Medical Device Sterilization

Medical Device Sterilization

What is Sterilization?

Sterilization is the process of destroying microorganisms on a particular item. The sterility of an item is determined by the probability of the item being non-sterile. In other words, the probability of a single viable microorganism occurring on the item after the sterilization process. This probability is referred to as the sterility assurance level (SAL). Our sterile needle electrodes have a 10-6 SAL, or a one in a million chance of being non-sterile. This allows for us to label them as “sterile.” It is deemed impossible to guarantee 100% sterility, but through intensive testing, we can be confident that the chances of our devices being compromised by viable microbial life are very, very low.

Common Sterilization Methods

Common Sterilization Methods and their symbols


The market can be broken down into two main sterilization methods:

  1. Ethylene Oxide Gas (50%)
  2. Radiation (45%)
    Other (5%)

1. Ethylene Oxide (EtO or EO) Gas Sterilization

Ethylene oxide is flammable and extremely explosive. It is a main component of aerosol bombs. It is also widely used in hospitals as a disinfectant. Items sterilized by EtO are exposed to the gas for a predetermined amount of time to allow for proper reaction and destruction of the local microbial DNA. Ethylene oxide is very effective in killing microorganisms and sterilizing medical devices, but it is also a toxin, difficult to control, and a pollutant. For these reasons, we choose to look to other sterilization methods first. 

2. Irradiation Sterilization [Exposure to Radiation]

To give some perspective to the scale of irradiation, a typical chest x-ray exam emits a radiation dose of 0.0001 Sv (sieverts), about the same amount of radiation you would receive if you stood in sunlight for 10 days. Radiation sickness symptoms may show up when you’re exposed to more than 0.5 Sv, or about 50,000 days’ worth of sunlight. The radiation level for sterilization ranges from 10,000 to 40,000 Sv (about 1-4 billion days’ worth of sunlight, if you’re wondering).

There are two main methods used to generate radiation for sterilization of medical devices:

  1. Radioactive Isotopes (such as Cobalt-60) to emit Gamma Rays
  2. Electron Beam Accelerators to emit Electron Beams (E-beams) or X-Rays

E-Beam Sterilization 3D Representation3D Representation of E-Beam Processing from Steri-Tek

E-Beam Sterilization:

Our needle electrodes are E-Beam sterilized. This method is best known for its relatively low penetration power and high-dosage rates. Electron beams are generated by accelerators capable of producing a continuous beam of high-energy electrons. As our electrodes absorb the energy from the electrons, the chemical bonds of the microbial life on the needles are destroyed along with their reproductive capabilities, leaving a one in a million chance of something being left behind on the product (10-6 SAL). With the packaging materials we enclose our electrodes in, the products are proven to hold the same sterility assurance level for 3 years. After these 3 years, the products are considered to be NON-sterile and unsafe for human use.

Fun fact: E-beams are often used to improve semiconductor switching speeds and can enhance many other material properties.

Key Differences - Irradiation Sterilization Methods

Irradiation Key Takeaways

To learn more about E-Beam and X-ray sterilization, visit | E-Beam & X-ray Sterilization


[1] Gillet. “Sterilisation of Your Medical Device”. (2020).
[2] Tilman. “Medical Device Sterilization Methodologies”. ATL Technology (2020).
[3] Lewelling. “Medical devices – Symbols to be used with medical device labels, labelling and information to be supplied”. ISO 15223 (2016).
[4] Sauter et al. “E-Beam”. Steri-Tek Expert Sterilization Services (2020).
[5] Jones. “Radiation Dose”. (2015).
[6] Periam Hardy, Lewis Gay, and Edward Husler. “Fuel-air type bomb”. U.S. Patent 4,132,170 US4132170A (1979).
[7] GIPA & iia. “A Comparison of Gamma, E-beam, X-ray and Ethylene Oxide Technologies for the Industrial Sterilization of Medical Devices and Healthcare Products” (2017).
[8] “Electron Beam Irradiation”. Sterigenics (2019).
[9] “Disinfection and Sterilization in Healthcare Facilities (2008)”. Centers for Disease Control and Prevention (CDC) (2008).
[10] "Radiation from Space (Cosmic Radiation)". Centers for Disease Control and Prevention (CDC) (2015). 

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