Clasped Weft Weaving with Conductive Thread and LEDs
Lots is happening in the world of eTextiles!
Electronically enhanced textiles have moved beyond scientific studies (such as wearable computers and chemical-sensing textiles), beyond adaptive uses and assistive clothing, and into the realm of high fashion and art.
One innovation that's helped eTextiles move out of the lab and into the studio is the LilyPad Arduino—a microcontroller conceived by Leah Buechley and produced by Sparkfun Electronics. This programmable hardware can drive electronic components such as light-emitting diodes (LEDs), soundboards, vibration motors (vibes) and even sonar-range finders, which can let your textile know when it's approaching an obstacle. If you can dream it, you can find the hardware to build it!
The majority of eTextile applications are created by artists who hand sew the conductive thread, soft circuits, and hardware to a textile base. The abrasion the conductive thread undergoes during sewing can cause fraying and often results in a messy final product.
Fortunately, weavers have an edge! We can plan the textile to incorporate the electronics directly into the cloth from the very beginning. This allows us to weave the most direct circuits, the most robust connections, and the most intricate designs, allowing our projects to be super groovalicious!
You can easily incorporate this fun and exciting technology into your weaving using clasped wefts.
With clasped wefts, you have two wefts—one coming in from either selvedge—that meet in the center and interlock before returning to their respective selvedges.
I experimented with clasped wefts using conductive thread, and identified three reasons why this technique was superior to my prior methods for inserting electronic components into my weaving:
- It reduces the length of conductive thread in the weave, thus decreasing the resistance of the electrical circuit. (This means more power reaches your components—think brighter LEDs and louder buzzers—and less waste-heat is generated by the garment.)
- It reduces the probability of short circuits as the positive and negative traces are in close proximity only at the point of connection to the electrical components.
- It allows flexibility and spontaneity in the electronic component's placement across the width of the warp.
- Loom. (The project illustrated in this article uses a four-shaft twill for the body of the cloth. You can, however, use the clasped weft technique to add electronics to any woven structure, including the most basic, two-shaft, plain weave.)
- Multimeter (optional) for testing the resistance of woven circuits and to identify short circuits.
100% wool (dark pink).
- 100% wool (light pink). This is the weft used to weave the body of the cloth. Because wool is non-conductive, it also serves as an insulator between rows of the conductive weft thread.
- 100% wool (neon green). This weft is for demonstration purposes in this article to highlight the path of the negative trace. In a real project, it is not necessary.
- Stainless-steel thread. This is the conductive thread that carries the electrical current.
Other options for conductive thread are wire wrapped in silk or cotton or even very thin wires plied together. For more information about conductive threads, see the online articles Conductive Thread Comparisons and Links and How to Wind your Own Conductive Thread
When I weave, I do not wind the conductive thread onto a bobbin. I leave it on the cone or spool and simply pull up the length that I need in order to interlock with the wool weft to create the 'clasp'. I also thread the loose end of the conductive thread through the electronic component I am attaching—in this example, a crimping bead soldered to a LED—as I weave.
- LEDs with crimping beads soldered to their positive and negative terminals.
- Battery, or other power source.
- Switch (optional) for turning the LEDs on and off.
There are a wide variety of electronic parts you can use in eTextiles: light-emitting diodes (LEDs), accelerometers (motion detectors), sonar units, Arduino boards, LilyPads microcontroller boards, and more. These can be found at your local electronics stores or ordered online.
Information and Sources for eTextile Components
10 ends per inch
This project uses a standard 2/2 twill with treadling variations, though the clasped-weft technique can be used with any weave structure, including plain weave.
A trace is term that describes the continuous electrical conduit through the cloth. In this case, the trace is the conductive thread. There are two traces: positive and negative. These traces ultimately connect the component to a power source, such as the positive and negative terminals of a battery.
In the following description, the wool weft (pink) is coming in from the right selvedge and the conductive thread and highlighting weft (green) for the negative trace are coming in from the left.
Note: The purpose of running the green weft along with the conductive thread is simply to highlight the path of the negative trace for demonstration purposes. In your design you could use the conductive thread by itself, or pair it with another yarn that supports your design.
- Open a shed.
- Toss the shuttle carrying the main weft (pink) from the right.
