Case Study: Self-Lubricated Polyisoprene for Medical Septum Applications

The project

Develop a system that reduces the needle drag and piercing resistance of the septum and injection site materials to increase product performance.

The solution

Chemists developed a family of self-lubricated polyisoprene materials that have been manufactured with a proprietary lubricant system and show a minimal reduction of physical and mechanical properties.

By Saman Nanayakkara and Shu Peng

Due to its availability as an ISO 10993 medical grade compound, polyisoprene rubber, which has a unique set of combined mechanical and chemical properties, has been widely used in medical device applications. The material is ideal for septums and injection sites for medical fluid transfer applications. Medical grade polyisoprene compounds have high tear strength and high elastic resilience. These characteristics can provide the desired resealability properties of the septum or injection site after piercing one or more times with a needle.

Medical device manufacturers have long sought a reduction in needle drag or piercing resistance of septum and injection site materials to increase product performance. Post molding surface treatment to modify coefficient of friction is the conventional approach taken to reduce tackiness for improved part handling. This process, however, is a surface treatment for reducing surface friction and does not effectively reduce needle drag, which is caused largely by friction within the septum and injection site materials. Furthermore, this secondary surface treatment adds additional cost to the component.