Zhang Qianqin, Wang Siyu, Song Jinlong, Yang Xiaolong
College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China.
Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China.
ACS Appl Mater Interfaces. 2024 Nov 13;16(45):62838-62850. doi: 10.1021/acsami.4c10213. Epub 2024 Oct 30.
Wedge-shaped superhydrophilic tracks have been considered as one of the most effective ways to transport droplets for diverse cutting-edge applications, e.g., energy harvesting and lab-on-a-chip devices. Although significant progress, such as serial wedge-shaped tracks with curved edges, has evolved to advance the liquid transport, the ultrafast and long-distance transporting of drop-shaped liquid remains challenging. Here, inspired by the cactus spine that enables fast droplet transport and the serial spindle knot of spider silk, which is capable of collecting condensate from a wide range of distances, we created serial wedge-shaped superhydrophilic patterns and optimized their side edges with a convex brachistochrone curve to boost the acceleration. The junctions of the serial patterns were meanwhile reformed into concave brachistochrone curves to lower the energy barrier for sustained transport. For transporting the liquid in drop shapes to the long distance at high velocity, the wedge-shaped tracks were slenderized to the greatest extent to suppress the liquid spreading and thus prevent the degradation of the Laplace driving force. Moreover, the junction that determines the energy barrier of droplet striding was carefully designed based on the principle of minimizing momentum loss. The exquisite architecture design pushed the droplet transport to a maximum instantaneous velocity of 207.7 mm·s and an outermost transport distance of 120.5 mm, exceeding most wettability or geometric gradient based reports. The transported volume of the droplets can be readily regulated by simply scaling the created architectures. The enhanced droplet transport facilitates the motion and departure of the cohered droplets, enabling a 1.9-fold rise of the water collection rate and 12-fold increase of the heat transfer coefficient during the fog harvest test. This scalable, controllable, and easily fabricatable surface design provides an essential pathway in realizing high-performance manipulation of droplets and possibly pioneers substantial innovative applications in multidisciplinary fields. Those include but are not limited to energy harvesting, lab-on-a-chip devices, and MEMS systems.
楔形超亲水轨道被认为是在各种前沿应用（如能量收集和芯片实验室设备）中传输液滴的最有效方法之一。尽管已经取得了重大进展，例如带有弯曲边缘的连续楔形轨道，以推动液体传输，但液滴状液体的超快和长距离传输仍然具有挑战性。在这里，受能够实现快速液滴传输的仙人掌刺以及能够从广泛距离收集冷凝水的蜘蛛丝连续纺锤结的启发，我们创建了连续楔形超亲水图案，并通过凸摆线曲线优化其侧边缘以提高加速度。同时，将连续图案的连接处改造成凹摆线曲线，以降低持续传输的能量障碍。为了将液滴高速长距离传输，楔形轨道被最大限度地细化，以抑制液体扩散，从而防止拉普拉斯驱动力的衰减。此外，基于最小化动量损失的原理，精心设计了决定液滴跨越能量障碍的连接处。这种精致的结构设计将液滴传输的最大瞬时速度提高到207.7毫米·秒，最远距离传输到120.5毫米，超过了大多数基于润湿性或几何梯度的报告。通过简单地缩放所创建的结构，可以很容易地调节液滴的传输体积。增强的液滴传输促进了凝聚液滴的运动和离开，在雾收集测试中使集水率提高了1.9倍，传热系数提高了12倍。这种可扩展、可控且易于制造的表面设计为实现液滴的高性能操纵提供了一条重要途径，并可能在多学科领域开创大量创新应用。这些应用包括但不限于能量收集、芯片实验室设备和微机电系统。
