Learning How to Clean From a Leaf

Have you ever wondered how things in nature generally look so clean? You don't see janitors out there in the woods, afterall, dusting off the trees. People use toxic detergents and costly cleaning treatments, but Nature employs a cleaning strategy as environmentally benign and energy efficient as it is strikingly ingenious. Imagine waking up, stepping outside, shaking your body a little bit, and heading off to your daily routine as clean as if you'd taken a shower. Because that's how Nature cleans; it takes what might be called a gravity shower. The leaves of many plants, large-winged insects, most water birds, and other organisms capitalize on basic physical characteristics in the way surfaces of materials interact, achieving cleanliness effortlessly and without detergents.

How It Works
Water has two major forces acting on it at the same time: its attraction to itself (which causes it to ball up) and adhesive forces (which cause it to stick to surfaces, pulling it down). Adhesive forces on water tend to be maximized on smooth surfaces, because the liquid-to-solid contact area is large. But because water and air are much less naturally adhesive than water and solids, roughened surfaces of certain microstructure tend to reduce adhesive force on water droplets, as trapped air in the interstitial spaces of the roughened surface result in a reduced liquid-to-solid contact area. This allows water's self-attraction to be expressed more fully, leading it to form a sphere.

At the same time, due again to natural adhesion between water and solids, dirt particles on a leaf's surface stick to the water, like a rolled snowball that picks up leaves from your lawn. Since a ball rolls more easily than a flattened bump, the role of gravity now becomes significant: the slightest angle in the surface of the leaf (e.g., caused by a passing breeze) causes balls of water to roll off the leaf surface, carrying away the attached dirt particles - without the leaf having to expend any energy or use any harmful chemical detergents. 

GreenShield?, a fabric finish inspired by the Lotus Effect from G3 Technology Innovations, coats textile fibers with liquid-repelling nanoparticles, reducing the need to use environmentally dangerous fluorocarbons.

Why It Matters
Nature's way of cleaning has major implications for the world we live in. Considering how damaging to the environment and our own health our cleaning practices are -- as well as how financially costly - we stand to gain a great deal from learning from the innovative cleaning strategies employed by Nature. Research and development of the "Lotus Effect" is actively underway. Several products exist already which use the Lotus Effect to improve on conventional products. GreenShield™, a product from G3 Technology Innovations, is a fabric finish that uses the principle of the Lotus Effect to create water and stain repellency on textiles, and results in a 10-fold decrease in the use of environmentally harmful fluorocarbons, the conventional means of achieving repellency. Other products inspired by the Lotus Effect include Lotusan paint and Signapur glass finish.

Help Conserve These Inspiring Organisms!
Through the Biomimicry Institute's Innovation for Conservation Program, the organisms teaching us how to live sustainably on this planet receive our help conserving their habitats in return. After all, shouldn't we properly honor the organisms and ecosystems that evolved these ingenious, sustainable ideas, and thank them for showing us the way? Help us in our efforts to protect the habitats of these inspiring organisms!

Photographic sources
Lotus leaf courtesy of Tanakawho

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