Fabrication and electrokinetic motion of electrically anisotropic Janus droplets in microchannels

Li, Mengqi; Li, Dongqing

doi:10.1002/elps.201600310

Cited by 16 publications

(10 citation statements)

References 73 publications

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“…Janus droplets with precise size and topology are synthesized one by one in a droplet microfluidic system by shearing two parallel streams of immiscible phases with a continuous phase. Apart from the two above-mentioned methods, it has been reported that the generation of electrically induced Janus droplets (EIJDs) was conducted by using a direct current (DC) electrical field to induce the redistribution of positively charged aluminum oxide (Al 2 O 3 ) nanoparticles adhering on the surface of oil droplets in water. , As the Al 2 O 3 nanoparticles and the oil–water interface carry surface charges of opposite signs, the EIJDs fabricated with this method are optically and electrically heterogeneous between the two hemispheres.…”

Section: Introductionmentioning

confidence: 99%

Janus Droplets and Droplets with Multiple Heterogeneous Surface Strips Generated with Nanoparticles under Applied Electric Field

2018

J. Phys. Chem. C

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A novel method of fabricating Janus droplets and droplets with heterogeneous strips is presented in this article. These droplets were made by covering the surfaces of oil droplets with different nanoparticles under an electric field in a microfluidic chip. The microfluidic chip was used to control the delivery of nanoparticles, and the electric field was employed to assemble the nanoparticles adhering on the droplet. By controlling the delivery of nanoparticles in the microfluidic chip under the electric field, different nanoparticles accumulate on the droplet surface and the desired Janus droplets and droplets with heterogeneous strips can be formed. Because of the presence of charged nanoparticles on droplets’ surfaces, the Janus droplets and droplets with heterogeneous strips have unique electrokinetic properties. The electro-osmotic flow fields around Janus droplets and droplets with heterogeneous strips in different pH solutions were visualized, and the electrokinetic velocities of these droplets in a microchannel were measured as a function of the electrical field. On the basis of their specific electrokinetic properties, two applications of the droplets coated with nanoparticles were developed: flow focusing and microvalve. The experimental demonstrations indicate that the Janus droplets and droplets with heterogeneous strips offer great potential in sensing, actuating, and controlling fluid flow.

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Section: Introductionmentioning

confidence: 99%

Janus Droplets and Droplets with Multiple Heterogeneous Surface Strips Generated with Nanoparticles under Applied Electric Field

2018

J. Phys. Chem. C

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“…Therefore, the motion mechanism of the interfacial particle in their study is different from that in this work. Li and Li , experimentally found that positively charged nanoparticles absorbed at an oil droplet surface move toward the negative electrode of the DC electric field and congregate on one side of the droplet but did not discuss the effect of the interface electrokinetic phenomenon on the particle motion in detail.…”

Section: Introductionmentioning

confidence: 99%

3D Numerical Study of the Electrokinetic Motion of a Microparticle Adsorbed at a Horizontal Oil/Water Interface in an Infinite Domain

Wang

Gao

2022

ACS Omega

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This work builds a three-dimensional (3D) simulation model and studies the electrokinetic velocity of a microparticle adsorbed at a horizontal oil/water interface in an infinite domain. The effects of the interface zeta potentials, the electric field, the oil dynamic viscosity, and the contact angle between the particle and the oil/water interface are investigated in detail. The results show that in an infinite oil/water interface system, both the negatively charged mobile oil/water interface and the negatively charged particle adsorbed to it move toward the positive electrode of the DC electric field, and the particle velocity increases along with the contact angle, the electric field strength, and the absolute values of negative zeta potential of both the particle and the oil/water interface. When the oil/water interface is positively charged with a relatively small zeta potential, the negatively charged microparticle also moves in the opposite direction of the electric field. The larger the oil dynamic viscosity, the smaller the electrokinetic velocity of the microparticle at the interface. Additionally, the numerical simulation results are compared with the reported experiment results under the same conditions, and they have good agreement.

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“…Until now, many functional PCs with PBGs have been fabricated with e-beam lithography [13,14], chemical vapour deposition [15], and interface selfassembly and templates [16][17][18][19]. Besides, coalescences of different liquids were also applied in the presence of an external electric field [20][21][22][23][24], magnetic field [25], high energy mixing [26][27][28][29], and immiscible droplets [8,[30][31][32]. Gu reported a kind of magnetic PC with anisotropic structural color via microfluidic emulsification and achieved controllable movement under magnetic fields [33].…”

Section: Introductionmentioning

confidence: 99%

Controlled diffusion of nanoparticles by viscosity gradient for photonic crystal with dual photonic band gaps

Zhang¹,

Zhang²,

He³

et al. 2020

Nanotechnology

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Coalescence of droplets containing nanoparticles has been paid much attention regarding fabrication of functional photonic crystal (PC) patterns. However, most studies focus on the coalescence of droplets containing the same nanoparticles. Currently, an active challenge comes from the coalescence of droplets containing different nanoparticles due to the spontaneous mutual diffusion of different nanoparticles between coalescing miscible droplets driven by the released Gibbs free energy. Such diffusion breaks the self-assembly of nanoparticles into promising PCs with dual photonic band gaps (PBGs). In this work, a viscosity gradient was induced in coalescing droplets containing different nanoparticles to control the diffusion of nanoparticles and impede the diffusion across the coalescing interface. Nanoparticles diffused along the viscosity gradient to droplet surfaces and self-assembled into a period structure which enhanced the interaction of nanoparticles and contributed to impeding the random diffusion between droplets. At the same time, the high viscosity at the coalescing interface slowed down the horizontal movement of nanoparticles further and consequently the diffusion of nanoparticles across the interface was impeded. By use of such controlled diffusion of nanoparticles in the viscosity gradient, PCs with PBGs were achieved. These results demonstrate the controlled diffusion of nanoparticles during the coalescence of miscible droplets to facilely fabricate PCs with PBGs in the absence of an existing external field.

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Fabrication and electrokinetic motion of electrically anisotropic Janus droplets in microchannels

Cited by 16 publications

References 73 publications

Janus Droplets and Droplets with Multiple Heterogeneous Surface Strips Generated with Nanoparticles under Applied Electric Field

Janus Droplets and Droplets with Multiple Heterogeneous Surface Strips Generated with Nanoparticles under Applied Electric Field

3D Numerical Study of the Electrokinetic Motion of a Microparticle Adsorbed at a Horizontal Oil/Water Interface in an Infinite Domain

Controlled diffusion of nanoparticles by viscosity gradient for photonic crystal with dual photonic band gaps

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