Abstract
We demonstrated bacterial (
Streptococcus mutans
) inactivation by a radio frequency power driven atmospheric pressure plasma torch with
H
2
O
2
entrained in the feedstock gas. Optical emission spectroscopy identified substantial excited state
*
OH
generation inside the plasma and relative
*
OH
formation was verified by optical absorption. The bacterial inactivation rate increased with increasing
*
OH
generation and reached a maximum 5-
log
10
reduction with 0.6%
H
2
O
2
vapor. Generation of large amounts of toxic ozone is drawback of plasma bacterial inactivation, thus it is significant that the ozone concentration falls within recommended safe allowable levels with addition of
H
2
O
2
vapor to the plasma.