We've updated our Privacy Policy to make it clearer how we use your personal data. We use cookies to provide you with a better experience. You can read our Cookie Policy here.


Fog Harvesting Potential Shown by Christmas-Colored Droplets

Alternating red and green droplets of water hanging from a wire.
Necklace-like, beautiful droplets on a fiber self-propel upon their coalescence — increasing their speed by up to 270% than before coalescence. Credit: Kyoo-Chul Kenneth Park and Leyun Feng, Northwestern University.
Listen with
Register for free to listen to this article
Thank you. Listen to this article using the player above.

Want to listen to this article for FREE?

Complete the form below to unlock access to ALL audio articles.

Read time: 1 minute

This image looks like a festive, holiday-inspired necklace. But it’s actually colorful water droplets clinging to a wire. Because the wire is engineered to attract water, the droplets glide along the line, eventually merging into one another.

Led by Northwestern University’s Kyoo-Chul Kenneth Park, this new research is not just beautiful. It also could help optimize many environmental processes, including collecting fog from the atmosphere for drinking water.

When the water-attracting wire is inclined, the droplets propel themselves to zip along the line. But the surprise occurs when two water droplets slide into one another and coalesce. By joining together, the droplets’ speed increases by up to 270% more than before the coalescence.

By understanding droplet transport along a wire, Park says his team is closer to optimizing the ability to harvest fog from the atmosphere. As water scarcity becomes an increasing problem around the world, fog harvesters have emerged as an inexpensive and accessible way to collect drinkable water. But they are inefficient, with water droplets often escaping through the mesh harvesting sheets. Park’s work could lead to new, more efficient designs for harvesters that outperform currently available meshes.

The findings also have implications for mist elimination, oil/water separation, microplastics remediation and even biomedical filters.

“The new phenomenon and mechanism about the sudden increase of droplet speed along a super-hydrophilic wire will benefit various fields,” Park said. “This includes biomedical research requiring a fast transport of liquid, such as masks and filters, to protect people from airborne microplastics and droplets containing viruses.” 

Reference: Jiang Y, Feng L, O’Donnell A, et al. Coalescence-induced propulsion of droplets on a superhydrophilic wire. Appl Phys Lett. 2022;121(23):231602. doi:10.1063/5.0124560

This article has been republished from the following materials. Note: material may have been edited for length and content. For further information, please contact the cited source.