Sterilization of 3D printed resins

Sterilization of 3D printed materials is required for medical applications. Unfortunately, 3D printed resins may suffer some physical and chemical changes after cleaning and sterilization due to chemical attack, excessive moisture, heating, and irradiation.

Cleaning of 3D prints

3D printed resins are often cleaned with isopropanol (IPA) or ethanol. The use of alcohols reduce significantly the mechanical properties of most materials, weakening and making them fragile: discover our processing auxiliaries and cleaning products for increasing the bicompatibility and safety of medical devices without reducing their mechanical strength, since our cleaning fluids do not attack 3D prints. For most applications their adequate usage is often enough for cleaning our biocompatible resins for most dental and biomedical applications.

Sterilization methods

The most used sterilization methods of medical devices are: 

Steam Autoclaving

  • Steam autoclaving is fast and cost effective. It is ideal for dental and biomedical applications. Typical sterilization temperatures are between 120°C and 135°C for up to 30 minutes. 3D printed resins with lower Tg and HDT than 120ºC  may deform during sterilization. Steam can also contribute to deformaton of prints and to humidity absorption, consequently sterilized prints need to be dehydrated in an oven to evaporate any trapped humidity inside the prints. Uncured monomers, residuals and byproducts can potentially leach out during sterilization affecting the biocompatibility of prints. 

Low temperature hydrogen peroxide gas plasma

  • Hydrogen peroxide gas plasma sterilization is ideal for 3D resins with relatively low Tg and HDT since this process operates at 37-44°C for 75 minutes. Low temperature sterilization uses concentrated hydrogen peroxide and electromagnetic fields to create a gas plasma, which creates free radicals and  UV energy for killing microorganisms and sterilizing the prints.

Ethylene Oxide

  • Ethylene oxide gas at room temperature is ideal for sterilization of low Tg and HDT 3D printed resins to avoid their deformation by heat and/or steam used in steam autoclaving. (EO) is often used to sterilize biomedical materials because it is toxic for microorganisms. Ethylene oxide can cause alkylation on the surface of prints, affecting a bit their mechanical and biocompatibility properties since ethylene oxide can react with the surface of printts yielding toxic residues. 

Irradiation

  • Electron beam or gamma rays are irradiated for sterilizing 3D prints, which can suffer some color and mechanical property shifts:

    Conclusions