Miao Jiaqi, Tsang Alan C H
Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong, 999077, China.
Adv Sci (Weinh). 2024 Oct;11(39):e2405641. doi: 10.1002/advs.202405641. Epub 2024 Jul 29.
Manipulating small-volume liquids is crucial in natural processes and industrial applications. However, most liquid manipulation technologies involve complex energy inputs or non-adjustable wetting gradient surfaces. Here, a simple and adjustable 3D liquid manipulation paradigm is reported to control liquid behaviors by coupling liquid-air-solid interfacial energy with programmable magnetic fields. This paradigm centers around a hierarchical rectifier with magnetized microratchets, using Laplace pressure asymmetry to enable multimodal directional steering of various surface tension liquids (23-72 mN m). The scale-dependent effect in microratchet design shows its superiority in handling small-volume liquids across three orders of magnitude (10-10 µL). Under programmed magnetic fields, the rectifier can reconfigure its morphology to harness interfacial energy to exhibit richer liquid behaviors without dynamic real-time control. Reconfigured rectifiers show improved rectification performance in the inertia-dominant fluid regime, i.e., a remarkable 2000-fold increase in the critical Weber number for pure ethanol. Moreover, the rectifier's switchable reconfigurations offer flexible control over liquid transport directions and spatiotemporally controllable 3D liquid manipulation reminiscent of inchworm motions. This scalable liquid manipulation paradigm promotes versatile engineering and biochemistry applications, e.g., portable liquid purity testing (screening resolution <1 mN m), logical open-channel microfluidics, and automated chemical reaction platforms.
在自然过程和工业应用中，操控小体积液体至关重要。然而，大多数液体操控技术涉及复杂的能量输入或不可调节的润湿梯度表面。在此，我们报道了一种简单且可调节的三维液体操控模式，通过将液 - 气 - 固界面能与可编程磁场相结合来控制液体行为。这种模式以带有磁化微棘轮的分级整流器为核心，利用拉普拉斯压力不对称性实现对各种表面张力液体（23 - 72 mN/m）的多模态定向操控。微棘轮设计中的尺度依赖效应显示出其在处理跨越三个数量级（10⁻¹⁰ - 10⁻⁷ μL）的小体积液体方面的优越性。在编程磁场下，整流器可以重新配置其形态，利用界面能展现出更丰富的液体行为，而无需动态实时控制。重新配置的整流器在惯性主导的流体状态下表现出改进的整流性能，即对于纯乙醇，临界韦伯数显著增加了2000倍。此外，整流器的可切换重新配置提供了对液体传输方向的灵活控制以及类似于尺蠖运动的时空可控三维液体操控。这种可扩展的液体操控模式推动了多种工程和生物化学应用，例如便携式液体纯度测试（筛选分辨率 <1 mN/m）、逻辑开放通道微流体以及自动化化学反应平台。
