GB1601826A

GB1601826A - Serum or plasma separator tube

Info

Publication number: GB1601826A
Application number: GB1753178A
Authority: GB
Original assignee: Greenspan D J
Current assignee: Greenspan D J
Priority date: 1977-05-03
Filing date: 1978-05-03
Publication date: 1981-11-04
Also published as: FR2401008A1; DE2819170C2; CA1087573A; DE2819170A1; JPS5415569A; JPS6250191B2; FR2401008B1

Description

(54) SERUM OR PLASMA SEPARATOR TUBE (71) I, DONALD JAY GREENSPAN, a citizen of the United States of America of 235 Pavilion Avenue, Riverside, New Jersey 08075, U.S.A., do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a separator tube used for the separation of formed elements, i.e., white cells, red cells and platelets of blood, from the serum or plasma of the blood.

Serum separation is typically performed by centrifuging a blood sample in a collection tube such that the heavier formed elements of the blood are forced to the bottom or closed end of the collection tube and the lighter plasma or serum of the sample remains on top or toward the open end of the collection tube.

After such separation by centrifugation, it is desirable to separate the formed elements of the blood from the serum or plasma in order to prevent the contamination of the serum or plasma. Such contamination can occur as the red blood cells begin to liberate potassium and cther contaminants which might interfere with tests performed on the serum or plasma. It is also possible that any fibrin which remains in the sample may produce some contamination.

In order to achieve this isolation or fluid separation of the formed elements of the blood from the serum or plasma, separator tubes have been utilized. The separator tubes which are adapted to be inserted into a collection tube typically comprise a tubular member having one end closed by a plug or valve apparatus which is formed from an elastomeric material. The plug includes a centrally located one-way valve which is forced open as the separator tube is forced downwardly through a blood sample in a collection tube so as to allow the serum or plasma to flow into the separator tube. When the separator tube becomes stationary relative to the collection tube i.e., just before contact with the formed elements of the blood, the one-way valve closes so as to isolate the plasma within the separator tube.

The separator tube may then be withdrawn.

However, it would be desirable to close the end of a separator tube with a plug or valve apparatus which maintains a more substantial seating form when closed than valve apparatus presently available.

It has been found to be particularly desirable to utilize the separator tube in and of itself as a transport device for transporting the serum or plasma to the laboratory from the point at which the blood sample is taken.

This requires that the one-way valve at the closed end of the separator tube be essentially leak-proof. My U.S. patents 3, 661, 265 and 3, 799, 342 disclose a substantially leakproof valve which does permit the use of the separator tube as a transport device. The one-way valve disclosed therein essentially relies upon the elastomeric properties of the plug to return the valve to the closed condition, i.e., there is no force or bias acting on the valve when the separator tube is in the stationary position and the valve is closed.

Rather, the valve elements, when properly structured, merely contact one another when returning to a natural or unbiased state in which they were originally molded. Proper closure of these valves may be assisted by the tubular member if the inside diameter of the tubular member is slightly smaller than the outside diameter of the plug but the tolerances on the inside diameter of the tubular member are difficult to control particularly where the tubes are extruded.

U.S. patent 3,954,614 also discloses a valve in a separator tube which is characterized by little or no seating forces when the valve is in the closed position. The same is true with respect to U.S. patent 3,962, 085 wherein the periphery of a disc acts as a valve which is closed when the disc is in the closed position.

However, there are no substantial seating forces beyond weight of the blood sample itself. Valves such as those shown in U.S.

patents 1,777,408 and 2,191,636 are biased so as to provide a substantial sealing force when in the closed position, but such valves are too complex for use in serum separators.

According to the present invention, there is provided a separator tube adapted to be pushed into a collection tube containing blood for separating serum or plasma from the formed elements of the blood, comprising a tubular member, means adapted to form a seal with the collection tube as the separator tube is pushed into the collection tube, and a valve comprising a valve body with a seat having a valve opening therein, the valve opening permitting serum or plasma to flow into the tubular member when the separator tube is plunged into the collection tube, a movable valve member adapted to seat on the valve seat so as to close the valve opening, and connective means extending between the valve member and the valve body and maintaining a substantial seating force on the valve member when the valve opening is closed.

