# Logic Flows, Literally, In This Water Adder

A lot of elementary electronic texts use water as an analogy for electricity. You know, pressure is voltage, flow is current, and pipe diameter is resistance. It is ironic, then, that some people use fluids to build logic gates and, in fact, you can make any logic circuit you like using nothing but water flowing through some structures. Don’t think so? Have a look at the video from [Steve Mould] below.

Fluidic logic isn’t anything new, but it has always been a bit exotic. Usually, replacing electrons with water or even air — which is a kind of fluid — means you are trying to operate in a tough environment or have some other special need. As far as we can tell, [Steve] did it just because he could, and we get that.

# Anderson’s Water Computer Spills The Analog Secrets Of Digital Logic

One of the first things we learn about computers is the concept of binary ones and zeroes. When we dig into implementation of digital logic, we start to learn about voltages, and currents, and other realities of our analog world. It is common for textbooks to use flow of water as an analogy to explain flow of electrons, and [Glen Anderson] turned that conceptual illustration into reality. He brought his water computer to the downtown Los Angeles Mini Maker Faire this past weekend to show people the analog realities behind their digital devices.

[Glen]’s demonstration is a translation of another textbook illustration: binary adder with two four-bit inputs and a five-bit output. Each transistor is built from a plastic jewel box whose lid has been glued to the bottom to form two chambers. A ping-pong ball sits in the upper chamber, a rubber flap resides in the lower chamber covering a hole, with a string connecting them so a floating ball would lift the flap and expose the hole.

# Manipulating Matter In A Digital Way

On a fundamental level a computer’s processor is composed of logic gates. These gates use the presence of electricity and lack thereof to represent a binary system of ones and zeros. You say “we already know this!” But have you ever considered the idea of using something other than electricity to make binary computations? Well, a team at Stanford University has. They’re using tiny droplets of water and bar magnets to make logic gates.

Their goal is not to manipulate information or to compete with modern ‘electrical’ computers. Instead, they’re aiming to manipulate matter in a logical way. Water droplets are like little bags that can carry an assortment of other molecules making the applications far reaching. In biology for instance, information is exchanged via Action Potentials – which are electrical and chemical spikes. We have the electrical part down. This technology could lead to harnessing the chemical part as well.

Be sure to check out the video below, as they explain their “water computer” in more detail.