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1. Overview
Attempts to imagine an alternate way of building circuits using fabric and thread and replacing the soldering iron with a needle. The results are washable, flexible, light and soft circuits. Possibilities endless (kind of). These circuits rely heavily on the use of conductive thread, you should consider the type of application and signal you need to transmit before trying to build anything out of thread.
2. Materials
3. Skills required
Sewing basics
Basic Circuitry building (depending on the application you want to create)
4. Instructions
A--Create main circuit first
Start by drawing out your circuit on the fabric. Decide where all you components will go including your battery or your switches and draw all of these connections out. You can choose to do a double sided circuit (ideal for grids or leds or input devices, or when your lines will come very close to each other) or a single sided circuit (easier to work with).
Conductive thread is often very fray so make sure to use it as bobbin thread combined with regular (100% cotton is best) thread as top bobbin. Flip the fabric upside down when doing double sided circuits.
First, draw your circuit on the fabric
Use conductive thread as bobine
Grid circuit is best done as double sided
Leave conductive thread at each end
You will use it to finish stitches by hand
B--Check conductivity and look for any shorts you could fix
Depending on how you designed your circuit you will want to check that no 2 parts of the threads touch each other if they shouldn't. Tape up your extra lengths of threads when you test because it usually comes in the way and makes it difficult to find real short circuits.
Once everything is good, try to stitch a layer of non-conductive fabric on top of the circuit to isolate it. If you can, stitch it throughout all of the circuit so that no bad contact can ever occur (seal it so you can bend it, fold it, flip it... with no risks of 2 conductive threads ever touching).
Set your multimeter to ring when 2 threads touch
First touching connections by hand
Stitch isolating layer where you can
Stitch the isolating layer in between each 2 lines
C--Embedded circuit components
Finally, you embed all your components into the circuit. Ideally you can just stitch your components in at the right place. If you've created a single side circuit try not to undo this when you hand stitch your left-over conductive thread all the way into / next to your components. Use an XXX stitch instead. You can solidify a connection by using NON-conductive thread around it to insure everything is in place and solid.
Your large components should fit right in
[-Use beads as connectors]
Or stitch parts right in -make it solid
Fray check keeps things clean
D--Connect to your circuit (optional)
If you have to make a connection to a circuit board or a larger component. Try these tricks --link to Grace's description + mine + leah Buechley Soft connections to microcontroller?
Different appraoches are available
5. Estimated Price
Conducive thread starts at around 10$.
A part for the multimeter, the rest can cost you less than 10$.
6. Estimated Time
I Cannot get anything done and debugged in less than 2 / 3 days but if you keep it real simple, it could take just a few hours.
7. Possible Applications / Projects using this
Soft Led Display
8. Credits
Clearly inspired by all instructions first published by Leah Buechley
9. Variations
10. Comments
The original writer suggests 100% cotton in case something should burn. Another option would be wool, as wool is naturally flame-resistant.