Vacuum Steered-Electron Electric-Field Sensor

ABSTRACT
In a new type of microelectromechanical system
(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 2000µm 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 at 10, 100, and 1000 Hz
are 470, 230, and 140 mV/m · Hz1/2, respectively; sensitivities
in a vacuum chamber at the same frequencies are 34, 6.3, and
2.4 mV/m · Hz1/2, respectively.