Dory Development Team - (L-R) Bridget Endler, Roy Dory principal investigator, Dr. Luis Martinez, Heather Grossman

NAMRU – San Antonio Investigators Develop Portable Ozone Sterilizer

By Roy E. Dory, Naval Medical Research Unit – San Antonio

Dory Development Team - (L-R) Bridget Endler, Roy Dory principal investigator, Dr. Luis Martinez, Heather Grossman
Dory Development Team – (L-R) Bridget Endler, Roy Dory principal investigator, Dr. Luis Martinez, Heather Grossman

Combat operations and humanitarian missions often place military clinicians, dentists, and front-line corpsmen in austere conditions. Currently available sterilization systems intended for field use are often bulky and require consumable resources, including chemicals or large sources of energy, which must be transported to the point of use.

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Combat operations and humanitarian missions often place military clinicians, dentists, and front-line corpsmen in austere conditions.

Recent testing by researchers in the Immunodiagnostic and Bioassay Department at the Naval Medical Research Unit – San Antonio (NAMRU-SA) demonstrated gaseous ozone, a strong oxidizing agent, can be generated from the oxygen in ambient air at sufficient concentrations to effectively destroy bacteria.  The technique offers an alternative method of sterilization that requires no consumable chemicals and a relatively small amount of energy.  With funding from the Marine Corps Systems Command, the NAMRU-SA researchers teamed up with engineers in the Expeditionary and Trauma Medicine Department at NAMRU-SA to develop the concept into a portable, prototype sterilization system.

The prototype ozone sterilizer has a sterilization compartment designed to accommodate small medical instruments and dental tools and is housed in a ruggedized carrying case. The system can be powered from external sources or from an internal battery pack, which allows for approximately five complete sterilization cycles between charges. The system is fully automated, with custom developed software to control ozone production, monitor conditions in the sterilization compartment, and convert remaining ozone back into oxygen at the end of a sterilization cycle.

The prototype recently underwent a battery of tests at NAMRU-SA to determine the effectiveness of the system at destroying twenty-four different bacterial strains of importance to military medicine. The sterilizer effectively eliminated all of the plated bacterial strains, including both Gram-positive and Gram-negative bacteria, and antibiotic resistant strains such as Methicillin-resistant Staphylococcus aureus (MRSA).

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The sterilizer effectively eliminated all of the plated bacterial strains, including both Gram-positive and Gram-negative bacteria, and antibiotic resistant strains such as Methicillin-resistant Staphylococcus aureus (MRSA).

Leveraging the recently collected data, efforts are currently underway to further optimize the prototype ozone sterilizer. The engineering team aims to improve the efficiency of the system, thereby extending battery life, while also increasing ozone production, which will allow the effective sterilization time to be reduced.  The team is also exploring methods to further reduce the size and weight of the sterilizer, while ruggedizing the system for environmental conditions at the point of care.

At the conclusion of the current design iteration, NAMRU-SA hopes to transition the prototype sterilizer to the Navy Advanced Medical Development Team to assist with further development and ultimately transition the technology to the fleet.

The ozone sterilizer development began as a set of bench-top experiments and has now emerged as a functional prototype, illustrates NAMRU-SA’s translational approach to biomedical research.  With further optimization, NAMRU-SA investigators hope to offer a truly portable and self-sufficient field sterilizer that can be deployed with medics and corpsmen to enhance the care available to the US warfighter in remote environments.