A synchronous computer from Stanford University operates using the unique physics of moving water droplets. The work combines the manipulation of droplet fluid dynamics with a fundamental element of computer science – an operating clock.

To build a clock for the fluid-based computer, arrays of tiny iron bars were built on glass slides. The researchers laid a blank glass slide on top and sandwiched a layer of oil in between. They then carefully injected into the mix individual water droplets that had been infused with tiny magnetic nanoparticles.

After turning on the magnetic field, the polarity of the bars reverses, drawing the magnetized droplets in a new, predetermined direction, like slot cars on a track. Every rotation of the field counts as one clock cycle, like a second hand making a full circle on a clock face, and every drop marches exactly one step forward with each cycle.

A camera records the interactions between individual droplets, allowing real-time observation of computation. The presence or absence of a droplet represents the 1s and 0s of binary code, and the clock ensures that all the droplets move in perfect synchrony.

Because of its universal nature, the droplet computer can theoretically perform any operation that a conventional electronic computer can crunch, although at significantly slower rates.

"We already have digital computers to process information. Our goal is not to compete with electronic computers or to operate word processors on this," said assistant professor Manu Prakash, the developer of the technology. "Our goal is to build a completely new class of computers that can precisely control and manipulate physical matter."

The ability to precisely control droplets using fluidic computation could have a number of applications in high-throughput biology, chemistry, and scalable digital manufacturing.


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