Fully 3D-printed carbon nanotube field emission electron sources with in-plane gate electrode

Abstract

We report the design, fabrication, and experimental characterization of the first fully additively manufactured carbon nanotube (CNT) field emission electron sources. The devices are created via direct ink writing (DIW)—one of the least expensive and most versatile additive manufacturing methods, capable of creating monolithic multi-material objects. The devices are 2.5 cm by 2.5 cm glass substrates coated with two imprints, i.e. a trace made of a CNT ink (the emitting electrode), symmetrically surrounded on both sides by a trace made of Ag microparticle ink (the in-plane extractor gate). The CNT ink is a mixture of (–COOH)-functionalized multiwalled CNTs (MWCNTs), N,N-Dimethylformamide, and ethyl cellulose. Optimization of the formulation of the CNT ink resulted in a MWCNT concentration equal to 0.82 wt% and in imprints with an electrical resistivity equal to 0.78 Ω cm. 3D-printed devices having CNT imprints with active length equal to 25 mm (a single, straight trace with 174.5 μm gap between adjacent Ag microparticle imprints) and 135 mm (a square-loop spiral with 499 μm gap between Ag microparticle adjacent imprints) were characterized in a triode configuration (i.e. using an external anode electrode) at ∼2.5 × 10–7 Torr, yielding emission currents as large as 120 μA (60 μA cm−2), start-up voltages as low as 62 V and gate transmission as high as 99%. The low-cost cold cathode technology is compatible with compact applications such as miniaturized mass spectrometry, handheld x-ray generation, and nanosatellite electric propulsion.

Low‐Cost, Compact Quadrupole Mass Filters with Unity Mass Resolution via Ceramic Resin Vat Photopolymerization

“…As a comparison, the manufacturing of the 3D‐printed quadrupoles takes about a day (including metallization) and costs tens of dollars; this is in strike difference with the cost of a commercial quadrupole (thousands of dollars) that typically requires integration of components from multiple vendors and whose individual component manufacturing processes can take weeks to complete. Other key components of the mass spectrometer, e.g., ionizer [ 38 , 39 ] , and vacuum chamber [ 40 ] have been demonstrated to properly work when made via 3D printing; manufacturing them also incurs a small fraction of the cost of commercial counterparts. Therefore, implementing a mass spectrometer made as much as possible via 3D printing should yield a significantly cheaper instrument.…”

3D-Printed MEMS in Italy

“…The most common manufacturing methods for CNTs are laser transfer, screen printing, and plasma-enhanced chemical vapour deposition. Nevertheless, these manufacturing techniques come with certain challenges, including expense, extended processing du-ration, the requirement for static masks to define specific locations for the nanostructured emitting material, and so on [ 125 ]. Thus, 3D-printing methods stand for an alternative method that lend themselves to overcoming these limitations, since they are maskless and allow one to implement hierarchical structures, with features spanning orders of magnitude in size.…”

“…Thus, 3D-printing methods stand for an alternative method that lend themselves to overcoming these limitations, since they are maskless and allow one to implement hierarchical structures, with features spanning orders of magnitude in size. Indeed, there are many works which are based on printing CNTs and other carbon-based materials to create freeform objects with a high electrical conductivity [ 125 ].…”

Field Electron Emission from Crumpled CVD Graphene Patterns Printed via Laser-Induced Forward Transfer

“…The transition from bulk to low-dimensional materials has opened up new opportunities in the creation of new electronic elements and the modification of existing ones, particularly field emitters, due to their adjustable band gap and promising electronic properties [ 1 , 2 , 3 , 4 ]. The interest in these materials has increased significantly due to the discovery of the unique properties of graphene [ 5 ].…”