# Fluiduino

A fluidic transistor that I designed and printed.

This blog post is a temperature check for how interested the community would be in an open source, 3d printable, fluidics hardware platform. I want to make sure that this is something that the maker community wants because this isn’t for me, it’s for you. So if you won’t use it, I won’t make it.  First, let me wet your appetite by listing cool projects and applications of fluidics, most of which can be printed on a 3d printer and then I’ll tell you how it works and what I want to do with it.

Awesome projects:

Educational. Teach electronics and logic via the fluid/electric analogy which is extremely strong.

3d printable pneumatic stepper motor made from plastic parts only.

Rocket propulsion control systems.

Steam punk steam robot that can function while on fire.

Robust space travel.

Wood wind magic key piano that opens up a trap door with wind.

Programmable digital computer with no electronics.

Programmable fountain with no electronics that you can interact with.

Microfluidics, biological control. This could be an open source project in its own right.

Smart meta-materials(speculative).

How it works:

The electric/fluid analogy is very strong. Electrons flowing in a wire is much like water flowing in a pipe and in fact, the two systems follow many of the same laws.  A pressure difference is like a voltage, a long narrow tube provides resistance, a membrane is like a capacitor and a coil of pipe is like an inductor. You can send power with electricity and also with fluids(i.e. hydraulic power systems). These are all analog components but the analogy between fluids and electric circuits goes even deeper.  Just like with electric circuits, you can make fluidic circuits digital.  The principle here is that streams of fluid interact with each other. That is, two streams will divert each other, not pass through, so that you can use a control stream of fluid to divert a power stream.  You can use this to build a fluidic amplifier/transistors, logic gates, flip-flops and even a digital computer.

Fluidic amplifier

I’ve taught electronics labs before and let me tell you, electronics are not intuitive to most people. Fluid flow is much more intuitive. One of my main motivations for an open source fluidics project is to make educational kits for high school and college students so that they can gain strong understanding for how electronics work by understanding how the more intuitive fluidic systems work.

Electronics are awesome. I love my computer and I love my Arduino.  But there are some applications that semiconductors are bad for. In particular, you can’t light your laptop on fire and expect it to function. Fluidic computers work just fine when on fire, provided the fluidic device is made of something like ceramics or metals and the fluid is something like gas or oil.  Indeed, you can make your power stream be rocket thrust, very hot, and use a perpendicular small control stream to divert the power stream, thus being able to steer a rocket! Nasa has a nice blurb about his here.

Rocket control

Fluidic rocket control.

Generally fluidics is practical in harsh conditions. Yet another example is space travel.  There are tons of charged particles and other radiation flying around in space that damage semiconductors.  Indeed, semiconductors have to be radiation hardened to withstand these harsh conditions. Because fluidics use fluids instead of electrons for their operation, they can be more reliable in such situations.

Fluidics is just plain cool. The number of steam punk applications are endless. You can make a robot that moves and thinks with steam, just steam! There was someone who made a desk that would play notes via a pipe organ when the drawers were opened. If you open the drawers in the right sequence, a trap door would open. It was made entirely from wood with no electronics. Cool huh?

Fluidic pipe organ desk with a secret compartment

Fluidic pipe organ desk with a secret compartment

One speculative application that’s on the forefront of science that I’m particularly interested in is digital meta-materials.  Digital meta-materials are materials that are made of bits of matter, put together like legos to make something that is functionally more powerful than each individual block.  In this case, I’m imagining fabric with a vascular system that responds to temperature and pressure  via fluidic logic.  I don’t think that 3d printers can beat traditional manufacturing in what traditional manufacturing does well already but I do think that 3d printers can win, hands down, when it comes to complex intricate objects like printing an intricate fluidic vascular system. The philosophy here is that we should be looking for applications of 3d printers that were not possible before.

