Clean Freqs

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Sponsored by Distinguished Professor Zoya Popovic

Sterilization refers to any process that removes, kills, or deactivates all forms of life, in particular referring to microorganisms such as fungi, bacteria, viruses, spores. Medical professionals, food processors, and others who work in high contact jobs have a need to sterilize their equipment and surfaces to prevent the transmission of pathogens. Current sterilization methods utilize a combination of heat, chemicals, pressure, and ultraviolet radiation, and are often not efficient, effective, or safe. 

Tools used by medical professionals in surgery are typically made from metal and are able to withstand the high temperatures involved with the standard sterilization process. There has been an increase in the use of medical devices made from other materials that are not as heat durable and require other forms of sterilization. The food processing industry also has a need for a different type of sterilization that does not involve large temperatures, since there are issues with the heating process reducing nutrition, deteriorating the quality of food, and being ineffective against specific bacteria types. Other sterilization methods not involving heat that are effective are, unfortunately, toxic or emit ionizing radiation which is harmful to any person in the immediate vicinity. One of these techniques utilizes ultraviolet (UV) radiation which is extremely effective and can kill over 99% of bacteria and viruses in a variety of time frames depending on the size of the object and distance to the source. This can mean complete sterilization of a petri dish with E. coli from the distance of one inch is possible in 1-2mins or 30 minutes for a 8 foot biosafety cabinet in a lab. However, UV radiation is ionizing (high photon energy) and not safe to humans, who need to be removed from the process. Another sterilization technique not involving heat or UV radiation involves hand-scrubbing and chemically cleaning each tool, resulting in a less efficient and unreliable process. There is evidence that current methods do not meet sterilizing standards and result in the transmission of “antibiotic-resistant infections that are almost impossible to cure.” Especially with the current pandemic, there is a need for an inexpensive, portable, safe device that can sterilize surfaces made of different materials, as well as address airborne pathogens.

PHASER provides this effective, efficient, and safe sterilization process. The handheld device uses the effects of electromagnetic fields in the microwave frequency range, (1-10GHz) to eliminate harmful microorganisms. PHASER uses the minimum required power density, which in a hand-held device directs power away from the user and allows for the sterilization of surface objects too large to reasonably fit inside e.g. a closed chamber. Limited work was done by dentists using a fixed-frequency microwave oven, with excellent results. However, they did not investigate the power that was required, or other wave parameters such as frequency, modulation, power density, and time exposure. PHASER takes into account the dependence on sterilization with these parameters. The feedback system of PHASER, determined by analyzing results from a Celigo Image Cytometer, controls the radiated microwave beam parameters to ensure that an effective sterile environment is achieved during use. Microwave radiation is non-ionizing and there are many safety limits already in place by the FCC, ICNRP, IEEE, etc. dictating specific field levels across frequency, e.g. Phaser works within these allowed frequency bands (e.g. ISM and amateur radio). Microwaves are unlikely to damage most surfaces and equipment and are easy to control electronically, making PHASER straightforward to adapt to additional use cases. One useful scenario would be the sterilization of airborne pathogens which are usually eliminated by air filtration, heat, or UV radiation. An air filtration system is one of the most common methods involved in mitigating the risk of airborne pathogens. While effective, a properly engineered filtration system necessitates maintenance and consistent operation. An example of a filtration system not being properly maintained has resulted in adverse effects on high risk patients. An environment such as a poorly maintained air filtration system containing dust, water, and air can be a perfect breeding ground for harmful microorganisms. PHASER allows the user to eliminate airborne pathogens that are present in the immediate area. 

Medical professionals and food manufacturing plants that require sterilized surfaces for operations will benefit greatly from the use of this sterilization device. This non-ionizing, efficient technique will reduce the potential of harm to the user and greatly remove contaminants from the work environment. Medical tools that have the possibility to be reused, can also benefit from this technique, removing viruses and bacteria and reducing the risk of pathogen transmission between patients. Food packaging plants can also use this device to sterilize packaging, thus eliminating cross contamination from animals and plants to humans. This handheld device reduces the cost of purchasing new equipment needed for each medical procedure or industrial use. This saves time and space in the daily operation of various industries that use these techniques, and mitigates the risk commonly found in sterilization processes. The portability of PHASER is particularly useful for implementing surface and air sterilization procedures where none were implemented before.