Breakthrough in Understanding Droplet Adhesion to Surfaces
Understanding exactly how droplets and bubbles stick to surfaces - such as dew on blades of grass - has eluded experimental answers. It's a question with implications for everything from how to improve power-plant efficiency to how to reduce fogging on windshields. MIT researchers Kripa Varanasi and Adam Paxson have used a modified version of a scanning electron microscope (SEM) in which the dynamic behavior of droplets on surfaces at any angle could be observed in action at high resolution. Sequences of high-resolution images captured using the SEM show how the base of a water droplet forms small 'necks' as it moves across a surface that has pillars etched on it to increase its water-shedding properties. These necks control the adhesion of the drop to the surface, and are important in designing superhydrophobic (water-repellent) materials.