The invention will be described in more detail, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a sectional view of a preferred embodiment of the invention comprising a separator tube and a collection tube; Fig. 2 is a sectional view of the valve plug incorporated in the separator tube of Fig. 1; Fig. 3 is a sectional view taken along line 3-3 of Fig. 2; Fig. 4 is an enlarged sectional view of the separator tube and collection tube of Fig. 1 as the separator tube is inserted into the collection tube; Fig. 5 is an enlarged sectional view of the separator tube of Fig. 1 wherein the separator tube is being withdrawn from the collection tube; Fig. 6 is a sectional view of an alternative plug which may be utilized in the apparatus of Fig. 1; Fig. 7 is a sectional view of yet another plug which is utilized in the apparatus of Fig.

1; Fig. 7a is a sectional view of part of the plug of Fig. 7 as the separator tube is withdrawn from the collection tube.

Fig. 8 is a view of the plug of Fig. 7 taken along line 8-8 of Fig. 7.

Fig. 9 is a sectional view of a mould in which the valve of Fig. 6 is moulded; Fig. 10 is a sectional view of the mould of Fig. 9 as the mould begins to open; Fig. 11 is a sectional view of the mould of Fig. 9 as the mould continues to open and the setting of the valve begins; Fig. 12 is a sectional view of the mold of Fig. 9 in a further state of opening with the valve opening deformed so as to permit setting of the valve; Fig. 13 is a sectional view of the mould of Fig. 9 in a still further state of opening with the mould beginning to release the valve during setting; and Fig. 14 is a sectional view of the mould of Fig. 9 with the valve apparatus substantially released from the mould and the valve member fully set in the valve opening.

Fig. 1 discloses separation apparatus comprising a collection tube 10 having a closed end 12 and an open end 14. As shown, the separator tube 16 has been inserted into the collection tube 10 through the open end 14.

The separator tube 16 comprises a tubular member 18 which is closed at one end by a plug 20.

The collection tube 10 is partially filled with a sample 22 which has been subjected toseparating, e.g., centrifugation, so as to move the formed elements of the blood 24 to the closed end 12 of the collection tube 10 while the serum or plasma 26 is located above the formed elements 24. As shown in Fig. 1, the separator tube 16 has been inserted into the collection tube 10 down through the serum or plasma 26 to a point where the serum or plasma has entered the separator tube 18 through a valve in a valve plug 20 which will now be described in detail with reference to Figs. 2-5.

As shown in Fig. 2, the valve plug 20 comprises a substantially cylindrical body portion 28 which is terminated at one end by a flange 30 which is adapted to form a seal along the wall of the collection tube 10 at a sealing surface 32. The other end of the body member 28 comprises a radially inwardly directed annular flange 34 which is adapted to form a valve seat along the surface 36 for a movable valve member 38. As shown in Fig.

2, the valve member 38 comprises a body portion 40 terminated by a sealing head portion 42 which is adapted to seat on the surface 36 along a surface 44 when the sealing portion or head 42 is pushed through an opening 46 in the flange 34 as shown in Figs. 4 and 5.

In order to provide a closing bias on the valve member 38 which is independent of the diameter of the tubular member 18, resilient strand or strut members 48 are attached to the interior walls 50 of the cylindrical body 28 of the plug 20. As shown in Fig. 3, three such struts or strands 48 may be utilized which are evenly spaced around the wall 50 and the valve member 38 at points of attachment 52 so as to assure that the appropriate seal will be formed between the sealing surface 44 and the seating surface 36 shown in Fig. 2.

