the inner surface of the glass tube; after separation of the liquid components, the central opening of the coil is at least te~p-orarily closed by a plug. In this case too, the plug ma~ be loosened from its sealing seat, e.g. during transport, so that remi~ing of the components again occurs. Furthermore, with all these devices, the liauid, e.g. blood, must be introduced into the device in a relatively laborious manner, either after perforation of a rubber cap or by means of a pipette, possibly through the axial bore of the coil-shaped separator element.
It is an object of the invention to eliminate or at least reduce these disadvantages by providing a device which is uncomplicated and may easily be produced, e.g. by an in-jection moulding process, and with which remixing of the com-ponents of a ~iquid or of a diffusion of aissolved ingred-ients is prevented after centrifuging, even during trans-port of the separator device or during protracted storage.
A further object is to simplify the charging of the separa-tor device.
In accordance with the present invention, there is pro-vided a device for the centrifugal separation o~ a liquid having at least two components, the device comprising a separator tube and a separator element having a specific gravity between those of the components to be separated, in which the separator tube is formed of plastics material and the separator element comprises a cylindrical ' ~Ll)74Z75 ~ember which has an e~.ternal diarneter effectively equal to the internal diaTneter of the tube and which is Tnovable into -the tube under sliding friction with the inner face of the tu~e.
It may be found surprising that the individual components can be separated with the inventi~e separator device ~ accord-ance with the sa~e principle as that o~ known devices, as the external diarneter of the separator element is equal to the internal dia~eter of the tube. However, this is due to the fact that the tube produced from plastics material expands slightly under pressure from the liquid in the tube being centrifuged, and thus the internal diameter of the tube in-creases slightly. ~he annular gap for~ed between the tube wall and the separator element only during centrifuging, allows a sepc~ration of what may be referred to as the heavier and lighter coTnponents. Once centrifu~in~ is coTnpleted, the -tube re$ains its original diaTneter, and effectivel~ holds the separator element fast in its position between the two co~-ponents; this acts against subsequent remiY~ing of liquid coTnponents, since there are two chambers effectively sepa-rated from one another.
In a preferred eTnbodiTnent, the separator eleTnent isreleasably connected to a piston or rod arranged to slide within the tube, so that, after completion of a suction intake operation and closure of the tube, the device Tnay be inserted directly into a centrifuOe without intermediate transfer of the liquid.
The separator ele~ent is preferably constructed as a cylindrical Tner,1ber which Tnay have end faces curved inwards .. . : . .:
- : : - : :
1~74z7s and/or outwards '~he separator element may also be formed with lateral ~uiding fins or ~Jebs to prevent jamming during the centrifuging operation.
~ urthermore, the separator ele~ent may be releasably connected to a sealing plug for the separator tube. After being filled, the tube is closed by this plug, and the centri-fuging operation is com~enced. 'rhe separator ele~ent remains connected a-t the beginning of the centrifuging action and becomes disconnected when a particular centrifu~al force is exceeded. It is only then that the separator element travels away from the axis of the centrifuge and to~ards the bottom part of the tube and the separating operation, which may even be completed, is not disturbed as the full centrifugal force continues durinO this displace~en~. ~he relea~able connection between the separator ele~ent and the plug or a piston may, for example, comprise complementary adhesive surfaces of pl~ne or curved form on both parts, or ~ay comprise interloc~ing parts, e.g. in the form of a recess and a projecting peg which may have an enlarged head to engage in an appropriate enlargement in the recess.
'~he separator device according to the invention may have means for connection to a hypodermic needle and have the sepa-rator element connected to a suction piston. In a preferred simple construction, the device may be used to take blood and then be inserted into a centrifuge with only a fe1J operations.
'~his is accomplished by means of a separator element connected through a predetermined fracture section to a piston rod which extcnds into the separator tube. In this case the separator .
- :1074275 element acts as a suction piston for the drawing-off of blood, and the piston rod is then separated from the separator ele~ent by brea~ing at the fracture section, after closure of the suction opening of the needle connectors. The separator tube i5 then closed by means of a conventional plug, whereupon the device is ready for insertion into the centrifuge.
Sui-tably, the fracture section is formed at thP side re~ote from the suction opening of the hypodermic needle con-nector, the separator element being of conical form and ~erging into the piston rod in this area.
For clo3ing off the h~poder~ic needle connector, a cover of preferably approxiMately hemispherical shape is provided, the rim of the cover being in snap-in engagement with a lower rim portion o~ the separator tube. ~he connector bore ~ay moreover be closed by means of a cap which is preferably joi~ed to the hemispherical cover through a trunk portion. It is advantageous, ~oreover, for the covering cap to have a finger sealingly engaging in the bore of the connector.
After the tube has been charged with blood and the piston rod has been removed, the separator tube is closed at the top by a conventional sealing plug and i9 then sealed off in the area of the hypoder~ic needle connector~ The device is then ready for insertion into the centrifuge. It is thus not nece-ssary to remove the connector fro~ tne separator tube and apply another closure appropriate for the centrifuge, or to centrifuge the tube in the reversed position, i.e. wi-th suction plunger, which may still re~ain, facing downwards.
Since separator devices are frequently intended to be in-~ 6 -: -. .
