Fabrication and Characterization of a 10 × 10 cm Cold Atmospheric Pressure Plasma Array

We report the development of a large area cold atmospheric plasma array. The device consists of a parallel stack of 43 linear-discharge plasma elements that create a 10 × 10 cm treatment area. The cold atmopsheric pressure plasma (CAP) device is fabricated using low-temperature co-fired ceramic (LTCC) layers to create 10-cm-long linear-discharge channels (1.1-mm discharge gap) with embedded opposing silver metal electrodes. A 21-kHz ac voltage of 1.55 kVrms applied to the electrodes generates an Ar plasma between the plates, with the gas flow directing the reactive species toward the intended biological sample (bacteria biofilms and so on) to affect the antimicrobial treatment. Internal ballast resistors (20 kΩ) were used on each side of the two electrode elements to improve discharge uniformity and to prevent large filamentary discharges. Typical element discharge currents were 3.5–4 mA with the total array current tested at 178-mA root mean square (rms) to provide optimal device uniformity at a 1.55 kV (rms), and an argon flow rate of 130 lpm. Furthermore, the gas flow system was optimized to obtain a uniform plasma. Treatment of Pseudomonas fluorescens bacterial biofilms on stainless steel coupons demonstrated a 91% decrease in colony-forming units (CFUs) after 150 s of treatment with a 1.5-cm gap.