A computer that works with water droplets

A computer is developed that is able to operate on the basis of the unique laws of physics for moving water drops. The goal of the researchers is to develop a new family of computers that can precisely control and manage physical matter.

[Translation by Dr. Nachmani Moshe]
A computer is developed that is able to operate on the basis of the unique laws of physics for moving water drops. The goal of the researchers is to develop a new family of computers that can precisely control and manage physical matter.

Computers and water don't usually coexist, but in the laboratory of researcher Manu Prakash they live together. Prakash, a professor of bioengineering at Stanford University, and his research team were able to build a synchronous computer that operates using the unique laws of physics for moving water droplets. The researcher has been working on the development of this computer for a decade, starting with the idea that popped up in his mind when he was an undergraduate student. The research combines his expertise in the field of fluid dynamics together with the fundamental component of a computer - a synchronizing clock. "As part of this research, we finally demonstrated a logic gate and synchronous control," said the lead researcher.

Thanks to its universal nature, the droplet computer could, theoretically, perform any operation that a normal electronic computer is currently able to perform, albeit at a much lower rate. "Already today we have digital computers capable of processing information. Our goal is not to compete with electronic computers or run a word processor with it," says the lead researcher. "Our goal is to develop a completely new family of computers capable of accurately controlling tangible material. Imagine being able to run a collection of calculations that would not only process information but also algorithmically affect physical matter. Now we have made it possible at the mesometric level (medium scale).” The ability to control precision in droplets with the help of liquid computing could grow a number of advanced applications in the fields of biology and chemistry, and possibly new digital applications as well. The research findings have long been published in the scientific journal Nature Physics.

For years, the researcher was interested in what would happen if he managed to use tiny drops as bits of information (like zero and one in a binary language) and utilize the precise movement of these drops both to process information and to physically manage material at the same time. In the end, the researcher decided to build a rotating magnetic field that could be used as a clock that synchronizes all the droplets in the system. Computer clocks are found in almost every everyday convenience product - smartphones, digital video recorders, airplanes, the Internet itself - without a clock, none of these products could operate without serious and frequent complications. Almost every computer program is required to perform several operations at the same time, each of which is performed perfectly one after the other. A clock ensures that these operations start and finish at the proper time, which allows synchronization of the information. If the clock is not present, the results go wrong - similar to soldiers marching in formation: if one soldier significantly disrupts the synchronized movements, soon the entire group structure will collapse. This is also true in the case of simultaneous computer operations that occur without a clock synchronizing them, explains the researcher.

Developing a clock for a liquid-based computer required the researchers to get a little creative. It should be simple to maneuver and one that can affect several drops at the same time. In addition, the system should be scalable in the future, so that a large number of drops can communicate with each other without missing any of them. The lead researcher believed that a magnetic field might be the solution.

The researchers built arrays of tiny iron needles on glass surfaces, an array that looks like the maze of the children's game Pacman. They placed an opaque glass surface on top of the lower surface and inserted a layer of oil between them. In the next step, they injected into the mixture individual drops of water into which tiny magnetic nanoparticles had been inserted. Then, they applied a magnetic field to this entire array. Every moment the direction of the field was reversed, the polarity of the needles was also reversed, a result that causes the magnetized droplets to organize in a new predetermined direction. Each reversal of the field is counted as completing one clock cycle.

A camera records the interactions between the individual drops, which allows you to watch the calculation as it happens in real time. The presence or absence of a drop represents the signs zero or one in the binary language, and the clock ensures that all the drops will move in perfect synchronization and therefore the system can operate, theoretically, forever and without any errors.

"In light of these rules, we were able to demonstrate that we can create all the universal logic gates used in the world of electronics, simply by changing the arrangement of the pins on the chip," explains the lead researcher. As part of the article, the researchers demonstrate a variety of different types of logic gates. The size of the current chips is about half the size of a postage stamp, with the size of the droplets smaller than poppy seeds, and the lead researcher even claims that the laws of physics governing the new system imply that it can be made even smaller. Along with the fact that the magnetic field is able to control millions of drops at the same time, the system should be suitable for any size.

The lead researcher notes that the most immediate application could be related to turning the computer into a highly advanced chemistry or biology laboratory. Instead of running reactions in large laboratory vessels, each drop can carry several reactants and become a laboratory vessel by itself, and the computer itself offers extraordinary control over these reactions.

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