MDTmag.com 10 / November/December 2014
Sterilization Expands the
Sterilization is a necessary process for virtually every type of medical device. Therefore, it is critical for
designers to be mindful of how materials will interact with a given process, at what stage the sterilization
will be best implemented, and other variables. With that in mind, this article highlights a sterilization
process that offers more flexibility than many of the options designers may be familiar with.
By Evan Goulet, Director — Sterilization
Operations, Noxilizer Inc.
Medical devices are increasingly complex with intricate geometries, long lumens, and drug-delivery
capabilities. This complexity has created challenges with compatibility between materials
processed and many traditional sterilization
methods. Room-temperature, nitrogen dioxide (NO2) sterilization technology is a tool for
medical device manufacturers that is helping
solve these challenges. Employing NO2 gas
as a sterilant offers unique benefits over traditional sterilization techniques. The greatest
benefits for manufacturers can be realized
when sterilization methods are considered
early in the product design process.
Evaluating Sterilization Methods
Evaluating sterilization options early in the
product design process and collaborating
with technical experts will ensure product
goals are achieved.
At the beginning of the design phase, a sterilization technique needs to be selected. The
method of sterilization will impact material
selection, device design, and packaging. Also,
the relevant standards need to be considered.
When using a gas sterilization process (e.g.,
EO or NO2), the gas path to all surfaces of the
device needs to be a part of the design. NO2
does not penetrate materials to the same degree as EO; therefore, aeration is faster. While
EO can penetrate through many polymers,
this comes with the cost of lengthy aeration of
the products after sterilization is complete.
Radiation sterilization methods avoid the
gas-penetration issue, but material might discolor or become brittle due to the radiation.
Commonly used medical device materials,
such as Teflon, polypropylene, and acetyl
compounds, are not tolerant of radiation
sterilization. However, gamma radiation is a
very fast process and product can be released
without waiting up to seven days for biological indicator incubation.
Most sterilization methods are performed
as part of contract sterilization. Contract sterilization is a necessity for all but the largest
medical device companies. Facility modifications required for EO and radiation sterilization systems can be prohibitively expensive.
An effective alternative is the use of NO2,
which can be installed in-house, without
NO2 technology is recognized as a flexible sterilization option to safely and efficiently sterilize
complex devices, materials, and drug-device
combination products. Noxilizer’s ( www.noxil-izer.com) advanced room-temperature surface
sterilization process uses NO2, in combination
with humidity, to inactivate resistant microorganisms and deliver sterile product. The NO2
process has a shorter cycle — typically less than
three hours. The process operates at room
temperature, with minimal vacuum, making it
ideally suited for heat, radiation, and mois-ture-sensitive products. Additionally, there are
no harmful sterilant residuals, and no lengthy
post-sterilization aeration needed.
NO2 is a well-researched gas with a favorable
safety profile — non-carcinogenic and non-flam-mable. An NO2 system can be safely and easily
The Noxilizer RTS 360 Industrial NO2 Sterilizer provides a flexible sterilization option for engineers
designing complex devices and drug-device combination products.