# Finding Paths With Water Is A-Mazing

We aren’t sure if it qualifies as fluidic logic, but [Steve Mould] was inspired by a simulation of water flowing through a maze and decided to build some actual mazes and watch water flowing through them. It turns out there are several physical effects in play, and you can see [Steve] discuss them in the video below.

The maze, of course, has to be oriented so that water flows into the top and flows out of the bottom. Without much thought, you’d think that the water just goes to the bottom and then fills up. Eventually, the part that is open at the bottom will have water coming out, right? Turns out it isn’t that simple.

A combination of air pressure and surface tension conspire to make the water do better than expected. Not that it perfectly solves it, but it doesn’t just fill up the entire maze, either. Even more interesting is that once the water has found the bottom, changing the water color will clearly show the path through the maze since nearly all of the new colored water will follow the flow path.

Practical? We can’t think of why. But it is a great think piece on how water flows and what sort of forces can affect it.

[Steve] is no stranger to making water work out algorithms, something called fluidic logic.

# Computing Fluidly

Computers come in many forms, depending on your definition. We’ve seen computers and computer gates built out of things as diverse as marbles, relays, and — of course — transistors. However, there are logic gate systems that use a property of moving fluids to form logic gates and a bistable element. That’s all the pieces you need to build a working computer.

It may sound far-fetched, but there have been general-purpose computers built using this technology. It is also used in specialized applications where fluids are already flowing, like shower heads, automotive transmissions, and in places where electronics are prone to misbehave. Many think the field will see a resurgence when we need to build logic at the molecular level for nanotech applications, too.

## Basics

In its most basic form, a fluidic gate uses flow as a logic 1 and less flow to be a logic 0. Merging two streams together provides an OR gate. Using a supply stream that you can divert with a control stream provides a NOT function. Given enough inverters and OR gates, you can build everything else.

# Microfluidics For Biohacking Hack Chat

Join us on Wednesday, July 7 at noon Pacific for the Microfluidics for Biohacking Hack Chat with Krishna Sanka!

“Microfluidics” sounds like a weird and wonderful field, but one that doesn’t touch regular life too much. But consider that each time you fire up an ink-jet printer, you’re putting microfluidics to work, as nanoliter-sized droplets of ink are spewed across space to impact your paper at exactly the right spot.

Ink-jets may be mundane, but the principles behind them are anything but. Microfluidic mechanisms have found their way into all sorts of products and processes, with perhaps the most interesting uses being leveraged to explore and exploit the microscopic realms of life. Microfluidics can be used to recreate some of the nanoscale biochemical reactions that go on in cells, and offer not only new ways to observe the biological world, but often to manipulate it. Microfluidics devices range from “DNA chips” that can rapidly screen drug candidates against thousands of targets, to devices that can rapidly screen clinical samples for exposure to toxins or pathogens.

There are a host of applications of microfluidics in biohacking, and Krishna Sanka is actively working to integrate the two fields. As an engineering graduate student, his focus is open-source, DIY microfluidics that can help biohackers up their game, and he’ll stop by the Hack Chat to run us through the basics. Come with your questions about how — and why — to build your own microfluidics devices, and find out how modern biohackers are learning to “go with the flow.”

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, July 7 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

[Featured image: Cooksey/NIST]

# 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.

# Deep Discounts Yield Deep Reverse Engineering Of Biotech Hardware

Hitting the electronic surplus shop is probably old hat to most of our readership. Somewhere, everyone’s got that little festering pile of hardware they’re definitely going to use some day. An old fax is one thing, but how would your partner feel if you took home an entire pallet-sized gene sequencing rig? Our friend [kaspar] sent along an interesting note that the folks at Swiss hackerspace Hackteria got their hands on an Illumina HiSeq 2000 last year (see funny “look what we got!” photo at top) and have generated a huge amount of open documentation about whats inside and how to use it.

Okay first off, what the heck is this machine anyway? The HiSeq is designed to automatically perform the sequencing step of Illumina’s proprietary multi step gene sequencing process (see manufacturer’s glossy for more), and to do so with minimal human intervention. That means that the unit contains a microfluidics system to manipulate samples, an extremely high performance optical scan system complete with controllable stage, imager, fluorescence modes, etc, and lots of other things this author isn’t sufficiently trained to guess at.

The folks at Hackteria have done a pretty thorough teardown of the system and produced block diagrams of most of its modules. They’ve also run some of the tools and recorded logs of what they were up to, including the serial commands sent to and from the machine to control certain subsystems. Of course a tool like this was meant to be driven by Illumina’s specific software, but unusually those are available and surprisingly usable which is how the aforementioned logs were captured. Right now it looks like Hackteria has put together tools to use the system as a fluorescent microscope.

Oddly the most interesting thing here might be how available these systems are. It appears that they’re being replaced en masse and have become easily available in the range of thousands of dollars on the secondary market. At that price point they’re almost worth snapping up for the enclosure and parts! But we prefer Hackteria’s goal of enabling the Citizen Scientist to make use of these incredible machines for their intended purpose. Who knows what exciting projects we’ll find when hackers start sequencing their cats!

Thanks for the tip [kaspar]!

# Logic Gates Under (Air) Pressure

We’ve always been fascinated at the number of ways logic gates can spring into being. Sure, we think of logic gates carrying electrons, but there are so many other mechanical means to do the same thing. Another method that sometimes has a practical use is fluidic or pneumatic logic. We guess [dAcid] has a similar interest since he’s written two posts on how to construct the gates. One post covers making them with ordinary tools. The other requires an SLA printer.

According to [dAcid], the design is effectively the same either way, but the SLA printing is more precise. Silicone is an important component, either way. Fluidic logic has applications in some mechanical systems, although digital logic has made it less important than it once was. However, it is very possible that nanotechnology systems will implement logic mechanically, so this is still an interesting technique to understand. You can see videos of how a D latch looks using both methods, below.

# Paper Circuit Does Binary Math With Compressed Air

Most of us can do simple math in our heads, but some people just can’t seem to add two numbers between 0 and 3 without using paper, like [Aliaksei Zholner] does with his fluidic adder circuit built completely of paper.

There’s some good detail in [Aliaksei]’s translated post on the “Only Paper” forum, a Russian site devoted to incredibly detailed models created entirely from paper. [Aliaksei] starts with the basic building blocks of logic circuits, the AND and OR gates. Outputs are determined by the position of double-headed pistons in chambers, with output states indicated by pistons that raise a flag when pressurized. The adder looks complicated, but it really is just a half-adder and full-adder piped together in exactly the same way it would be wired up with CMOS or TTL gates. The video below shows it in action.

If [Aliaksei]’s name seems familiar, it’s because we’ve featured his paper creations before, including this working organ and a tiny working single cylinder engine. We’re pleased with his foray into the digital world, and we’re looking forward to whatever is next.