Figs. 2 and 3 show an integrally moulded plug 20 which comprises an elastomeric material such as Kraton or rubber. As shown in. Fig. 2, the valve member 38 is in the unbiased position since there is no tension on the strands 48. However, once the head or sealing portion 42 is forced through the opening 46 as shown in Figs. 4 and 5, the strands 48 are under tension and store energy so as to force the sealing surface 44 into contact with the seating surface 36 when the separator tube is in the stationary position as shown in Fig. 1.

As also shown in Figs. 2 and 3, the flange 30 comprises annular relieved areas 54 located on opposite sides of the flange 30. The relieved areas 54 allow the sealing surface 32 to be extended radially outwardly or retracted radially inwardly so as to accommodate different internal diameters in the collection tube 10 as shown in Fig. 1. Fig. 2 also shows an annular bead 55 which is adapted to form a seal with the separator tube 16 as shown in Figs. 4 and 5. By relying on the bead 55 to form the necessary seal, the tolerances on the diameter of the tubular member 18 as shown in Figs. 4 and 5 becomes less critical. Similarly, an annular recess 57 is provided around the valve opening 46 so as to preclude contact between the tubular member 18 and the plug 20 at the valve opening, which could impair proper operation of the valve.

Referring now to Figs. 4 and 5, the valve plug 20 is shown in the operable position, i.e., the head 42 is located above the seating surface 36. As also shown in Figs. 4 and 5, a filter 56 is inserted into the central cavity formed by the wall 50 of the body member 28 so as to filter out fibrin and any formed elements of blood which remain suspended in the plasma or serum as the separator tube 16 is inserted into the collection tube 10 in the direction indicated by arrow I as shown in Fig. 4. As the separator tube 16 is pushed in the direction indicated by the arrow I, the head 42 is forced upwardly off the seating surface 36 so as to permit the filtered serum or plasma to flow around the valve body 40 and the head 42 and through the opening 46 in the flange 34 as depicted by arrows II.

In Fig. 5, the separator tube 16 is being withdrawn from the collection tube 10 in the direction indicated by the arrows III. Under these circumstances, the seating surface 44 of the head 42 is in sealing engagement with sealing surface 36 so as to prevent the flow of the serum or plasma through the valve opening 46. As the separator tube 16 is withdrawn from the collection tube 10, air passes between the sealing surface 32 and the collection tube 10 as depicted by the arrows IV.

Reference will now be made to Fig. 6 wherein a modification of the valve plug of Figs. 1-5 is shown. More particularly, the valve plug 20a includes a hood 58 adjacent the valve opening 46 and the head 42. The hood 58 includes a radially inwardly directed flange 60 and a central opening 62. The flange 60 serves to deflect the serum or plasma which flows through the opening 46 so as to avoid any squirting of the plasma out the end of the separator tube. The arrows V depict the deflection of the serum or plasma.

The remainder of the plug 20a shown in Fig.

6 is substantially identical to the plug 20 shown in detail in Figs. 2-5.

Referring now to the valve plug shown in Fig. 7, a plug 20b comprises a modified valve member 38b having substantially no body but merely the head 42. The struts or strands 48b are attached to a wafer-like projection 40b. Due to the forces exerted by the strands 48b at the periphery of the head 42, the head 42 of the valve member 38b is particularly resistent to any deformation which could result in squirting of the plasma or serum through the opening 62. In other words, these forces exerted by strands tend to maintain the valve head 42 in the shape shown in Fig.

7 and this is also particularly important in preventing the head 42 from becoming jammed open in the opening 46. As shown in Fig. 8, the strands 48b extend across the valve opening 46 from the wall 50. This assures that the strands 48b do not rub or become hung up on the flange 34 at the edge of the opening 46 which might occur if the strands 48b did not cross to the opposite side of the opening 46. It will be appreciated that even the projection 40b may be eliminated and the strands attached directly to the head 42. In order to avoid interference at point 63, the strands 48b are attached at different elevations on the wall 50.

