Plastic stopper

1. A syringe comprising:

a) a substantially cylindrical syringe barrel comprising a fluid dispensing end and an open end;

b) a stopper configured to be received within the open end of the syringe barrel, the stopper comprising:

i) a main body portion defining an open rearward end configured to receive a plunger rod, an engagement portion provided along an inner circumference of the main body portion, and a closed front end forming a flexible roof; and

ii) a first perimetrical skirt extending around an outer circumference of the main body portion toward the closed front end of the main body portion; and

c) a plunger rod having a plunger rod body extending along a longitudinal axis, the plunger rod body comprising a front attachment end having a radially extending member configured to engage the engagement portion provided along the inner circumference of the main body portion of the stopper and a back end,

wherein, when fluid pressure is increased inside the syringe barrel during an injection, the flexible roof expands in a radial direction toward an inner wall of the syringe barrel, the first perimetrical skirt is forced against the inner wall of the syringe barrel, and an engagement between the plunger rod and the engagement portion forces the main body portion to expand in the radial direction toward the inner wall of the syringe barrel, thereby providing a sealing pressure between the stopper and the inner wall of the syringe barrel, wherein the front attachment end of the syringe plunger body comprises an extension portion separate from the radially extending member and extending in a longitudinal direction with respect to the longitudinal axis of the plunger rod and toward the closed front end of the stopper, said extension portion configured to contact a lower surface of the flexible roof during an injection to limit the expansion of the flexible roof in the radial direction.

2. The syringe of claim 1 wherein, during an injection, the extension portion prevents inversion of the roof.

3. A syringe comprising:

a) a substantially cylindrical syringe barrel comprising a fluid dispensing end and an open end;

b) a stopper configured to be received within the open end of the syringe barrel, the stopper comprising:

i) a main body portion defining an open rearward end configured to receive a plunger rod, an engagement portion provided along an inner circumference of the main body portion, and a closed front end forming a flexible roof; and

ii) a first perimetrical skirt extending around an outer circumference of the main body portion toward the closed front end of the main body portion; and

c) a plunger rod having a plunger rod body extending along a longitudinal axis, the plunger rod body comprising a front attachment end configured to engage the engagement portion provided along the inner circumference of the main body portion of the stopper and a back end,

wherein, when fluid pressure is increased inside the syringe barrel during an injection, the flexible roof expands in a radial direction toward an inner wall of the syringe barrel, the first perimetrical skirt is forced against the inner wall of the syringe barrel, and an engagement between the plunger rod and the engagement portion forces the main body portion to expand in the radial direction toward the inner wall of the syringe barrel, thereby providing a sealing pressure between the stopper and the inner wall of the syringe barrel,

wherein the front attachment end of the syringe plunger body comprises an extension portion configured to contact a lower surface of the flexible roof during an injection, thereby limiting the expansion of the flexible roof in the radial direction, and

wherein the main body portion further comprises an annular segment extending forward from the engagement portion to support a peripheral portion of the flexible roof, such that an interior space is defined by the flexible roof, the annular segment, and the plunger rod.

4. The syringe of claim 3 , wherein the extension portion extends beyond a distal end of the annular segment.

5. The syringe of claim 3 , wherein, when fluid pressure is increased inside the syringe barrel during an injection, the flexible roof flexes inward across a diameter of the main body portion into the interior space, and wherein the extension portion prevents the flexible roof from fully inverting during the injection.

6. The syringe of claim 3 , wherein the engagement portion comprises an upwardly angled portion and a downwardly angled portion, which together form an angled notch extending along an inner circumference of the main body portion.

7. The syringe of claim 6 , wherein each of the upwardly angled portion and the downwardly angled portion forms an acute angle with a horizontal line extending between the upwardly angled portion and the downwardly angled portion.

8. The syringe of claim 6 , wherein the engagement between the plunger rod and the angled notch forces an upper portion of the annular segment to bend outwardly during movement of the plunger.

9. A syringe comprising:

a) a substantially cylindrical syringe barrel comprising a fluid dispensing end and an open end;

b) a stopper configured to be received within the open end of the syringe barrel, the stopper comprising:

i) a main body portion defining an open rearward end configured to receive a plunger rod, an engagement portion provided along an inner circumference of the main body portion, and a closed front end forming a flexible roof; and

ii) a first perimetrical skirt extending around an outer circumference of the main body portion toward the closed front end of the main body portion; and

c) a plunger rod having a plunger rod body extending along a longitudinal axis, the plunger rod body comprising a front attachment end configured to engage the engagement portion provided along the inner circumference of the main body portion of the stopper and a back end,

wherein, when fluid pressure is increased inside the syringe barrel during an injection, the flexible roof expands in a radial direction toward an inner wall of the syringe barrel, the first perimetrical skirt is forced against the inner wall of the syringe barrel, and an engagement between the plunger rod and the engagement portion forces the main body portion to expand in the radial direction toward the inner wall of the syringe barrel, thereby providing a sealing pressure between the stopper and the inner wall of the syringe barrel,

wherein the stopper further comprises an extension extending from a tip of the stopper main body portion toward the open rearward end, the extension configured to be connected to the plunger rod to cause the flexible roof to expand in the radial direction toward the inner wall of the syringe barrel during an aspiration.