What I want to do:

I’d like to start an open source fluidics project. Something like Arduino, easy to use, but with fluids. Maybe we could call it the Fluiduino? My primary motivations are educational and inspirations.  I want students to have a deep understanding of electronics and I want makers and hobbyists to easily be able to make rocket control systems, steam robots and programmable fountains. What I want from you is feedback as to whether an open source fluidics platform is something you’d be interested in playing with in the future? I’m not doing this for me, I’m doing this for the community as whole so if you’re not interested, I won’t do it. If however, you feel as inspired as I do, I’d love to find people to work with on this project.

-Sebastian Spiegel

# Tesla valve:print in one piece

Tesla valve is a one way valve with no moving parts that gives a preferential direction of air/liquid flow.  It’s exciting because most one way valves have a flap that closes are a ball that blocks flow in a particular direction.  But not the Tesla valve. It uses air itself to block air from passing.

Today I decided that I wanted to print a Tesla valve but all the designs I’ve seen require you to print it in two parts and then use screws to hold it together. That seems like too much work so I decided to design a Tesla valve that prints all in one piece.  You can download it here. This is all part of a bigger project which I plan to unveil in the future 😉

My first design was  kind of wonky. Blowing in one direction you would get smooth air flow and in the other, turbulent air flow but still quite a bit of flow.  added the fins in as well but the airflow is still substantial. I guess I’ll have to get back to it some other time.

Here’s my printer printing this Tesla valve:

# What if the world used hydraulic power?

Electricity is awesome.  It used to be, back in olden days, that if you wanted to get mechanical power, you would build a giant windmill and then use that mechanical motion to do something like mill wheat.  That’s where the “mill” part of windmill comes from. You either had to have your own windmill or share one with other farmers.  The awesome thing about electricity is that you can transfer that energy over vast distances and then use it for whatever you want. In short, electricity is universal.  What if we, as the human race, had never discovered electricity?  Would we the industrial revolution never have happened? What else could act as a universal portable source of energy? The problem boils down to this:

1. How do you convert mechanical energy in one form, like wind or water turbines, into another useful form, like plowing a field or mixing cookie dough?

2. How do you move mechanical energy over vast distances?

My first thought would be to take a rotating disk and move it from one location to another. But even the fastest rotating things I’ve seen only rotate for at most 10 minutes, which doesn’t leave much time to move it a long distance. But then the answer, an answer, hit me.

Water.

Think about it, water in pipes could have replaced electricity.  You could harness the energy in flowing water and pipe it from one location to another, satisfying both conditions above.  Yes hydraulic power is analogous to electrical power.

It would probably be best to keep the system closed so that you don’t lose any water. The whole system needs less maintenance that way.  But then you’re left with the problem of extracting energy from a closed system.  You could do the same thing that we do for electricity today, use oscillating pressure/voltage. Imagine that instead of a power outlet you had a vibrating membrane that you could connect a hose to. That hose would power your device by converting that mechanical energy to whatever mechanical motion you needed.

It’s no surprise that this hydraulic power acts synonymous to electricity. Electricity is essentially electrons flowing through pipes, i.e. wires. Electrical inductors are like coils of pipe that store a large mass of moving water, that is inertia, and capacitors are like elastic membranes placed between two sections of pipe. The equations of motion are identical.  A one way valve could act as a diode and pressure dependent valves could even act as logic gates, closing off a tube if the pressure is high, 0, and opening the tube when the pressure is low, 1.  So we could even build a computer using hydraulics! That’s pretty freakin’ amazing.

There are some draw backs. If you wanted to power your house by storing a tank of water on top of your house, say 3 meters off of the ground, you would need a pipe of a diameter of 7 or 8 cm(about 3 inches) to produce 1000 Watts.  That’s much bigger than an electrical wire but not unreasonable.

