ISO 11135
EtO Sterilization for Medical Devices

ISO 11135 EtO Sterilization for Medical Devices


One of the most popular methods of sterilization of medical devices is through exposure to Ethylene Oxide gas (EtO/EO). The gas is an alkaline agent that infiltrates packaged medical devices to kill microorganisms and thus achieve sterilization. EtO is toxic and flammable/explosive at low temperatures (flash point of -20°C) and so is used on products that could get damaged or cannot withstand high temperature processes. Typically the process is applied on:

  • Plastic products/packaging that get discolored with irradiation
  • Devices that incorporate electronic components
  • Materials that get damaged at higher temperatures
  • Custom kits
  • Materials that are not compatible with other methods such as Gamma and Steam sterilization

Due to its reactive nature the actual EtO process must occur within enclosed chambers to prevent leaks and exposure to the ethylene oxide gas. Also EtO Sterilization is a lengthier process than other methods such as Gamma as it involves three stages:

  1. Preconditioning and/or Conditioning of device through temperature & humidity variations
  2. Gas Dwell Phase/Sterilizing Cycle where the device is exposed to the EtO gas
  3. Aeration of exposed device for removal of gas from the product

Tests conducted on EtO sterilized Medical Device are inclusive of but not limited to: