| 摘要 |
A pneumatically activated retractable-needle syringe comprising a syringe barrel, a plunger, a needle, a needle hub, a locking tip, a propellant gas release cell and a rupture mechanism is provided. The plunger is slidably disposed within and sealingly engaged with the syringe barrel, the plunger having a retraction lumen defined for receiving a needle when the retractable-needle syringe is actuated. The needle is coupled to a distal end of the syringe barrel and in fluid communication with a medicament chamber defined within the syringe barrel distally of the plunger. The needle hub is for securing the needle at the distal end of the syringe barrel, the needle hub being initially secured within a false wall against a loading force or an injection force applied by a user, and releasable from the false wall in response to a post-injection force applied by a user. The locking tip is provided at a distal end of the plunger, the locking tip being in sealing engagement with and initially secured within the retraction lumen against a loading force or an injection force applied by a user, and releasable for sliding retraction within the plunger lumen in response to release of propellant upon a post-injection force applied by a user, the locking tip being engageable with the needle hub in response to the post-injection force to provide a retraction assembly comprising the locking tip, the needle header, and the needle. The propellant release cell is positioned distally of the needle hub and contains a propellant. The rupture mechanism is positioned to puncture the propellant release cell in response to the application of the post-injection force by a user to thereby drive retraction of the retraction assembly within the retraction lumen. |
