A new way to control how liquids dry on surfaces which could bring benefits to a range of industries has been discovered by researchers from Northumbria University and The Open University.
The findings of the research team have been published today, Wednesday 11 April, by the journal Nature Communications.
Watermarks remain when a droplet dries on a solid surface, for example, when raindrops dry on the surface of a car, or when water dries on a wine glass after washing-up.
The way in which watermarks appear on a surface is uncontrollable because the shape and location of a droplet as it evaporates is unpredictable. This poses limits to many applications, such as inkjet printing, where an ink droplet can leave a distorted shape on paper, and micro-engineering, where watermarks can spoil the performance of delicate microstructures.
However, the researchers from Northumbria University’s Smart Materials and Surfaces Laboratory, and The Open University’s School of Mathematics and Statistics, have found a new way to control the shape and location of drying droplets for the first time, known as ‘snap evaporation’.
When a droplet evaporates on a solid surface, its edge ‘pins’ and ‘depins’ in an uncontrolled manner. This effect occurs due to the microscopic roughness of the bare solid surface. However, the researchers were able to control the way droplets dried, through a combination of wavy solid geometry and an ultra-smooth surface treatment.
Their findings could have an impact on many everyday applications – for example, the motor industry could treat car surfaces differently to minimize watermarks, and the smartphone and computer industry could improve the efficiency of micro-heat pipes, which remove heat from microprocessors.
thumbnail courtesy of 3dprint.com