In this section you will learn:


what Lotus effect is,


the mechanism of Lotus effect,


how the Lotus effect can be applied technologically.


Take a walk in a park and look at lotus leaves. Have you ever noticed and wondered why the leaves of Lotus always remain dry and clean?

It seems that water forms droplets on Lotus leaves and the droplets can easily roll off the leaves if the leaves are inclined. Lotus leaves also have an ability to clean themselves, despite their constant exposure to a dirty environment. A closer look at the lotus leaves will reveal something rather interesting. First, water does not stick to the leaves well. Instead, spherical water droplets with only little contact with the leaves are formed (Fig. 1). The droplet rolls off the leaf when you shake it slightly. Second, dirt likes to stick to water instead of the leaves. Therefore, when the droplet rolls on the leave, it carries the dirt with it. Dew drops on a leaf surface, not necessarily lotus, shows a similar phenomenon (See Activity 1).

Scientists had been puzzled by these observations for a very long time, until two German scientists, W. Barthlott and C. Neinhuis, examined the surface of Lotus leaves by using high reolsution electron microscope recently. They found that the surface of the leaves contains nanometer-sized waxy bumps that prevent both dirt and water from sticking to it. Since the valleys between the bumps are too small for dirt particles to get in, the dirt always stays on top of the bumps (Fig. 2). When a water droplet rolls of the leaf, it carries the dirt with it, thus accomplishing the cleaning action.

After understanding the phenomenon, scientists start thinking how one can mimic this "Lotus effect" and apply Lotus effect to our daily technology. For example, raincoats and umbrella will perform much better if one can apply Lotus effect. In addition, paints incorporating the Lotus effect could keep houses and buildings clean and dry.

Lotus effect
Carbon nanostructures
Euler's formula
Social issues