The plug 20b of Fig. 7 also comprises an annular projection or bead 64 located on the wall 50 just above the filter 56. The bead 64 assures that the filter is not forced upwardly toward the valve member 38b thereby preventing interference therewith. An additional annular bead 55 on the body 28 is also provided to form the seal with the tubular member 18. In addition, a plurality of check valves 66 extend through the flange 30 beneath the tubular member 18. These valves are closed when the separator tube 16 is inserted into the collection tube 10 as shown in Fig. 7, but opened as the separator tube 18 is removed from the collection tube 10 as shown in Fig. 7a so as to allow air to enter the collection tube. Such check valves 66 are disclosed in U.S. patent 3,954,614.

The valve plugs 20, 20a and 20b are all made by a similar method and therefore only the manufacture of plug 20a will be specifically described by reference to Figs. 9-14.

As shown in Fig. 9, a valve plug 20a has been moulded between a first mould section 100 and a second mould section 102. The first mould section 100 includes an outer portion 104 which partially forms the flange 30 and a central portion 106 which partially forms the walls 50 and a portion of the valve member 38 as well as the strands 48 within the chamber formed by the walls 50.

The second section 102 of the mould comprises an outer portion 108, an inner or central portion 110 and a sleeve 112 therebetween. The outer portion 108 forms the wall of the plug 20 including the beads 55.

The inner or central portion 110 forms the flanges 34 and 60 as well as the valve opening 46. The central portion 110 also forms a substantial portion of the valve member 40 including the head 42 as well as cooperating with the first section 100 of the mould to form the strands 48. After the moulding has been completed as depicted by Fig. 9, the mould sections 100 and 102 begin to separate as shown in Fig. 10. As the second section 102 separates from the first section 100, the flange 30 is released from the outer portion 104 of the first section 100 and the inner portion 106 is withdrawn from the interior chamber of the plug 20a. The plug 20a remains in place with respect to the outer portion 108, the inner portion 110 and the sleeve 112 of the second mould section 102 which, at this initial stage of release, move as a unit.

In Fig. 11, the sleeve 112 has become stationary as the outer mould portion 108 and the inner mould portion 110 of the second section 102 continue to move so as to hold the flange 60 and the flange 34 and begin the release of the plug 20a with respect to the second mould section 102. Simultaneously the setting of the valve member 40 is initiated as the flange 34 which forms the valve opening 46 begins to deform so as to permit passage of the head 46 therethrough.

Referring now to Fig. 12, the opening 46 in the flange 34 is now fully deformed as the head 42 of the valve member 38 passes therethrough. This is accomplished by permitting the outer portion 108 and the inner portion 110 of the mould section 102 to continue opening or moving with respect to the valve section 110 while the stationary sleeve 112 holds the flanges 60 and 34. It will be noted that the valve member 38 including the head 42 is fully retained within the mould members 108 and 110 as long as the flange 34 continues to be deformed so as to enlarge the opening 46. It will be further noted that the strands 48 of the connective means are extensively stretched at this stage in the mould opening procedure.

In Fig. 13, as the mould section 102 exclusive of the sleeve 112 continues to move, the strands 48 are stretched to a point so as to provide sufficient force to pull the valve member 38 from the inner portion 110 of the mould section 102. Since the flange 34 has now returned to the original moulded state, i.e., underformed, the head 42 of the valve member 38 will not pass through valve opening 46 when the valve member 38 is fully released from the inner mould portion 110 as shown in Fig. 14.

It will therefore be appreciated that valve member 38 is moulded within the chamber formed by the walls 50 of the plug 20a.

However, prior to removal of the valve from the mould, the valve member 38 with the head 42 is moved from one side of the valve opening to the other side to set the valve.

Simultaneously with the setting of the valve, the connective means, i.e., the strands 48, are subjected to stretching so as to ultimately bias the valve member 38 to the closed position.

