The best sterilization method for silicone devices depends on the type of silicone used and its purpose. For medical grade silicones, heat sterilization is preferred in the form of steam autoclaving. A steam autoclave looks like a small microwave that sterilizes the desired part in a high-pressured steam chamber. The temperature of the autoclave should be no higher than 120 degrees celsius and should be subject to high-pressure steam for no more than 20 minutes.

Steam Autoclave

Devices that consist of other features including electronics will deform when subject to high-pressure steam. For these devices, gas sterilization is preferred. Ethylene oxide or EtO sterilization consists of three processes: preconditioning, sterilizer, degasser. The preconditioning phase is used to create the necessary micro organisms through temperature and humidity regulation. The sterilization process is a controlled, 60 hour cycle that controls the temperature, pressure and vacuum of the environment. The entire cycle is executed through a computer so every step is recorded in a batch report. The phases of the sterilization process include: temperature check, vacuum phase, leak rate, flush phase, environment conditioning (DEC), gas injection, post dwell vacuum phase, wash phase, final air cycle phase.Each sterilization cycle will have its own batch number, and each batch will go through a degasser phase; a temperature controlled system, where all the EtO gases are removed.  

Devices that are both heat and pressure sensitive can be sterilized using gamma radiation. Exposing the silicone to a radiation value between 25 and 50 kGy will create additional crosslinks. One concern about gamma radiation is the possibility of too much crosslinking. Additional crosslinking may deform the product and decrease its flexibility and tensile strength as well as increase the durometer of the silicone. Bond rupturing also occurs in extreme cases. Polymers, such as phenyls specifically, show the most resistance to radiation deformation therefore gamma radiation sterilization is recommended. Occasionally, the rubber becomes too hard as a result of sterilization therefore a softer rubber is recommended at the beginning of the process. Unfortunately, not all parts have this type of material flexibility so this may not work for everyone.