EP0040022A2 — Filter element for serum separating apparatus

Claim 1

Independent Claim 111 words

A filter element for insertion into a centrifuge tube containing clotted whole blood for separating serum from the cellular and fibrous components, comprising a laterally compressible and expandable cylindrical body formed of a multiplicity of fibers randomly oriented primarily in a longitudinal direction and defining generally longitudinal flow passages therebetween; said fibers being composed of an inert polymeric material of a specific gravity between 1.10 to 1.50, and having diameters within the range of about 10 to 40 micrometers; said body having a bulk density of 0.20 to 0.60 grams per cubic centimeter, a diameter of 9 to 15 millimeters, and a length of from 75 to 125% of said diameter.

Claim 2

Dependent Claim 111 words

A filter element for insertion into a centrifuge tube containing clotted whole blood for separating serum from the cellular and fibrous components, comprising a laterally compressible and expandable cylindrical body formed of a multiplicity of fibers randomly oriented primarily in a longitudinal direction and defining generally longitudinal flow passages therebetween; said fibers being composed of an inert polymeric material of a specific gravity between 1.10 to 1.50, and having diameters within the range of about 10 to 40 micrometers; said body having a bulk density of 0.20 to 0.60 grams per cubic centimeter, a diameter of 9 to 15 millimeters, and a length of from 75 to 125% of said diameter.

Claim 3

Dependent Claim 23 words

The filter element of Claim 1 in which the specific gravity of said polymeric material is within the range of 1.20 to 1.40.

Claim 4

Dependent Claim 31 words

The filter element of Claim 1 in which said polymeric material is selected from the group consisting of cellulose acetate, ethyl cellulose, cellulose propionate, cellulose acetate butyrate, nylon and polyvinyl chloride.

Claim 5

Dependent Claim 16 words

The filter element of Claim 3 in which said fibers are bonded together at spaced-apart junctures.

Claim 6

Dependent Claim 56 words

The filter element of Claim 4 in which said fibers are bonded together at spaced-apart junctures by bonding agent selected from the group consisting of glycerol triacetate, diethoxyethyl phthalate, dimethoxyethyl phthalate, triethyl citrate, tributyl citrate, tricresyl phosphate, glycerol tripropionate, triphenylphosphate, ethyl glycolate, acetyl triiso hexyl citrate, acetyl triethyl citrate, dimethyl phthalate, diethyl phthalate and triethyl phosphate.

Claim 7

Dependent Claim 38 words

The filter element of Claim 5 wherein said polymeric material is cellulose acetate and said binding agent is glycerol triacetate, said glycerol triacetate being present in said filter element at a percentage by weight no greater than 10%.

Claim 8

Dependent Claim 20 words

The filter element of Claim 1 in which said fibers have diameters within the range of 15 to 25 micrometers.

Claim 9

Dependent Claim 152 words

The combination comprising an open-topped glass centrifuge tube and a fibrous cylindrical filter element receivable in said tube; said filter element being laterally compressible and expandable and being formed entirely of a multiplicity of fibers randomly oriented primarily in a longitudinal direction and bonded together only at spaced-apart junctures to define a multiplicity of generally longitudinal flow passages through said element; said fibers being composed of an inert polymeric material of a specific gravity between 1.10 to 1.50, and having diameters within the range of about 10 to 40 micrometers; said element having a bulk density of 0.20 to 0.60 grams per cubic centimeter and a length of from 75 to 125% of the diameter thereof; said centrifuge tube having a substantially uniform inside diameter throughout its length; said diameter of said filter element in an unexpanded and uncompressed state falling within 85 to 110% of said inside diameter of said tube.

Claim 10

Dependent Claim 152 words

The combination comprising an open-topped glass centrifuge tube and a fibrous cylindrical filter element receivable in said tube; said filter element being laterally compressible and expandable and being formed entirely of a multiplicity of fibers randomly oriented primarily in a longitudinal direction and bonded together only at spaced-apart junctures to define a multiplicity of generally longitudinal flow passages through said element; said fibers being composed of an inert polymeric material of a specific gravity between 1.10 to 1.50, and having diameters within the range of about 10 to 40 micrometers; said element having a bulk density of 0.20 to 0.60 grams per cubic centimeter and a length of from 75 to 125% of the diameter thereof; said centrifuge tube having a substantially uniform inside diameter throughout its length; said diameter of said filter element in an unexpanded and uncompressed state falling within 85 to 110% of said inside diameter of said tube.