10. The syringe of claim 9 , wherein the front attachment end of the syringe plunger includes a rod having a head extending therefrom, said head being configured to engage the extension of the stopper.

11. A plunger rod and stopper assembly adapted for use with a syringe barrel, the assembly comprising:

a) a stopper comprising:

i) a main body portion defining an open rearward end configured to receive the plunger rod, an engagement portion provided along an inner circumference of the main body portion, and a closed front end forming a flexible roof; and

ii) a first perimetrical skirt extending around an outer circumference of the main body portion toward the closed front end of the main body; and

b) a plunger rod having a plunger rod body extending along a longitudinal axis, the plunger rod body comprising a front attachment end having a radially extending member configured to engage the engagement portion provided along the inner circumference of the main body portion of the stopper and a back end,

wherein, when fluid pressure is increased inside the syringe barrel during an injection, the flexible roof expands in a radial direction toward an inner wall of the syringe barrel, the first perimetrical skirt is forced against the inner wall of the syringe barrel, and an engagement between the plunger rod and the engagement portion forces the main body portion to expand in the radial direction toward the inner wall of the syringe barrel, thereby providing a sealing pressure between the stopper and the inner wall of the syringe barrel, wherein the front attachment end of the syringe plunger body comprises an extension portion separate from the radially extending member and extending in a longitudinal direction with respect to the longitudinal axis of the plunger rod and toward the closed front end of the stopper, said extension portion configured to contact a lower surface of the flexible roof during an injection to limit the expansion of the flexible roof in the radial direction.

12. The plunger rod and stopper assembly of claim 11 , wherein, during an injection, the extension portion prevents inversion of the roof.

13. A plunger rod and stopper assembly adapted for use with a syringe barrel, the assembly comprising:

a) a stopper comprising:

i) a main body portion defining an open rearward end configured to receive the plunger rod, an engagement portion provided along an inner circumference of the main body portion, and a closed front end forming a flexible roof; and

ii) a first perimetrical skirt extending around an outer circumference of the main body portion toward the closed front end of the main body; and

b) a plunger rod having a plunger rod body extending along a longitudinal axis, the plunger rod body comprising a front attachment end configured to engage the engagement portion provided along the inner circumference of the main body portion of the stopper and a back end,

wherein, when fluid pressure is increased inside the syringe barrel during an injection, the flexible roof expands in a radial direction toward an inner wall of the syringe barrel, the first perimetrical skirt is forced against the inner wall of the syringe barrel, and an engagement between the plunger rod and the engagement portion forces the main body portion to expand in the radial direction toward the inner wall of the syringe barrel, thereby providing a sealing pressure between the stopper and the inner wall of the syringe barrel,

wherein the front attachment end of the syringe plunger body comprises an extension portion configured to contact a lower surface of the flexible roof during an injection, thereby limiting the expansion of the flexible roof in the radial direction and,

wherein the main body portion further comprises an annular segment extending forward from the engagement portion to support a peripheral portion of the flexible roof, such that an interior space is defined by the flexible roof, the annular segment, and the plunger rod.

14. The assembly of claim 13 wherein the extension portion extends beyond a distal end of the annular segment.

15. The assembly of claim 13 , wherein, when fluid pressure is increased inside the syringe barrel during an injection, the flexible roof flexes inward across a diameter of the main body portion into the interior space, and wherein the extension portion prevents the flexible roof from fully inverting during the injection.

16. The assembly of claim 13 wherein the engagement portion comprises an upwardly angled portion and a downwardly angled portion, which together form an angled notch extending along an inner circumference of the main body portion.

17. The assembly of claim 16 , wherein each of the upwardly angled portion and the downwardly angled portion forms an acute angle with a horizontal line extending between the upwardly angled portion and the downwardly angled portion.

18. The assembly of claim 16 , wherein the engagement between the plunger rod and the angled notch forces an upper portion of the annular segment to bend outwardly during movement of the plunger.