'' ' ' " ~ - ' ~ ''.
serted into a centrifuge just after blood has been withdrawn and charged into -the tube, it is sometime~ necessar~ to add solutions such as anti-coagulant or stabilising solutions t during or shortly after charging. ~o render this possible, it may be advantageous to incorporate a closed chamber wherein the required solid or fluid additives may already be present.
~he additives are then mixed directl~ with the blood, during intake by suction, so that the separator device ~a~ be placed di-rectly in the centrifuge, possibly after re~oval of the suction piston or piston rod and possibly after sealing off the hypo-dermic needle connector.
In a preferred e~bodiment, the separator tube is provided with a needle connector having a bore which extends inwardly through a tubular extension leading into the inside of the separator tube. ~he bore of the tubular extension ~ay be arranged to be closed by a finger-like projec-tion from the base o~ the separator element. It is desirable for the bores of the connector and the tubular extension to be coaxial In another e~bodiment in accordance with the invention, the wall thickness of the separator tube is increased towards the bottom of the tube which maintains a constant internal diameter. ~his construction acts to delay the release or tra~el of the separator element until the phase separation has already started. In an alternative eMbodim2nt, the in-ternal dia~eter of the separator tube is slightl~ increased in its lower portion, to acco~plish a si~ilar purpose. In both cases, the separator element travels more slowl~ to the phase boundary uncler the action of centrifu~al force, because 1C~7427S
the increase of the internal diameter of the tube by expansion is s~aller due to the increased wall thiclmess, and/or because the internal dia~eter of the separator tube is reduced -towards the lower area. ~he increase of the wall thickness, or the reduction of the internal diameter, preferably lies within a range from 0.01 to 0.4 ~m.
In the case of inco~pletely charged separator tubes, the e~pansion of the tube diameter is s~aller during centrifuging because of inadequate internal pressure, so that the forming of an annular gap ~a~ not occur and the separator element ~ay ~erely co~press the air present above the fluid. To prevent this occurring, spirally extending grooves may be formed in the upper portion of the internal surface of the tube. Also, the internal surface of the tube, and particularly the grooves, ~ay be coated with a paste such as a silicone oil or a sili-cone grease, in order to delay the movement of the separator element. This is o~ importance in cases of blood treated to prevent coa~ulation, since thrombocytes for example, follow the separation of the red blood corpuscles from the upper already separated phase, with a slight delay.
~mbodiments of the invention will now be described, by way of exa~ple, ~rith reference to the acco~panying dra~Jings in which:
~igures 1a to 1c are diagra~s illustrating the mode of operation of a separa-tor device according to the invention;
~igure 2 is a fragmentary cross-section through the upper part of a separator tube wherein a separator ele~ent is re-leasably connected to a sealinG plug;
`
Figure 3 is a cross-section, partly broXen away, through a separator tube whe.rein the separa-tor ele~ent is releas~bly connected to a pis-ton in the tube;
Figure 4 is a cross-sec-tion througn a modified form of separator device prior to a blood withdra~ing operation;
Figure 5 is a fragmentary section corresponding to Figure 4, but after the withdrawal of the blood;
Figure 6 is a cross-secti.on through a further ~odified form of separator device com~rising a tube having a cover at its lower end;
Figure 7 is a detail view of the covered lower end of the separator tube according to Figure 6;
Figure 8 is a fragmentary cross-section through yet a further ~odified form of separator device which includes a chamber for additives;
Figure 9 is a cross-section -through a separator tube havin~ a wall thicl-~ess which increases in the downward direc-tion;
Figure 10 is a cross-section through a separator tube having a do~mwardly decreasing internal diameter;
Figure 11 is a cross-section through a separa~or tube having internal axial grooves; and, Figure 12 is a cross-section through a separator tube having internal spiral grooves.
Referring to the dralJings, Figures la to 1c show the mode of operation of the separator device according to the invention.
~he illustrations show the separator tube horizontal, which is the position often assu~ed in centriflIges. Initially, separator _ 9 _ 1~)74Z75 tube 2 is closed by sealing plug 4, a separator element 6 in the form of a cylindrical me~ber bei~g connected to the under-side of the plug 4 by means of a coupling element 8. Referring to ~igure 1a,the two phases of liquid which are to be separated are denoted by lines or dots, the lines denoting the liquid phase and -the dots denoting a heavier,and, ~or example, solid phase dispersed in the liquld phase. ~igure 1_ shows the con- -dition established after a particular period of operation of the centrifuge, the ele~ent 6 being detached from the coupling element 8, and a partial separation already having occurred.
~he separation between the two phases occurs through an annular gap (f) between the separator ele~ent 6 and the side of the tube, formed b~ expansion of the tube due to the pressure exerted by the liquid being centrifuged. Upon continuing the centrifuging action, the liquid phase travels past the separator element 6, which slides towards the botto~ of the tube and floats on the heavier phase.
'~he separator element 6 may be formed of suitable materials, in particular a plastics ~aterial, and the element may be solid, hollow, or weighted. In the separation of blood, use is preferably made of a separator ele~ent of polystyrene, having a specific weight of 1.05, that is lighter than the erythrocyte layer which has specific weight of 1.09 and a little heavier than the plasma or serum layer which has a speci~ic weight of 1.04 to 1.045.
