Effects Of Sterilization Methods On Key Properties Of Specialty Optical Fibers Used In Medical Devices

By Andrei A. Stolov, Brian E. Slyman, David T. Burgess, Adam S. Hokansson, Jie Li and R. Steve Allen

Optical fibers with different types of polymer coatings were exposed to three sterilization conditions: multiple autoclaving, treatment with ethylene oxide and treatment with gamma rays. Effects of different sterilization techniques on key optical and mechanical properties of the fibers are reported. The primary attention is given to behavior of the coatings in harsh sterilization environments. The following four coating/buffer types were investigated: (i) dual acrylate, (ii) polyimide, (iii) silicone/PEEK and (iv) fluoroacrylate hard cladding/ETFE.

Optical fibers are successfully used in various areas of medicine, including urology, general surgery, ophthalmology, cardiology, endoscopy, dentistry and medical sensing.1-4 Prior to use inside a human body the fiber must be sterilized to ensure it is free of microorganisms such as fungi, bacteria, and virus or spore forms. Sterilization can generally be defined as any process that effectively kills or eliminates all microorganisms from a surface, contained in a fluid, equipment, food, medication or biological culture medium.5 Many types of physical or chemical treatments are known as effective sterilization techniques. Roughly, the methodologies can be subdivided into three groups: (i) use of elevated temperatures, (ii) chemical treatment, and (iii) exposure to radiation. The first group includes flaming, exposures to dry heat and hot steam (autoclaving) and boiling in water. Chemicals such as ethylene oxide (EtO), formaldehyde, ozone, hydrogen peroxide, phthalaldehyde and peracetic acid in the gas phase and/or solutions are used for chemical sterilization. Finally, microorganisms can be effectively killed by UV light, X-rays, gamma- and e-beam radiation.