Lotus beaters

Researchers at the Georgia Institute of Technology are mimicking the waterproof qualities of lotus leaves to make more reliable electrical and electronic systems which stay clean and dry.

These could be used for electric transmission systems, photovoltaic arrays that retain their efficiency,  Micro Electro-Mechanical Systems (MEMS) unaffected by water and improved biocompatible surfaces able to prevent cells from adhering to implanted medical devices.

The research aims to duplicate the self-cleaning surfaces of the lotus plant, which grows in waterways of Asia. Despite growing in muddy conditions, the leaves and flowers remain clean because their surfaces are composed of micron- and nanoscale structures that, along with a waxy coating, prevent dirt and water from adhering. Despite their unusual surface properties, the rough surfaces allow photosynthesis to continue in the leaves.

‘When rain hits the leaves of the lotus plant, it simply beads up,’ said Professor C.P. Wong from Georgia Tech’s School of Materials Science and Engineering. ‘When the leaves are also tilted at a small angle, the beads of water run off instantaneously. While the water is rolling off, it carries away any dirt on the surface.’

The plant’s ability to repel water and dirt results from an unusual combination of a superhydrophobic, or water-repelling, surface and a combination of micron-scale hills and valleys and nanometre-scale waxy bumps that create rough surfaces that don’t give water or dirt a chance to adhere.

Synthesising a surface like that of lotus leaves would solve a problem that plagues electric utilities. The build-up of dirt and dust on ceramic or silicone insulators used by high-voltage power lines can eventually create a short circuit that can damage the electric distribution network. It is impractical to manually clean the insulators.

Wong and collaborators Yonghao Xiu, Lingbo Zhu and Dennis Hess have developed a lotus surface able to withstand ultraviolet radiation using a combination of silicone, fluorocarbons, and inorganics such as titanium dioxide and silicon dioxide. Their prototype coating has shown excellent durability in long-term testing.