The Resistor JelTone is an edible toy piano created by NYC Resistor members Ranjit Bhatnagar, Astrida Valigorsky, Mimi Hui and myself for the Jello Mold Competition.

As part of our experiments we realized that jello and fruit, which contain a lot of water, are conductive. Embedded in each jello/fruit key is a sterling silver pin (food safe) connected to an Arduino microcontroller underneath the piano’s base. Below the piano’s case is another sterling silver pin. With this setup, the JelTone can either be played with a metal utensil connected to the Arduino, gloves enhanced with conductive thread, or bare hands by touching both a key and the piano’s case.

If you’d like to make your own, you can get the project files, code and instructions from Thingiverse.

Shown below in its fruit and jello versions. Both JelTones were exhibited on June 25th at the 2011 Solid Sound Festival, Mass MoCA and at the Jello Mold Competition (where it was awarded the creativity prize and was both played and eaten by the exhibit visitors).

Heat Reactive Materials
Heat reactive materials change state, shape and/or color when exposed to temperatures above ambient. Naturally, many materials change shape, eg. melt, at high temperatures. What’s special about some of them is that their state, shape and/or color can be altered at relatively low temperatures (provided through hot water, body heat, hair dryers, ambient heaters, ovens, or just a hot summer day), making them easy to use and suitable for DIY projects. In this post I’ll go over thermochromic pigments and a few materials they have been incorporated into, namely paint, fabric, film and glass.

Thermochromic Pigments change color when exposed to heat and turn back to their original color when the temperature drops again. According to TEP:

Most thermochromic materials are based on liquid crystal technology. At specific temperatures the liquid crystals re-orientate to produce an apparent change of colour. The liquid crystal material itself is micro-encapsulated - i.e., contained within microscopic spherical capsules typically just 10 microns in diameter. Billions of these capsules are mixed with a suitable base to make thermochromic printing ink or, for example, plastics destined for injection molding.

These pigments can be mixed with an acrylic base or screen printing ink. At room temperature the pigment appears in its original color, but at temperatures between 27° and 30°C (80° to 86°F) this color disappears, eg, if a black pigment is applied to a white surface, the surface turns from black to white at the change-over temperature. When mixed with an acrylic base each pigment will turn instead into the color of the acrylic base or color blender, eg., if a blue pigment is mixed with a yellow acrylic base the resulting color will be green, but at the change-over temperature the blue will disappear and the green will turn into yellow. The ratio of acrylic base to coloring pigment depends entirely on the application and density of color required. For a detailed explanation of the functioning and applications of thermochromic pigments see the TEP Smart Colors info sheet (PDF) and this little demo animation.

Shi Yuan’s thermochromic wallpaper

Temperature-Sensitive Glass results from the application of thermochromic pigments to glass tiles which change color based on ambient, body or water temperature:

The textured glass surface layer protects and highlights the color-change film on the tile. The base color of the tile can match almost any color, and the temperature change point can be fit to the user’s environment and requirements. The dynamic color change begins at the selected activation temperature and shimmers through three phases, one with each 6–10° rise in temperature. Once the temperature peak is passed, the base color returns and remains the same until the temperature drops.
(source: Inventables)

Temperature-sensitive glass tile (image by Inventables)

Thermochromic Film has adhesive on one side and thermochromic ink on the other. The film is normally black but changes to bright green/blue at temperatures between 29.4 and 33°C (84º - 91º F). Due to its low change-over temperatures, touching a piece of thermochromic film for a few seconds will cause the contact area to change color - it can also be used with nichrome or any other heat source.

Thermochromic film (image by Mindsets)

Suppliers
Body Faders (US) :: thermochromic fabric
Inventables (US) :: thermochromic fabric, thermochromic film, temperature-sensitive glass tiles
Mindsets (UK): thermochromic pigments, thermochromic film
Paint with Pearl (US) :: thermochromic pigment powder

Share your knowledge
If you’d like to contribute content or corrections regarding thermochromic materials, please use the comment form below.

