School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China.
Laboratory of Bio-inspired Smart Interface Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Nature. 2016 Apr 7;532(7597):85-9. doi: 10.1038/nature17189.
Numerous natural systems contain surfaces or threads that enable directional water transport. This behaviour is usually ascribed to hierarchical structural features at the microscale and nanoscale, with gradients in surface energy and gradients in Laplace pressure thought to be the main driving forces. Here we study the prey-trapping pitcher organs of the carnivorous plant Nepenthes alata. We find that continuous, directional water transport occurs on the surface of the 'peristome'--the rim of the pitcher--because of its multiscale structure, which optimizes and enhances capillary rise in the transport direction, and prevents backflow by pinning in place any water front that is moving in the reverse direction. This results not only in unidirectional flow despite the absence of any surface-energy gradient, but also in a transport speed that is much higher than previously thought. We anticipate that the basic 'design' principles underlying this behaviour could be used to develop artificial fluid-transport systems with practical applications.
许多自然系统都包含能够实现定向水传输的表面或纤维。这种行为通常归因于微观和纳米尺度上的分层结构特征，表面能的梯度和拉普拉斯压力的梯度被认为是主要的驱动力。在这里，我们研究了食虫植物猪笼草的诱捕器器官。我们发现，由于其多尺度结构，连续的、定向的水传输发生在“口盖”——瓶子的边缘——表面上，这种结构优化并增强了在传输方向上的毛细上升，并通过固定任何正在反向移动的水前沿来防止回流。这不仅导致了尽管没有任何表面能梯度但仍为单向流动，而且还导致了传输速度比之前认为的要高得多。我们预计，这种行为背后的基本“设计”原则可以用于开发具有实际应用的人工流体传输系统。