In the construction shown in Figure 2, sealing plug 4' extends beyond and around the rim of the separator tube 2.
~he separator elelQent 6 has a peg 14 engaging,as a coupling . ........ , , ~ - .
'' ' ' ' -1~74Z75 element, in a corresponding recess in the plug~ ~he ele~ent 6 is, moreover, pro-tected against ja~ming within the separator tube b~ ~eans of integral fingers 10.
In the arrangement shown in Figure 3, the separator tube is provided at one end with a piston 16 and, at the other end, with an end ~ember 18 arranged to receive a h~podermic needle.
The hollow ste~ on the ~ember 18 which provides a spigot con-nector for the needle, may be posi-tioned coaxially with respect to the tube, but is preferred to be eccentric thereto. ~he separator ele~ent 6 is connected to the piston 16 b~ a coupling element. With a separator device of this kind, it is possible to draw blood after attaching the hypodermic needle, remove the end me~ber 18, replace this ~ember b~ a sealing ele~ent, and then insert the separator tube directly into the centrifuge after re~oval of the piston rod 15.
In the construction shown in FiO~ure 4, the separator ele~ent or me~be-r 6 is situated, within the separator tube
So that the components of a liquid, e.g. bloodt of different specific gravities ~ay be separated by centrifuging, and that subsequent re~i~ing of the components may be prevented, use has been ~ade until now o~ glass vessels containing a plug consisting of an elastomeric material and dispiaceable by centrifugal force, the diameter of the plug being greater than that of the glass vessel. Separator elements of this nature, such as disclosed in U.S. Patent No. 3,508,653, have the disadvantage that they must be produced to very close tolerances to secure an effective seal, with these instru-ments, the frictional forces can be so great that no sepa-ration or only poor separation ~ay occur. Centrifuging containers are also ~nown from ~E-OS 2,535,580, where a sepa-rator element is located in the separator tube, the specific gravity of the element being between those of the co~onents rhich are to be separated, and the external diameter being considerably smaller than the internal diameter of the tube;
in this case, sealing is intended to be established by an elastic disc or wash~r bearing against the side of the vessel and operating as a filter. With such separator tubes, con-siderable remixing of substances dissolved in the one phase, such as potassium ions or enzymes such as ~D~ ay be caused b~ diffusion throu~h the filter, so that the vessels are un-suitable for protracted storage or for transporting after centrifuging. An analoOous device is known, moreover, from DE-OS 2,2l~3,569, for maintaining the separation of heavier .
,, ~
- . . . .
.
'' ' . ' . ' ~ . ' ' - . . : .
. . : , : ., -: . :: ~ :: . : : .
and lighter phases of a 1lquid, wherein a cylindrical coil having a central axial opening carries an annular flange at one extre- -mity to establish a sliding sealing contact with the inner surface of the glass tube; after separation of the liquid components, the central opening of the coil is at least te~p-orarily closed by a plug. In this case too, the plug ma~ be loosened from its sealing seat, e.g. during transport, so that remi~ing of the components again occurs. Furthermore, with all these devices, the liauid, e.g. blood, must be introduced into the device in a relatively laborious manner, either after perforation of a rubber cap or by means of a pipette, possibly through the axial bore of the coil-shaped separator element.
It is an object of the invention to eliminate or at least reduce these disadvantages by providing a device which is uncomplicated and may easily be produced, e.g. by an in-jection moulding process, and with which remixing of the com-ponents of a ~iquid or of a diffusion of aissolved ingred-ients is prevented after centrifuging, even during trans-port of the separator device or during protracted storage.
A further object is to simplify the charging of the separa-tor device.
In accordance with the present invention, there is pro-vided a device for the centrifugal separation o~ a liquid having at least two components, the device comprising a separator tube and a separator element having a specific gravity between those of the components to be separated, in which the separator tube is formed of plastics material and the separator element comprises a cylindrical ' ~Ll)74Z75 ~ember which has an e~.ternal diarneter effectively equal to the internal diaTneter of the tube and which is Tnovable into -the tube under sliding friction with the inner face of the tu~e.
It may be found surprising that the individual components can be separated with the inventi~e separator device ~ accord-ance with the sa~e principle as that o~ known devices, as the external diarneter of the separator element is equal to the internal dia~eter of the tube. However, this is due to the fact that the tube produced from plastics material expands slightly under pressure from the liquid in the tube being centrifuged, and thus the internal diameter of the tube in-creases slightly. ~he annular gap for~ed between the tube wall and the separator element only during centrifuging, allows a sepc~ration of what may be referred to as the heavier and lighter coTnponents. Once centrifu~in~ is coTnpleted, the -tube re$ains its original diaTneter, and effectivel~ holds the separator element fast in its position between the two co~-ponents; this acts against subsequent remiY~ing of liquid coTnponents, since there are two chambers effectively sepa-rated from one another.
In a preferred eTnbodiTnent, the separator eleTnent isreleasably connected to a piston or rod arranged to slide within the tube, so that, after completion of a suction intake operation and closure of the tube, the device Tnay be inserted directly into a centrifuOe without intermediate transfer of the liquid.
The separator ele~ent is preferably constructed as a cylindrical Tner,1ber which Tnay have end faces curved inwards .. . : . .:
- : : - : :
1~74z7s and/or outwards '~he separator element may also be formed with lateral ~uiding fins or ~Jebs to prevent jamming during the centrifuging operation.
