Water Droplets Power Stanford Created Computer

A unique computer that operates using the physics of moving water droplets has been built by a Stanford University professor and his students.

Manu Prakash, an assistant professor of bioengineering, said: “In this work, we finally demonstrate a synchronous, universal droplet logic and control,” Prakash said.

Grown from an idea that struck Prakash when he was a graduate student, the device has been almost ten years in the making. The work blends his expertise in manipulating droplet fluid dynamics with a basic element of computer science, an operating clock.

Theoretically, due to its universal nature, the droplet computer can perform any operation that an electronic computer can, albeit at drastically slower speed.

Fluidic Computation

Prakash and his colleagues, however, have a more demanding application in mind. Explains Prakesh:

“We already have digital computers to process information. Our goal is not to compete with electronic computers or to operate word processors on this. Our goal is to build a completely new class of computers that can precisely control and manipulate physical matter. Imagine if when you run a set of computations that not only information is processed but physical matter is algorithmically manipulated as well. We have just made this possible at the mesoscale.”

Capability of precisely controlling droplets using fluidic computation could have a range of applications, not only in high-throughput biology and chemistry, but possibly brand new applications in the field of scalable digital manufacturing.

Since the system is so remarkably robust, and because the team has uncovered universal design rules, Prakash plans to make a design tool for these droplet circuits available to the public. Any group of people could assemble the basic logic blocks and make any complex droplet circuit they desire.

In terms of basic science, part of why the work is so exciting, Prakash comments, is that it opens up a new way of thinking of computation in the physical world.

Although the physics of computation has up until now been applied to understand the limits of computation, the physical aspects of bits of information has never been exploited as a new way to manipulate matter at the mesoscale, which is 10 microns to 1 millimeter.

Currently, the team’s computer chips are about half the size of a postage stamp. The droplets themselves are smaller than poppy seeds, but according to first author Georgios Katsikis, the physics of the system suggest it can be made even smaller.

And combined with the fact that the magnetic field can control millions of droplets simultaneously, this makes the system exceptionally scalable.

“We can keep making it smaller and smaller so that it can do more operations per time, so that it can work with smaller droplet sizes and do more number of operations on a chip,” said graduate student and co-author Jim Cybulski. “That lends itself very well to a variety of applications.”

Georgios Katsikis, James S. Cybulski & Manu Prakash
Synchronous universal droplet logic and control
Nature Physics (2015) doi:10.1038/nphys3341

William A. Sirignano (2014)
Fluid Dynamics and Transport of Droplets and Sprays

Photo: Screenshot from Stanford University Video