Step into assistant professor Manu Prakash's bioengineering lab, and you'll find scientists making waves with water droplets.
One team—Prakash, graduate student Nate Cira and postdoc Adrien Benusiglio—documented the science behind a curious phenomenon: that water droplets "dance" when they're mixed with another chemical and placed on glass. The explanation? As water evaporates from the outside of the droplet, the surface tension changes and creates a flow within. It works with 40 chemicals so far.
"Now we think we've found a clever trick to extend the work to nearly all chemical mixtures," Cira wrote in an email. And they are starting to show how the discovery might enable certain surfaces—perhaps solar panels, for example—to self-clean.
Nearby, graduate students Georgios Katsikis and Jim Cybulski worked with Prakash to create a water droplet-based computer. The goal is to build a new class of computers than can control and manipulate physical matter.
The computer looks like a miniature sandwich: a couple glass slides, with a maze of tiny iron bars and a layer of oil in between. The researchers inject water droplets infused with magnetic nanoparticles into the sandwich and set it within a rotating magnetic field.
The possible uses of the system are exciting—for example, in high-throughput biology and chemistry labs. The droplets can replace test tubes as containers, Katsikis said, making reaction times faster and costs cheaper while the computer would improve control over the movement of the chemicals.
