Densely Packed, Additively Manufactured, In-Plane Gated Carbon Nanotube Field Emission Electron Sources

We present additively manufactured, in-plane gated field emission electron sources with 35% lower startup voltage (~40 V) and 65% larger current density (~100 μA/cm
²
) compared to state-of-the-art, 3D-printed, in-plane gated field emission devices. Our sources are made via direct ink writing (DIW) on a custom printed circuit board (PCB) and are composed of two concentric spiral traces: a trace made of a novel, high-concentration carbon nanotube (CNT) ink acting as the emitting electrode, and a conventional PCB copper trace acting as the extractor gate. The work is of great interest to miniaturized electric space propulsion and compact mass spectrometry.