Nonspherical Double Emulsions with Multiple Distinct Cores Enveloped by Ultrathin Shells

Microfluidics has provided means to control emulsification, enabling the production of highly monodisperse double-emulsion drops; they have served as useful templates for production of microcapsules. To provide new opportunities for double-emulsion templates, here, we report a new design of capillary microfluidic devices that create nonspherical double-emulsion drops with multiple distinct cores covered by ultrathin middle layer. To accomplish this, we parallelize capillary channels, each of which has a biphasic flow in a form of core–sheath stream; this is achieved by preferential wetting of oil to the hydrophobic wall. These core–sheath streams from the parallelized channels are concurrently emulsified into continuous phase, making paired double-emulsion drops composed of multiple cores and very thin middle shell. This microfluidic approach provides high degree of controllability and flexibility on size, shape, number, and composition of double-emulsion drops. Such double-emulsion drops are useful as templates to produce microcapsules with multicompartments which can encapsulate and deliver multiple distinct components, while avoiding their cross-contamination. In addition, nonspherical envelope exerts strong capillary force, leading to preferential coalescence between innermost drops; this is potentially useful for nanoliter-scale reactions and encapsulations of the reaction products

Nonspherical Double Emulsions with Multiple Distinct Cores Enveloped by Ultrathin Shells

Microfluidics has provided means to control emulsification, enabling the production of highly monodisperse double-emulsion drops; they have served as useful templates for production of microcapsules. To provide new opportunities for double-emulsion templates, here, we report a new design of capillary microfluidic devices that create nonspherical double-emulsion drops with multiple distinct cores covered by ultrathin middle layer. To accomplish this, we parallelize capillary channels, each of which has a biphasic flow in a form of core–sheath stream; this is achieved by preferential wetting of oil to the hydrophobic wall. These core–sheath streams from the parallelized channels are concurrently emulsified into continuous phase, making paired double-emulsion drops composed of multiple cores and very thin middle shell. This microfluidic approach provides high degree of controllability and flexibility on size, shape, number, and composition of double-emulsion drops. Such double-emulsion drops are useful as templates to produce microcapsules with multicompartments which can encapsulate and deliver multiple distinct components, while avoiding their cross-contamination. In addition, nonspherical envelope exerts strong capillary force, leading to preferential coalescence between innermost drops; this is potentially useful for nanoliter-scale reactions and encapsulations of the reaction products

Nonspherical Double Emulsions with Multiple Distinct Cores Enveloped by Ultrathin Shells

Microfluidics has provided means to control emulsification, enabling the production of highly monodisperse double-emulsion drops; they have served as useful templates for production of microcapsules. To provide new opportunities for double-emulsion templates, here, we report a new design of capillary microfluidic devices that create nonspherical double-emulsion drops with multiple distinct cores covered by ultrathin middle layer. To accomplish this, we parallelize capillary channels, each of which has a biphasic flow in a form of core–sheath stream; this is achieved by preferential wetting of oil to the hydrophobic wall. These core–sheath streams from the parallelized channels are concurrently emulsified into continuous phase, making paired double-emulsion drops composed of multiple cores and very thin middle shell. This microfluidic approach provides high degree of controllability and flexibility on size, shape, number, and composition of double-emulsion drops. Such double-emulsion drops are useful as templates to produce microcapsules with multicompartments which can encapsulate and deliver multiple distinct components, while avoiding their cross-contamination. In addition, nonspherical envelope exerts strong capillary force, leading to preferential coalescence between innermost drops; this is potentially useful for nanoliter-scale reactions and encapsulations of the reaction products

Nonspherical Double Emulsions with Multiple Distinct Cores Enveloped by Ultrathin Shells

Microfluidics has provided means to control emulsification, enabling the production of highly monodisperse double-emulsion drops; they have served as useful templates for production of microcapsules. To provide new opportunities for double-emulsion templates, here, we report a new design of capillary microfluidic devices that create nonspherical double-emulsion drops with multiple distinct cores covered by ultrathin middle layer. To accomplish this, we parallelize capillary channels, each of which has a biphasic flow in a form of core–sheath stream; this is achieved by preferential wetting of oil to the hydrophobic wall. These core–sheath streams from the parallelized channels are concurrently emulsified into continuous phase, making paired double-emulsion drops composed of multiple cores and very thin middle shell. This microfluidic approach provides high degree of controllability and flexibility on size, shape, number, and composition of double-emulsion drops. Such double-emulsion drops are useful as templates to produce microcapsules with multicompartments which can encapsulate and deliver multiple distinct components, while avoiding their cross-contamination. In addition, nonspherical envelope exerts strong capillary force, leading to preferential coalescence between innermost drops; this is potentially useful for nanoliter-scale reactions and encapsulations of the reaction products

Hydrate Growth Inhibition by Poly(vinyl caprolactam) Released from Microcarriers under Turbulent Mixing Conditions

Core–shell microcarriers were microfluidically prepared by using water-in-oil-in-water double-emulsion drops as a template. The aqueous core contained a kinetic hydrate inhibitor (KHI) of poly­(vinyl caprolactam) (PVCap), and the shell was made of a cross-linked polymer. To make the microcarriers selectively release PVCap at temperatures where hydrate formation occurs under a constant shear flow, the relative shell thickness to the radius of the microcarrier was set to 0.11. The hydrate inhibition performance of PVCap released from the microcarriers was investigated using continuous cooling and constant subcooling in a high-pressure autoclave. Longer hydrate onset times were observed for the PVCap microcarriers compared to bulk water, suggesting that hydrate nucleation was inhibited by PVCap released from the microcarriers. The obtained subcooling temperature for the PVCap microcarriers was 11.3 °C, which was close to that of the PVCap bulk solution at 10.8 °C. The hydrate growth was faster for the PVCap microcarriers than for bulk water, but the effective growth period was shorter, resulting in a lower hydrate fraction in the liquid phase. Although the PVCap microcarriers performed successfully under continuous cooling, limited performance was observed with constant subcooling. Successful hydrate inhibition was sometimes observed, but fast hydrate formation was also observed over repeated experiments. This result is because microcarriers are designed to rupture under a constant shear flow. Thus, more studies are required to improve the design of microcarriers to release the inner KHI solution, even in cold-restart operations. Nevertheless, microcarriers provide a flexible way to inject KHI into subsea flowlines, as many different types of KHIs can be simultaneously delivered at a proper dose using a set of distinct microcarriers

Photolithography-Based Patterning of Liquid Metal Interconnects for Monolithically Integrated Stretchable Circuits

We demonstrate a new patterning technique for gallium-based liquid metals on flat substrates, which can provide both high pattern resolution (∼20 μm) and alignment precision as required for highly integrated circuits. In a very similar manner as in the patterning of solid metal films by photolithography and lift-off processes, the liquid metal layer painted over the whole substrate area can be selectively removed by dissolving the underlying photoresist layer, leaving behind robust liquid patterns as defined by the photolithography. This quick and simple method makes it possible to integrate fine-scale interconnects with preformed devices precisely, which is indispensable for realizing monolithically integrated stretchable circuits. As a way for constructing stretchable integrated circuits, we propose a hybrid configuration composed of rigid device regions and liquid interconnects, which is constructed on a rigid substrate first but highly stretchable after being transferred onto an elastomeric substrate. This new method can be useful in various applications requiring both high-resolution and precisely aligned patterning of gallium-based liquid metals