The preparation for boric acid caramel is similar to sugar caramel. Both are glass soluble in the water. One is edible, the other not.

Ingredients
:: ½ cup of boric acid powder
:: 3 teaspoons of water
:: ¼ cup of silicone oil
:: optional colored mineral pigment

Precautions
Boric acid (H3BO3) is a weak acid, used for medical applications (antiseptic and antibacterial) and also as a neutron absorber in the nuclear industry. Do not inhale or allow its vapors to reach your eyes when heated. It is sold in drugstores.

Recipe
Combine together the ingredients and bake in the oven at 480°F. After one hour, the boric acid will be dissolved and the liquid viscous and transparent. Cool for 90 minutes by slowly turning the oven temperature down, to avoid thermic shock (when hot material hits cold air, it often cracks). While cooling, the mass becomes solid. Sugar caramel results mainly from a series of chemical reactions (caramelizing reactions), boric acid caramel develops from a physical transformation (fusion). Both materials look alike on a macroscopic level. They are both brittle and water soluble.

Tips
Out of the oven, the glass cools and hardens in a few seconds. There is no time for pouring it into a mold. Adding silicone oil instead of water, before baking, allows the caramel to get more viscous and malleable. Adding water is useless, because it evaporates as soon as the temperature reaches 212°F.

The recipes to obtain the materials inside the e-book are easy but it’s important to note the main concept: the tie between culinary ingredients and non-culinary materials. An ingredient is a material! Do you know that we temper chocolate in the same way we quench titanium/nickel alloy to obtain shape-memory metal? The rank of temperature is of course different. In the case of chocolate, I get new properties (crunchiness and shiny exterior) but the process is the same: quickly cool a material (or an ingredient) previously heated to permit an atomic reorganization of the material (or the ingredient).

I believe that cooking is not only about nourishing our body but about material change of states (from water you get ice cream or a crystallize material!) and about control of shelf life of material (you make jam to conserve fruit as cheese to conserve milk!).

Material change of states and control of shelf life of materials are two important topics in material sciences.

In this video Becky Stern from Adafruit shows how to make a simple circuit on a transparent sheet of plastic coated with indium tin oxide.

Light is much harder to handle than electricity. How do we transfer large amounts of light over distances and around many corners? Fiber optics is one method of transferring light around corners efficiently, but using solid fiber optics to transfer large amounts of light is very expensive, and losses at the point of light injection are very high. If we could transfer large amounts of light around corners, we could capture the sunlight striking the roofs of office buildings and use it to light the interior offices; natural, free sunlight, better for the eyes and better for the environment.

A very early experiment of a neon sign replacement. Tygon SE-200 tubing, mineral oil and rutile TiO2 scattering agents. Low power LED light sources

What about high power LEDs? Today’s high power LEDs are far more efficient than incandescent bulbs, but their pinpoint brilliant brightness is hard to use. Can we create glowing panels using LEDs emitting smooth, even light across their surfaces, tunable to any color you would like, to match your décor or your mood?

To meet these challenges, I developed Liquid Core Light Guides, basically fiber optic type light transport, but far more efficient and able to transport huge amounts of light. I also developed methods of embedding LED dies directly into these liquid core light guides, avoiding optical insertion losses, and developed methods to spread high power LED light into a smooth, even glow.

In 2003-2007 I spent about 2500 hours and $70,000 developing these technologies, but never found a clear path to a profitable business. I am now publishing some of this work on OpenMaterials.org, in the hopes that someone out there will be able to expand on this work, and find useful applications for it. If anyone knows of a high-value application where this technology might be useful, please let me know.

How to Transport Light Around Corners and Over Distance
If you want to pipe light a long distance, a pipe with an inner mirror surface might seem a reasonable answer. However, mirrors are not very efficient at reflecting light. A mirror will typically absorb or scatter 5% of the light striking it. Almost all the light that enters a long reflecting tube will be absorbed as it travels along any distance, reflecting dozens or hundreds of times, losing 5% with each bounce.

Example of Total Internal Reflection in a Tube or Panel.

However, nature has a better mirror, the phenomenon of Total Internal Reflection (TIR). Total Internal Reflection occurs when a light ray is traveling in a medium of high refractive index, such as a transparent solid like the silica glass used in fiber optics, and strikes an interface with a medium of lower refractive index, such as a fluoropolymer, at a low enough angle. In this situation, the light ray is reflected back into the high-refractive index medium without loss, the interface forming a perfect mirror. In this way, a fiber optic cable can bounce a light ray down its’ core for miles, reflecting millions of times, with little loss.