>> about the materials 101 series.

If you haven’t yet, check out this great blog post on recycling of 3D printing materials by i.materialise’s Joris Peels:

Last week in a comment, Paul asked me, “When will more eco and sustainable materials be available for use in these printers? Something like hemp plastic or other biodegradable materials? What are the technical limitations and who is working on them?” His question was a bit too big for a comment so I’m trying to answer it here. Below I outline, very broadly, four mayor developments in recycling and 3D printing. These developments are: recycling existing 3D printing materials, using materials that are already recycled as 3D printing materials, bioplastics & recycling on location.

MAKING STUFF: Stronger, Smaller Cleaner, Smarter is a four-part PBS television series focusing on materials science:

While reports on “smart materials” or “bionic humans” are familiar enough from TV news and magazine shows, Making Stuff will be the first documentary to provide the basic science behind these and many other technology breakthroughs. Each of the four one-hour public television programs – Stronger, Smaller, Cleaner, and Smarter – will embrace developments in traditional and emerging materials as well as current research in rapidly expanding fields such as nanotechnology and biomaterials. This series will also explore the human stories that helped shape important breakthroughs in the past – the visionary talent, sheer luck, and dogged determination that turned a wild idea into a useful material.
>>Materials Research Society

For more details check out the Materials Research Society and PBS/NOVA websites.

Interesting article at The Japan Times :)

TSUKUBA, Ibaraki Pref. (Kyodo) Researchers at the National Institute for Materials Science have found that an iron compound becomes superconductive — where electrical resistance disappears in a substance — if it is dipped in wine, sake or beer.

“It is still not known what it is in sake that causes (the phenomenon), but it will provide a clue to the development of new superconductive materials,” said Yoshihiko Takano, leader of the Nano Frontier Materials Group at the institute.

The researchers said they first produced an iron telluride compound, which has a similar structure to a superconductive substance.

It didn’t immediately show signs of superconductivity but then did so after being left on a desk for about a week. Assuming that the change was due to moisture in the air, the researchers experimented with water, ethanol and other substances but couldn’t attain results showing high conductivity.

In March, Takano came up with the idea of trying alcoholic drinks after seeing a wide range of liquors at an institute party.

They found that the compound showed superconductivity after it was immersed for 24 hours in each of six types of liquors, including red wine, white wine, beer and sake, all heated up to 70 degrees. Red wine proved to be most effective.

* “wine glass” image by Scmtb49 - wikimedia commons

Treehugger recently reported on BioCouture, a fashion research project based at Central Saint Martin’s College in London and led by Suzanna Lee, which seeks to grow textiles from a vat of liquid:

The process uses a sugary green tea recipe, to which, a bacterial culture is added. It takes about 2-4 weeks to grow a sheet that is thick enough to use. Sheets are then dried down; either shaped over a wooden dress form–like the ghost dress and ruff jacket –or sewn together conventionally. Depending on the recipe the material can either feel like paper or–more desirably–like a vegetable leather.

In testing with dyes we found no need for mordant [a substance used for dyeing fabrics] and an incredibly small amount of dye goes a long way so it’s eco-credentials go through the entire process. We also recycle a percentage of the fermentation liquid.

vegetable leather grown from a vat of green tea

We look forward to more information about the project and the process. Read more about it at treehugger.

Thanks Rob for pointing this out :)

The transfer of scientific data has emerged as a significant challenge, as datasets continue to grow in size and demand for open access sharing increases. Current methods for file transfer do not scale well for large files and can cause long transfer times. In this study we present BioTorrents, a website that allows open access sharing of scientific data and uses the popular BitTorrent peer-to-peer file sharing technology. BioTorrents allows files to be transferred rapidly due to the sharing of bandwidth across multiple institutions and provides more reliable file transfers due to the built-in error checking of the file sharing technology. BioTorrents contains multiple features, including keyword searching, category browsing, RSS feeds, torrent comments, and a discussion forum. BioTorrents is available at http://www.biotorrents.net.

