Simple Soft Circuit Button

Ever wanted a durable and reliable soft circuit button? With just a little bit of conductive thread, two pieces of fabric and some batting you can make your very own.

The materials you’ll need:

1/8 yard of non-conductive fabric 1/16 yard of non-conductive batting 36″ of conductive thread 2 conductive snaps A little bit of velcro tape A piece of paper to draw a pattern with An Arduino circuit to test with You can get most of these materials from any fabric or craft store. Batting comes in different weights depending on how fluffy you want it to be. You can also replace it with neoprene or felt, but that won’t be as soft or as pliable.

And the tools:

Sewing Machine Hand Sewing Needle Tailor’s Chalk Quilters’ Pins Multimeter To test out the soft circuit button, I made a quick circuit for my Arduino. The button can be attached to any of the digital pins to act as a simple on/off switch. When attached to an analog pin, it can even act as a rudimentary pressure sensor. Plus, if you have some anti-static foam (the stuff your electronics are usually packed with) you can stuff it inside your button and turn it into a DIY Force Sensitive Resistor!

Step 1: Sewing on the Conductive Thread

Cut out three squares of paper of the same size. Take one of them and cut out a smaller square in the middle. Place the one with the hole in the middle on the batting. This is going to be the pattern you follow. Whenever sewing things together, you always want to leave a little bit of room on the fabric for seam allowance. So pin down the paper pattern on your batting then cut out outside the paper’s edges, leaving about 5/8″ of room on each side. Cut out the middle also with a little bit of seam allowance.

To prepare your fabric, pop a bobbin of conductive thread into your sewing machine. You can wind your own, or you can get these pre-wound from several sources like Adafruit, Sparkfun or Seeedstudio.

Take two pieces of fabric larger than the square patterns that you cut out. Sew diagonally across the fabric pieces on the bias. You may want to practice on a scrap piece first. Check the tension of your machine. A good trick for sewing with conductive thread in the bobbin is slightly lowering the tension of the top thread so the bobbin thread floats a little bit. This sometimes jams the machine, however, so be aware.

After sewing diagonally, sew a square pattern on one of the pieces and a cross-hair pattern on the other. You may want to draw it out with tailor’s chalk beforehand to help guide you. Test the pieces with a multimeter to make sure the conductive thread connects to each other from end to end.

When you’re finished sewing with conductive thread, line up the fabric pieces so the conductive thread is facing up. Make the diagonals face the same way. If you flip one over and place it on top of the other piece, it should create an X with the conductive threads. This will prevent short circuiting and make things easier later when we have to attach it to some wires for the circuit.

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Thanks for watching.

Nice idea - but probably of more interest in the E-Textiles and Craft forum

regards

Allan.