Characterization of Plastic Hypodermic Needles

Abstract

A significant potential for plastic hypodermic needles exists as an alternative to current steel needles. This paper presents the design and testing of one type of plastic hypodermic needle. The buckling and penetration characteristics of the needles were modeled and analyzed analytically and by finite element analyses. Experimental penetration tests using plastic and steel control hypodermic needles with skin mimics, specifically polyurethane film and pig skin, were performed to determine penetration and friction forces. Lubricated plastic needles achieved successful penetrations in 25–75% of the tests in both polyurethane film and pig skin with penetration forces ranging from 7 N to 10 N. Penetration tests into butyl rubber stoppers also were conducted with lubricated plastic needles penetrating in 75% of the tests with an average penetration force of 8.3 N. Various lubricants, including silicone oil and a medical grade silicone dispersion, were also studied. In addition, the needles underwent successful perpendicular bending tests and cannula stiffness tests. Finally, fluid flow tests determined fluid flow rates through the needles. Experimental results were compared with each other and to finite element analyses and are discussed.