Category

PH

P28

Effects of Sterilization using One Atmosphere Cold Plasma

Abstract

The basis of this study was to analyze the sterilizing effects of cold

plasma in non-pathogenic bacteria. Plasma is very similar to a gas, and is

naturally created during storms when lightning strips the electrons off

atoms at extremely high temperatures. Another way of creating plasma is

with an enormous flux. Flux is the change in magnetic field, and a large

enough flux can influence any charged particle, even electrons. By

generating a large flux, the electrons from atoms in the air can be stripped

off, thus creating a cold plasma. This can be done with a 24 volt DC power

source and a circuit which converts it to 15,000 hertz AC. Next, the

voltage must be stepped up to several thousand volts and run through a

wire. While in the wire, this high voltage, high frequency current emits a

flux which is strong enough to strip the electrons off nearby air particles.

To test the sterilization effects of the plasma, two strains of non-

pathogenic bacteria, Micrococcus luteus and Escherichia coli strain K12,

were exposed to the plasma. Next, the growth of each bacteria strain

was observed over several days and compared to that of a control dish.

Data concerning the growth of each strain was acquired, quantified, and

analyzed using two different methods. For the first method, pictures were

taken of each dish everyday, and a computer program, written in Matlab,

was used to count the number of pixels in a certain range of hues and

compare that number to the total number of pixels. The second method

involved streaking each plate for isolation, so that each proceeding

quadrant had diminishing concentration of bacteria. The number of

quadrants showing growth was then noted, and a two sample T-Test

comparing growth in control dishes to growth in dishes exposed to plasma

was used to analyze the data and test for significance.

Bibliography

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