Laser‐Induced Nanodroplet Injection and Reconfigurable Double Emulsions with Designed Inner Structures

Guo, Jinkun; Hong, Seung‐Ho; Yoon, Hyun‐Jin; Babakhanova, Greta; Lavrentovich, Oleg D.

doi:10.1002/advs.201900785

Cited by 18 publications

(18 citation statements)

References 39 publications

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“…In bright-field images very small droplets can be observed within the LC droplets. This is a phenomenon previously reported − (Figure a). For droplets with a bipolar director field (planar alignment) a more complex image is observed (Figures d and c).…”

Section: Results and Discussionsupporting

confidence: 83%

Control of Director Fields in Phospholipid-Coated Liquid Crystal Droplets

et al. 2020

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In liquid crystal (LC) droplets, small changes in surface anchoring energy can produce large changes in the director field which result in readily detectable optical effects. This makes them attractive for use as biosensors. Coating LC droplets with a phospholipid monolayer provides a bridge between the hydrophobic world of LCs and the water-based world of biology and makes it possible to incorporate naturally occurring biosensor systems. However, phospholipids promote strong perpendicular (homeotropic) anchoring that can inhibit switching of the director field. We show that the tendency for phospholipid layers to promote perpendicular anchoring can be suppressed by using synthetic phospholipids in which the acyl chains are terminated with bulky tert-butyl or ferrocenyl groups; the larger these end-group(s), the less likely the system is to be perpendicular/radial. Additionally, the droplet director field is found to be dependent on the nature of the LC, particularly its intrinsic surface properties, but not (apparently) on the sign of the dielectric anisotropy, the proximity to the melting/isotropic phase transition, the surface tension (in air), or the values of the Frank elastic constants.

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Section: Results and Discussionsupporting

confidence: 83%

Control of Director Fields in Phospholipid-Coated Liquid Crystal Droplets

et al. 2020

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“…This prediction agrees with a recent study showing that cargo release from flat LC films into water is driven by a propagating N-I interface across the LC as the LC undergoes the N-I phase transition, leading to continuous cargo release during the phase transition, followed by no cargo release once the LC is entirely isotropic ( 27 ). Our model hints that the long-distance F cap caused by the curved capillary meniscus of the LC wetting ridge provides an additional driving force to transport the cargo microdroplets to the wetting ridge and activate the subsequent cargo release, which is consistent with a previous report ( 51 ) and our own experimental observations.…”

Section: Resultssupporting

confidence: 92%

Liquid crystal–based open surface microfluidics manipulate liquid mobility and chemical composition on demand

Rather

Yao

et al. 2021

Sci. Adv.

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The ability to control both the mobility and chemical compositions of microliter-scale aqueous droplets is an essential prerequisite for next-generation open surface microfluidics. Independently manipulating the chemical compositions of aqueous droplets without altering their mobility, however, remains challenging. In this work, we address this challenge by designing a class of open surface microfluidic platforms based on thermotropic liquid crystals (LCs). We demonstrate, both experimentally and theoretically, that the unique positional and orient ational order of LC molecules intrinsically decouple cargo release functionality from droplet mobility via selective phase transitions. Furthermore, we build sodium sulfide-loaded LC surfaces that can efficiently precipitate heavy metal ions in sliding water droplets to final concentration less than 1 part per million for more than 500 cycles without causing droplets to become pinned. Overall, our results reveal that LC surfaces offer unique possibilities for the design of novel open surface fluidic systems with orthogonal functionalities.

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“…Furthermore, when droplets are produced by agitating a mixture of the LC and a solution of the surfactant, this not only produces an emulsion of LC in water but also an emulsion of water in LC; the LC droplets contain inclusions of small droplets of water that can affect their properties. 22,49,50…”

Section: Resultsmentioning

confidence: 99%