~ urthermore, the separator ele~ent may be releasably connected to a sealing plug for the separator tube. After being filled, the tube is closed by this plug, and the centri-fuging operation is com~enced. 'rhe separator ele~ent remains connected a-t the beginning of the centrifuging action and becomes disconnected when a particular centrifu~al force is exceeded. It is only then that the separator element travels away from the axis of the centrifuge and to~ards the bottom part of the tube and the separating operation, which may even be completed, is not disturbed as the full centrifugal force continues durinO this displace~en~. ~he relea~able connection between the separator ele~ent and the plug or a piston may, for example, comprise complementary adhesive surfaces of pl~ne or curved form on both parts, or ~ay comprise interloc~ing parts, e.g. in the form of a recess and a projecting peg which may have an enlarged head to engage in an appropriate enlargement in the recess.
'~he separator device according to the invention may have means for connection to a hypodermic needle and have the sepa-rator element connected to a suction piston. In a preferred simple construction, the device may be used to take blood and then be inserted into a centrifuge with only a fe1J operations.
'~his is accomplished by means of a separator element connected through a predetermined fracture section to a piston rod which extcnds into the separator tube. In this case the separator .
- :1074275 element acts as a suction piston for the drawing-off of blood, and the piston rod is then separated from the separator ele~ent by brea~ing at the fracture section, after closure of the suction opening of the needle connectors. The separator tube i5 then closed by means of a conventional plug, whereupon the device is ready for insertion into the centrifuge.
Sui-tably, the fracture section is formed at thP side re~ote from the suction opening of the hypodermic needle con-nector, the separator element being of conical form and ~erging into the piston rod in this area.
For clo3ing off the h~poder~ic needle connector, a cover of preferably approxiMately hemispherical shape is provided, the rim of the cover being in snap-in engagement with a lower rim portion o~ the separator tube. ~he connector bore ~ay moreover be closed by means of a cap which is preferably joi~ed to the hemispherical cover through a trunk portion. It is advantageous, ~oreover, for the covering cap to have a finger sealingly engaging in the bore of the connector.
After the tube has been charged with blood and the piston rod has been removed, the separator tube is closed at the top by a conventional sealing plug and i9 then sealed off in the area of the hypoder~ic needle connector~ The device is then ready for insertion into the centrifuge. It is thus not nece-ssary to remove the connector fro~ tne separator tube and apply another closure appropriate for the centrifuge, or to centrifuge the tube in the reversed position, i.e. wi-th suction plunger, which may still re~ain, facing downwards.
Since separator devices are frequently intended to be in-~ 6 -: -. .
'' ' ' " ~ - ' ~ ''.
serted into a centrifuge just after blood has been withdrawn and charged into -the tube, it is sometime~ necessar~ to add solutions such as anti-coagulant or stabilising solutions t during or shortly after charging. ~o render this possible, it may be advantageous to incorporate a closed chamber wherein the required solid or fluid additives may already be present.
~he additives are then mixed directl~ with the blood, during intake by suction, so that the separator device ~a~ be placed di-rectly in the centrifuge, possibly after re~oval of the suction piston or piston rod and possibly after sealing off the hypo-dermic needle connector.
In a preferred e~bodiment, the separator tube is provided with a needle connector having a bore which extends inwardly through a tubular extension leading into the inside of the separator tube. ~he bore of the tubular extension ~ay be arranged to be closed by a finger-like projec-tion from the base o~ the separator element. It is desirable for the bores of the connector and the tubular extension to be coaxial In another e~bodiment in accordance with the invention, the wall thickness of the separator tube is increased towards the bottom of the tube which maintains a constant internal diameter. ~his construction acts to delay the release or tra~el of the separator element until the phase separation has already started. In an alternative eMbodim2nt, the in-ternal dia~eter of the separator tube is slightl~ increased in its lower portion, to acco~plish a si~ilar purpose. In both cases, the separator element travels more slowl~ to the phase boundary uncler the action of centrifu~al force, because 1C~7427S
the increase of the internal diameter of the tube by expansion is s~aller due to the increased wall thiclmess, and/or because the internal dia~eter of the separator tube is reduced -towards the lower area. ~he increase of the wall thickness, or the reduction of the internal diameter, preferably lies within a range from 0.01 to 0.4 ~m.
In the case of inco~pletely charged separator tubes, the e~pansion of the tube diameter is s~aller during centrifuging because of inadequate internal pressure, so that the forming of an annular gap ~a~ not occur and the separator element ~ay ~erely co~press the air present above the fluid. To prevent this occurring, spirally extending grooves may be formed in the upper portion of the internal surface of the tube. Also, the internal surface of the tube, and particularly the grooves, ~ay be coated with a paste such as a silicone oil or a sili-cone grease, in order to delay the movement of the separator element. This is o~ importance in cases of blood treated to prevent coa~ulation, since thrombocytes for example, follow the separation of the red blood corpuscles from the upper already separated phase, with a slight delay.
