Rapidly make your Attinies sewable! The Lilypatch is a quick and easy way to get many of the advantages of Lilypad-style sewable arduinos without a lot of the cost or effort.
In short, it is a piece of felt, laminated with a piece of conductive lycra that is then laser-cut into a solder-free prototyping platform (with a built-in battery holder!). To build and use it just needs 3 steps:
- Glue felt to lycra and laser-cut
- Punch DIP socket into Lilypatch, bend pins and remove backing (no soldering)
- Flip over pads (if needed) and sew to attach to devices or clothing.
In this instructable, I'll go into a bit more depth to help guide you along, and also hopefully to get all your ideas about how to improve, what I hope could be a very useful "patch." This one is formatted to work specifically with Arduino ATTINY85's, but with advice from you people out there, we could make a whole ecosystems of cheap, simple circuit boards floating freely around the internet for other microcontrollers or electronics. I'm sure lots of people have made very similar things before, and can give all sorts of great feedback. This project was created with very specific needs in mind, but hopefully releasing this design out can help out others too!
Why was this created?
In my PhD research (digitalnaturalism.org), I go out to far out of the way places, like the jungles of Panama or Singapore/Malaysia, and try to teach workshops for creating digital devices to interact with animals in their natural environment. In some of my upcoming trips, I am hoping to actually run some hiking hackathons where we will be out in the woods living for several days or weeks. This poses many design challenges, primarily was how to do electronics out in environments without wall electricity or soldering irons. Soft-circuitry was a good choice, because we can just sew connections together, but for a not-well funded researcher like myself, buying and giving away a bunch of Lilypads can get really expensive. The Gemma is the cheapest sewable platform (http://www.adafruit.com/products/1222), but $8 +shipping, makes it still too expensive to not want to ask for them back from my participants. Also with a cheaper solution, I can build lots of different things and not have to worry about harvesting their boards later. This is what got me into using ATTinies in the first place (they are dirt cheap and do most the stuff I want, and they're the chip already in the Gemma). Their problem is that they can be hard to use without soldering them
Thus I wanted to re-create the capabilities of the Gemma but in a cheaper, more disposable way. So I set up the following design goals for myself:
- The price to beat is $8 for the Gemma, and Ideally I want to keep it around 1-2 dollars, letting me supply 50-100 people in workshops with a budget of just $100.
- The material cost of one of these lilypatches with an attiny in them is just around $1.00-$1.40 (felt, lycra, attiny, thread).
- I wanted to figure out a 1-step process to rapidly make something I could take and put together however I wanted out in the field.
- Manufacturing during a trip is fine (there’s plenty of time for tinkering late at night while camping, but anything that needs exotic tools like laser cutters should be taken care of previously).
- Another regard was that I wanted to use this to teach electronics, so by not making it too complicated, people could use it as a platform to learn some basics on.
- I wanted to limit myself to using only 1 non-conventional material. In this case this was the conductive lycra.
- I’ve gone through dozens of ideas trying to figure out how to do this, (eg. mix shapelock and wires, make conductive glue and run leads to conductive fabric, …etc).
- The pads can be sewn to, gator-clipped to, folded over and stapled together, or used as touch-pads themselves.
- The pads stick out so that they can be flipped over for sewing on either side when attached to a garment or other device.
- I went through all sorts of geometry problems figuring out balances between making good contacts, making the backing peel easily, determining how to lock the pin legs to the right leads, while also trying to balance how this thing could be used. This hybrid, flip-if-you-want method with a battery pouch seemed to be my best option (after lots of personal iterations!)
- This design is also left open to lots of simple techniques that could make it a lot more robust (like if you aren't in the jungle, use some hot glue to seal the connections better!), though these aren't 100% necessary for simple projects.
What can it be used for?
All kinds of stuff! In theory anything you can do with an Attiny85 (which is a lot!). For many projects at home or in the lab, you might want to do some good old soldering for really good firm connections, but if you want to get started on an idea quick, and especially with soft-circuits stuff anyway, this might be a good option for you.
Also if you need to do some projects but get sick of sitting at the soldering iron, this can be a kind of fun activity, sewing together these different parts, that you can do while watching a movie or something.
I give three examples at the end of this instructable, a simple flashing costume, a plush, light-up cell model, and a device for monitoring where your pet tortoise may have run off to!
Help and Inspirations
Tom Jenkins, an awesome auteur of tinkering platforms (http://thomasjenkins.net/), helped me think thought this thing a lot
HOWTOGETWHATYOUWANT (http://www.kobakant.at/DIY/), as with most things soft-circuitry-related, the folks over at kobakant have compiled many great resources and ideas. For instance, the idea of making a conductive battery pouch like this comes straight from them: http://www.kobakant.at/DIY/?p=4432
Update: I just saw this other similar project they have http://www.kobakant.at/DIY/?p=2672 where they make a breakout board from laser cut fabric, but they also use somewhat specialized things like fabric fusing and pourable acrylic or soldering. This design I'm presenting here hopes to accomplish a very similar goal (in perhaps not as robust ways) with more limited materials.