Claim 11

Dependent Claim 122 words

The combination of a serum filter element and a supporting cap therefor, said filter element comprising a laterally compressible and expandable cylindrical body consisting essentially of a multiplicity of fibres randomly oriented primarily in a longitudinal direction and bonded together only at spaced-apart junctures to define generally longitudinal flow passages therebetwee; said fibers being composed of an inert polymeric material of a specific gravity between 1.10 and 1.50, and having diameters within the range of about 10 to 40 micrometers; said cap being formed of resilient stretchable plastic material having a top wall and an integral depending side wall extending about and frictionally engaging said filter element; said side wall being stretchable outwardly to an extent sufficient to release said filter element.

Claim 12

Dependent Claim 122 words

The combination of a serum filter element and a supporting cap therefor, said filter element comprising a laterally compressible and expandable cylindrical body consisting essentially of a multiplicity of fibres randomly oriented primarily in a longitudinal direction and bonded together only at spaced-apart junctures to define generally longitudinal flow passages therebetwee; said fibers being composed of an inert polymeric material of a specific gravity between 1.10 and 1.50, and having diameters within the range of about 10 to 40 micrometers; said cap being formed of resilient stretchable plastic material having a top wall and an integral depending side wall extending about and frictionally engaging said filter element; said side wall being stretchable outwardly to an extent sufficient to release said filter element.

Claim 13

Dependent Claim 40 words

The combination of Claim 9, in which said side wall of said cap is provided with an inwardly projecting rib; said rib frictionally engaging said filter element to retain the same within said cap when said side wall is unstretched.

Claim 14

Dependent Claim 30 words

The combination of Claim 10, in which said rib is annular and defines an opening having a diameter smaller than the diameter of said filter element in an uncompressed state.

Claim 15

Dependent Claim 69 words

The combination of Claim 10 in which said side wall of said cap includes a downwardly and outwardly flared skirt portion terminating in an enlarged opening at the bottom of said cap, said opening being dimensioned to receive the upper end of a centrifuge tube for enlarging said side wall and releasing said filter element into such tube when said cap is forced downwardly over the tube's upper end.

Claim 16

Dependent Claim 39 words

The combination of Claim 12, wherein said combination includes a centrifuge tube having an inside diameter larger than the diameter of said filter element and an outside diameter capable of being received within said enlarged opening of said cap.

Claim 17

Dependent Claim 45 words

The combination of Claim 12, wherein said centrifuge tube includes an external lip at the upper end thereof; said side wall of said cap being stretchable outwardly to an extent sufficient to position said rib beneath said lip to latch said cap upon said tube.

Claim 18

Dependent Claim 26 words

The combination of Claim 9 in which said filter element has a bulk density within the range of about 0.20 to 0.60 grams per cubic centimeter.

Claim 19

Dependent Claim 35 words

The combination of Claim 9 in which said filter element when undistorted has a diameter within the range of 9 to 15 millimeters and a length of from said 75 to 125% of said diameter.

Claim 20

Independent Claim 176 words

A method of treating a sample of blood to separate clear serum therefrom, comprising the steps of collecting a sample of blood and allowing the same to coagulate in a centrifuge tube to form a fibrin- cell clot therein; then inserting a laterally-expandable, porous and fibrous cylindrical filter element into said tube and centrifuging said tube and its contents to cause said element to descend towards the bottom of said tube behind said clot while allowing serum to flow longitudinally upwardly through the pores of said element; said element being composed of a multiplicity of fibers randomly oriented primarily in a longitudinal direction and formed of an inert polymeric material having a specific gravity within the range of 1.10 to 1.50; said fibers having diameters within the range of about 10 to 40 micrometers and said filter element having a bulk density of about 0.20 to 0.60 grams per cubic centimeter; and continuing centrifugation of said tube and its contents until said filter element engages and compresses said clot within the lower portion of said tube.

Claim 21

Independent Claim 176 words

A method of treating a sample of blood to separate clear serum therefrom, comprising the steps of collecting a sample of blood and allowing the same to coagulate in a centrifuge tube to form a fibrin- cell clot therein; then inserting a laterally-expandable, porous and fibrous cylindrical filter element into said tube and centrifuging said tube and its contents to cause said element to descend towards the bottom of said tube behind said clot while allowing serum to flow longitudinally upwardly through the pores of said element; said element being composed of a multiplicity of fibers randomly oriented primarily in a longitudinal direction and formed of an inert polymeric material having a specific gravity within the range of 1.10 to 1.50; said fibers having diameters within the range of about 10 to 40 micrometers and said filter element having a bulk density of about 0.20 to 0.60 grams per cubic centimeter; and continuing centrifugation of said tube and its contents until said filter element engages and compresses said clot within the lower portion of said tube.

