A Miniaturized Ionization Vacuum Sensor Based on Thermionic Electron Emission From Carbon Nanotubes

Traditional hot-cathode ionization vacuum sensor (IVS) has long suffered from bulky size and integration difficulties. Here, to overcome these problems, a hot-cathode IVS is scaled down to nail size by utilizing micro-electromechanical system (MEMS) technology and exploiting carbon nanotubes (CNTs) as microscale filaments for the first time. Silicon-based grid and ion collector are bonded vertically on the hot-cathode chip to form a compact and scalable MEMS-type device with dimensions of $13\times 9\times2.7$ mm. The ratio of ion current ( ${I}_{i}$ ) to emission current ( ${I}_{e}$ ) shows measurement linearity from 0.05 to 6.50 Pa. Also, benefiting from the good reproducibility of the CNT thermionic electron emission, a minor variation (< 10%) is observed when the vacuum level is toggled repeatedly between 0.02 and 1.00 Pa. All these features make our miniaturized hot-cathode IVS a promising device for vacuum detection.