~mbodiments of the invention will now be described, by way of exa~ple, ~rith reference to the acco~panying dra~Jings in which:
~igures 1a to 1c are diagra~s illustrating the mode of operation of a separa-tor device according to the invention;
~igure 2 is a fragmentary cross-section through the upper part of a separator tube wherein a separator ele~ent is re-leasably connected to a sealinG plug;
`
Figure 3 is a cross-section, partly broXen away, through a separator tube whe.rein the separa-tor ele~ent is releas~bly connected to a pis-ton in the tube;
Figure 4 is a cross-sec-tion througn a modified form of separator device prior to a blood withdra~ing operation;
Figure 5 is a fragmentary section corresponding to Figure 4, but after the withdrawal of the blood;
Figure 6 is a cross-secti.on through a further ~odified form of separator device com~rising a tube having a cover at its lower end;
Figure 7 is a detail view of the covered lower end of the separator tube according to Figure 6;
Figure 8 is a fragmentary cross-section through yet a further ~odified form of separator device which includes a chamber for additives;
Figure 9 is a cross-section -through a separator tube havin~ a wall thicl-~ess which increases in the downward direc-tion;
Figure 10 is a cross-section through a separator tube having a do~mwardly decreasing internal diameter;
Figure 11 is a cross-section through a separa~or tube having internal axial grooves; and, Figure 12 is a cross-section through a separator tube having internal spiral grooves.
Referring to the dralJings, Figures la to 1c show the mode of operation of the separator device according to the invention.
~he illustrations show the separator tube horizontal, which is the position often assu~ed in centriflIges. Initially, separator _ 9 _ 1~)74Z75 tube 2 is closed by sealing plug 4, a separator element 6 in the form of a cylindrical me~ber bei~g connected to the under-side of the plug 4 by means of a coupling element 8. Referring to ~igure 1a,the two phases of liquid which are to be separated are denoted by lines or dots, the lines denoting the liquid phase and -the dots denoting a heavier,and, ~or example, solid phase dispersed in the liquld phase. ~igure 1_ shows the con- -dition established after a particular period of operation of the centrifuge, the ele~ent 6 being detached from the coupling element 8, and a partial separation already having occurred.
~he separation between the two phases occurs through an annular gap (f) between the separator ele~ent 6 and the side of the tube, formed b~ expansion of the tube due to the pressure exerted by the liquid being centrifuged. Upon continuing the centrifuging action, the liquid phase travels past the separator element 6, which slides towards the botto~ of the tube and floats on the heavier phase.
'~he separator element 6 may be formed of suitable materials, in particular a plastics ~aterial, and the element may be solid, hollow, or weighted. In the separation of blood, use is preferably made of a separator ele~ent of polystyrene, having a specific weight of 1.05, that is lighter than the erythrocyte layer which has specific weight of 1.09 and a little heavier than the plasma or serum layer which has a speci~ic weight of 1.04 to 1.045.
In the construction shown in Figure 2, sealing plug 4' extends beyond and around the rim of the separator tube 2.
~he separator elelQent 6 has a peg 14 engaging,as a coupling . ........ , , ~ - .
'' ' ' ' -1~74Z75 element, in a corresponding recess in the plug~ ~he ele~ent 6 is, moreover, pro-tected against ja~ming within the separator tube b~ ~eans of integral fingers 10.
In the arrangement shown in Figure 3, the separator tube is provided at one end with a piston 16 and, at the other end, with an end ~ember 18 arranged to receive a h~podermic needle.
The hollow ste~ on the ~ember 18 which provides a spigot con-nector for the needle, may be posi-tioned coaxially with respect to the tube, but is preferred to be eccentric thereto. ~he separator ele~ent 6 is connected to the piston 16 b~ a coupling element. With a separator device of this kind, it is possible to draw blood after attaching the hypodermic needle, remove the end me~ber 18, replace this ~ember b~ a sealing ele~ent, and then insert the separator tube directly into the centrifuge after re~oval of the piston rod 15.
In the construction shown in FiO~ure 4, the separator ele~ent or me~be-r 6 is situated, within the separator tube
2, close to the bottom of the tube or rather to the region of the end member 18 which again provides a tubular spigot connector for a hypoder~ic needle. ~he separator ele~ent 6 is conical at its side facing away from the end ~e~ber 18 and extends to piston rod 15 through a thinner or weaker section 7 which is defligned as a fracture section.
In use of the construction shown in ~igure 5, the sepa-rator tube i8 sealed off after drawing blood, in a conventional ~anner not described at this stage. Separator element 6 is situated in the upper part of the separator tube 2 ~hich is closed by a conventional sealing p1u~ 4. ~he separator tube ,, .
.,, .
- - ~ . .
:, , - - ~ ; , -is placed in the centrifuge in thi~ position and, af~er co~ple-tion of the centrifuging operation and the formation of two la~ers of different specific gravities, the separator ele~ent in its new posi-tion prevents re~ixing in the boundar~ areas of these la~ers.
In the construction sho~n in ~igure 6, the separator element 6 is located within the separator tube 2 above the blood drawn in. In this arrange~ent, -the piston rod is already re~oved and the separator tube 2 closed by ~eans of a conven-tional sealing plug 4. The lower end ~ember 18 which is formed with a tapered tubular spigot connector 19, is then closed by a cover 40 which is appro{i~ately he~ispherical, the rim of the hemispherical cover 40 being snapped into engagement with lower end r~ember 18. The cover 40 has a projecting lip 42 in its ri~ which is in engagement wi-th a corresponding re-ce~s formed behind annular lip ~l on the end member 18.
