Abstract

A micro-plasma jet device that uses a flowing working gas and a species electrode design to prevent arcing has been developed. It deposits materials at lower temperatures, makes it suitable for a wide range of biomedical applications. For non-thermal low-pressure plasma, the size of the object that can be treated is limited by the size of the vacuum chamber and complicated equipment is necessary. Micro-plasma does not have these limitations. Compared to the other non-thermal atmospheric-pressure plasma, micro-plasma jet allows a lower breakdown voltage and a lower gas temperature, which is beneficial for thermally sensitive substrates. In addition, a homogeneous and uniform discharge can be generated by micro-plasma jet for applications on irregular-shaped surfaces. In this thesis, the application of micro-plasma jet for antibacterial properties to the surface modification of polyethylene (PE) induced triclosan is studied. Argon and argon mixed with a nitrogen micro-plasma jet are used as the working gas under atmospheric pressure. The surface of PE is activated by plasma treatment to produce more hydrophilic groups so that antibacterial agent triclosan can be coated more effectively on the surface (P-TC) and reloaded into plasma (P-TC-P). The surface characteristics are evaluated using static contact angle measurements and X-ray photoelectron spectroscopy analysis. The inhibition zone on agar is used as an in vitro test of antibacterial properties on Escherichia coli. Results confirm that after reload into plasma, more antibacterial agent is immobilized on the surface. The highest increase of antibacterial activity is observed for the sample P-TC-P obtained with a 60-s plasma exposure time. An Ar micro-plasma jet is better than Ar mixed with nitrogen in terms of improving the antibacterial properties of PE.

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