Investigation of a spatially resolved open microchannel substrate using a He/Ar APPJ*

Atmospheric pressure plasmas are of great interest due to their applications in surface modification, medicine, and advanced manufacturing. There is still much to learn about these plasma systems, including how plasmas interact with complex and multiphase surfaces. The goal of this work is to use an open microchannel substrate utilizing capillary flow to investigate the spatially resolved generation of hydroxyl radicals perpendicular to the plasma impinging on the substrate.  This configuration provides a controlled delivery of liquid for plasma exposure to quantify interaction through plasma diagnostics and post exposure liquid treatment. The open microchannel substrate allows for flow control of 0.35$ml/min$ to 1.2$ml/min$. Channels have a rectangular cross-section of 100$\mu m$ wide and 200$\mu m$ in depth with a pitch of 100$\mu m$. Gas phase investigations include gas temperatures via $N_{2}$ and state densities of argon. Plasma is generated using an APPJ with two power delivery configurations: 1.) 13.56$MHz$ RF and 2.) pulsed high voltage DC, using a He/Ar mixture with varying flow rate.  The goal of this study is to quantify the power delivery of the plasma to the substrate as well as quantify the plasma interactions with the solid and liquid area of the substrate.