Vacuum steered-electron electric-field sensor

In a new type of MEMS electric-field sensor, a sheet of electrons is thermionically emitted by a hot cathode, flows through a vacuum, and is collected by a pair of anodes 2000 um away. As the electrons move through the vacuum, they are steered by external electric fields, resulting in a differential current at the anodes. The micromachined tungsten cathode has a low-work-function coating and is suspended over a cavity on a glass chip. These sensors have been operated both in a vacuum chamber and sealed in glass vacuum tubes. Measured sensitivities in a vacuum tube are 470 mV/mHz1/2 at 10 Hz, 230 mV/mHz1/2 at 100 Hz, and 140 mV/mHz1/2 at 1 kHz; sensitivities in a vacuum chamber at the same frequencies are 34, 6.3, and 2.4 mV/mHz1/2, respectively.

Citation

Williams, K.; De Bruyker, D.; Limb, S.; Amendt, E.; Overland, D. Vacuum steered-electron electric-field sensor. To be published in IEEE/ASME Journal of Microelectromechanical Systems.