Dielectrophoretic Assembly of Electrically Functional Microwires from Nanoparticle Suspensions

Hermanson, Kevin D.; Lumsdon, Simon O.; Williams, Jacob P.; Kaler, Eric W.; Velev, Orlin D.

doi:10.1126/science.1063821

Cited by 539 publications

(446 citation statements)

References 27 publications

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“…DEP is defined as the translational motion of particles caused by an inhomogeneous electric field (14) and has been previously used for particle manipulation (16)(17)(18)(19)(20), particle/cell separation (21-26), and particle assembly/trapping. (17,19,(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38) Electrically driven particle motion depends on the dielectric constant contrast between the solvent and the particle. A particle with a dielectric constant (« p ) different from the suspending medium (« m ) acquires a dipole moment under the influence of an electric field and is either attracted toward (if « p > « m , "positive" DEP), or repelled from (if « p < « m , "negative" DEP) the regions with the strongest electric field.…”

Section: Resultsmentioning

confidence: 99%

Periodically microstructured composite films made by electric- and magnetic-directed colloidal assembly

Demirörs

Courty

Libanori

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Living organisms often combine soft and hard anisotropic building blocks to fabricate composite materials with complex microstructures and outstanding mechanical properties. An optimum design and assembly of the anisotropic components reinforces the material in specific directions and sites to best accommodate multidirectional external loads. Here, we fabricate composite films with periodic modulation of the soft-hard microstructure by simultaneously using electric and magnetic fields. We exploit forefront directed-assembly approaches to realize highly demanded material microstructural designs and showcase a unique example of how one can bridge colloidal sciences and composite technology to fabricate next-generation advanced structural materials. In the proof-of-concept experiments, electric fields are used to dictate the position of the anisotropic particles through dielectrophoresis, whereas a rotating magnetic field is used to control the orientation of the particles. By using such unprecedented control over the colloidal assembly process, we managed to fabricate ordered composite microstructures with up to 2.3-fold enhancement in wear resistance and unusual site-specific hardness that can be locally modulated by a factor of up to 2.5.L ightweight composites offer an attractive alternative toward minimization of the energy demand of mobility systems from automobiles and airplanes to trains and ships. Continuous stiff fibers or discontinuous anisotropic particles have often been used as reinforcing phase to enhance the specific mechanical properties of such lightweight polymer-based composites. Although the fabrication costs of long-fiber reinforced composites remain prohibitive for the large-scale production of high-performance materials, the processing of polymer-based composites reinforced with discontinuous stiff elements can often be adapted to the automated manufacturing processes commonly used in the polymer industry, such as injection molding. However, these fabrication processes usually offer a limited control over the alignment and spatial distribution of the reinforcing particles, preventing a full optimization of the microstructural design in composite materials. Thus, the development of new strategies to assemble microstructured composites with tailored reinforcing architectures is crucial for the design and fabrication of even lighter and cheaper structural materials.Control over the spatial distribution and orientation of particles in composites can be achieved using colloidal assembly tools that guide/template the organization of the reinforcing particles while the material is still in a fluid state. Recently, we have shown that control of particle orientation using an external magnetic field can lead to a significant increase in the materials' resistance against deformation, wear, and crack initiation, widening their range of applications (1, 2). Independent of orientation control, tuning the spatial distribution of particles through magnetic fields, centrifugal forces, or film welding techniq...

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Section: Resultsmentioning

confidence: 99%

Periodically microstructured composite films made by electric- and magnetic-directed colloidal assembly

Demirörs

Courty

Libanori

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…Procedures developed for contacting large ensembles of randomly positioned nanodevices on a substrate with electron beam lithography have not been published. Other approaches in the literature to place many nanowires in parallel in a controlled way on wafer scale to pre-patterned sites include dielectrophoresis [28][29][30][31][32] and contact printing [33].…”

Section: Introductionmentioning

confidence: 99%

Electrical contacts to single nanowires: a scalable method allowing multiple devices on a chip. Application to a single nanowire radial p-i-n junction

Heiß

Colombo

Mallorquí

et al. 2013

IJNT

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Semiconductor nanowires are currently at the forefront of research in the areas of nanoelectronics and energy conversion. In all these studies, realising electrical contacts and statistically relevant measurements is a key issue. We propose a method that enables to contact hundreds of nanowires on a single wafer in an extremely fast electron beam lithography session. The method is applied to nanowire-based radial GaAs p-i-n junction. Currentvoltage characteristics are shown, along with scanning photocurrent mapping.

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“…[6][7][8][9][10] One of the most efficient, robust and widely used methods for directing the colloidal assembly and controlling the interparticle interactions is the application of external electric or magnetic fields. [11][12][13][14][15] Depending upon the physiochemical characteristics of the particles and the applied field(s), the colloids can be assembled into linear chains, 2D or 3D bundles or crystals of desired symmetry. 4,[16][17][18][19][20] In the case of isotropic spherical particles, the application of an external field induces a dipole in the particles and lead to their unidirectional chaining.…”

Section: Introductionmentioning

confidence: 99%

Multidirectional colloidal assembly in concurrent electric and magnetic fields

et al. 2016

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a Dipolar interactions between nano-and micron sized colloids lead to their assembly into domains with well-defined local order. The particles with a single dipole induced by an external field assemble into linear chains and clusters. However, to achieve the formation of multidirectionally organized nano-or microassemblies with tunable physical characteristics, more sophisticated interaction tools are needed.Here we demonstrate that such complex interactions can be introduced in the form of two independent, non-interacting dipoles (double-dipoles) within a microparticle. We show how this can be achieved by the simultaneous application of alternating current (AC)-electric field and uniform magnetic field to dispersions of superparamagnetic microspheres. Depending on their timing and intensity, concurrent electric and magnetic fields lead to the formation of bidirectional particle chains, colloidal networks, and discrete crystals. We investigate the mechanistic details of the assembly process, and identify and classify the non-equilibrium states formed. The morphologies of different experimental states are in excellent correlation with our theoretical predictions based on Brownian dynamics simulations combined with a structural analysis based on local energy parameters. This novel methodology of introducing and interpreting double-dipolar particle interactions may assist in the assembly of colloidal coatings, dynamically reconfigurable particle networks, and bidirectional active structures.

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Dielectrophoretic Assembly of Electrically Functional Microwires from Nanoparticle Suspensions

Cited by 539 publications

References 27 publications

Periodically microstructured composite films made by electric- and magnetic-directed colloidal assembly

Periodically microstructured composite films made by electric- and magnetic-directed colloidal assembly

Electrical contacts to single nanowires: a scalable method allowing multiple devices on a chip. Application to a single nanowire radial p-i-n junction

Multidirectional colloidal assembly in concurrent electric and magnetic fields

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