Positive displacement stopper for a pre-filled syringe

A stopper adapted for attachment with a plunger rod for use within a syringe barrel for positively displacing fluid out from within such syringe barrel, said stopper comprising:

• (a) a main body having a closed front end and a shoulder extending around a perimeter of said main body;
• (b) a core member integrally formed with said main body adjacent said closed front end, said core member including a nose portion, said nose portion having a profile adapted to create a positive seal with an interior surface of an outlet of such syringe barrel;
• and
• (c) a perimetrical skirt extending toward said front end of said main body, said skirt cooperating with said shoulder for establishing a space between said main body and said skirt so as to create a positive fluid pressure chamber.

A stopper adapted for attachment with a plunger rod for use within a syringe barrel for positively displacing fluid out from within such syringe barrel, said stopper comprising:

• (a) a main body having a closed front end and a shoulder extending around a perimeter of said main body, said main body including an inner surface having a taper adapted for contact with a corresponding taper on a forward end of such plunger rod, said contacting tapers cooperating together such that said stopper applies a radial force to such syringe barrel upon the application of a forward force to such plunger rod;
• (b) a core member integrally formed with said main body adjacent said closed front end, said core member including a nose portion, said nose portion having a profile adapted to create a positive seal with an interior surface of an outlet of such syringe barrel and wherein said inner surface of said main body is a continuous contour from a side wall portion of said main body to said core member;
• and
• (c) a perimetrical skirt extending toward said front end of said main body, said skirt cooperating with said shoulder for establishing a space between said main body and said skirt so as to create a positive fluid pressure chamber.

A positive displacement stopper adapted for attachment with a plunger rod for use within a syringe barrel of a flush syringe, said stopper comprising:

• (a) a main body having a closed front end and a first body portion having a first diameter;
• (b) a shoulder extending around a perimeter of said first body portion of said main body;
• (c) a core member integrally formed with said main body adjacent said closed front end, said core member including a nose portion, said nose portion adapted for contacting an interior surface of an outlet opening of such syringe barrel;
• and
• (d) a perimetrical skirt extending toward the front end of said main body, said skirt cooperating with said shoulder for trapping air pockets therein upon insertion of said stopper within such syringe barrel such that upon release of a force on such plunger rod, fluid remaining within such syringe barrel is forced through such outlet opening through positive displacement thereof.

A method of positively displacing fluid from and preventing reflux within a syringe barrel, said method comprising the steps of:

• (a) providing a stopper comprising a main body having a closed front end, a first body portion having a first diameter, a second body portion having a second diameter which is larger than said first diameter, and a core member integrally formed with said main body adjacent said closed front end, said core member including a nose portion, a shoulder extending around a perimeter of said first body portion of said main body, and a skirt extending about said first body portion of said main body, said skirt cooperating with said shoulder for trapping at least one air pocket therein;
• (b) advancing the stopper through the syringe barrel until the nose portion of the core member contacts an outlet opening at the forward end of the syringe, thereby forming a seal therewith and trapping fluid within the syringe to prevent flow out of the opening;
• (c) applying additional force to the stopper to compress the nose portion, thereby compressing the trapped air and increasing the pressure within said air pockets;
• and
• (d) releasing the force on the stopper to release the seal between the nose portion and the outlet opening at the forward end of the syringe while maintaining the main body of the stopper in an advanced position relative to a starting position within the syringe barrel, such that the increased pressure within the air pocket causes any trapped fluid to be expelled through said outlet opening.

A method of preventing reflux within a syringe barrel, said method comprising the steps of:

• (a) providing a stopper comprising a main body defining an open rearward end and a closed front end, said open rearward end adapted to receive a front attachment member of a plunger rod therein, a core member integrally formed with said main body adjacent said closed front end, said core member including a nose portion;
• (b) inserting a front attachment member of a plunger rod within the open rearward end of said stopper;
• (c) applying a force to said plunger rod to advance the stopper into the syringe barrel until the nose portion of the core member contacts an outlet opening at the front end of the syringe barrel forming a seal and trapping fluid from flowing out into the outlet opening;
• (d) applying additional force to said plunger rod to compress at least a portion of said stopper, so as to advance the at least one rib within the syringe barrel and to compress the trapped fluid to form increased pressure;
• (e) releasing the force on said plunger rod to release the seal between the nose portion and the outlet opening of the syringe barrel wherein friction force maintains said rib in an advanced position relative to a starting position within the syringe barrel such that the increased pressure causes any trapped fluid to be pushed through said outlet opening.

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

• (a) a plunger rod having a front attachment end and a back end and extending along a longitudinal axis;
• (b) at least one deflecting arm associated with said attachment end of said elongated member, said deflecting arm adapted to deflect radially inward upon an application of force thereto and to deflect radially outward upon a release of such force;
• and
• (c) a stopper having a main body defining an open rearward end, a closed front end, and a core member integrally formed with said main body adjacent said closed front end, said core member including a nose portion, said nose portion having a profile adapted to create a positive seal with an outlet opening of such syringe barrel, said open rearward end defined by an inside wall surface and an undercut portion, said open end adapted for receiving said front attachment end of said plunger rod such that said deflecting arm is deflected during insertion of said front attachment end and deflects outward after insertion to become trapped between at least a portion of said inside wall surface and said undercut portion to lock said plunger rod within said stopper.

A stopper adapted for attachment with a plunger rod for use within a syringe barrel, said stopper comprising:

• (a) a main body defining an open rearward end and a closed front end, said open rearward end adapted to receive a front forward end of such plunger rod;
• (b) at least one rib extending radially outward around a perimeter of said main body;
• and
• (c) at least one forward extending skirt extending from a front end of said main body.

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

• (a) a plunger rod having a front attachment end and a back end and extending along a longitudinal axis;
• (b) a stopper having a main body defining an open rearward end, a closed front end, and a core member integrally formed with said main body adjacent said closed front end, said open rearward end defined by an inside wall surface, said open end adapted for receiving said front attachment end of said plunger rod and locking said plunger rod within said stopper wherein a gap is provided between a front surface of said front attachment end of said plunger and a back end of said core member;
• and
• (c) a flexible membrane extending between said core member and said main body for interconnecting said core member with said main body, wherein during application of a forward force to said plunger rod, said flexible membrane is adapted for causing said core member to retract with respect to said stopper main body and store potential energy such that upon a release of the forward force thereto, the potential energy is released causing said core member to advance with respect to said main body of said stopper and prevent mid-stream reflux within such syringe barrel.