From driving water wheels to turning turbines, waterhas been used as the prime mover of machinery and the powerhouse of industry for many centuries. In ancient times,the forces of flowing water were even harnessed to power the first rudimentaryclocks. Now, engineers at Stanford University have created the world’s first water-operated computer.Using magnetized particles flowing through a micro-miniature network ofchannels, the machine runs like clockwork and is claimed to be capable ofperforming complex logical operations.
Using poppy-seed sizeddroplets of water impregnated with magnetic nanoparticles (those handy little elementsbeing used in everything from drug delivery inhumans to creating e-paper whiteboards),the new fluidic computer uses electromagnetic fields to accurately pump thesedroplets around a set of physical gates to perform logical operations. Suspendedin oil and timed to move in very specific steps, the droplets in the system cantheoretically be used to accomplish any process that a normal electroniccomputer can, albeit at considerably slower speeds.
Stanford assistant professor Manu Prakash has spent almost a decadethinking about such a device, ever since he was a graduate student. The manyand varied components required of a fluidic computer have slowly coalesced inhis mind over that time, with the most fundamental component of all – an accurateoperating clock to drive the logic – being the crucial element in bringing hisinvention to fruition. Ultimately, Prakash built a rotating magnetic field to synchronize the flow of all the droplets in a precisely timed manner, andact as the clock.
"The reason computers work so precisely is that every operationhappens synchronously; it's what made digital logic so powerful in the firstplace," says Prakash. "In this work, we finally demonstrate asynchronous, universal droplet logic and control."
According to the Stanfordresearchers, this new type of computer offers up a way to produce analternative to high-speed, complex, electronic computers and take logicprocessing to the physical world. In this way, the fluidic computer may findapplications in such areas as biology, chemistry, and other physical sciencesand technology that use processes more akin to the properties of organizationfound in nature.
"We already havedigital computers to process information," says Prakash. "Our goal is not to compete with electroniccomputers or to operate word processors on this. Ourgoal is to build a completely new class of computers that can precisely controland manipulate physical matter. Imagine if when you run a set of computationsthat not only information is processed but physical matter is algorithmicallymanipulated as well. We have just made this possible at the mesoscale."
To create the fluidic logic,Prakash and Stanford graduate student Georgios Katsikis constructed assortmentsof miniscule iron blocks on glass slides to act as physical logic gates.Resembling a Pac-Man maze, the whole structure is filled with oil and toppedwith a clear glass slide, so that the fluid is sandwiched between the layers.To this, the researchers syringe in separate magnetic-nanoparticle-infuseddroplets of water.
They then surrounded thedevice with a series of large electromagnetic coils that, when turned on inducea magnetic field in the iron bars. As this magnetic field has its polarityalternately and continuously changed, so too there is a change in the inducedmagnetic field of the iron bars, and the magnetized water droplets are drawnaround the circuit. Each alternation of the electromagnetic field amounts toone clock cycle, and each drop moves exactly one step onward with each of thesecycles.
To observe the process, avideo camera is used to capture the exchanges between individual droplets, andto observe fluidic computation in real time. As such, the ones and zeroes of binarycode are represented by the presence or absence of a water droplet, with themagnetically-induced clock cycle ensuring that the droplets transfer in aflawless symphony that, the researchers believe, means the system canpractically run forever without errors.
"Following these rules,we've demonstrated that we can make all the universal logic gates used inelectronics, simply by changing the layout of the bars on the chip," says Katsikis. "The actual design space in our platform is incredibly rich.Give us any Boolean logic circuit in the world, and we can build it with theselittle magnetic droplets moving around."
The team also believes that,from the viewpoint of fundamental science, the work is exciting because itprovides a new aspect on computation in the physical world. As such, just asthe physics of calculation have been used to understand the limits ofelectronic computation, now the physical features of bits of information may beexploited in some novel way to control matter at the mesoscale (10 microns to 1mm).
Given that the new system isalso physically strong compared to electronic devices and adheres to universaldesign rules, Prakash and his team intend to produce a design tool for thesefluidic circuits for anyone to use.
"We're very interestedin engaging anybody and everybody who wants to play, to enable everyone todesign new circuits based on building blocks we describe in this paper ordiscover new blocks," Prakash says. "Right now, anyone can put these circuits together to forma complex droplet processor with no external control – something that was avery difficult challenge previously. If you look backat big advances in society, computation takes a special place. We are trying tobring the same kind of exponential scale up because of computation we saw in thedigital world into the physical world."
The results of this researchhave been published in the journal Nature Physics.
The short video below shows the fluidic computer in action.
Source: Stanford University
