Additive Manufacturing (AM) is creating many opportunities in the medical device manufacturing industry, but one of the most important aspects of plastic AM medical devices has not yet been closely examined; sterility of implantable products.
Devices that go inside the body need to be sterile to prevent infection. However, sterilization of AM plastics is not a straightforward process. The most common steam sterilization process reaches temperatures up to 145 degrees Celsius, often deforming or melting the plastics in the process. Alternative sterilization methods are available with lower temperatures such as; hydrogen peroxide vapour, gamma irradiation, electron-beam irradiation, and ethylene oxide gas. Not all of these methods are safe for plastics.
Gamma and e-beam can lead to hardening of the materials (risk of fracture) as well as oxidation which can cause cracking and delamination. Peroxide and EtO are lower temperature and don’t affect the chemical structure, however they may chemically degrade or dissolve the plastics during sterilization. Further, AM inherently creates porosity in the products, which could create small pockets which are inaccessible to external sterilization gases or chemicals.
Over the next 4 months, the Orthopaedic Innovation Centre (OIC) Clinical Engineering and Research group will be performing research into these areas and trying to answer these important questions:
- What is the most effective available method to ensure an AM plastic product is sterile, both on the external surface and internally?
- Does this method affect the mechanical or chemical properties of the material?
If you would like further information on this work, please contact us.