Capillary tube closure

1. A tube assembly comprising:

a tube having a first end and an opposed second end and a bore extending therethrough, the tube adapted to draw a liquid into the tube by virtue of capillary action or a fluid by gravitational action;

a closure at least partially inserted in the first end and adapted to be slidably movable between a first position and a third position;

the closure including:

a substantially cylindrical body having an outer surface and a proximal end inserted inside the bore and a distal end in close proximity with the first end, the body having a plurality of channels extending along the outer surface between the proximal end and the distal end; and

a seal region extending along a periphery of the outer surface between the distal end and the plurality of channels,

wherein with the closure in the first position, vapor contained in the bore is adapted to exit the bore from the first end via a plurality of passageways each defined by the bore and a corresponding channel in response to the liquid being drawn into the tube bore by capillary action,

wherein with the closure in a second position, the seal region is sufficiently inserted inside of the first end, defining a fluid tight seal therebetween and preventing the drawn liquid within the tube bore from escaping, and

wherein in response to slidable movement of the closure relative to the tube from the second position toward the third position, at least a portion of the liquid inside the bore is urged to exit the tube from the second end.

2. The tube assembly of claim 1 , wherein each of the plurality of channels defines a tortuous path.

3. The tube assembly of claim 1 , wherein at least a portion of at least one channel has a uniform cross section.

4. The tube assembly of claim 1 , wherein at least a portion of at least one channel has a non-uniform cross section.

5. The tube assembly of claim 1 , wherein the closure is composed of an elastically compressible material.

6. The tube assembly of claim 1 , wherein a force sufficient to slidably move the closure from the first position toward the second position and from the second position toward the third position is less than a predetermined force.

7. The tube assembly of claim 6 , wherein the predetermined force is a force applied along the longitudinal axis of the tube and having a magnitude insufficient to permanently damage the tube.

8. The tube assembly of claim 6 , wherein the predetermined force is a force applied at a non-zero acute angle to the longitudinal axis of the tube and having a magnitude insufficient to permanently damage the tube.

9. The tube assembly of claim 1 , wherein the closure is an elastomer.

10. The tube assembly of claim 1 , wherein the capillary tube assembly is adapted to be placed in a centrifuge with the closure in the second position or the third position.

11. The tube assembly of claim 1 , wherein the distal end includes a flange extending outwardly from the body, the flange is adapted to form a fluid tight seal in the third position.

12. The tube assembly of claim 11 , wherein the flange is perforated.

13. The tube assembly of claim 11 , wherein the flange is adapted to be separable from the distal end in response to a sufficient force applied to the distal end of the closure in the third position.

14. The tube assembly of claim 1 , wherein the closure has a pigment visually contrasting with the fluid or the liquid.

15. The tube assembly of claim 1 , wherein the closure has a pigment visually contrasting with blood.

16. The tube assembly of claim 1 , wherein the proximal end is tapered.

17. The tube assembly of claim 1 , wherein the outer surface has a coefficient of friction less than 0.5.

18. A closure adapted for insertion in a tube having a first end and an opposed second end and a bore extending therethrough, the tube adapted to draw a liquid into the tube by virtue of capillary action, the closure at least partially insertable in the first end and adapted to be slidably movable between a first position and a third position, the closure comprising:

a substantially cylindrical body having an outer surface and a proximal end adapted to be inserted inside the bore and a distal end in close proximity with the first end, the body having a plurality of channels extending along the outer surface between the proximal end and the distal end; and

a seal region extending along a periphery of the outer surface between the distal end and the plurality of channels,

wherein with the closure in the first position, vapor contained in the bore is adapted to exit the bore from the first end via a plurality of passageways each defined by the bore and a corresponding channel in response to the liquid being drawn into the tube by capillary action,

wherein with the closure in a second position, the seal region is sufficiently inserted inside of the first end, defining a fluid tight seal therebetween and preventing the drawn liquid within the tube bore from escaping, and

wherein in response to slidable movement of the closure relative to the tube from the second position toward the third position, at least a portion of the liquid inside the bore is urged to exit the tube from the second end.

19. The closure of claim 18 , wherein the closure has a pigment visually contrasting with the fluid or the liquid.

20. A capillary tube assembly comprising:

a tube having a first end and an opposed second end and a bore extending therethrough, the tube adapted to draw a liquid into the tube by virtue of capillary action;

a closure at least partially inserted in the first end and adapted to be slidably movable between a first position and a third position;

the closure including:

a substantially cylindrical body having an outer surface and a proximal end inserted inside the bore and a distal end in close proximity with the first end, the body having a plurality of channels extending along the outer surface between the proximal end and the distal end; and

a seal region extending along a periphery of the outer surface between the distal end and the plurality of channels,

wherein with the closure in the first position, vapor contained in the bore is adapted to exit the bore from the first end via a plurality of passageways each defined by the bore and a corresponding channel in response to the liquid being drawn into the tube bore by capillary action,

wherein with the closure in a second position, the seal region is sufficiently inserted inside of the first end, defining a fluid tight seal therebetween and preventing the drawn liquid within the tube bore from escaping, and

wherein in response to slidable movement of the closure relative to the tube from the second position toward the third position, at least a portion of the liquid inside the bore is urged to exit the tube from the second end.