A ~crew cover may alternatively be applied to a ~odified centrally-positioned spigot 19.
In the use of a cover of the just described kind, the fluid of greater specific grav.ity ~a~ pass into the he~i-spherical cover during centrifuging and may be withdra~m therefrom after the centrifu~ing operation In the modified construction shown in .Fi~ure 7, the tapered spigot connector 19 is closed b~ a sealing cap 46.
~he cap 46 extends fro~ the cover 40 through a trunk portion 48, and a sealing finger 50 extends into the bore of the con-nector 19.
r~he covex 40 i.s preferabl~ for~ed from plastics ~aterial, '.
.. , , . . - . - . .
,. .. .,-: ~ . .
` 1074Z75 for example a polyethylene of low flexibilit~.
ln the construction shown in Figure 8, the separator element 6,which acts as a suction piston, is again located within the separator tube 2. ~he lower portion of the separator tube is again so constructed that a tapered spigot connector 19 ex-tends from the end member 18 to receive a h~podermic needle.
The bore of the connector 19 continues in a tubular in-wara extension 2~ from the end member 18 ~he tubular exten-sion 21 extends into a storage chamber 23 which is defined b~
the inner surface of the separator tube 2 and, at the top and botto~, b~ the bottom face of the separator element 6 and the inner face of the member 1~.
~o prevent egress of the contents of the chamber 23, a finger-like proaection 7 extends from the base of the element 6 to enter the upper end of the extension 21 and close the bore thereof.
The bore3 of the tapered connector 19 and the tubular extension 21 are preferably coaxial. ~he connector 19 may be arranged centrall~, but alternativel~ eccentrically, with res-pect to the separator tube. ~he former arrangement facilitates the charging of the chamber with substances which are to be added to the blood, and the subsequent closure by engagement of the finger-like projection 7 in the bore of the tubular extension 21, while the latter facilitates the manipulation of the hypodermic device during the drawin~ of blood, part-icularly in the handling of the device whilst seeking a vein.
After being charged with additive, the separator tube ma~
be sealed off both at the tapered spigot connector and at the :'' ~ ': `: ' :
: ::. : . . : :
,. : : - .
`` 1074Z75 upper extre~ity.
In ~igure 9, the separator tube 2 has the sa~e internal diameter (D) throughout, but the wall thickness increases (S) downwardl~ to (S + x). ~he result is that the expansion of the plastics ~aterial of the tube, under the action of the cen-trifugal force, is reduced in the lower portion, and so the separator ele~ent does ~ove downwards, but slowl~, after the establish~ent or the substantial establish~ent of the sedi-~entation balance. B~ increasing the speed of rotation during centrifuging, it is also possible to produce expansion of the tube even in the lower portion having the greater wall thick-ness, and thereb~ a continued upward transfer of the lighter component.
In Figure 10, the internal diameter of the tube 2 is also reduced downwardly to (D - 2x) to obtain similar results.
Such variations in wall thickness or internal dia~eter vary within a range fro~ 0.001 to 0.2 or 0 l~ m~, depending on the nature of the material used for the separator tube and sepa-rator ele~ent.
In ~igure 11, axial grooves 60 having a depth of 0.02 to 0.5 mm are for~ed in the inner face of the tube. These grooves act to prevent a deposit of thro~boc~tes at the upper edge and on the tapering surface of the separator element when the device is being used to separate co~ponents of blood.
Alternatively, as shown in Figure 12, internal spiral grooves 62 may be provided for the sa~e purpose.
It is appropriate for these grooves 60 and 62 to be coated with a silicone oil or silicone grease, ~hich initially assures . :.
:
.
.
a total seal but then passes downwards under centrifugal force and thus opens the way for the thromboc~te layer.
: , - . . : , . . . . . ... . . ..
.
.. . , , , ,
In use of the construction shown in ~igure 5, the sepa-rator tube i8 sealed off after drawing blood, in a conventional ~anner not described at this stage. Separator element 6 is situated in the upper part of the separator tube 2 ~hich is closed by a conventional sealing p1u~ 4. ~he separator tube ,, .
.,, .
- - ~ . .
:, , - - ~ ; , -is placed in the centrifuge in thi~ position and, af~er co~ple-tion of the centrifuging operation and the formation of two la~ers of different specific gravities, the separator ele~ent in its new posi-tion prevents re~ixing in the boundar~ areas of these la~ers.
In the construction sho~n in ~igure 6, the separator element 6 is located within the separator tube 2 above the blood drawn in. In this arrange~ent, -the piston rod is already re~oved and the separator tube 2 closed by ~eans of a conven-tional sealing plug 4. The lower end ~ember 18 which is formed with a tapered tubular spigot connector 19, is then closed by a cover 40 which is appro{i~ately he~ispherical, the rim of the hemispherical cover 40 being snapped into engagement with lower end r~ember 18. The cover 40 has a projecting lip 42 in its ri~ which is in engagement wi-th a corresponding re-ce~s formed behind annular lip ~l on the end member 18.
A ~crew cover may alternatively be applied to a ~odified centrally-positioned spigot 19.
