Though its processing speed is significantly slower than that of a conventional electronic computer, this computer, which works by moving water droplets, can theoretically perform the same operations. The work, according to Stanford University’s Bjorn Carey, combines “droplet fluid dynamics with a fundamental element of computer science — an operating clock.”
The water computer is described in the article “Synchronous universal droplet logic and control,” which appears in the journal Nature Physics. Article co-authors are Georgios Katsikis, James S. Cybulski, and Manu Prakash, all of Stanford University. (Prakash is also behind the design of a paper microscope that has possible uses for disease detection in developing countries.)
“Droplets are fascinating material because they are a little bag; you can put anything you want in it,” says Prakash. In this case, the research team added tiny amounts of magnetic nanoparticles to the water droplets before placing them on a miniature Pac-Man maze containing miniscule iron bars. The entire structure was filled with oil and sandwiched between glass slides. A magnetic field was then turned on.
“Every time the field flips, the polarity of the bars reverses, drawing the magnetized droplets in a new, predetermined direction, like slot cars on a track,” says Stanford’s Carey. “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 observation of computation as it occurs in real time,” he adds. “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 … thus the system can run virtually forever without any errors.”