19. A plunger rod and stopper assembly adapted for use with a syringe barrel, the assembly comprising:

a) a stopper comprising:

i) a main body portion defining an open rearward end configured to receive the plunger rod, an engagement portion provided along an inner circumference of the main body portion, and a closed front end forming a flexible roof; and

ii) a first perimetrical skirt extending around an outer circumference of the main body portion toward the closed front end of the main body; and

b) a plunger rod having a plunger rod body extending along a longitudinal axis, the plunger rod body comprising a front attachment end configured to engage the engagement portion provided along the inner circumference of the main body portion of the stopper and a back end,

wherein, when fluid pressure is increased inside the syringe barrel during an injection, the flexible roof expands in a radial direction toward an inner wall of the syringe barrel, the first perimetrical skirt is forced against the inner wall of the syringe barrel, and an engagement between the plunger rod and the engagement portion forces the main body portion to expand in the radial direction toward the inner wall of the syringe barrel, thereby providing a sealing pressure between the stopper and the inner wall of the syringe barrel,

wherein the stopper further comprises an extension extending from a tip of the stopper main body portion toward the open rearward end, the extension configured to be connected to the plunger rod to cause the flexible roof to expand in the radial direction toward the inner wall of the syringe barrel during an aspiration.

20. The assembly of claim 19 , wherein the front attachment end of the syringe plunger includes a rod having a head extending therefrom, said head being configured to engage the extension of the stopper.

21. A syringe comprising:

a) a substantially cylindrical syringe barrel comprising a fluid dispensing end and an open end;

b) a stopper configured to be received within the open end of the syringe barrel, the stopper comprising:

i) a main body portion defining an open rearward end configured to receive a plunger rod, an engagement portion provided along an inner circumference of the main body portion, and a closed front end forming a flexible roof, wherein the closed front end forming the flexible roof of the stopper comprises a first angled portion and a second angled portion cooperating together to form a single continuous conical surface extending toward a tip, said flexible roof cooperating with the plunger rod to define a substantially hollow main body portion; and

ii) a first perimetrical skirt extending around an outer circumference of the main body portion toward the closed front end of the main body portion; and

c) a plunger rod having a plunger rod body extending along a longitudinal axis, the plunger rod body comprising a front attachment end having a radially extending member configured to engage the engagement portion provided along the inner circumference of the main body portion of the stopper and a back end,

wherein, when fluid pressure is increased inside the syringe barrel during an injection, the flexible roof expands in a radial direction toward an inner wall of the syringe barrel, the first perimetrical skirt is forced against the inner wall of the syringe barrel, and an engagement between the plunger rod and the engagement portion forces the main body portion to expand in the radial direction toward the inner wall of the syringe barrel, thereby providing a sealing pressure between the stopper and the inner wall of the syringe barrel.

22. The syringe of claim 21 , wherein the front attachment end of the syringe plunger body comprises an extension portion separate from the radially extending member and extending in a longitudinal direction with respect to the longitudinal axis of the plunger rod and toward the closed front end of the stopper, said extension portion configured to extend within the substantially hollow main body portion and to contact a lower surface of the flexible roof during an injection to prevent inversion of the roof and to limit the expansion of the flexible roof in the radial direction.

23. A plunger rod and stopper assembly adapted for use with a syringe barrel, the assembly comprising:

a) a stopper comprising:

i) a main body portion defining an open rearward end configured to receive the plunger rod, an engagement portion provided along an inner circumference of the main body portion, and a closed front end forming a flexible roof, wherein the closed front end forming the flexible roof of the stopper comprises a first angled portion and a second angled portion cooperating together to form a single continuous conical surface extending toward a tip, said flexible roof cooperating with the plunger rod to define a substantially hollow main body portion; and

ii) a first perimetrical skirt extending around an outer circumference of the main body portion toward the closed front end of the main body; and

b) a plunger rod having a plunger rod body extending along a longitudinal axis, the plunger rod body comprising a front attachment end having a radially extending member configured to engage the engagement portion provided along the inner circumference of the main body portion of the stopper and a back end,

wherein, when fluid pressure is increased inside the syringe barrel during an injection, the flexible roof expands in a radial direction toward an inner wall of the syringe barrel, the first perimetrical skirt is forced against the inner wall of the syringe barrel, and an engagement between the plunger rod and the engagement portion forces the main body portion to expand in the radial direction toward the inner wall of the syringe barrel, thereby providing a sealing pressure between the stopper and the inner wall of the syringe barrel.

24. The assembly of claim 23 , wherein the front attachment end of the syringe plunger body comprises an extension portion separate from the radially extending member and extending in a longitudinal direction with respect to the longitudinal axis of the plunger rod and toward the closed front end of the stopper, said extension portion configured to extend within the substantially hollow main body portion and to contact a lower surface of the flexible roof during an injection to prevent inversion of the roof and to limit the expansion of the flexible roof in the radial direction.