3D Printing Macroscale Engineered Materials Using Ultrasound Directed Self‐Assembly and Stereolithography

Greenhall, John; Raeymaekers, Bart

doi:10.1002/admt.201700122

Cited by 79 publications

(64 citation statements)

References 42 publications

(66 reference statements)

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“…The acoustic radiation potential as a quadratic form. For a superposition of plane waves of the form (4), the acoustic radiation potential at a point x can be written as (7) ψ(x; u) = u * Q(x)u,…”

Section: Study Of the Acoustic Radiation Potentialmentioning

confidence: 99%

Periodic particle arrangements using standing acoustic waves

Vasquez

Mauck

2019

Proc. R. Soc. A.

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We determine crystal-like materials that can be fabricated by using a standing acoustic wave to arrange small particles in a non-viscous liquid resin, which is cured afterwards to keep the particles in the desired locations. For identical spherical particles with the same physical properties and small compared to the wavelength, the locations where the particles are trapped correspond to the minima of an acoustic radiation potential which describes the net forces that a particle is subject to. We show that the global minima of spatially periodic acoustic radiation potentials can be predicted by the eigenspace of a small real symmetric matrix corresponding to its smallest eigenvalue. We relate symmetries of this eigenspace to particle arrangements composed of points, lines or planes. Since waves are used to generate the particle arrangements, the arrangement’s periodicity is limited to certain Bravais lattice classes that we enumerate in two and three dimensions.

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Section: Study Of the Acoustic Radiation Potentialmentioning

confidence: 99%

Periodic particle arrangements using standing acoustic waves

Vasquez

Mauck

2019

Proc. R. Soc. A.

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“…While rotation of particles alone can produce desirable properties for certain applications, such as mechanical reinforcement, particle alignment without a translational component is detrimental for conductivity due to disruption of percolation . For other functional properties, versatility in the particle patterns that can be assembled is important for optimizing properties, and acoustic focusing meets this need by allowing assembly of complex patterns, even of user‐defined patterns . Acoustic focusing can also handle a larger variety of particle and fluid materials than electromagnetic assembly because it depends only on the contrast in density and compressibility between the particle and fluid material, not polarizability, conductivity, or other material properties.…”

Section: Introductionmentioning

confidence: 99%

“…Though used primarily for cell sorting and other biological characterization, acoustic focusing has recently garnered interest for use in 3D printing via direct ink writing and stereolithography . Electrical elements have successfully been printed with the latter method in recent years, although the need for well‐controlled modulation between a variety of material properties is still unfulfilled. Additionally, a more scalable printing framework would be valuable, since the acoustic focusing reservoirs in stereolithography produced to date limit it to printing < 50 mm components .…”

Section: Introductionmentioning

confidence: 99%

“…Electrical elements have successfully been printed with the latter method in recent years, although the need for well‐controlled modulation between a variety of material properties is still unfulfilled. Additionally, a more scalable printing framework would be valuable, since the acoustic focusing reservoirs in stereolithography produced to date limit it to printing < 50 mm components . Previous work investigated the assembly and printing dynamics of direct ink writing with acoustophoresis using insulating particles and a similar device design .…”

Section: Introductionmentioning

confidence: 99%

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Flexible Conductive Composites with Programmed Electrical Anisotropy Using Acoustophoresis

Melchert

Collino

Ray

et al. 2019

Adv Materials Technologies

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Developing mechanically flexible composite materials with high electrical conductivity is currently hindered by the need to use high loading of conductive filler, which severely limits flexibility. Here, acoustic focusing is used to control arrangement of conductive particles in photopolymer matrices to create composites with both tunable conductivity and flexibility. Acoustophoresis patterns filler particles into highly efficient percolated networks which utilize up to 97% of the particles in the composite, whereas the inefficient stochastic networks of conventional dispersed‐fiber composites utilize <5%. These patterned materials have conductivity an order of magnitude higher than conventional composites made with the same ink, reaching 48% the conductivity of bulk silver within the assembled silver‐particle networks (at 2.6 vol% loading). They also have low particle loading so that they are flexible, withstanding >500 bending cycles without losses in conductivity and changing conductivity only 5% within cycles on average. In contrast, conventional unpatterned composites with the same conductivity require such high loading that they are prohibitively brittle. Finally, modulating the applied acoustic field controls the anisotropy of the conductive networks and produces materials which are either 2D conductive, 1D conductive, or insulating, using the same nozzle and ink, paving the way for versatile multifunctional 3D printing.

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“…PATs and phase plates have been used to demonstrate acoustic tweezing of single particles in water and air . Ultrasound has also been used in conjunction with other fabrication methods, for example 3D printing, to position fibers in a composite object that is shaped via stereolithography . However, with the existing methods it has not been feasible to generate acoustic fields for particle assembly in truly arbitrary shapes.…”

mentioning

confidence: 99%

Acoustic Fabrication via the Assembly and Fusion of Particles

et al. 2017

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Acoustic assembly promises a route toward rapid parallel fabrication of whole objects directly from solution. This study reports the contact-free and maskless assembly, and fixing of silicone particles into arbitrary 2D shapes using ultrasound fields. Ultrasound passes through an acoustic hologram to form a target image. The particles assemble from a suspension along lines of high pressure in the image due to acoustic radiation forces and are then fixed (crosslinked) in a UV-triggered reaction. For this, the particles are loaded with a photoinitiator by solvent-induced swelling. This localizes the reaction and allows the bulk suspension to be reused. The final fabricated parts are mechanically stable and self-supporting.

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3D Printing Macroscale Engineered Materials Using Ultrasound Directed Self‐Assembly and Stereolithography

Cited by 79 publications

References 42 publications

Periodic particle arrangements using standing acoustic waves

Periodic particle arrangements using standing acoustic waves

Flexible Conductive Composites with Programmed Electrical Anisotropy Using Acoustophoresis

Acoustic Fabrication via the Assembly and Fusion of Particles

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