Optimization of an electron impact ion source on a MEMS time-of-flight mass spectrometer

[Display omitted] •We have microfabricated an electron impact ion source for integrated mass spectrometry.•Simulations were used to optimize the total ion current.•Ions are efficiently extracted and focused outside the ion source.•Hundreds of picoamperes of ion current is collected using this MEMS ion source. This study reports the optimization of the first stages of a MEMS-based, microfabricated time-of-flight mass spectrometer. The authors present an acceptable match between simulations and experimental results. It validates the use of simulations as a time efficient approach as to predict optimal experimental set points. Chips with three differently meshed ionization grids have been tested and show a significant impact of the grid size on both ionization and extraction. An optimal trade-off is found for 3mm×3mm grid, with about 5×10−6 ion/atom ionization efficiency and over 50% extraction rate. Optimized parameters for ion focussing are found faster with the help of simulations as the experimental optimal settings are found near the predicted simulated voltages. A total ionic current of hundreds of picoamperes is measured, confirming the potential of this electron-impact ion source as the first step of the full time-of-flight mass spectrometer integrated on a single MEMS chip.