Temperature difference propels droplets
Researchers at MIT and elsewhere have developed a new way of driving fluid droplets across surfaces in a precisely controlled way. The method could open up new possibilities for highly adaptable microfluidic devices, as well as for de-icing technologies, self-cleaning surfaces, and highly efficient condensers. The new system uses differences in temperature to push droplets of water or other fluids across a smooth surface, allowing precise control by simply turning heaters and coolers on and off. The finding is described this week in the journal Physical Review Fluids, in a paper by MIT associate professor of mechanical engineering Kripa Varanasi, professor David Quere at ESPCI in Paris, MIT postdoc Nada Bjelobrk, graduate student Henri-Louis Girard, Srinivas Subramanyam PhD ’16, and Hyuk-Min Kwon PhD ’13. The differences in temperature on a surface, the researchers report, cause a change in the amount of surface tension across the droplet. That causes the droplet to move...