Plasma-based treatment of chronic wounds or skin diseases as well as tissue engineering or tumor treatment is an extremely promising field. First practical studies are promising, and plasma medicine as an independent medical field is emerging worldwide. While during the last years the basics of sterilizing effects of plasmas were well studied, concepts of tailor-made plasma sources which meet the technical requirements of medical instrumentation are still less developed. Indeed, studies on the verification of selective antiseptic effects of plasmas are required, but the development of advanced plasma sources for biomedical applications and a profound knowledge of their physics, chemistry, and parameters must be contributed by physical research. Considering atmospheric-pressure plasma sources, the determination of discharge development and plasma parameters is a great challenge, due to the high complexity and limited diagnostic approaches. This contribution gives an overview on plasma sources for therapeutic applications in plasma medicine. Selected specific plasma sources that are used for the investigation of various biological effects are presented and discussed. Furthermore, the needs, prospects, and approaches for its characterization from the fundamental plasma physical point of view will be discussed.

The technological potential of non-thermal plasmas for the antimicrobial treatment of heat sensitive materials is well known. Despite a multitude of scientific activities with considerable progress within the last few years, the realization of industrial plasma-based decontamination or sterilization technology remains a great challenge. This may be due to the fact that an antimicrobial treatment process needs to consider all properties of the product to be treated as well as the requirements of the complete procedure, e.g. a reprocessing cycle of medical instruments. The aim of this work is to demonstrate the applicability of plasma-based processes for the antimicrobial treatment on selected heat sensitive products. The strategy is to use modular, selective and miniaturized plasma sources, which are driven at atmospheric pressure and adaptable to the products to be treated.

A series of different discharge configurations suitable for surface treatment at atmospheric pressure is discussed, including a non-thermal modular radio frequency (13.56, 27.12 or 40.78 MHz) jet plasma. The capacitively coupled configuration allows the operation with both rare gases (e.g. Ar) and reactive gases (N 2 , air, reactive admixtures of siliconcontaining compounds). Several capillaries are arranged in an array to allow plasma assisted treatment of surfaces including non-flat geometries. Optical emission spectroscopy, mass spectrometry and measurements of the axial and radial temperature profiles are used to characterize the discharge. The surface energy of different polymer materials is significantly enhanced after plasma treatment. Many applications are possible, such as plasma activation of surfaces for adhesion control, surface cleaning, plasma enhanced CVD, plasma cleaning, plasma activation and biomedical applications.

Since several years a number of activities on the field of antimicrobial treatment by using non-thermal plasmas are known. But although there are quite a few plasma based processes commercially available, the complexity of interaction between plasma and micro organisms prevents the breakthrough of this technology up to now. Thus plasma generation and treatment method needs to be adapted for each individual application. The aim of this work is to demonstrate the industrial applicability of plasma technological processes for medical devices. Therefore a non-thermal plasma jet operated in argon at atmospheric pressure and driven by radio frequency (27.12 MHz) is applied to antimicrobial treatment of samples made of heat sensitive materials, such as used in medical devices. Due to its compact design and low power consumption, typical 10 W to 60 W, it is predestined for modularisation. Therefore it can be adapted to nearly any geometry such as given by medical devices to be treated. The plasma is characterised by UV/VIS optical emission spectroscopy. In order to analyse the effect of the plasma on the micro organisms (Bacillus atrophaeus spores and Escherichia coli vegetative bacteria) microbiological tests are performed. First results on lethal effects of the plasma treamtent will be discussed.

The UV/VUV spectrum of a non-thermal capillary plasma jet operating with Ar at ambient atmosphere and the temperature load of a substrate exposed to the jet have been measured. The VUV radiation is assigned to N, H, and O atomic lines along with an Ar*2 excimer continuum. The absolute radiance (115-200 nm) of the source has been determined. Maximum values of 880 µW/mm 2 sr are obtained. Substrate temperatures range between 35˚C for low powers and high gas flow conditions and 95˚C for high powers and reduced gas flow. The plasma source (13.56, 27.12 or 40.78 MHz) can be operated in Ar and in N2. The further addition of a low percentage of silicon containing reactive admixtures has been demonstrated for thin film deposition. Several further applications related to surface modification have been successfully applied.