Microwave disinfection and sterilization
Inventors
STULL, JR., WILLIS DON • Neuber, Andreas Alfred • Sharbutt, David E. • Brashears, Michel Todd • Brashears, Mindy M. • Alvarado, Christine • Brooks, J. Chance
Assignees
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Publication Number
US-9125958-B2
Publication Date
2015-09-08
Expiration Date
Abstract
A method and apparatus comprising microwave radiation pulses to reduce a microorganism population in an object.
Core Innovation
The invention relates to microwave disinfection/sterilization that reduces a microorganism population on an object. It uses predominantly non-thermal microwave radiation pulses with controlled pulse timing to achieve microorganism population reduction while limiting thermal effects. The disclosed approach addresses disinfection/sterilization by manipulating electromagnetic coupling and electric field effects rather than relying on substantial temperature increase.
The disclosure provides an apparatus architecture that includes a tumbling chamber capable of tumbling an object and exposing the object to microwave radiation. Microwave radiation pulses are provided by magnetrons and delivered through waveguides, including configurations such as waveguides/telescoping or slot radiators. The system is controlled by a programmable control panel that delivers one or more microwave radiation pulses as a series of repetitive pulses with specified pulse period and pulse duration.
To improve exposure homogeneity, the disclosure includes object movement such as tumbling and/or conveyor movement, including a conveyor belt or stationary platform. The invention also contemplates electric field amplification without substantial temperature rise by using pulse timing and hardware arrangements such as multiple magnetrons positioned at different locations. Example results are described for reductions of microorganisms, including MRSA and Salmonella on respective object categories.
Claims Coverage
The partial content provides four independent claims. Across these claims, the inventive features focus on a tumbling chamber with magnetron-generated microwave radiation pulses delivered via waveguides and slot radiators, together with a programmable control panel that delivers repetitive pulses defined by pulse period and pulse duration within a specified range, and in some instances additional pulse-control parameters such as duty cycle and duty cycle frequency.
Tumbling chamber with magnetron microwave pulse delivery
A tumbling chamber capable of tumbling and exposing an object to microwave radiation, the tumbling chamber having at least one magnetron to provide one or more microwave radiation pulses.
Waveguide communication with programmable repetitive pulse timing
At least one waveguide positioned in communication with the at least one magnetron, with a control panel programmable to deliver the one or more microwave radiation pulses as a series of repetitive pulses for a pulse period and a pulse duration from a fraction of a second to multiple seconds to reduce the microorganism population on the object.
Dual magnetron/waveguide pulse trains with duty-cycle control
A first magnetron and first waveguide providing first microwave radiation pulses at a first axis, and one or more second magnetrons and second waveguides providing second microwave radiation pulses at one or more second axes, with a control panel controlling first pulse period and first pulse duration, second pulse period and second pulse duration, a duty cycle and a duty cycle frequency to reduce the microorganism population.
Slot radiator waveguide with a specified slot count
A waveguide comprising a slot radiator having 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 slots positioned in communication with the at least one magnetron.
Slot radiator magnetron configuration
At least one magnetron comprising a slot radiator having 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 slots positioned to provide one or more microwave radiation pulses, together with waveguides and a programmable control panel delivering repetitive microwave pulses for a pulse period and a pulse duration from a fraction of a second to multiple seconds.
Overall, the independent claims cover apparatuses that reduce a microorganism population on an object using a tumbling chamber exposed to magnetron-generated microwave radiation pulses delivered via waveguides and slot radiators, with programmable control of repetitive pulse timing defined by pulse period and pulse duration within a specified range; one independent claim further requires duty cycle and duty cycle frequency control and multiple emission axes.
Stated Advantages
Rapid microorganism population reduction.
Uniformity described as improved exposure via tumbling and controlled microwave delivery.
Preservation of object characteristics by limiting thermal effects.
Reduced environmental impact versus harsh chemicals and/or energy-intensive methods.
Documented Applications
Disinfection/sterilization to reduce a microorganism population on objects including cotton fabric with MRSA and food items such as cantaloupe, jalapeno peppers, dog food, peanuts, and other items referenced with Salmonella.
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