SELF-RETRACTABLE SAFETY (SRS) SYRINGE FOR SINGLE USE

摘要

The present subject matter relates to self-retractable safety syringe (100) for single use comprising a plunger assembly including a plunger barrel (102) and a plunger plug (103), a needle carrier assembly (114), and an outermost barrel (108). The plunger plug (103) holding a centrally positioned furrowed axial knob (134) housed in plunger barrel (102) at the proximal end and firmly held by the inner teeth T-2 & T-4 of finger locks (126) and (128) respectively. A needle carrier assembly (114) is housed in conical jacket of outermost barrel 108 holding a needle (110) along with a compressed spring (184). The needle is locked inside the needle carrier assembly with the help of finger lock (166) provided with outwardly protruded flange (168). The flange (168) is placed in contact with a slidable elastic O-ring (182) holding the needle carrier assembly inside the conical jacket. At the completion of injection process, the furrowed knob inserts into the distal cavity of needle (110) to lock the needle with plug. When the elastic O-ring slides in forward direction due to the axial movement of plunger barrel in forward direction, the O-ring pushes the flange (168) of finger lock (166), to unlock the lock. At the same time, the teeth outer T- 1 & T-3 of the finger locks (126) & (128) respectively become in alignment of inner circumferential conical groove (148) of outermost barrel (108) and restore their normal state by expanding in outward direction to occupy the outer space provided by the groove (148). This result the respective inner teeth T-2 & T-4 of the finger locks (126) & (128) to retract and release the plunger plug (103) due to expansion of locks in outward direction. Consequently, the plunger plug (103) holding the (needle 110) moves smoothly in backward direction due to the pressure exerted by expansion of (spring 184) in backward direction. Simultaneously, the finger lock (124) provided at the distal end of plunger barrel (102) slips into the inner circumferential conical groove (146) and click locks the plunger barrel (102) inside the outermost barrel (108) to render the syringe assembly completely locked with the needle encapsulated within the plunger barrel. The distally directing, outwardly protruded finger locks (125) and (127) provided at the proximal end of plunger barrel prevent the removal of plunger barrel (102) from the outermost barrel (108).