Cold Atmopsheric Pressure Plasma Planar and Radial Arrays for Biofilm Remediation

Cold Atmospheric pressure Plasma (CAP) has the ability to both inactivate and remove bacterial biofilms from wounds and surfaces. Planar CAP arrays 1 (2.4 x 2 cm) have been developed using linear discharge elements (2.4 cm long), operating with a 0.75 mm gap at 0.5-2 kV, 20 kHz AC. The elements are fabricated using Low Temperature Co-fired Ceramic (LTCC). Hydrated argon gas flows (1-5 slm) between two plates to create the discharge element. Each discharge element draws 0.5 – 1.5 mA depending upon operating conditions. The elements are stacked together to form the arrays. Measurements of reactive oxygen species have shown generation of peroxide and hydroxyl radicals which increase linearly with plasma exposure times from the arrays. Measurements of the Colony Forming Units (CFUs) shown >99% reduction in <60 s for bacterial biofilms on a range of substrates (stainless steel, glass, plastic). Removal (etching) of bacterial biofilms on steel has also been demonstrated when using water vapor with the argon gas mixture. Etch time are 100-200 s depending upon biofilm thickness and operating conditions. Finally, radial plasma arrays (4 cm diameter) are also under development for use in structures such as pipes. These have been operated in a 3-element configuration. Additional biofilm etching results for the planar arrays and new results from the radial arrays will be presented.