A Waterproof Solution
A major international clothing maker and a major producer of coatings for electronics are interested to test possible applications for their products.
Professor Liqiu Wang (right) and Mr Pingan Zhu (left) showcase the liquid-repellent surface they innovated
Professor Liqiu Wang (third from left) and his team demonstrate droplet manipulation using liquid-repellent materials
HKU engineers have created a novel solution to make surfaces liquid-repellent that was inspired by an insect and has potential applications in clothing, electronics, water vessels, buildings and a whole host of other fields.
The work, by Professor Liqiu Wang of the Department of Mechanical Engineering and his PhD student, Mr Pingan Zhu, uses mechanical engineering to solve a problem that has typically been solved through chemical engineering.
“The chemical method can be damaging to the environment. We use a physical method instead that creates very small physical structures at the microscale to get a liquid-repelling performance,” Professor Wang said.
Their discovery also has a number of other advantages. It is able to repel both water and oil (and every liquid in between), whereas the current technology can only do one or the other. It can be produced to a large scale at the very cheap price of about HK$1 per square meter, versus HK$1,000 for conventional materials. It is also 21 times stronger than conventional, chemical-based technology.
The discovery’s design is based on the cuticles of the springtail, an insect that lives in soil in habitats that experience heavy rains and floods. The cuticles are strong enough to resist friction from soil particles while also repelling liquids.
Professor Wang and his team replicated these features into microfluidic droplets that can be applied to surfaces. This method can ensure uniformity of coverage and allow for better control by manipulating the size, structure and composition of the droplets.
The discovery was published in Nature Communications last year and industrial manufacturers have taken note. A major international clothing maker and a major producer of coatings for electronics are interested to test possible applications for their products.
“We are now working together with them to make real products, hopefully within the next two years,” Professor Wang said. “Until now, the work has just been in my laboratory but for real industrial production, we need to do large-scale testing with them.”
The hope is that the discovery will have much spring in its tail, opening up the possibility of such things as clothing that does not need to be washed, self-cleaning buildings, and vessels that can travel much more quickly through water by reducing the drag caused by friction.