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.

Here we report the fabrication of a carbon-nanotube (CNT) based lithium ion electrode architecture, consisting of alternating layers of multi-walled carbon nanotubes (MWNT) and lithium ion active material, to significantly increase the aerial power and energy density of lithium ion battery cathodes. The CNT-based architecture aims to address engineering limitations of nanoscale active materials such as poor packing density, electrolyte reactivity, and costly fabrication. The alternating layers create a highly porous and highly conductive scaffolding to enhance ionic and electronic transport pathways within the electrode. The results show that the presented CNT-based architecture yielded excellent rate capability and highly stable cycling of lithium manganese oxide (LiMn 2 O 4 ) active materials and lithium (Li) rich layered (xLi 2 MnO 3 • (1-x)LiMO 2 ) materials. For LiMn 2 O 4 materials, the CNT-based architecture demonstrates 14-20x higher aerial capacity over standard fabrication electrodes at discharge rates of 10C. For Li-rich layered materials, the CNT-based architecture demonstrates 70% higher aerial capacity over standard fabrication electrodes at discharge rates of C/2. Highly stable cycling for 100 cycles at 15C for LiMn 2 O 4 and 500 cycles at 1C for Li-rich layered materials is also observed using the CNT-based architecture. The effect of the number of layers, layer thickness, and composition of the active material is investigated.

No abstract

We report a nanolithography technique for the high aspect-ratio nanostructure manufacturing using DODE (double oxide deposition and etching) process. Conventional microfabrication processes are integrated to manufacture nanostructure arrays with sub-100 nm of linewidth. This lithography method is developed to overcome resolution limits of photolithography. High aspect-ratio nanostructures with sub-100 nm of lindewidth were fabricated on wafer-scale substrate without nanolithography techniques. The DODE lithography process presented enabled to pave a way to overcome limitations of nanolithography processes and allowed to manufacture large-scale nanostructures using photolithography and thin film deposition and dry etching processes.

No abstract