Assembly of Highly Aligned Carbon Nanotubes Using an Electro-Fluidic Assembly Process

Abstract

Carbon nanotubes (CNTs) are promising building blocks for emerging wearable electronics and sensors due to their outstanding electrical and mechanical properties. However, the practical applications of the CNTs face challenges of efficiently and precisely placing them at the desired location with controlled orientation and density. Here, we introduce an electro-fluidic assembly process to assemble highly aligned and densely packed CNTs selectively on a substrate with patterned wetted areas at a high rate. An electric field is applied during the electro-fluidic assembly process, which drives the CNTs close to the patterned regions and shortens the assembly time. Meanwhile, the electric field orientates the CNTs perpendicular to the substrate and anchors one end of the CNTs onto the substrate. When pulling the substrate out of the CNT suspension, the capillary force at the air–water–substrate interface stretches the free end of the CNTs and aligns the CNTs along the pulling direction. By adjusting two governing parameters, the direct current voltage and the pulling speed, we have demonstrated well aligned CNTs assembled in patterns with widths from 1 to 100 μm and lengths from 20 to 120 μm at a rate 20 times higher than a fluidic assembly process. The aligned CNTs show improved electrical conductivity compared with the random networks and prove possibility for strain detection. Precise and reproducible control of the orientation and the placement of the CNTs opens up their practical application in the next-generation electronics and sensors.

Assembly of Gold Nanowires on Gold Nanostripe Arrays: Simulation and Experiment

“…Surface patterns can be powerful tools in the bottom-up assembly of nanomaterials by controlling the locations at which particles are assembled on the substrate as well as the geometry of the assembly. , For example, NWs have been deposited on/into lithographically fabricated electrodes on solid substrates and attracted/aligned there by electrophoretic forces. − Significant efforts have been directed toward achieving ordered NW and nanorod (NR) arrays via capillary assembly, in which convective flow and capillary forces that occur at an evaporating/receding liquid–solid interface can order and orient nanoparticles on a patterned substrate. ,,,,− Chemically patterned substrates have also been used to align NWs and NRs. ,− In this work, we adopt a relatively simple method, in which NWs in an aqueous suspension sediment onto a patterned substrate and are attracted to the pattern by van der Waals (vdW) forces. They subsequently diffuse and assemble on the patterned features, exhibiting a surprisingly diverse variety of ordered patterns.…”

Discontinuous Dewetting, Template-Guided Self-Assembly, and Liquid Bridge-Transfer Printing of High-Resolution Single-Walled Carbon Nanotube Lines for Next-Generation Electrodes and Interconnects

“…The SWCNT lines adhered well over the electrodes, demonstrating the ability to transfer onto varying materials and topology (Figure D–G). Contact resistance was determined by the three-electrodes method (see Supporting Information for details) as described in the literature. , Resistance of the lines was determined by the measurement between electrodes minus the contact resistance, and each SWCNT line was treated as a resistor connected in parallel. Arrays were used to obtain an approximate average over many SWCNT lines.…”

“…LBT also allows for possible R2R compatibility when combined with DD. While inking speed is currently at around 0.6 mm min –1 for SWCNTs, future work may incorporate electrophoresis of the SWCNTs to increase the SWCNT deposition rate within the cavities. ,, Evaporation during SWCNT deposition and during LBT may also be increased through controlling the environment (temperature, pressure, humidity), which may increase process speed.…”

3D motion tracking display enabled by magneto-interactive electroluminescence

“…The measured EL intensity arising from the dielectrophoretic force was three or four orders of magnitude lower than that resulting from the magnetophoretic one, making the dielectrophoretic contribution negligible in our NV-MED ( Supplementary Figs. 16) [31][32][33][34] . The NV-MED EL changes are plotted as a function of magnetic field, as shown in Fig.…”