Claim 22

Dependent Claim 38 words

The method of Claim 17 in which said filter element expands outwardly into wiping engagement with the inner surface of said tube in response to the invasion of serum between the fibers thereof upon commencement of centrifuging step.

Claim 23

Independent Claim 144 words

A method of treating a coagulated sample of blood in an open-topped centrifuge tube to separate clear serum from the clot of fibrin and cellular components, comprising the steps of inserting a laterally-expandable, porous, cylindrical filter element into the open top of said tube and then centrifuging said tube and its contents to cause said element to descend towards the bottom of said tube behind said clot while allowing serum to flow upwardly into and through said element; said element being formed of a multiplicity of fibers randomly oriented primarily in a longitudinal direction and bonded together only at spaced-apart junctures; said fibers being composed of an inert polymeric material having a specific gravity greater than any of the constituents of said blood sample; and continuing said centrifugation until said filter element engages and compresses said clot within the lower portion of said tube.

Claim 24

Independent Claim 144 words

A method of treating a coagulated sample of blood in an open-topped centrifuge tube to separate clear serum from the clot of fibrin and cellular components, comprising the steps of inserting a laterally-expandable, porous, cylindrical filter element into the open top of said tube and then centrifuging said tube and its contents to cause said element to descend towards the bottom of said tube behind said clot while allowing serum to flow upwardly into and through said element; said element being formed of a multiplicity of fibers randomly oriented primarily in a longitudinal direction and bonded together only at spaced-apart junctures; said fibers being composed of an inert polymeric material having a specific gravity greater than any of the constituents of said blood sample; and continuing said centrifugation until said filter element engages and compresses said clot within the lower portion of said tube.

Claim 25

Dependent Claim 22 words

A method of Claim 19 in which there is the further step of decanting the serum from said tube following said centrifugation.

Claim 26

Independent Claim 171 words

A method of treating a sample of coagulated blood contained in an open-topped centrifuge tube for the purpose of separating clear serum from the fibrin-cellular clot therein, comprising the steps of positioning a cap having a depending stretchable annular side wall above the open top of said tube, said stretchable side wall including a cylindrical upper portion, a downwardly flared skirt portion, and an internal rib therebetween, said rib defining an opening smaller than the inside of said tube when said side wall is in an unstretched state, said rib engaging and releasably holding a cylindrical filter element dimensioned to be axially received within said tube through the open top thereof, then lowering said cap over the open end of said tube to insert said filter element into said tube and bring the inside surface of said skirt portion into engagement with the top of said tube, then forcing said cap downwardly over said tube to cause said side wall to stretch outwardly and release said filter element within said tube.

Claim 27

Independent Claim 171 words

A method of treating a sample of coagulated blood contained in an open-topped centrifuge tube for the purpose of separating clear serum from the fibrin-cellular clot therein, comprising the steps of positioning a cap having a depending stretchable annular side wall above the open top of said tube, said stretchable side wall including a cylindrical upper portion, a downwardly flared skirt portion, and an internal rib therebetween, said rib defining an opening smaller than the inside of said tube when said side wall is in an unstretched state, said rib engaging and releasably holding a cylindrical filter element dimensioned to be axially received within said tube through the open top thereof, then lowering said cap over the open end of said tube to insert said filter element into said tube and bring the inside surface of said skirt portion into engagement with the top of said tube, then forcing said cap downwardly over said tube to cause said side wall to stretch outwardly and release said filter element within said tube.

Claim 28

Dependent Claim 55 words

The method of Claim 21 in which said tube has a lip extending about the open top thereof, and in which there is the further step of continuing to force said cap downwardly over said tube until said rib is located beneath said lip, thereby latching said cap upon the upper end of said tube.

Claim 29

Dependent Claim 49 words

The method of Claim 21 or 22 in which there is the further step of centrifuging said tube and its contents to cause said filter element to travel towards the bottom of said tube behind said clot, while allowing serum to flow upwardly into and through said filter element.

Claim 30

Dependent Claim 60 words

The method of Claim 23, in which said filter element is formed of a multiplicity of fibers randomly oriented primarily in a longitudinal direction and bonded together at spaced-apart junctures to define a multiplicity of longitudinal flow passages between said fibers, said fibers being composed of an inert polymeric material having a specific gravity greater than the constituents of blood.

Filter element for serum separating apparatus

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