I wonder how thick the pipe would have to be to send hundreds of megawatts thousands of miles away without more than a few percent energy loss? I don’t know the answer but I have some thoughts about how to minimize energy loss. You would want to minimize motion as to reduce energy loss from friction and so you would naturally use very large pressures in transmitting energy long distances hydraulically. This is exactly what we already do with electricity. We step up the voltage to ridiculously high values, about 100,000 volts compared to the 120 volts that I use in my home power outlet (I live in the U.S.). Energy is force times distance and so if the pressure is high, the force is very high and the distance moved doesn’t have to be large to transmit a lot of power.  Frictional force times distance the water moves is the frictional energy loss and frictional force doesn’t depend on pressure. So by maximizing pressure, we minimize the percentage of energy lost due to friction.

Imagine a world powered by hydraulic power? People into steam punk would love this world! I want to experiment with this. Maybe I should experiment with hydraulic systems? What do you think? I don’t know about you, but I’m getting excited about making some stuff using hydraulics.

-Sebastian Spiegel

# Generating electricity by shaking it

I want to start this post by acknowledging that technology is exciting, making stuff is fun and sharing that stuff and how to build it makes all of our lives better.  I recently started reading an autobiography by Olaudah Equiano with a long winded title about his experience with being abducted and thrown into slavery. While his account of the institution of slavery is well worth reading, what struck me is the description of his life before being forced into slavery.  He was a young boy and he and his family were subsistence farmers.  They made their own homes with local materials, made their own pottery and grew their own cotton which they turned into thread and then into fabric. There were no beggars and no one was idle.  Everyone ate.  It reminds me that life really isn’t very complicated. We need safety, food and those we love. That’s it.  I feel like technology should enable us to firstly do those things more easily and secondly play.

Inspired by simplicity, I want to build something like this:

When I go for a walk I see leaves shaking in the wind and water flowing down streams.  Sure, you could build a giant turbine to pick up this energy. But I imagine a world full of little simple generators like this shake generator.  It’s hard to build a turbine but it’s easy to attach a shake generator to some fabric or hang it from a string while rushing current goes by.  Its shear simplicity as a bit of power generation, would make it very easy to incorporate into the design for a larger generator. What’s more is that the design would be naturally fault-tolerant. If any one generator goes out, the rest can still generate power.

Sure you might need hundreds, even thousands of these things to power your home.  I’m ok with that. A shake generator hanging from some vibrant cloth could be quite beautiful.  Having several thousand would be dazzling.

-Sebastian Spiegel

# I’ve got the AWG wire thickness blues

I’m thinking about making a vibration charger for my phone and so I need magnet wire, i.e. thin copper wire to wrap around a magnet. So I discovered, to my disgust, that AWG is the unit of wire thickness. For some reasons, the powers that be decided that it would be smarter to use a logarithmic function of diameter to measure wire thickness, instead of just, hmmm, using the fucking wire diameter to measure the wire thickness!

I decided to make a table of conversions for those of us that still strive for sanity. In terms of the AWG number, you can get the wire thicknessm, in millimeters, using this formula:

$Diameter=0.127mm \ \times 92^{\frac{36-n}{39}}$

I know someone is goint to respond to this post and say something like “they use that equation to make it a logarithmic scale”. The only reason you use a logarithmic scale is because the range of values are so vast that it becomes annoying to write out all of the digits. I question whether the range of values of wire thickness is vast enough to warrants the use of a logarithmic scale.