For a light ray to stay within a fiber optic core, it must reflect at a low enough angle. This angle is determined by Snell’s law: ni * sin Өi = nr * sin Өr, where n is the refractive index of the material. The critical angle that a light ray must meet to be reflected losslessly by TIR is sin ӨC = nr / ni .

Fiber optics are wonderful for sending light-based communication signals for miles, but are far too expensive to use to transport large amounts of light. A huge diameter fiber using Silica glass would be heavy, expensive and prone to instant cracking. Acrylic fiber optics of large diameter have been developed, but have very high attenuation over 10’s of meters, and are also very expensive. How can we use the phenomenon of Total Internal Reflection to transport light less expensively? One answer is to use a liquid filled light guide.

A liquid “fiber optic” cable could be inexpensive, flexible, and of large diameter. In the case of using high-power LEDs, the LEDs could actually be embedded into the liquid, and the surrounding liquid could provide some of the needed LED cooling. However, any such liquid light guide would need to meet Snell’s law for Total Internal Reflection. The liquid core would have to have a higher index of refraction than the solid cladding. In general, liquids have lower indexes of refraction than solids, so finding a pair of materials where the solid has a lower index of refraction then the liquid is challenging.

One reasonable choice for a core fluid is regular transparent mineral oil, which has a refractive index near 1.47. Experiments can be made with mineral oil you can find in any drugstore, however mineral oil meant for consumption has certain additives which can cause yellowing under the influence of UV. Very few solids have low refractive indices. Aside from some expensive epoxies, most of the low-refractive transparent index solids are perfluoropolymers, such as various forms of Teflon.

Therefore, some of my earliest experiments used tubing such as Tygon SE-200, which has a co-extruded FEP Teflon lining, of approximately 1.33 refractive index. A Tygon SE-200 tube filled with mineral oil makes a reasonably good liquid filled light guide. However, at $6/foot for 0.5” ID tubing, it is also an expensive solution for most applications. In addition, the co-extruded FEP lining is stiff and prone to kinking and cracking.

Teflon is a substance that is almost universally heat-processed, at temperatures often in the 350C range at a minimum. Therefore, coating tubing with Teflon, or creating a light-capturing cavity of any kind, require substrates that can accept the high temperatures of Teflon processing (such as your kitchen non-stick frying pans). To achieve TIR, the coating of low-refractive index material need only be a few microns thick. How would we inexpensively coat pipes, plates of glass, or other solid cavities with a thin coating of low-refractive index material?

The answer, which is being published for the first time here, is THV. THV is a rarely used special form of Teflon that can be dissolved in solvents, unlike other forms of Teflon. I have found that a 9% by weight solution of THV in MEK (Methyl Ethyl Ketone) can be simply dip-coated on glass and many plastics, and result in a perfect ~10 micron layer of low-refractive index solids. When I first tracked down this solution, I found one of the few bags of this material then in existence. At that time I was told that my 50 pound bag represented about 1/3 of the world’s supply of THV.

Making Chambers that Glow Evenly
Once I found that I could create liquid light guides, and that I could embed LED dies (without lenses), directly into the core fluid, I saw that a potential application could be a replacement for neon type signs and accent lighting. Some of the advantages of a liquid light guide over a neon light are that a liquid light guide using RGB LEDs can change color instantly and dynamically, making it better at attracting attention, which is the purpose of neon signs.

Liquid filled glowing “windows”, driven by LEDs

However, to do this, I would need to scatter the light evenly through a length of tube or sign volume. The final solution that I came up with was nano-crystalline rutile Titanium DiOxide (TiO2). Crystals of TiO2, approximately ~2 microns in size that were properly processed into the core fluid would remain in suspension essentially permanently. These crystals would scatter light, rather than absorbing or coloring the light, very effectively. The high index of refraction of TiO2 is only challenged by powdered diamond, an obviously more expensive substitute.

Applications We Have Considered
We reviewed many applications for this technology. These applications include:
:: Piping sunlight into the interior of office buildings
:: Replacement for Neon signs
:: Replacement for accent lighting
:: Glowing transparent windows
:: Glowing wall accent panels
:: Replacement for standard 2’ x 4’ fluorescent overhead lighting panels, flat panels powered by LEDs.

Resources
Patent filings were made on some of the early applications, later abandoned. While they don’t cover the more recent developments, they do provide much background and describe various techniques. Copies of these filings can be found here: http://www.freepatentsonline.com/20050084229.pdf, and http://www.freepatentsonline.com/20030147261.pdf.

I would be happy to answer any serious questions or comments at victor_babbitt (at) hotmail (dot) com

I used to buy magnetic paint, but I wasn’t very happy with its strength, consistency and color, so Nick Vermeer and I decided to make our own. More often than not, things turn out to be more complicated than they appear, but in this case it was the other way around!

