Spontaneous liquid marble formation on packed porous beds

Whitby, Catherine P.; Bian, Xun; Sedev, Rossen

doi:10.1039/c2sm26529j

Cited by 26 publications

(25 citation statements)

References 43 publications

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“…In fact, in both cases the shape deviates from a sphere having a slight concave surface at the center. In this configuration the concave polymer profile resulting from the surface charge distribution is additionally modified as a consequence of the kinetic behavior of the slowly solvent evaporation process in the droplet well known in literature [33]. Fig.…”

Section: Fabrication Processmentioning

confidence: 81%

Electrohydrodynamic Assembly of Multiscale PDMS Microlens Arrays

Vespini

Gennari

Coppola

et al. 2015

IEEE J. Select. Topics Quantum Electron.

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In this paper, we introduce an easy multiscale approach for the fabrication of polymer microlens arrays through a self-assembling process driven by the electrohydrodynamic (EHD) pressure. This method represents a simple alternative to the conventional soft lithography techniques. A thin layer of liquid polymer is deposited on a microengineered ferroelectric crystal and can be self-assembled and cross-linked in a single-step process as a consequence of the pyroelectric effect activated by simply heating the substrate. Although the EHD instability induced by the pyroelectric effect was discovered in principle few years ago, here we demonstrate a systematic investigation for fabrication of microlens arrays in a multiscale range (i.e., between 25 to 200 μm diameter) with high degree of uniformity. By controlling the polymer instability driven by EHD, we report on two different microoptical shapes can be obtained spontaneously, i.e., spherical or toroidal. Here, we show how the geometrical properties and the focal length of the lens array are modulated by controlling two appropriate parameters. Such microlenses can be useful also as polymer patterned arrayed microstructures for optical data interconnections, OLEDs efficient light extraction, concentrating light in energy solar cells, imaging and 3-D display solutions, and other photonics applications.

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Section: Fabrication Processmentioning

confidence: 81%

Electrohydrodynamic Assembly of Multiscale PDMS Microlens Arrays

Vespini

Gennari

Coppola

et al. 2015

IEEE J. Select. Topics Quantum Electron.

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“…1a) and 100 µL liquid droplets. Upon gentle contact of the liquid with the bed of copper flakes, spontaneous LM formation was observed; the copper flakes migrated around the droplet of liquid, forming a completely coated LM without the need of rolling (this phenomenon has been previously observed using ethanol/water binary solutions and hydrophobised glass beads [38]). The experimental LM fluid core was a single walled-CNT ( Fig.…”

Section: Methodsmentioning

confidence: 57%

Neuromorphic Liquid Marbles with Aqueous Carbon Nanotube Cores

et al. 2019

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Neuromorphic computing devices attempt to emulate features of biological nervous systems through mimicking the properties of synapses, towards implementing the emergent properties of their counterparts, such as learning. Inspired by recent advances in the utilisation of liquid marbles (microlitre quantities of fluid coated in hydrophobic powder) for the creation of unconventional computing devices, we describe the development of liquid marbles with neuromorphic properties through the use of copper coatings and 1.0 mg ml −1 carbon nanotube-containing fluid cores. Experimentation was performed through sandwiching the marbles between two cup-style electrodes and stimulating them with repeated DC pulses at 3.0 V. Our results demonstrate that 'entrainment' of a carbon nanotube filled-copper liquid marble via periodic pulses can cause their electrical resistance to rapidly switch between high to low resistance profiles, upon inverting the polarity of stimulation: the reduction in resistance between high and low profiles was approximately 88% after two rounds of entrainment. This effect was found to be reversible through reversion to the original stimulus polarity and was strengthened by repeated experimentation, as evidenced by a mean reduction in time to switching onset of 43%. These effects were not replicated in nanotube solutions not bound inside liquid marbles. Our electrical characterisation also reveals that nanotube-filled liquid marbles exhibit pinched loop hysteresis IV profiles consistent with the description of memristors. We conclude by discussing the applications of this technology to the development of unconventional computing devices and the study of emergent characteristics in biological neural tissue.

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“…1a). In contrast, drops remain stationary on horizontal beds of coarse powders (98 μm in diameter) [10]. We observed particles coating stationary liquid drops on powder beds when θ a ~ 90° [10].…”

Section: Resultsmentioning

confidence: 91%

“…We demonstrate that the drop mobility and the resulting particle coverage of the liquid surfaces is controlled by γ and the drop kinetic energy. These results, together with our previous experiments on spontaneous coating [10], provide a detailed picture of droplet behaviour on non-wetting surfaces. …”

Section: Introductionmentioning

confidence: 89%

Free running droplets on packed powder beds

Whitby¹,

Bian²,

Sedev³

2013

AIP Conference Proceedings

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Abstract. We observed that water drops placed on horizontal beds of fine molybdenite particles move freely over the bed surface for about 1 second. The drops collect an irregular coating of unevenly distributed particles as they bounce and roll. We manipulated the distance that the drops travel, and hence the area of the droplet surface coated with particles, by varying the water surface tension and the kinetic energy of the initial droplet impact on the bed surface. Our results highlight the role of contact angle hysteresis in particle encapsulation of liquid drops.

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Spontaneous liquid marble formation on packed porous beds

Cited by 26 publications

References 43 publications

Electrohydrodynamic Assembly of Multiscale PDMS Microlens Arrays

Electrohydrodynamic Assembly of Multiscale PDMS Microlens Arrays

Neuromorphic Liquid Marbles with Aqueous Carbon Nanotube Cores

Free running droplets on packed powder beds

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