A protective sleeve (20) placed within the cylinder of a syringe (2), the sleeve protects a piston (4) and a computer controlled device or human operator pushing the piston from material leaking past a piston assembly (4). The sleeve has lips (22, 24) or ridges at either end, one (22) that is attached to the piston assembly at the output end (8) of the syringe and a second lip (24) that is attached with a retention plate at the far end of the syringe. The sleeve may have a bellows or accordion configuration that slides along the inner surface (12) of the syringe cylinder (14) without appreciably loading the drive mechanism.
