HMOS sensing of oxidizing species in an atmospheric plasma jet

Abstract

A novel implementation of heated metal-oxide semi-conductor gas sensing (HMOS) is utilized to map the oxidizing species concentration in the effluent of a low-temperature plasma jet. Optical breadboard, posts and feet accessories are repurposed to position a small HMOS sensor accurately at coordinates in the plane of effluent emanating from the KinPEN MED® plasma jet, a commercial atmospheric plasma system. Operating with an argon carrier gas, oxidizing species concentrations of 240–11 ppb can extend 500 mm from the 1-mm-diameter nozzle encompassing a radius of 20 mm. For jet operation with compressed air, larger oxidizing species concentrations up to 1100 ppb were found surrounding the jet. This diagnostic approach shows potential for continuous and spatially resolved monitoring of collective concentrations of oxidizing/reducing reactive species (O3, NOx, H2O2), which is of particular interest in characterizing treatment areas, informing dosage, and enabling control systems in emerging clinical and industrial application environments.