The different types of sterilization processes used with tray sealing

Tray sealing is commonly used to package medical devices that need to be shipped and stored under sterile conditions. The sterilization process happens post-packaging, i.e., after the sealed package has exited the tray sealer. The sealed tray is sent to a sterilization facility which applies one of these sterilization processes: ethylene oxide (EtO) sterilization, electron beam (e-beam) sterilization, radiation sterilization, or steam sterilization.

sterilization is the most common process used to sterilize medical devices packaged in sealed trays; however, it does require at least some part of the packaging material to be permeable and yet able to maintain a sterile barrier. That is why medical devices packaged with Tyvek or medical paper are often sterilized using EtO. In the case of a sealed tray with a lid made of Tyvek, the EtO gas passes through the Tyvek material, killing any contaminating microorganisms that are inside the package.

Then, the pressure is relieved, as regular air is pumped back into the sterilization chamber, dispersing the EtO gas. The Tyvek fibers are bonded in a way that prevents penetration by microorganisms while allowing penetration by air molecules, which are much smaller. As a result, as long as the tray remains sealed, the contents are sterile.

Some sealed trays are sterilized using electron beam (e-beam) sterilization or radiation sterilization. These sterilization processes are ideal for sealed trays made from materials with little to no permeability like foils or plastics, or for products that are very dense. As the names imply, e-beam sterilization uses electron beams to sterilize the medical product after packaging, and radiation sterilization uses radiation, usually in the form of high energy gamma rays.

Lastly, sealed trays can also be sterilized using high temperature and pressure (i.e., steam). Products and packaging that are sterilized by steam must be able to withstand high temperatures and possibly condensation. Steam sterilization cannot be used if there is concern that process could create water vapor or droplets that affect the product packaged in the sealed tray.