7th Asia-Pacific Conference on Plasma Physics, 12-17 Nov, 2023 at Port Messe Nagoya

Testing the capabilities of a commercial economical power supply in plasma
medicine
S. KC1, A.D. Roberts1, S.H. Hong1, B. Ghimire2, J.S. Oh3, EJ. Szili1
1Future Industries Institute, University of South Australia, 2 University of Alabama, USA,
3
Osaka City University, Japane-mail (speaker): sushil.kc@mymail.unisa.edu.auPlasma medicine is an emerging research field withpotential to impact across a range of healthcare andindustrial sectors including wounds, cancers, dentistry,gene transfection, stem cell therapy, and in food andagriculture [1,2,3]. The biological and medical effects ofplasma are generally attributed to reactive oxygen species(ROS) and reactive nitrogen species (RNS), commonly
known as RONS, generated by plasma in ambient air.
Plasma jets are highly preferred for this as they provide ameans to remotely deliver these reactive species tobiological surfaces. Depending on the type andconcentrations of RONS, plasma jets can induce
stimulatory effects (e.g., for promoting wound healing) or
inhibitory effects (e.g., for killing cancer cells or bacteria).
A variety of power supplies are used to operate plasma jetswith some costing tens of thousands of US dollars (e.g.,high voltage DC power supplies that enable precise
control over the electrical parameters). However, a lot ofplasma medicine researchers have utilised a more
economical power supply PVM500 (InformationUnlimited, USA) which fits within their budgetaryrequirements as it costs well below 1000 US dollars. The
PVM500 provides AC high voltage with capability of
being operated over a wide voltage and frequency range(depending on how it is optioned). Despite the widespreaduse of the PVM500 in plasma medicine, no prior studies
have examined the implementation of its in-built duty
cycle control feature. Therefore, this paper explores thisfeature through a comprehensive investigation of how
adjustment of the duty cycle influences the intrinsic
properties of the plasma jet and subsequently how this canbe used to optimise the plasma jet for plasma medicine.

Our results obtained from electrical and optical methods
highlight the correlation between duty cycle, power
dissipation, and gas temperature in the plasma jet. As thetime-on period increases, more energy is transferred into
the gas that affects the production rate of H and O atoms,
which is an important precursor for the generation ofhydrogen peroxide (H2O2). H2O2 is a major ROS producedby plasma jets in medicine that intervenes in cellularsignaling processes important for disease treatment.
Figure 1 demonstrates the influence of varying the duty
cycle on the efficiency of the plasma jet to produce H2O2.
This was assessed by measuring the concentrations ofH2O2 in 300 µL of water following 1, 2 and 4 minutes
treatment in a 96-well plate as per previously publishedprotocols [4]. Furthermore, to assess the biological impact,skin-like HaCaT keratinocyte cells were plasma treatedusing different duty cycles. The results indicate that thehigher duty cycles could be more detrimental to the cells
under study.
Overall, this study the duty cycle of PVM500 power
supply can effectively modulate the thermal and chemical
characteristics of the plasma jet in a similar level ofcontrol as more expensive DC power systems.
References[1] G. Isbary et al, Br.J.Dermatol. 163, 78-82, (2010)[2] M. Gherardi et al, Trends Biotechnol. 36, 583-5,(2018)[3] DB. Graves, J.Phys.D. 45, 263001, (2012)[4] EJ. Szili et al, J.Phys.D. 47, 152002 (2014)

100%

1 min
2 minsCell viaibility (%)

80%

4 mins
60%
40%
20%0%

91828405163

Ar

Duty cycle (%)

Figure 1. Plasma jet used in this study with the concentration of H2O2 (mM) as a function of duty cycle (%) (leftgraph) and the effect of duty cycle on HaCaT cell viability (right graph).