Plastic Stopper

Abstract

A stopper includes 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 configured to engage at least a top portion of the plunger rod, a closed front end forming a flexible roof, and a first perimetrical skirt extending around an outer circumference of the main body portion toward the closed front end of the main body portion. 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.

1 . A stopper adapted for attachment with a plunger rod for use within a syringe barrel, the stopper comprising:
 a main body portion defining an open rearward end configured to receive the plunger rod, an engagement portion comprising a protruding portion provided along an inner circumference of the main body portion configured to engage at least a top portion of the plunger rod, and a closed front end forming a flexible roof; and   a first perimetrical skirt extending around an outer circumference of the main body portion toward the closed front end of the main body portion,   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.   
     
     
         2 . The stopper of  claim 1 , wherein the closed front end of the main body has a conical shape with a tip. 
     
     
         3 . The stopper of  claim 2 , wherein the tip comprises an extended portion configured to fit inside a tip of the syringe barrel. 
     
     
         4 . The stopper of  claim 1 , wherein the stopper, the plunger rod, and the syringe barrel are manufactured from the same material. 
     
     
         5 . The stopper of  claim 1 , wherein the stopper is manufactured from a rigid or semi-rigid polymeric material. 
     
     
         6 . The stopper of  claim 5 , wherein the rigid or semi-rigid polymeric material has an elastic modulus in the range of about 0.01 GPa to about 5 GPa. 
     
     
         7 . The stopper of  claim 6 , wherein the rigid or semi-rigid polymeric material has an elastic modulus in the range of about 0.6 GPa to about 2 GPa. 
     
     
         8 . The stopper of  claim 6 , wherein the rigid or semi-rigid polymeric material is selected from the group consisting of: polyolefines, polyamides, polyesters, polystyrene, polyurethane, polycarbonate, acrylonitrile-butadiene-styrene, fluoropolymers, ionomers, polyacrylates, or any combination thereof. 
     
     
         9 . The stopper of  claim 1 , wherein the flexible roof has a thickness of about 0.1 mm to about 3 mm. 
     
     
         10 . The stopper of  claim 9 , wherein the flexible roof has a thickness of about 0.3 mm to about 1.2 mm. 
     
     
         11 . The stopper of  claim 1 , wherein the first perimetrical skirt has a thickness of about 0.05 mm to about 3 mm and a length of about 1 mm to about 10 mm. 
     
     
         12 . The stopper of  claim 11 , wherein the first perimetrical skirt has a thickness of about 0.2 mm to about 0.5 mm. 
     
     
         13 . The stopper of  claim 1 , further comprising:
 a second perimetrical skirt extending around an outer circumference of the main body portion toward the open rearward end of the main body such that the second perimetrical skirt provides stability to the stopper in an axial direction,   wherein, when fluid pressure is decreased inside the syringe barrel during an aspiration, the second perimetrical skirt is forced against the inner wall of the syringe barrel, thereby providing a sealing pressure between the stopper and the inner wall of the syringe barrel.   
     
     
         14 . The stopper of  claim 13 , wherein the second perimetrical skirt has a thickness of about 0.05 mm to about 3 mm and a length of about 1 mm to about 10 mm. 
     
     
         15 . The stopper of  claim 14 , wherein the second perimetrical skirt has a thickness of about 0.2 mm to about 0.5 mm. 
     
     
         16 . The stopper of  claim 1 , wherein the top portion of the plunger rod includes a notch formed around an outer circumference thereof that engages the protruding portion of the main body such that the engagement between the plunger rod and the protruding portion forces the main body portion to expand in the radial direction toward the inner wall of the syringe barrel during both an injection and an aspiration. 
     
     
         17 . 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 the plunger rod, an engagement portion comprising a protruding 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.   
     
     
         18 . The syringe of  claim 17 , 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. 
     
     
         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 comprising a protruding 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.   
     
     
         20 . The assembly of  claim 19 , 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.