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Abstract
This lecture deals with the design, fabrication, characterization and biomedical applications of microwave-excited non-thermal microplasma sources based on coaxial transmission line resonators. The sources are capable of generating electric fields of ∼106 V/m with microwave power. These devices can self-ignite helium or argon discharges in a wide pressure range including atmospheric pressure. The gas temperature in an argon discharge open to atmospheric air is ∼400 K. The working gases passed through the device can result in the formation of plasma jets suitable for surface treatments. The device efficiency on transferring the input power into the plasma is 50–85 % depending on the gas used. No thermal damage or electrode erosion has been observed in the devices. A low-power palm-size microwave power module for portable microwave-excited plasma applicable to various fields is integrated on a single printed circuit board. The designed board includes a power amplifier chip, a phase-locked loop (PLL) chip, and an impedance matching network with microstrip lines. In addition, as a part of the true one-chip integration of the plasma power module, the PLL is designed and fabricated in a semiconductor chip with a 0.18-μm CMOS technology for dedicated use to our plasma source. Biomedical applications such as bacteria inactivation, tooth bleaching and protein removal with the handheld plasma system will be introduced.