Patterned electromagnetic alignment of magnetic nanowires

Abstract

A combination of electromagnetic alignment and topological pattern assisted alignment to position magnetic nanowires, which is referred to as the Patterned Electromagnetic Alignment (PEA), is developed and examined. Electrodeposited, FeNiCo nanowires with different lengths were used as the test nanomaterial, and the microscale grooved surface was formed by UV nanoimprint lithography. The accuracy of the PEA with FeNiCo nanowires was evaluated by measuring the deviation angle from the direction of the magnetic field line for different magnetic field strengths and nanowire lengths, and a statistical alignment distribution was reported for different nanowire length groups. The results were compared with those of the electromagnetic alignment on flat surfaces and in grooved-patterned substrates without electromagnetic alignment. Overall, the deviation angle for the PEA was lower than that for the electromagnetic alignment when all other experimental conditions were identical, indicating that the alignment accuracy along the direction of the magnetic field lines was enhanced in the presence of surface micro grooves. This can be attributed to the fact that, upon attachment of nanowires to the substrate surface, the surface micro grooves in the PEA add additional deterministic characteristics to the otherwise stochastic nature of the nanowire deposition and solvent evaporation processes compared to the sole electromagnetic alignment.

A 3-D NanoMagnetoElectrokinetic model for ultra-high precision assembly of ferromagnetic NWs using magnetic-field assisted dielectrophoresis

“…14 One such technique is magnetic eld directed deposition of nanowires. 15,16 This technique involves controlled manipulation of NWs through magnetic elds that are created either by external magnets 15 or by magnetized contact pads/electrodes, to produce micro-and nano-devices. A key requirement in this technique is that the NW either contains capped magnetic ends 17 or is itself magnetic in nature.…”

“…A key requirement in this technique is that the NW either contains capped magnetic ends 17 or is itself magnetic in nature. 16 This method of magnetic eld directed assembly of nanowires has found application in fabrication of transparent conductive thin lms, 18 biosensors, 19 ultra-high density recording devices, 20 and biomedical applications. 21,22 Further, the manipulation of nanostructures by magnetic elds has several benets, 23 which include: (i) the nanomaterial response to the assembly eld can be tuned by changing its magnetic properties, (ii) similar to electric eld, the magnetic eld offers a non-invasive means of manipulating nanomaterial, (iii) magnets (permanent and electromagnetic) are readily available in a range of strengths commercially, and (iv) in contrast to electric elds, magnetic elds don't induce any current in the suspension solution, and are insensitive to surface charge or pH.…”

Self-assembly, alignment, and patterning of metal nanowires

“…The magnetic field can be used to align MNWs along the lines of magnetic force. [60][61][62][63] This method is only applicable to NWs either made of or modified with magnetic materials, such as nickel NWs (NiNWs) and Fe 3 O 4 -modified AgNWs (Fe 3 O 4 -AgNWs). 191,192 In a magnetic field, thousands of magnetic NWs can be aligned in one step and form a head-to-tail chain.…”

“…The self-assembly strategies of MNWs, such as the coffeering effect and ice template methods, are first described to show their advantages of low cost, easy operation, and flexible controllability. 32,34,35,[45][46][47][48][49][50][51] Subsequently, we discuss the methods to realize the alignment of MNWs, including the classical Langmuir-Blodgett (LB) technique, 30,[52][53][54][55][56][57][58][59] assembly in an electric and magnetic field, [60][61][62][63][64][65][66][67][68][69][70][71][72] bubble blowing technique, 73,74 electrospinning, [75][76][77][78][79][80][81] electrohydrodynamic (EHD) jet printing, 12,[82][83][84][85] and recently developed assembly at air/solid-liquid interfaces like the Marangoni flow-assisted float assembly.…”

Flow-Directed Growth of Aligned Metal Nanowire Films: Toward Light-Polarizing Transparent Conductors

“…Fan et al presented alignment using mechanically applied shear forces, and Pevzner et al demonstrated alignment by knocking-down vertically grown NWs . Other alignment techniques include electric field induced alignment, , electrostatic interactions with patterned surfaces, magnetic fields, , the oil–water–air interface, and a push–pull nozzle system to form aligned NWs by injecting and pumping the reactants through different nozzles . A frequently used NW alignment technique involves the use of shear forces in microfluidic systems.…”