Prototyping Kit for E-textile Circuits

This instructable will teach you how to make a simple kit for prototyping e-textile circuits. This kit consists of leads and connection points which are reusable but robust. The goal of this project is to provide e-textile crafters with a system that allows for quickly mocking up a circuit on an e-textile project without having to cut and sew. This design provides reliable electrical connections for your circuits using magnets to maintain continuity. The leads can also be additionally secured in the connection points to provide a strong mechanical connection, so that these circuits can be implemented and used in actual e-textile projects.

This project was developed in the Craft Tech Lab at the University of Colorado Boulder. This material is based upon work supported by the National Science Foundation under Award #1742081. The project page can be found here.

• Conductive thread - link
• Steel roll pins (used as crimps) - link
• Nickel-coated neodymium magnets - 6mm x 3mm - link
• Bicycle cable cutting and crimping tool - link
• Plastic straw
• Scissors
• Optional: 3d printer

We are going to be assembling a reusable kit of parts for prototyping. The first step is to make our leads, which we are made from regular conductive thread modified with crimps on each end.

1. Cut a length of thread about 2” longer than the intended final length of the lead.
2. Tie a double knot about 1” from each end
3. Slide the crimp over the double knot
4. Crimp using the uppermost (tighter) crimping area, perpendicular to the typical crimping orientation.
5. Trim extra thread with scissors.

Since there are no crimps this small which are also magnetic we are using a ‘roll pin’ as a crimp. If you cannot find roll pins locally which are short enough, they can be cut to length using the bicycle cable cutting and crimping tool (depicted in last image, though unlike the image you should cover it with your hand or a towel before cutting, or else the pins will fly across the room and into oblivion).

The connectors allow us to quickly link together the lead we assembled to fabricate functional e-textile circuits. The connectors provide both the electrical continuity and mechanical strength for our circuit. We will make them from a section of drinking straw and a magnet.

1. Cut a ¾” section of drinking straw
2. Carefully press magnet into straw using the palm of your hand to get it started, then use any item smaller than the diameter of the straw to press the magnet in so that it is centered in the straw (we used a retractable ballpoint pen)
3. Cut 2 slits on each end of the staw. Each slit should be about ¼ the length of the straw.

We have designed 3D printed connectors which can be used in place of the drinking straw connector. The advantages of the 3D printed connectors is they can have more than 2 openings for leads (these have 4), and they can be sewn for a more secure fixture. Print the attached .stl file, and press a 6mm x 3mm magnet into it from the bottom.

While this design does offer some upgrades over the plastic straw it may not actually be needed for most prototyping. The simplest solution is usually the best.

Play with the leads and connectors that you have made. You may notice that the crimped ends of the thread easily snap to the magnet inside the straw, however they can almost as easily be pulled out. Now try securing the thread in the connector using one of the slits cut into the straw, notice how this adds mechanical strength to your connection, resisting that pull force.

The connectors can be secured to garment or other e-textile projects using a second magnet. Place the connector where you want it on the fabric, and place the second magnet on the other side of the fabric to secure it in place.