Microplasmas are nowadays a powerful tool with multiple
practical applications. The performance of a specific instrumentation for a
plasma needle capable of producing non-thermal plasmas and a DBD reactor
able to produce atmospheric pressure plasmas, both of them designed and
already constructed, is reported. These devices operate at 13.56 MHz and are
driven by a specifically built radio frequency (RF) resonant converter. The
reactors, which operate at atmospheric pressure in a He-air gas mixture at a
1.5 SLPM flow, have been successfully applied to eliminate E. coli bacteria. In the
needle case, bacterial samples were submitted typically to a 500 V peak
voltage plasma discharge for 120 s. In the DBD treatment, the samples were
processed with typical 750 V peak voltage plasma discharges for 80 s. The
sample pH was used as a criterion to measure the effectiveness of the plasma
treatment, in such a way that the return to the basal pH value after the
treatment can be assumed as the validation of the complete bacterial
elimination.