Wu Dong, Zhang Zhen, Zhang Yiyuan, Jiao Yunlong, Jiang Shaojun, Wu Hao, Li Chuanzong, Zhang Chenchu, Li Jiawen, Hu Yanlei, Li Guoqiang, Chu Jiaru, Jiang Lei
CAS Key Laboratory of Mechanical Behavior and Design of Materials, Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei, 230027, China.
CAS Key Laboratory of Geospace Environment, USTC, Hefei, 230026, China.
Adv Mater. 2020 Dec;32(48):e2005039. doi: 10.1002/adma.202005039. Epub 2020 Oct 30.
The high-performance unidirectional manipulation of microdroplets is crucial for many vital applications including water collection and bioanalysis. Among several actuation methods (e.g., electric, magnetic, light, and thermal actuation), mechanical vibration is pollution-free and biocompatible. However, it suffers from limited droplet movement mode, small volume range (V /V < 3), and low transport velocity (≤11.5 mm s ) because the droplet motion is a sliding state caused by the vertical vibration on the asymmetric hydrophobic microstructures. Here, an alternative strategy is proposed-horizontal vibration for multimode (rolling, bouncing/reverse bouncing, converging/diffusing, climbing, 90 turning, and sequential transport), large-volume-range (V /V ≈ 100), and high-speed (≈22.86 mm s ) unidirectional microdroplet manipulation, which is ascribed to the rolling state on superhydrophobic slant microwall arrays (SMWAs) fabricated by the one-step femtosecond laser oblique ablation. The unidirectional transport mechanism relies on the variance of viscous resistance induced by the difference of contact area between the microdroplet and the slant microwalls. Furthermore, a circular, curved, and "L"-shaped SMWA is designed and fabricated for droplet motion with particular paths. Finally, sequential transport of large-volume-range droplets and chemical mixing microreaction of water-based droplets are demonstrated on the SMWA, which demonstrates the great potential in the field of microdroplet manipulation.
微滴的高性能单向操控对于包括集水和生物分析在内的许多重要应用至关重要。在几种驱动方法（例如，电驱动、磁驱动、光驱动和热驱动）中，机械振动无污染且具有生物相容性。然而，它存在液滴运动模式有限、体积范围小（V /V < 3）和传输速度低（≤11.5 毫米/秒）的问题，因为液滴运动是由不对称疏水微结构上的垂直振动引起的滑动状态。在此，提出了一种替代策略——水平振动，用于多模式（滚动、弹跳/反向弹跳、汇聚/扩散、爬升、90度转向和顺序传输）、大体积范围（V /V ≈ 100）和高速（≈22.86 毫米/秒）的单向微滴操控，这归因于通过一步飞秒激光斜向烧蚀制造的超疏水倾斜微壁阵列（SMWA）上的滚动状态。单向传输机制依赖于微滴与倾斜微壁之间接触面积差异引起的粘性阻力变化。此外，还设计并制造了圆形、弯曲和“L”形的SMWA，用于特定路径的液滴运动。最后，在SMWA上展示了大体积范围液滴的顺序传输和水基液滴的化学混合微反应，这证明了其在微滴操控领域的巨大潜力。
