Spontaneously jumping dew drops clean nature’s surfaces
First published May 1, 2013
Scientists at James Cook University along with collaborators at Duke University have shown for the first time how nature can use dew drops to clean surfaces such as plant leaves and the bodies of insects.
The dew forms small droplets that merge together spontaneously and are self-propelled automatically off the surface by changes in energy (see links below for a demonstration)
The droplets can carry away dirt and other contaminants such as pollens to clean the surface.
JCU’s Dr Greg Watson said the research may have a wide range of applications.
“The findings gives us a blueprint to copy and make the next new generation of man-made self-cleaning surfaces that can clean themselves of dirt, bacteria and other environmental contaminants,” he said.
“These types of surfaces may find applications as self-cleaning windows, hospital surfaces, environmentally green surfaces, construction materials, pipes, kitchen surfaces, roof tiles, machine components and water resistant surfaces.”
Dr Jolanta Watson said it also opened the door for a whole new area in scientific research to investigate self propelled droplets which can carry specific chemical particles/packages and deposit them onto a range of surfaces for a new range of micro biosensors and nano delivery systems.
“Traditionally, cleaning of natural surfaces was thought to take place primarily by the so-called ‘lotus effect’. This effect was first seen on lotus leaves, where rain water droplets roll along the leaf and carry away dirt from the surface, much like water droplets on the bonnet or hood of a freshly waxed car.”
Dr Greg and Jola Watson said they always suspected that Nature would use other ways to clean surfaces especially in areas where rain does not occur for very long periods of time.
Their previous work and observations with small droplets on insect wings led them to the hypotheses that when dew droplets merge on surfaces and jump away they could carry away contaminants and self clean the surface.
They contacted a fellow researcher at Duke University, A/Prof Chuan-Hua Chen, with expertise in droplet interactions to test the hypothesis and the group of researchers were delighted to see this new cleaning effect.
The droplets that carry the contaminants can be carried away from surfaces with only the smallest of breezes.
The husband and wife team have dubbed the cleaning effect the ‘Cicada Effect’ as the cicada wing was the first natural surface to illustrate the phenomena, now published in the prestigious journal - Proceedings of the National Academy of Sciences.
Captions for attachments: the video (.mov) file is a slow motion video of the jumping drops, slowed 13 times. The PowerPoint (.ppt)is a diagrammatic representation of what actually happens as the drops come into contact with particles, merge together and jump off.
JCU Media contact: Caroline Kaurila (07) 4781 4586 or 0437 028 175