 AWG Millimeters Inches Light years -10 26.307 1.2331 0.00000000000000000278 -9 23.427 1.0981 0.00000000000000000248 -8 20.862 0.9779 0.00000000000000000221 -7 18.578 0.8709 0.00000000000000000197 -6 16.544 0.7755 0.00000000000000000175 -5 14.733 0.6906 0.00000000000000000156 -4 13.120 0.6150 0.00000000000000000139 -3 11.684 0.5477 0.00000000000000000124 -2 10.405 0.4877 0.00000000000000000110 -1 9.266 0.4343 0.00000000000000000098 0 8.251 0.3868 0.00000000000000000087 1 7.348 0.3444 0.00000000000000000078 2 6.544 0.3067 0.00000000000000000069 3 5.827 0.2732 0.00000000000000000062 4 5.189 0.2433 0.00000000000000000055 5 4.621 0.2166 0.00000000000000000049 6 4.115 0.1929 0.00000000000000000044 7 3.665 0.1718 0.00000000000000000039 8 3.264 0.1530 0.00000000000000000035 9 2.906 0.1362 0.00000000000000000031 10 2.588 0.1213 0.00000000000000000027 11 2.305 0.1080 0.00000000000000000024 12 2.053 0.0962 0.00000000000000000022 13 1.828 0.0857 0.00000000000000000019 14 1.628 0.0763 0.00000000000000000017 15 1.450 0.0679 0.00000000000000000015 16 1.291 0.0605 0.00000000000000000014 17 1.150 0.0539 0.00000000000000000012 18 1.024 0.0480 0.00000000000000000011 19 0.912 0.0427 0.00000000000000000010 20 0.812 0.0381 0.00000000000000000009 21 0.723 0.0339 0.00000000000000000008 22 0.644 0.0302 0.00000000000000000007 23 0.573 0.0269 0.00000000000000000006 24 0.511 0.0239 0.00000000000000000005 25 0.455 0.0213 0.00000000000000000005 26 0.405 0.0190 0.00000000000000000004 27 0.361 0.0169 0.00000000000000000004 28 0.321 0.0151 0.00000000000000000003 29 0.286 0.0134 0.00000000000000000003 30 0.255 0.0119 0.00000000000000000003 31 0.227 0.0106 0.00000000000000000002 32 0.202 0.0095 0.00000000000000000002 33 0.180 0.0084 0.00000000000000000002 34 0.160 0.0075 0.00000000000000000002 35 0.143 0.0067 0.00000000000000000002 36 0.127 0.0060 0.00000000000000000001 37 0.113 0.0053 0.00000000000000000001 38 0.101 0.0047 0.00000000000000000001 39 0.090 0.0042 0.00000000000000000001 40 0.080 0.0037 0.00000000000000000001

# Hello world!

This is my maker blog devoted to sharing my projects and other peoples cool projects. I think stuff like this:

is pretty amazing.

Stirling engines are kind of awesome but at their best, they still under perform compared to combined gas-jet steam cycles. The benefit of Stirling engines though, is that you don’t need to build at an industrial level, as the person in the youtube video so clearly demonstrates.

I have so many questions, like is it cost effective to make a Stirling engine out of plastic rather than metal? The problem is that plastics tend to have thermal conductivity(i.e. how quickly they can give off heat) of between .19 to .5 $\frac{W}{mK}$ whereas iron has a thermal conductivity of 80 $\frac{W}{mK}$. That’s about 400 times better than the best plastic, which is high density polyethylene. What this means is that to make a Stirling engine out of plastic with a similar power output as an iron engine, you would need 400 times the surface area between the working gas and the hot and cold reservoirs.

But what if 400 times the material was still cheaper if it was made out of plastic? Plastic typically comes form oil and oil is currently trading at about $93/barrel. Each barrel has about 159 liters in it so the raw materials for plastic cost at least$0.58/liter.  By contrast, iron ore is trading at about $100/metric ton and a ton of iron has about 142 liters of volume. That’s about$0.70/liter for iron ore. I’m sort of shocked by the outcome. Oil and iron ore are trading for close to the same price per volume. If this translates into the cost of producing a Stirling engine, and this is a big if, then that would mean that a plastic stirling would cost several hundred times more than an iron stirling for the same energy output. Warning! These numbers are so rough that they should hardly be believed. They’re only meant to give some intuitive insight into the cost effectiveness.

There’s a lot that could be wrong with this picture. Plastics are easier to work with and you might require less plastic than metal, especially for low temperature stirling engines. There are so many questions and so little time!!!……..