Apparatus and method for fine mist sterilization or sanitation using a biocide - Nanomist Systems, LLC

USA Patent number: 7326382

"SUMMARY OF THE INVENTION

The invention provides a method of producing a sterilizing mist that is effective in sterilizing a volume and it's contents within a room or building. The mist is generated at ambient pressure using electronic ultrasonic transducers to convert electrical frequency input into mechanical ultrasonic vibrations. The mist throughput is scalable using variations of frequency and oscillator surface area, and delivery devices may be designed for application by hand to small areas, to medium scale applications suitable for devices designed to be carried by backpack, or for large scale applications delivered to entire rooms or buildings.

The quality of the mist is maintained by using sufficient frequency and conditions to produce a plume of mist having a high number of extremely fine droplets concentrated about the exterior portions of the plume. The invention provides for primarily extremely fine droplets to be extracted from the plume using a swirling flow of carrier gas that is applied tangential to the extraction column to entrain only the smaller droplets. The larger droplets are left in the center of the plume to fall back into the reservoir of solution as a fountain of water. The unique tangential related flow of carrier medium and the in-situ extraction column markedly improves throughput of mist.

The sterilizing mist is delivered having very low momentum wherein the flow of mist and carrier gas is nearly a free convection flow. The low momentum provides enhanced mist stability whereby the mist is dispersed without coalescing because of low kinetic energy created by the motion of the mist droplets. The throughput and stability of mist droplets provided by the methodology produce sterilizing mist droplets that diffuse with a concentration gradient effective in sterilizing volumes of space and contents using a sterilizing mist of hydrogen peroxide solution or other biocide solution. Further, the extremely fine droplet size of the mist is maintained and controlled after the mist is produced and as the mist is delivered, which is necessary for diffusing the mist at the effective concentration gradient discussed.

A mist produced from a three percent solution of hydrogen peroxide is highly efficient for sterilizing an area due to dramatic gains in reactivity and improved flow behavior provided by a high number of nanoscale size droplets of less than one micron. In particular, droplets in the size range less than 10 micron have been found to be very effective.

The large surface area of mist provided by the large number of small droplets provides for increases in reactivity related directly to the increased reactive surface area. If nanoscale droplets are used, droplets provide an additional dynamic not found in larger scale droplets. The molecules within the droplets tend to become very surface concentrated, such that 80 to 90 percent of the reactive molecules are near the surface of the droplet and contribute to enhanced reactivity. Therefore, the mist is highly reactive and highly effective in sterilization applications.

The mist of extremely small droplets exhibit improved flow that makes the mist suitable for sterilizing areas such as rooms and buildings. The mist flows very much like a gas to sterilize nooks and corners of small and large-scale rooms without being obstructed by physical objects in the path of the mist."

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