In the use of a cover of the just described kind, the fluid of greater specific grav.ity ~a~ pass into the he~i-spherical cover during centrifuging and may be withdra~m therefrom after the centrifu~ing operation In the modified construction shown in .Fi~ure 7, the tapered spigot connector 19 is closed b~ a sealing cap 46.
~he cap 46 extends fro~ the cover 40 through a trunk portion 48, and a sealing finger 50 extends into the bore of the con-nector 19.
r~he covex 40 i.s preferabl~ for~ed from plastics ~aterial, '.
.. , , . . - . - . .
,. .. .,-: ~ . .
` 1074Z75 for example a polyethylene of low flexibilit~.
ln the construction shown in Figure 8, the separator element 6,which acts as a suction piston, is again located within the separator tube 2. ~he lower portion of the separator tube is again so constructed that a tapered spigot connector 19 ex-tends from the end member 18 to receive a h~podermic needle.
The bore of the connector 19 continues in a tubular in-wara extension 2~ from the end member 18 ~he tubular exten-sion 21 extends into a storage chamber 23 which is defined b~
the inner surface of the separator tube 2 and, at the top and botto~, b~ the bottom face of the separator element 6 and the inner face of the member 1~.
~o prevent egress of the contents of the chamber 23, a finger-like proaection 7 extends from the base of the element 6 to enter the upper end of the extension 21 and close the bore thereof.
The bore3 of the tapered connector 19 and the tubular extension 21 are preferably coaxial. ~he connector 19 may be arranged centrall~, but alternativel~ eccentrically, with res-pect to the separator tube. ~he former arrangement facilitates the charging of the chamber with substances which are to be added to the blood, and the subsequent closure by engagement of the finger-like projection 7 in the bore of the tubular extension 21, while the latter facilitates the manipulation of the hypodermic device during the drawin~ of blood, part-icularly in the handling of the device whilst seeking a vein.
After being charged with additive, the separator tube ma~
be sealed off both at the tapered spigot connector and at the :'' ~ ': `: ' :
: ::. : . . : :
,. : : - .
`` 1074Z75 upper extre~ity.
In ~igure 9, the separator tube 2 has the sa~e internal diameter (D) throughout, but the wall thickness increases (S) downwardl~ to (S + x). ~he result is that the expansion of the plastics ~aterial of the tube, under the action of the cen-trifugal force, is reduced in the lower portion, and so the separator ele~ent does ~ove downwards, but slowl~, after the establish~ent or the substantial establish~ent of the sedi-~entation balance. B~ increasing the speed of rotation during centrifuging, it is also possible to produce expansion of the tube even in the lower portion having the greater wall thick-ness, and thereb~ a continued upward transfer of the lighter component.
In Figure 10, the internal diameter of the tube 2 is also reduced downwardly to (D - 2x) to obtain similar results.
Such variations in wall thickness or internal dia~eter vary within a range fro~ 0.001 to 0.2 or 0 l~ m~, depending on the nature of the material used for the separator tube and sepa-rator ele~ent.
In ~igure 11, axial grooves 60 having a depth of 0.02 to 0.5 mm are for~ed in the inner face of the tube. These grooves act to prevent a deposit of thro~boc~tes at the upper edge and on the tapering surface of the separator element when the device is being used to separate co~ponents of blood.
Alternatively, as shown in Figure 12, internal spiral grooves 62 may be provided for the sa~e purpose.
It is appropriate for these grooves 60 and 62 to be coated with a silicone oil or silicone grease, ~hich initially assures . :.
:
.
.
a total seal but then passes downwards under centrifugal force and thus opens the way for the thromboc~te layer.
: , - . . : , . . . . . ... . . ..
.
.. . , , , ,
Claims (22)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS-
1. For use in centrifugal separation of a liquid having at least two components having different specific weights, a device comprising:
wall means of a predetermined thickness of synthetic plastic material defining a separator tube having an inner face of generally round transverse cross-sectional figure;
a generally cylindrical, piston-like, substantially rigid, separator element having a specific weight which lies between the respective specific weight of said two compo-nents;
said separator element having an outer peripheral surface with a generally round transverse cross-sectional figure;
said separator element outer peripheral surface having at least an axially intermediate portion thereof which is of said separator tube wall means;
said separator element being frictionally, axially slidably received in said separator tube;
said separator element being comparatively rigid relative to said separator tube wall means and said separator tube all means being sufficiently flexible relative to said separator element, to enable substantially only that portion of said tube wall means conincident to said separator element to flex and thereby increase in a diameter suffi-cient to enable passage of liquid between said that portion and said separator element, in response to centrifugal force.
wall means of a predetermined thickness of synthetic plastic material defining a separator tube having an inner face of generally round transverse cross-sectional figure;
a generally cylindrical, piston-like, substantially rigid, separator element having a specific weight which lies between the respective specific weight of said two compo-nents;
said separator element having an outer peripheral surface with a generally round transverse cross-sectional figure;
said separator element outer peripheral surface having at least an axially intermediate portion thereof which is of said separator tube wall means;
said separator element being frictionally, axially slidably received in said separator tube;
said separator element being comparatively rigid relative to said separator tube wall means and said separator tube all means being sufficiently flexible relative to said separator element, to enable substantially only that portion of said tube wall means conincident to said separator element to flex and thereby increase in a diameter suffi-cient to enable passage of liquid between said that portion and said separator element, in response to centrifugal force.