Nick sourced fine magnetite powder and we then experimented with several media. The one that seemed to offer the best combination of strength, appearance and consistency was the glossy acrylic medium. Here’s the super simple process for making your own magnetic paint:

Ingredients: magnetite powder + acrylic medium (see suppliers below)

1) The magnetite powder is really fine so wear a dust mask and goggles.

2) Mix 2 parts acrylic medium with 1 part magnetite powder by volume (we use measuring spoons).

3) Stir very well and get rid of all the clumps. You can do this by hand or use a vortex mixer (Cathal Garvey shows how to make your own on this video).

4) Apply 2 or 3 coats of the mix, depending on how strong you want it to be. On the video above I used 3 thin coats. Once it’s dry you can paint over it with regular paint or cover it with some thin material like paper.

You can also try other solutions, it’ll work with almost anything, though the proportions will vary depending on the consistency of the medium. One approach is to start with the amount of magnetite powder you want to use and add the medium to it little by little until it has the desired consistency.

Suppliers
Chemical Store (magnetite powder)
Utrecht (acrylic medium)

A few months ago I visited Pumping Station: One where I met William McShane and saw his magnetic + conductive paint LED display. On the video above William explains how it works. This was recorded with my phone so the audio isn’t great, but here’s a summary:

The display is first covered with a layer of magnetic paint and then coated with regular paint. William then drew the circuit traces with conductive paint. The LEDs have a magnet attached to each leg, so they will stick to the display when placed over the traces.

A few months ago, Jordan Bunker from the hackerspace Pumping Station: One shared his experiments and simple recipe for a DIY conductive ink. Now, Nick Vermeer from the hackerspace NYC Resistor, arrived at a different process for another conductive ink you can make yourself. Here’s Nick’s process:

I’ve recently had success in making a conductive ink using a fine copper powder suspended in an acrylic airbrush medium. This paper on conductive epoxies was really the key to getting this ink working.

The paper shows that etching the metal filler slightly before mixing it with the binder improves the conductivity of the ink. In this test I first used ammonium persulfate as the initial etching solution. After decanting off the resulting copper sulfate solution, the powder was then washed with deionized water. The wet powder was then mixed with an acrylic airbrush medium to make the resulting ink.

There is still quite a bit of experimentation to be done, but this is a very encouraging result!

Both Jordan and Nick based their experiments on academic papers whose authors described the processes in great detail, including exact quantities, ingredients and suppliers.

Jordan Bunker from Pumping Station: One has been making his own conductive ink based on a paper written by researchers at the UIUC Materials Research Laboratory. This technique uses easily obtainable materials and tools, and can be reproduced at most hackerspaces. For now, the ink doesn’t work on porous materials, such as a paper, and plastic and glass substrates must be etched first, but Jordan is working on addressing these issues and will keep posting developments. In the meantime he worked out a pretty simple process to manufacture conductive ink!

This ink seems to address many of the problems that other inks have. It’s particle free (won’t clog print heads!), is easy to make, and anneals to the conductivity of bulk silver at only 90 degrees Centigrade (194 degrees Fahrenheit).

Check out his description of the process on the video above and then head over to his website for a detailed tutorial on how to make your own conductive ink. Bonus points for making your own vortex mixer based on onetruecathal’s video tutorial.

University of Illinois researchers explain how they make their conductive ink on this step-by-step tutorial.

(via Boing Boing)

LED Dragon Kite by Jie Qi

Jie Qi, from MIT’s High-Low Tech group, posted a couple really nice tutorials on how to combine paper, electronics and smart materials to create beautiful objects:

LED Dragon Kite
SMA Origami Crane

Today it’s possible to print organic field transistors (OFETs), organic light emitting diodes (OLEDs), and other devices using sophisticated laboratory equipment. But why should academics have all the fun? The goal of this project is to design a fabrication process that allows MakerBot owners to print their own electronics using (ideally) inexpensive and easy-to-source materials. In the first phase of the project we are using a RepRap, plotter pens, and research grade materials to create devices. The second phase of the project will focus on exploring new device materials. This is an ongoing project and we are looking for collaborators.

Mr. Kim and Sarik experimented with a variety of conductive materials (silver ink, P3HT, CP1 resin), which they inserted into rapidograph and pigma micron pens. According to the researchers, this is a nine step process:

The project doesn’t yet have a website but, in the DIY spirit of this research, Mr. Kim uploaded the field effect transistor patterns to Thingiverse and made the talk’s slides publicly available at mrkimrobotics.com.

All photos provided by John Sarik and Mr. Kim. John: thank you so much for discussing this fascinating research with me and for sending us the presentation materials.