In the foregoing, a description is provided as to how tension is developed on the strands 48. It will also be understood that the tension on the strands 48 may be relieved by forcing the head 42 back through the opening 46. It will also be understood that the head 42 may be moulded in place on the opposite side of the valve opening and then pushed through the opening thereby placing tension on the strands which are appropriately positioned on the wall 50 for this purpose.

WHAT I CLAIM IS: 1. A separator tube adapted to be pushed into a collection tube containing blood for separating serum or plasma from the formed elements of the blood, comprising a tubular member, means adapted to form a seal with the collection tube as the separator tube is pushed into the collection tube, and a valve comprising a valve body with a seat having a valve opening therein, the valve opening permitting serum or plasma to flow into the tubular member when the separator tube is plunged into the collection tube, a movable valve member adapted to seat on the valve seat so as to close the valve opening, and connective means extending between the valve member and the valve body and maintaining a substantial seating force on the valve member when the valve opening is closed.

2. A separator tube according to claim 1, wherein the connective means is maintained under tension when the valve member is seated on the valve seat so as to close the valve opening.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. shown in Fig. 7a so as to allow air to enter the collection tube. Such check valves 66 are disclosed in U.S. patent 3,954,614. The valve plugs 20, 20a and 20b are all made by a similar method and therefore only the manufacture of plug 20a will be specifically described by reference to Figs. 9-14. As shown in Fig. 9, a valve plug 20a has been moulded between a first mould section 100 and a second mould section 102. The first mould section 100 includes an outer portion 104 which partially forms the flange 30 and a central portion 106 which partially forms the walls 50 and a portion of the valve member 38 as well as the strands 48 within the chamber formed by the walls 50. The second section 102 of the mould comprises an outer portion 108, an inner or central portion 110 and a sleeve 112 therebetween. The outer portion 108 forms the wall of the plug 20 including the beads 55. The inner or central portion 110 forms the flanges 34 and 60 as well as the valve opening 46. The central portion 110 also forms a substantial portion of the valve member 40 including the head 42 as well as cooperating with the first section 100 of the mould to form the strands 48. After the moulding has been completed as depicted by Fig. 9, the mould sections 100 and 102 begin to separate as shown in Fig. 10. As the second section 102 separates from the first section 100, the flange 30 is released from the outer portion 104 of the first section 100 and the inner portion 106 is withdrawn from the interior chamber of the plug 20a. The plug 20a remains in place with respect to the outer portion 108, the inner portion 110 and the sleeve 112 of the second mould section 102 which, at this initial stage of release, move as a unit. In Fig. 11, the sleeve 112 has become stationary as the outer mould portion 108 and the inner mould portion 110 of the second section 102 continue to move so as to hold the flange 60 and the flange 34 and begin the release of the plug 20a with respect to the second mould section 102. Simultaneously the setting of the valve member 40 is initiated as the flange 34 which forms the valve opening 46 begins to deform so as to permit passage of the head 46 therethrough. Referring now to Fig. 12, the opening 46 in the flange 34 is now fully deformed as the head 42 of the valve member 38 passes therethrough. This is accomplished by permitting the outer portion 108 and the inner portion 110 of the mould section 102 to continue opening or moving with respect to the valve section 110 while the stationary sleeve 112 holds the flanges 60 and 34. It will be noted that the valve member 38 including the head 42 is fully retained within the mould members 108 and 110 as long as the flange 34 continues to be deformed so as to enlarge the opening 46. It will be further noted that the strands 48 of the connective means are extensively stretched at this stage in the mould opening procedure. In Fig. 13, as the mould section 102 exclusive of the sleeve 112 continues to move, the strands 48 are stretched to a point so as to provide sufficient force to pull the valve member 38 from the inner portion 110 of the mould section 102. Since the flange 34 has now returned to the original moulded state, i.e., underformed, the head 42 of the valve member 38 will not pass through valve opening 46 when the valve member 38 is fully released from the inner mould portion 110 as shown in Fig. 14. It will therefore be appreciated that valve member 38 is moulded within the chamber formed by the walls 50 of the plug 20a. However, prior to removal of the valve from the mould, the valve member 38 with the head 42 is moved from one side of the valve opening to the other side to set the valve. Simultaneously with the setting of the valve, the connective means, i.e., the strands 48, are subjected to stretching so as to ultimately bias the valve member 38 to the closed position. In the foregoing, a description is provided as to how tension is developed on the strands 48. It will also be understood that the tension on the strands 48 may be relieved by forcing the head 42 back through the opening 46. It will also be understood that the head 42 may be moulded in place on the opposite side of the valve opening and then pushed through the opening thereby placing tension on the strands which are appropriately positioned on the wall 50 for this purpose. WHAT I CLAIM IS:

