Professor Kijung Yong of the Department of Chemical Engineering researched the ‘Impact dynamics of water droplets on chemically modified WOx nano-wire arrays’, based on the ‘Lotus Effect’. This research was introduced as the cover of ‘Applied Physics Letters’ issue 95.

Leaves of the lotus flower have very high water repellency due to the complex and nano-scopic architecture of their surfaces. The research team took notice of it, and experimentally investigated the effects of surface energy on the wetting transition for impinging water droplets on the chemically modified WOx nano-wire surfaces. Three states of wetting, defined as wetting, partial wetting, and bouncing states, could be identified through the balance between anti-wetting and wetting pressures. So, this research could be used for establishing a strategy for design of water-repellent surfaces for impinging droplets.

Furthermore, what makes this different from other research is the way the architecture could be made and more easily commercialized. First, the research team could make a change of the characteristics on a surface through two ways: synthesizing nano-waves, called Bottom-up, and exposure of the already-synthesized nano-wave to ultra-violet rays, called Top-down. Also, using a high speed camera to check the variation of a water droplet’s dynamic behavior due to surface energy,  they made sure that this technique is suitable for a daily environment, such as a rainy day or any water-dropping situation.

This research is expected to be applied to, for example, environment-friendly paint which has an anti-dirt characteristic, no-damp car windows, and smart windows able to adjust the transparency by themselves.