Haripriya.S

Horticultural College & Research Institute

Tamil Nadu Agricultural University, Coimbatore

The Lotus (Nelumbo nucifera), commonly recognized as Water Lily, an aquatic perennial

plant and native to Asia is the national flower of India and Vietnam. The sacred Lotus is

considered to be an important spiritual symbol in Eastern religions. The Poet philosopher,

Zhou Dunyi of china described lotus in his poem titled “On Loving Lotus” that lotuses are not

dirty although born in mud and bathed in ripples of water. When rain water drops on the leaf,

it beads up and rolls off the waxy surface, washing away dirt as it goes. In religious

perspective, this behaviour represents the lotus leaf as a symbol of purity. Scientists, amazed

by its peculiar water-resistant and self-cleaning property, tried to understand its base secret.

A German botanist named Wilhelm Barthlott studied about this nature’s creation and

found that the lotus leaf has two levels of structure affecting this behaviour: micron-sized

bumps (hydrophobic) on the leaf surface and nano-hair (hydrophilic) like structures, coupled

with the leaf’s waxy chemical composition on the bump. Water droplets splashing on the

leaves, gets trapped between the nano-scale hairs on the leaf. The drops then coalesce with

other and fill the cavities created by the micron-sized bumps. The contact angle between

water and leaf surface is very small, such that the raindrop rolls down the leaf with little

friction rather than sliding. On rolling, the drop collects dirt and other contaminants on its way,

and in effect cleans itself. This nature inspired technology of self-cleaning phenomenon was

known as “Lotus Effect” and since 1997, Barthlott owns a patent for this discovery.

The most successful application of Lotus Effect is Sto Lotusan paints introduced in 1999

by the German multinational Sto AG. Now “Lotus Effect” is a household name in Germany and

was considered as one of the 50 most significant German inventions of recent years. Another

application breakthrough is from Textile Industry i.e., water repellency and stain removing

fabrics developed by inventor- entrepreneur David Soane. He made the Nano-fabric using

minuscule whiskers attached to the cotton threads. The whiskers used are less than a

thousandth of the height of lotus bumps and is currently being manufactured by his company

Nano Tex.

This self- cleaning knowledge inspired from Lotus Leaf has started transforming surface

coating technology with wide-utilities incorporated like micro-organism resistant, self-

deodorizing, non-allergic, long lasting coating enhanced products especially for Hospitals and

Laboratory. Beside, ranges of Nano products are also available in the market like self cleaning

windows, mirrors, roofs, vehicle body, fabrics, tiles, papers etc., to state a few. Likewise, leaves

of Taro (Colocasia esculenta) and Naustartium (Tropaeolum species) also possess this

behaviour in plant kingdom. Hence, the journey continues to explore novel potentials from

Lotus leaf inspired Nanotechnology, which was measured to be one of the most successful

Nano outcome inspired from nature.