FLUID ACTIVATED RETRACTABLE SAFETY SRYINGE

摘要

A retractable safety syringe is provided wherein a retraction force retracts a needle and a needle holder into a syringe body when a piston engages the needle holder. The engagement between the piston and the needle holder may be fluid activated such that engagement between the piston and needle holder exists only when fluid is in a variable fluid chamber. In particular, surface tension from the fluid on an annular suction groove or pocket and a textured top surface of the needle holder creates a suction force applied to the needle holder. The retraction force acts on the needle holder via the suction force to retract the needle holder and needle into the syringe body.