Low-energy electron beam sterilization for medical technical applications

New and highly functionalized medical products cannot be sterilized by standard sterilization methods like hot steam or sterilizing gases, as they are temperature sensitive, contain electronic parts like microchips or consist of polymeric materials. The use of gamma irradiation for the sterilization of such products is also problematic due to long exposure times under radical process conditions, which lead to an increased degradation and therefore a loss of functionality or product stability. Using low-energy electron beam irradiation (eB) enables sterilization of medical surfaces within seconds as this technology offers high dose rates in comparison to gamma irradiation. Therefore, degradation processes can be prevented. Electron beam irradiation complies with international standards (ISO 11137) and is a worldwide accepted sterilization method. In addition, by using low-energy electron beam irradiation it is possible to define the penetration depth in order to prevent electronic parts damage. We investigated whether complex 3D geometries can be sterilized using a mini-eB source and low-energy eB treatment with a source smaller than the packed medical product. Therefore, a process for 3D handling using a small eB source was developed and investigated in terms of efficacy and safety. Furthermore, a suitable packaging material was evaluated for sterile handling of the medical products. We demonstrated that B. pumilus and P. aeruginosa surface-contaminated test specimens were sterilized reproducibly by the process developed, while the eB treatment had no negative influence on the biocompatibility, form and function of the sterilized test specimens and the selected packaging material.