Electron Impact Ionizers

We are interested in developing MEMS/NEMS enabled gas ionizers for portable mass spectrometry applications using carbon nanotube (CNT)-based field emission cathodes that produce ions through electron impact ionization because of the remarkable physical and chemical properties of CNTs. Mass spectrometers are powerful analytical tools that are helpful to quantitatively determine the chemical composition of a sample. Conventional mass spectrometry hardware is bulky and power hungry, which limits its applicability. The development of rugged scaled-down mass spectrometry (MS) systems would enable their portability and therefore, it would extend the use of mass spectrometry to a wide range of in-situ applications including geological survey, law enforcement, environmental monitoring, process control, and space exploration.

The power consumption, size, and weight of an MS system are driven by its vacuum requirements. Therefore, the relaxation of the vacuum level at which the MS components can operate would enable its portability. In addition, the use of micro- and nanofabrication technologies to implement miniaturized MS hardware would facilitate component batch-fabrication, further reduce the dimensions of the components, and potentially enable the implementation of systems with higher performance through better component integration. Our research has focused on the development of MEMS/NEMS enabled electron impact ionizers (EIIs) using vertically aligned multi-walled carbon nanotubes (MWCNTs) with a proximal gate as electron source.