SBIR-STTR Award

The filtration of bacteria and viruses from indoor air is hindered by two characteristics of the organisms extremely small size and the ability to propagate. The typical diameter of bacteria is a few micrometers, but viruses can be 1/100 this diameter. It is well known that the effective filtration of particles less than one micrometer is difficult. It also is known that the organisms that are captured by the filter can propagate on the filter surface, necessitating frequent filter changes.The use of electric fields and electric discharges can address both of these challenges. The improvement of filter capture efficiency through the application of electrostatic fields is well established. Polarization effects brought about by an electric field produces an attractive force between particles and filter fibers resulting in significantly enhanced filter efficiency, especially for small particles.The sterilization of surfaces through exposure to low temperature gas discharges has been demonstrated to be very effective. The purpose of this SBIR project is to apply the combination of electrostatic filter enhancement and plasma filter sterilization to a conventional air filter. The resulting device would effectively capture even the smallest organisms and would destroy the organisms thus captured.

The filtration of pathogens from indoor air is hindered by two characteristics of the organisms: extremely small size and the ability to propagate. It is well known that the effective filtration of particles less than one micrometer is difficult. It also is known that the organisms captured by the filter can flourish on the filter surface and migrate through the filter, only to be reintroduced into the airstream.The use of electric fields and electric discharges can address these challenges. Enhancement of filter capture efficiency through the application of electrostatic fields is well established. Polarization effects brought about by a direct current (DC) electric field produce an attractive force between particles and filter fibers resulting in significantly enhanced filter efficiency, especially for small particles. The sterilization of surfaces through exposure to the University of Tennessee's One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) has been demonstrated to be very effective. Microbe destruction occurs through attack by atomic oxygen and oxygen radicals created by the plasma.Thin electrodes, attached to both sides of a filter, yield enhanced capture efficiency when a DC voltage is applied across these electrodes. Furthermore, periodic radio frequency alternating current energization of the electrodes generates a plasma on the filter surface that kills captured organisms. This project demonstrates these effects by constructing and operating such a filter.Infectious disease takes a tremendous toll on people and on the U.S. economy. The causes of many of these diseases are airborne pathogens. For example, in 1994 there were more than 90 million cases of influenza nationwide resulting in 170 million bed days. This led to more than 69 million work-loss days and $13.2 billion of lost earnings.A Phase I program has shown that the field-enhanced plasma-sterilized filter will effectively capture and kill airborne microorganisms at reasonable energy use. It is anticipated that the filter will represent a solution for the problem of indoor air pathogens for both public and private buildings.Supplemental

Keywords:
small business, SBIR, indoor air, engineering, chemistry Control