Droplet最新文献

Liquid directional transport surfaces have the ability to control the movement of liquids in specific directions, making them highly applicable in various fields such as heat transfer, fluid management, microfluidics, and chemical engineering. This review aims to summarize the research progress on liquid directional transport surfaces and spacecraft fluid management devices. Among the different liquid control technologies available, certain surface design methods based on principles of fluid dynamics under microgravity show remarkable potential for space fluid management. Precise fluid management is crucial for the in-orbit operation of spacecraft. Utilizing surface tension effects represents the most direct and effective approach to achieve directional liquid transport in space. The intrinsic flow characteristics of the two-dimensional plane of directional transport surfaces are advantageous for managing fluids in the confined spaces of spacecraft. By analyzing the functional characteristics of these liquid directional transport surfaces, we assess their feasibility for integration into spacecraft fluid management devices. Considering the features of the space environment, this review also provides design guidelines for liquid directional transport surfaces suitable for use in spacecraft fluid management devices, serving as a significant reference for future research.

Liquid marbles (LMs) have become a focal point in microfluidics for their efficient manipulation of small liquid volumes. These non-wetting droplets, typically coated with hydrophobic particles, offer enhanced stability, reduced evaporation and diverse utility, distinguishing them from bare droplets. This review examines advancements in LMs from 2014 to 2024, focusing on their rapid formation, robust manipulation, and revolutionary applications—termed the “3R trilogy.” We delve into the generation mechanisms, analyzing laboratory and engineering production techniques, and explore how surface particles affect LMs’ physicochemical properties. The structural dynamics and motion control of LMs are investigated, detailing their response to external forces and environmental factors. The review also highlights the state-of-the-art applications of LMs in digital microfluidics, biochemical analysis, materials synthesis, environmental monitoring, soft robotics, and energy harvesting. Concluding with a discussion on significant progress and future development trends, this review provides insights and ideas for broader applications of LM-based microfluidic platforms.

Compartmentalization in living systems, where multiple reactions occur in parallel within confined spaces, has inspired the development of droplet networks in the past decade. These fascinating assemblies offer unique and versatile functions that are unattainable by single droplets and have shown their potential as advanced platforms for chemical and biological applications. This review highlights recent progress in the creation and application of droplet networks, covering strategies for generating the droplets and assembling them into functional networks. Key applications such as microreactors, signal conductors, actuators, and power sources are summarized. We also discuss the challenges and future trends in this field, aiming to narrow the gap between fundamental research and real applications.

Fog collection can be an affordable, practical solution to water scarcity in many regions around the world. Commercial fog harvesters typically use mesh structures composed of cylindrical wires or thin strips. The choice of their length scale, especially the width, has been a challenge due to a trade-off problem—wide wires or strips cause fog droplets to avoid contact and display lower deposition efficiency, while meshes comprising thin cylinders or strips often suffer from clogging and exhibit low drainage efficiency. In this study, we propose a cost-effective dual-scale structure, a vertical core composed of two twisted cylindrical wires surrounded by thin hairs protruding along radial direction, which can greatly improve the water collection efficiency by decoupling the mechanisms for droplet deposition and drain: while thin hairs allow fog droplets to retain high Stokes number and deposit with high efficiency, a vertical core functions as a wicking mechanism for deposited droplets to drain quickly. Fabricated hairy wires have a water collection rate of more than two and a half times that of smooth cylindrical wires of the same diameter, and their steady-state performance does not suffer from clogging, in contrast to conventional meshes composed of thin wires. Proposed hairy wires can be mass-produced by slightly modifying commercial products. This study provides a practical solution for the optimal design of fog collectors, benefiting the fight against the global water crisis.

Frontispiece: The cover image is based on the Research Article Water-proofing mechanism of coupling structures observed in ladybird elytra and its bionic application by Zhang et al.

Cover description: Using high-speed imaging, we examine the collision of a waterdrop with the coupling structures of elytra systems. Through a combination of experimental and theoretical approaches, we analyze how the geometry of these coupling structures affects their water-proofing performance. Inspired by this biological mechanism, a water-proofing device is proposed for solar panels to enhance their light energy conversion efficiency. (DOI: 10.1002/dro2.162)

Front Cover: The cover image is based on the Research Article Droplet menisci recognition by deep learning for digital microfluidics applications by Danesh et al.

Cover description: This work showcases the use of a U-Net deep learning model to accurately identify droplet menisci in electrowetting-on-dielectric (EWOD) systems. By achieving high precision, even with complex or low-quality images, the model enhances droplet control and reveals critical insights into fluid properties, reaction kinetics, and dynamic behaviors, advancing the performance and reliability of EWOD microfluidic devices. (DOI: 10.1002/dro2.151)

Back Cover: The cover image is based on the Research Article Design and preparation of a simplified microdroplet generation device for nanoliter volume collection and measurement with liquid microjunction–surface sampling probe–mass spectrometry by Reddy et al.

Cover description: What if creating microdroplets could be as fun and simple as blowing bubbles? Here, we use a laser-micromachining protocol with a surface hydrophobicity treatment to create the ‘NanoWand’ from a glass cover slip, which generates microdroplets within the nanoliter volume range for direct introduction to and volume estimation with ambient ionization mass spectrometry. (DOI: 10.1002/dro2.158)

Inside Front Cover: The cover image is based on the Review Article Advances in precise cell manipulation by Ma et al.

Cover description: Advancing precise clinical care relies on innovative cell manipulation strategies. External fields such as acoustic, optical, electronic, and magnetic fields have significantly improved the feasibility and efficiency of precise cell sorting and assembly. A systematic review of these external-field-assisted techniques provides valuable insights and references for enhancing clinical diagnosis and treatment. (DOI: 10.1002/dro2.149)

Inside Back Cover: The cover image is based on the Research Article Programmable optical window bonding enabled 3D printing of high-resolution transparent microfluidic devices for biomedical applications by Ye et al.

Cover description: We introduce a novel “programmable optical window bonding” 3D printing method that incorporates the bonding of an optical window during the printing process, facilitating the fabrication of transparent microfluidic devices with high printing fidelity. Our approach allows direct and rapid manufacturing of complex microfluidic structure without the use of molds for PDMS casting. (DOI: 10.1002/dro2.153)

The development of 3D cell culturing toward labor saving and versatility is highly desired. Here, we propose a platform consisting of a multiwell plate and liquid marbles (LMs). The inner walls of the plate are covered with particle-detachable superhydrophobic coatings that serve as both the substrates and particle sources for LM production. A produced LM, which serves as a minireactor for the 3D culture, features a monolayer nanoparticulate shell and naked-droplet-like transparency. The LM-in-plate platform provides a double-superhydrophobic environment that increases the stability of the 3D culture and reduces the necessary operational cautions. In addition, both cell observation and high-throughput applications can be conducted in situ, owing to the high LM transparency and the multiwell structure, respectively. This platform integrates the advantages of naked droplets (transparent and clean), LMs (stable non-wetting), and multiwell plates (high-throughput capability) and thus is promising for labor-saving and versatile 3D culturing.