2. A separator device according to claim 1, in which the separator element is releasably connected to a piston or rod arranged to slide within the tube, and is equipped with a connector for a hypodermic needle.
3. A separator device according to any of claims 1 or 2, in which the connector for the hypodermic needle is releasably arranged on the separator tube.
4. A separator device according to any of claims 1 2, or 3, in which the separator tube or a space in communication with a connector for a hypodermic needle is connected to a reduced-pressure chamber.
5. A separator device according to claim 1, in which the separator element is connected to a piston rod in the separator tube through a fracture section, and acts as a suction piston.
6. A separator device according to claim 5, in which the separator element is of conical form at the side remote from the hypodermic needle connector, and merges into the piston rod in the area of the apex of the cone.
7. A separator device according to claims 5 or 6, in which the piston rod has lateral guiding fins.
8. A separator device according to claim 1, in which the separator tube is provided with a connector for a hypodermic needle, and a cover for said connector.
9. A separator device according to claim 8, in which the cover is of approximately hemispherical form, and a rim of the hemispherical cover is in snap-in engagement with the lower rim portion of the separator tube.
10. A separator device according to claim 8 or claim 9, in which a sealing cap is provided to close off the connector, the cap being joined through a trunk portion of the hemispherical cover.
11. A separator device according to claim 10, in which the sealing cap for the connector has a sealing finger arranged to extend into the bore of the connector.
12. A separator device according to claim 8, in which the bore of the connector extends through a tubular extension into the interior of the separator tube.
13. A separator device according to claim 12, in which a finger-like projection on the base surface of the separator element is arranged to close the bore of said connector.
14. A separator device according to claim 12 or claim 13, in which the bores of the connector and of the tubular extension are arranged coaxially.
15. The device of claim 1 in which:
said separator element has an axailly intermediate region of greatest outer diameter, lead and trailed by respective regions of decreasing diameter.
said separator element has an axailly intermediate region of greatest outer diameter, lead and trailed by respective regions of decreasing diameter.
16. The device of claim 15, wherein:
said respective regions of decreasing diameter are generally conically curved coaxially of said separator element.
said respective regions of decreasing diameter are generally conically curved coaxially of said separator element.
17. The device of claim 1, further including:
means defining a plurality of axially extending lateral guiding fins on said separator element.
means defining a plurality of axially extending lateral guiding fins on said separator element.
18. The device of claim 1, wherein:
the wall means of said separator tube is of progressively increasing thickness and thus of decreasing flexibility along the length thereof in the axial direction of movement of the separator element therealong during centrifuging.
the wall means of said separator tube is of progressively increasing thickness and thus of decreasing flexibility along the length thereof in the axial direction of movement of the separator element therealong during centrifuging.
19. The device of claim 1, wherein:
the wall means of said separator tube is of progressively decreasing internal diameter along the length thereof in the axial direction of movement of the separator element therealong during centrifuging.
the wall means of said separator tube is of progressively decreasing internal diameter along the length thereof in the axial direction of movement of the separator element therealong during centrifuging.
20. The device of claim 1, wherein:
said separator tube wall means inner face is provided with a plurality of axially extending grooves distributed about the circumference thereof at least in the vicinity of said separator element during initiation of centri-fuging, for preventing deposition of thrombocytes when the device is being used to separate components of blood.
said separator tube wall means inner face is provided with a plurality of axially extending grooves distributed about the circumference thereof at least in the vicinity of said separator element during initiation of centri-fuging, for preventing deposition of thrombocytes when the device is being used to separate components of blood.
21. The device of claim 20, wherein:
said grooves proceed spirally of said inner face as they proceed axially thereof.
said grooves proceed spirally of said inner face as they proceed axially thereof.
22. The device of claim 20, wherein:
said grooves are initially coated with a sealant which is subject to flow under centrifugal force during centrifuging in order to pass a thrombocyte layer.
said grooves are initially coated with a sealant which is subject to flow under centrifugal force during centrifuging in order to pass a thrombocyte layer.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19772711336 DE2711336C2 (en) | 1977-03-16 | 1977-03-16 | Separation tubes for centrifugal separation |
| DE19772734730 DE2734730A1 (en) | 1976-08-05 | 1977-08-02 | SILICONE GLAZING ARRANGEMENT AND METHOD OF APPLYING A WINDOW GLASS |
| DE19772734764 DE2734764A1 (en) | 1977-03-16 | 1977-08-02 | Tube for sepn. by centrifugation - is made of synthetic material and contains moving cylindrical separator preventing subsequent remixing |
| DE19772734781 DE2734781A1 (en) | 1977-03-16 | 1977-08-02 | Tube for sepn. by centrifugation - is made of synthetic material and contains moving cylindrical separator preventing subsequent remixing |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1074275A true CA1074275A (en) | 1980-03-25 |
Family
ID=27432195
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA298,331A Expired CA1074275A (en) | 1977-03-16 | 1978-03-06 | Device for use in the centrifugal separation of components of a liquid |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1074275A (en) |
-
1978
- 1978-03-06 CA CA298,331A patent/CA1074275A/en not_active Expired
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| Date | Code | Title | Description |
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| MKEX | Expiry |