- With the shuttle now on the left side of the open shed, pass it under the conductive thread to loop the conductive thread around the pink weft.
- Put the shuttle back into the open shed, from left-to-right, drawing the interlocked "clasp" of the main weft and the conductive thread into place in the body of the fabric.
Note how you can adjust the placement of this clasp, by pulling on the weft or conductive thread. In addition, both weft threads are now doubled in the shed.
- Thread the free end of the conductive thread through the crimping bead on the negative connection of a LED.
- Slide the LED up to the clasp in the body of the fabric.
- Lower the shed.
- Gently beat the clasped wefts into place.
- Throw another row or two of the main weft (pink) to insulate the conductive thread and to span the distance to the next electrical connection.
In the example shown below, it took three shots of the main weft to reach the other (positive) side of the LED
When weaving the negative trace, the conductive thread came in from the left. In weaving the positive trace, we will use a second conductive thread that comes in from the right.
(Throughout this woven sample, the negative trace conductor is running along the left selvedge, and the positive trace conductor along the right.)
- Open a shed.
- Toss the shuttle carrying the main weft (pink) from the left.
- Loop the conductive thread over the main weft to create the clasp.
- As you are looping back around the main weft, thread the free end of the conductive thread through the crimping bead soldered to the positive connection of the LED.
- Feed the free end of the conductive thread back into the shed, through to the right selvedge, and pull taught.
- Lower the shed.
- Gently beat the weft into place.
As before, weave rows of the main weft to insulate the conductive thread and span the distance to the next electrical connection.
Continuous Circuit with Multiple Connections
Adding LEDs to your textile is all well and good, but if you want them to light up, you need to weave a complete and continuous circuit that includes a power supply, such as a battery.
To weave a continuous circuit, you need to have an unbroken connection in both the positive and negative traces.
The easiest way to do this is to use a single, continuous, conductive thread for each trace.
You can weave in electronic components as described above, then—between components—run the conductive thread up along the selvedges, so they are available when you want to weave in the next component. To conceal and secure the conductive thread while it is running along the selvedge, catch it inside weft shots.
Make sure, when weaving in electrical components, that you always attach the positive trace to the positive terminal of the component, and the negative trace to the negative terminal.
Depending upon the type of electrical components and the conductive thread you may need to sew additional conductive thread at the point of connection. This will make your connection robust, secure and less likely to develop a short.
If you run out of conductive thread simply tie more on to your short end. Make sure this is a secure and robust connection. You can even use a bit of Fray-Check to help hold the knot in place.
If you weave an eTexile as described above, you will have created a parallel circuit. In order for the LEDs to light up, the next step is to add a power source, such as a battery and (optionally) a switch to control whether the lights are on or off.
You would connect these to the positive and negative traces as shown in the diagram to the right.
If you have a multimeter, you can test the resistance of the woven circuit (the lower the resistance, the brighter your LEDs will glow) and check for short-circuits due to crossed or broken conductive threads.
If you find a short due to crossing threads, you can repair it by darning in an insulating yarn between the conductive threads to isolate them.
A short due to a broken conductive thread can be repaired by sewing in a length of conductive thread to bridge the gap, making robust connections at the connection points.
Care and Washing
Many components designed for eTextiles, such as the Lilypad Arduino, can be carefully hand-washed in cold water and lay flat to dry. If you live in an area where the water contains mineral deposits, distilled water may give you the best results. As always, before committing a large art piece, test your wet-finishing process on a sample.
Additional links for Exploring the World of eTextiles
- Fashionable Technology by Sabine Seymour
- Craft video on working with the LilyPad
- Fashioning Technology: a social networking site
- Talk2MyShirt - Blog
- Techno Textiles: Revolutionary Fabrics for Fashion and Design by Sarah E. Braddock Clarke and Marie O'Mahony
- Leah Buechley's list of links to materials and supplies
Textile enchantress, weaver of gossamer threads, deviating from the norm like a spider on acid. Educated with a BA in neurophysiology and physiological psychology from Smith College with a Masters degree in architecture, Lynne is frequently embracing yet another design challenge. Otherwise she can be found lounging on black sand beaches in a tangerine bikini surfing the Internet. You can find out more about her work at her website.