22nd International Symposium on Plasma Chemistry
July 5-10, 2015; Antwerp, Belgium
Plasma sources for wound treatment and decontamination: adjusting
parameters independently to understand the modes of action
K. Stapelmann1, S. Baldus1, M. Engelhardt1, F. Kogelheide1, K. Kartaschew2, M. Havenith2, J.-W. Lackmann1 and
P. Awakowicz1
1
Ruhr-University Bochum, Institute for Electrical Engineering and Plasma Technology, Department of Electrical
Engineering and Information Technology, DE-44780 Bochum, Germany
2
Ruhr-University Bochum, Physical Chemistry II, Department of Chemistry and Biochemistry, DE-44780 Bochum,
Germany
Abstract: A dielectric barrier discharge (DBD) and a dielectric barrier plasma jet are
investigated by means of current-voltage measurements and optical emission spectroscopy.
Both of the two plasma setups are equipped with a generator with customized circuit in
order to allow adjustment of the output voltage amplitude, of pulse repetition frequency, of
duty-cycle and change of polarity of the discharge, all of them independently of each other.
Keywords: DBD, plasma jet, biomedical application, current-voltage, OES
1. Introduction
Atmospheric pressure plasmas have gained increasing
interest in the last years, especially in the fast growing
field of plasma medicine. When applying plasma for
medical purposes, it is essential to understand the modes
of action and to find optimized conditions for treatment.
The conditions depend on various settings, first of all the
process gas, which is air or a noble gas in most cases, but
also on the polarity of the discharge, the applied voltage,
and frequency. One major drawback of most plasma
generators is that all of these settings cannot be adjusted
alone, but if one setting is changed the others change as
well. Therefore, we developed a circuit that allows
adjusting any parameter of the discharge individually,
keeping the other parameters constant. The circuit can be
applied to any kind of discharge, presented here for a
DBD and a plasma-jet.
2. Experimental Setup
The developed circuit is depicted in figure 1. It is based
on a design used in [1]. Output voltage amplitude is up to
23 kV, with a pulse repetition frequency from a few
hundred Hz up to 25 kHz. Duty-cycle can be varied and
thus the total power output. All parameters can be
adjusted independently of each other; this enables a
multitude of possible investigations.
The circuit can be used to drive a DBD or a plasma-jet.
More detailed information about the DBD can be found in
[2-4], as well as in the contribution of F. Kogelheide et al.
In brief, the DBD is sustained in air with a driven
electrode of 10 mm diameter. The electrode is composed
of copper and coated with aluminum oxide as dielectric.
As grounded electrode, glass slides or human skin can be
used. Investigations are performed with 1 mm distance to
the grounded electrode, since this is the distance
established for clinical trials [4] allowing easily ignition
on human skin. The lowest ignition voltage is limited to 6
kV, due to Paschen’s law. The trigger frequency can be
varied from 75 Hz to 900 Hz.
Fig. 2: The plasma-jet, 500 sccm Ne with 5 kHz pulse
repetition frequency
Fig. 1: Circuit diagram
P-II-11-10
The plasma-jet is basically a dielectric tube with a noble
gas flow and an external driven electrode. With highvoltage pulses, the noble gas can be ignited and ionization
waves start to propagate through the tube [6]. Out of the
open end of the tube, a so-called effluent is ejected, for a
distance of up to a few centimeters. By adding various
1
other feed gases to the noble gases, numerous chemically
active species can be produced in this discharge.
Especially for geometrically challenging applications, this
device offers new possibilities, e.g. treatment of narrow
margins, thin tubes, long cracks, etc.
3. Results
The dielectric barrier plasma jet and the DBD are
characterized by different diagnostic methods, such as
voltage-current characteristics (see figure 2) and optical
emission
spectroscopy.
The
voltage-current
characteristics are measured with a current monitor and a
HV probe, both connected to an oscilloscope.
Fig. 3: Voltage-current characteristics of the dielectric
barrier plasma jet in argon
0.45
75Hz
150Hz
300Hz
600Hz
0.40
Power / W
0.35
0.30
0.25
0.20
0.15
0.10
The DBD is investigated regarding the power input for
different plasma settings, since this is of special interest
for therapeutic use in order to estimate the effect and
possible damage to human tissue. Figure 4 shows the
power as a function of applied voltage determined for
negative polarity, for different trigger frequencies. Not
surprisingly power input rises with increasing voltage.
With doubling the trigger frequency, also power doubles,
thus power and trigger frequency behave proportional to
each other. Hence, power of one pulse can be defined as
independent from frequency.
With both plasma sources, a simple biological assay is
performed to determine and compare the efficiency of the
sources for biomedical applications and with that to
investigate the modes of action on biological material
dependent on the discharge parameters. Therefore, the
impact of the two different plasma discharges on the
amino acid cysteine is investigated. The degree of
oxidation of cysteine is measured by means of Fouriertransformed infrared microspectroscopy (as presented in
the contribution of Jan-Wilm Lackmann et al. for the
DBD), and compared to the results obtained with the
dielectric barrier jet.
4. References
[1] A. Bergner, S. Groeger, T. Hoebing, C. Ruhrmann, U.
Hechtfischer, G. Tochadse, J. Mentel, P. Awakowicz.
Journal of Physics D: Applied Physics 47 355204 (2014)
[2] P. Rajasekaran, P. Mertmann, N. Bibinov, D. Wandke,
W. Viöl, P. Awakowicz. Plasma Processes and Polymers,
7, 8 (2010)
[3] P. Rajasekaran, N. Bibinov, P. Awakowicz.
Measurement Science and Technology, 23, 8 (2012)
[4] K. Heuer, M. A. Hoffmanns, E. Demir, S. Baldus, C.
M. Volkmar, M. Röhle, P. C. Fuchs, P. Awakowicz, C. V.
Suschek, C. Opländer. Nitric Oxide 44, 52-60 (2015)
[5] S. Emmert, F. Brehmer, H. Hänßle, A. Helmke, N.
Mertens, R. Ahmed, D. Simon, D. Wandke. D. MausFriedrichs, G. Däschlein, M. P. Schön, W. Viöl. Clinical
Plasma Medicine, 1, 1 (2013)
[6] X. Lu, G.V. Naidis, M. Laroussi, K. Ostrikov. Physics
Reports 540 (3), 123–166 (2014)
0.05
0.00
-10
-13.5
-16.5
Voltage / kV
Fig. 4: DBD: power as a function of applied voltage at
negative polarity for different trigger frequencies
2
5. Acknowledgements
The authors gratefully acknowledge the financial
support of the Deutsche Forschungsgemeinschaft DFG
with the grants PAK728 and PAK816.
P-II-11-10