VACUUM-RETRACTABLE SAFETY (VRS) SYRINGE FOR SINGLE USE

Patent Pending The present invention Vacuum-retractable Safety Syringe 100 for Single use relates to a safety syringe having an auto retractable needle for use in the medical or dental profession or in personal drug administration so that the physicians, surgeons or other needle operators may be protected from the needle-stick injury during its use. The invention, in particular, relates to an assembly of the safety syringe which is simple and easy in handling, in which the hypodermic needle retracts itself automatically by virtue of self- generated vacuum and encapsulate within the barrel as soon as the last drop is injected in the body of patient. The syringe thereafter becomes finally locked to become non-reusable. The handling of syringe does not require any special training to the operators. It is simple in manufacture. The Vacuum Retractable Safety Syringe (VRS) for singe use comprises a plunger barrel assembly, outermost barrel and a needle carrier assembly holding a detachable needle along with needle cover. The plunger barrel assembly comprises an inner and an outer plunger barrels. The outer plunger barrel is provided with two diametrically opposite longitudinal slots holding conical notches of finger locks, provided at the distal end of the inner plunger barrel. The inner plunger barrel housing inside the outer plunger barrel is also provided with a second piston seal at proximal end. The outer plunger barrel opening at proximal end is provided with a first piston seal at the outer surface. The plunger plug provided with a centrally positioned furrowed knob at proximal surface is fixedly mounted at the proximal end of the outer plunger barrel. The finger lock is provided at the distal end of outer plunger barrel to prevent the removal of plunger assembly from the outermost barrel. The outer most barrel comprises a uniformly elongated hollow cylindrical tubular body, provided with a conical jacket opening at the proximal end, a finger rest and two sets of uniform, inner circumferential C-grooves at distal end. A conical needle carrier assembly comprising a hollow conical needle carrier holding a detachable straight hollow hypodermic needle is fixedly mounted in the conical jacket of the outermost barrel with the help of an elastic O-ring. The needle carrier is provided with a cavity with locking means to capture the knob provided in the plunger plug, which opens in a detachable straight hollow hypodermic needle at proximal end. While working with the syringe, the plunger assembly is pulled in backward direction until the notches get engage therein the conical groove to fix the inner plunger barrel. Further push of the plunger barrel in forward direction, creates a vacuum between the plunger plug and inner plunger barrel. The medicinal dosage may be sucked into the chamber between the outermost barrel and plunger assembly as usual. As soon as the last drop of medicine is injected into the body of patient, the furrowed nipple inserts and snaps locks into the cavity of needle carrier assembly with the help of locking members. The plunger assembly pushes the O-ring in forward direction to dislodge the needle carrier, consequently, the plunger plug holding needle carrier along with needle gently retracts in backward direction and finally encapsulates inside the plunger barrel due to the pull of vacuum. Simultaneously, the outwardly protruded finger lock snap locks within the conical groove to completely lock the plunger barrel inside the outermost barrel to render the complete syringe assembly quite unusable for any further use.