Design of a unidirectional water valve in Tillandsia.,Nature Communications

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Design of a unidirectional water valve in Tillandsia.
Nature Communications ( IF 14.7 ) Pub Date : 2020-01-20 , DOI: 10.1038/s41467-019-14236-5
Pascal S Raux ₁ , Simon Gravelle ₁ , Jacques Dumais ₁

Affiliation

The bromeliad Tillandsia landbeckii thrives in the Atacama desert of Chile using the fog captured by specialized leaf trichomes to satisfy its water needs. However, it is still unclear how the trichome of T. landbeckii and other Tillandsia species is able to absorb fine water droplets during intermittent fog events while also preventing evaporation when the plant is exposed to the desert's hyperarid conditions. Here, we explain how a 5800-fold asymmetry in water conductance arises from a clever juxtaposition of a thick hygroscopic wall and a semipermeable membrane. While absorption is achieved by osmosis of liquid water, evaporation under dry external conditions shifts the liquid-gas interface forcing water to diffuse through the thick trichome wall in the vapor phase. We confirm this mechanism by fabricating artificial composite membranes mimicking the trichome structure. The reliance on intrinsic material properties instead of moving parts makes the trichome a promising basis for the development of microfluidics valves.

中文翻译：

铁兰单向水阀的设计。

智利的阿塔卡马沙漠中的凤梨铁兰（Tillandsia landbeckii）依靠专门的叶毛家庭捕获的雾气来满足其水需求。然而，目前尚不清楚在间歇性雾事件中，兰氏锥虫和其他铁兰种的毛状体如何能够吸收细小水滴，同时当植物暴露于沙漠的高干旱条件下时也能防止蒸发。在这里，我们解释了由厚的吸湿壁和半透膜的巧妙并置引起的水导率的5800倍不对称性。虽然吸收是通过液态水的渗透来实现的，但在干燥的外部条件下的蒸发会改变液-气界面，从而迫使水以蒸汽相扩散通过厚的毛状体壁。我们通过制造模仿毛状体结构的人造复合膜来确认这种机制。对固有材料特性的依赖而不是对运动部件的依赖使trichome成为开发微流体阀的有希望的基础。

更新日期：2020-01-22

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