Characterization and design of Low-Temperature Plasma based probes for ambient sampling of chemicals

Jason D Harper, Purdue University

Abstract

This research involves the characterization and design of low-temperature plasma based probes for ambient sampling of chemicals and detection via mass spectrometry. A novel ambient plasma based ionization source termed the Low-Temperature Plasma (LTP) Probe is chemically and electrically characterized. The use of dielectric barrier discharge (DBD) to create a low-temperature plasma fashioned into a probe facilitates the analysis of gaseous, solid, and liquid molecules in the ambient environment with little or no sample preparation. The LTP probe is chemically characterized by analyzing an array of chemicals varying from explosives to pharmaceuticals. This research also focuses on the miniaturization and portability of the LTP probe. Prototypes have been designed, manufactured, and tested, with promising results. Initial data involving non-proximate ion transfer over long distances (>20 ft) is provided. The electrical characterization of the LTP probe provides an electrical equivalent model as well as design equations. The effect of the inner electrode displacement is explored as well as the discharge power of the LTP probe with both air and helium discharges. This research also looks at the LTP probe's frequency dependence as well as the driving circuit's efficiency. The goal of this work is to provide the next researcher a solid background and guide for the optimization of the LTP probe ambient desorption ionization source.

Degree

M.S.

Advisors

Denton, Purdue University.

Subject Area

Analytical chemistry|Electrical engineering

COinS