Not only is this great news for scientists, but I can see this being a great source of inspiration for artists seeking data for visualisations, mash ups etc…

Refarm the city (aka re:farm) is a collective project started and led by Hernani Dias with the purpose of developing open source software and hardware tools for urban farmers.

In its creators’ words, the project is a cross between a good meal (the crop, the seeds, the friends), hardware (the urban farm, the composter, the electronics, the sensors, the recycled materials), and software (applications that help you build a farm according to your needs, local crops, and gastronomy).

Re:farm seeks to provide people with tools to easily create, manage and visualize their urban farms. Its ultimate goals are to encourage the production and consumption of local goods, using methods that respect the environment, and promote organic agriculture, science, biodiversity, and local gastronomy.

The group has been hard at work for about a year now and, as you can see on their wiki, already has several sensors and boards ready to be reproduced, while other components (such as the software) are in advanced stages of design and development.

The tools being developed by the refarm the city project allow urban farmers to:

:: design a farm according to location, physical conditions, materials available, social network, and local gastronomy.

:: open access to low budget solutions and instructions on how to build, and what materials to use, for different models of urban farms.

:: monitor and control the farm in real time, on the computer (re:farm on the sofa), remotely (re:farm on vacations), and on the wall (re:farm on the wall).

:: visualize the relationship between personal needs and local farming conditions, based on data provided by the user, as well as data about local crops and different sustainable farming methods.

:: visualize the relationship between the current time of the year, local weather, vegetable growth, and farm maintenance.

Tiago Henriques, a member of the re:farm development team, is starting an urban vegetable patch at altLab (our Lisbon hackerspace). It would be great to see other hackerspaces join in :)

low budget humidity and water level sensors

watering system

physical interfaces for visualization of water level, humidity, temperature, and light

online data visualization of humidity, temperature, and light

xs farm on wheels (recently built in Buenos Aires during a 2 day re:farm workshop)

xl farm on wheels

re:farm on the wall :: 3 electronic boards and 1 chicken :)

the re:farm software helps urban farmers design a farm (according to location, physical conditions, materials available, social network, and local gastronomy), and visualize/control their farms in real time

the scarecrow contains the re:farm on vacations electronic board (watering control, soil temperature, soil humidity, and light information)

More information about refarm the city:
blog :: refarmthecity.org
wiki :: refarmthecity.org/wiki
photos :: refarm on flickr

The book is controversial, as many of the experiments contained in the book are now considered too dangerous for the general public. There are apparently only 126 copies of this book in libraries worldwide. Despite this, its known as one of the best DIY chemistry books every published.

It was also a source of inspiration to teenager David Hahn, who tried to collect a sample of every chemical element and also built a model nuclear reactor in his back shed in the 1990’s.

Because it was published in 1960, before the US copyright laws were rewritten, and the original copyright was never renewed, it’s legal now to share it with you online.

openMaterials has cached it here, and you can also download it here and at scribd. The pdf contains 114 scanned pages and is 27.9mb.

Below is the table of contents-

This solar clothes washer was made by 2nd year art students from the École Supérieure d’Art d’Aix-en-Provence (France). The challenge was to make a DIY washing machine using only materials available in the sahara. The prototype shown above uses bicycle parts (the tires and wheel), bamboo, and a solar panel connected directly to a recycled electric motor (from a photocopier).

The Open Source Washing Machine project was created by France Cadet, Jean-Noël Montagné and Jean-Pierre Mandon at the École Supérieure d’Art d’Aix-en-Provence. Three machines were designed by the 2nd-year students over a three-day period.

Here’s a short video and photos. More about the project at oswash.org.

I’m looking at the machine right now and trying to resist the urge to do my laundry in the school’s patio :)