1. A separator tube adapted to be pushed into a collection tube containing blood for separating serum or plasma from the formed elements of the blood, comprising a tubular member, means adapted to form a seal with the collection tube as the separator tube is pushed into the collection tube, and a valve comprising a valve body with a seat having a valve opening therein, the valve opening permitting serum or plasma to flow into the tubular member when the separator tube is plunged into the collection tube, a movable valve member adapted to seat on the valve seat so as to close the valve opening, and connective means extending between the valve member and the valve body and maintaining a substantial seating force on the valve member when the valve opening is closed.

3. A separator tube according to claim 2,

wherein the connective means comprises at least one flexible strand maintained under tension.

4. A separator tube according to claim 3, wherein there is a plurality of flexible strands.

5. A separator tube according to claim 4, wherein the strands cross over across the valve opening.

6. A separator tube according to claim 3, 4 or 5, wherein the or each strand is of elastomeric material.

7. A separator tube according to any of claims 3 to 6, wherein the valve member comprises a head above the seat and a part projecting through the valve opening and to which the strand(s) are attached.

8. A separator tube according to any of claims 3 to 7, wherein the valve member has a head above the seat which head floats above the seat when liquid flows up into the tubular member and separates from the seat all round its periphery.

9. A separator tube according to any of claims 1 to 8, wherein the valve body has a hollow chamber with the seat at one end and wherein the connective means are connected to the body inside the chamber.

10. A separator tube according to any of claims 1 to 9, wherein the valve member is capable of being pushed through the seat between a non-working position below the seat, in which the connective means are unstressed, and a working position above the seat, in which the connective means are stressed and urge the valve member against the seat.

11. A separator tube according to claim 9, further comprising a filter element lodged in the hollow chamber, the body including a projection extending into the hollow chamber above the filter element to prevent the filter element from moving upward and interfering with the valve member and connective means.

12. A separator tube according to any of claims 1 to 11, including a hood means located adjacent the valve opening for deflecting serum or plasma passing through the valve opening.

13. A separator tube according to claim 12, wherein the hood comprises a flange forming an opening located above the valve opening, the flange deflecting the serum or plasma before its passage through the central opening.

14. A separator tube according to any of claims 1 to 13, wherein the valve body, including the valve seat, the valve member and the connective means are an integrally moulded structure.

15. A separator tube according to claim 14, wherein the structure is moulded from elastomeric material.

16. A separator tube according to any of claims 1 to 15, wherein the valve body is a plug in one end of the tubular member.

17. A separator tube according to claim 16, wherein the plug comprises an annular recess around the valve opening so as to space the plug from the tubular member at the valve opening and thereby prevent the tubular member from affecting the operation of the valve member at the valve opening.

18. A separator tube according to claim 16 or 1;7, wherein the plug comprises a sealing bead projecting outwardly for forming the seal with the tubular member.

19. A separator tube according to claim 16, 17 or 18, wherein the plug further comprises a sealing flange extending radially outwardly beyond the tubular member so as to form the seal with the collection tube.

20. A separator tube according to claim 19, wherein the plug further comprises a check valve associated with the flange arranged to allow air to pass into the collection tube for preventing the valve member from being pulled into the valve opening as the separator tube is removed from a collection tube.

21. A separator tube substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.