Intro: Place LEDs Like Perfboard, Light Them on Fabric Using Conductive Thread
This article instructs Fast & Easy way to construct electric circuit on fabric. Place LEDs at your desired positions like universal perfboard, and enjoy your self-lighting fabric! (Lighting quilt, lighting T-shirt, etc...)
We think this "embroidered perfboard" is suit for first step of e-Textile, since you can make your original design easily without modifying embroidery data. And more, in e-Textile class, we recommend teacher to prepare dozen of "embroidered perfboards" using embroidery machine, then beginner students can light LEDs on fabric in quickly.
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Step 1: Materials and Tools
- Battery Holder x 1
- This example uses Sparkfun Coin Cell Battery Holder - 20mm (CR2032 type holder)
- If you use others, 3V - 5V power source is required to light LEDs.
- In this example, we use Mitsufuji AGposs Silver-Metalized Fiber
- Please also refer the article Selection Guide of Conductive Thread for Machine Sewing
- Lilypad LED used here
- We use denim. We recommend thicker fabric for this work. If you use thin fabric, you may also need backing material.
- We use Innov-is NS2750D.
- Attached example requires 5" x 7" or larger hoop.
If you want to create original circuit pattern, you need PE-DESIGN 10. Instead, you can download pre-build embroidery pattern attached on step 3 (Embroidery_5x7in_for_LilyPad_LEDs.pes), continue reading from step 4.
Step 2: Design a Draft of Circuit Pattern
First of all, measure the dimensions between the terminals of the battery holder and the dimensions between the terminals of the LED.
The distance between LED terminals will be used as the spacing width (d) shown in the diagram. In case of Lilypad LEDs, d=0.41 in.
Before drawing the pattern, let us introduce some important points to make your pattern reliable and stable.
Conductive threads are easier to get frayed at the end of thread than normal threads. In addition, since it has conductivity, if frayed lint sticks to the other circuit part, that would cause a short circuit. In order to prevent such unintended short circuit, do not start / finish at the end but place the first/last stitch at 3-4th stitch from the end to make reinforcement stitches as shown in the figure.
Make reliable junction
To make reliable electric conductivity, it is necessary to stably connect the junction. We recommend putting additional zigzag stitch block at all junctions to make the connection reliable and stable, since even if it looks likely contacting the thread with your eyes, there is a possibility to cause the electrical disconnection or higher resistance
Step 3: Create Embroidery Data on Software
There are two ways to create the embroidery data.
- Fully rely on embroidery software (i.e. PE-DESIGN 10), drawing the pattern and creating the embroidery data.
- Draw the pattern on vector drawing software first, and convert it to embroidery data on PE-DESIGN 10.
In this article, we would like to explain with 1. scenario. The 2. will be touched upon in another article.
Making embroidery pattern
From here on, let’s start making the embroidery pattern. Let us show you how to draw using PE-DESING 10. As detailed usage of PE-DESIGN 10 is referred in the instruction manual, so here, we want to focus to the setting values.
- Drawing pattern.
Select [Shapes] -> [Outline] -> [Open Straight Line]
Draw your pattern which was designed at step 2. Then reflect some special customization for making the connectivity better as introduced in previous step. (endpoint, junction)
- How to change stitch type
We recommend using Triple Stitch (Run pitch 2.0mm(0.08") - default). Triple stitch reduces electrical resistance compared to single stitch. For junction, our recommendation is Zigzag Stitch (Width 2.0mm(0.08"), Density 4.5line/mm(114line/in) - default)
- Change sewing order.
Finally, change the sewing order to minimize the thread jumps.
Step 4: Making Embroidery
Set up your sewing machine. Both side of thread should be stably attached as below.
- Upper thread : Conductive thread
- Bobbin thread : Ordinal embroidery thread
- Embroidery hoop : 5"x7" (In case of attached sample)
In this example, we use denim. Also, if you want to use cotton, thin fabric, stretchy fabric, etc., please use backing material to minimize shrinkage.
When the embroidery is done, sew the battery holder on the fabric with conductive thread by hand, to connect the battery holder terminal and embroidered circuit.
After that, place the LED where you like and complete it as the battery holder. Or you might be able to use conductive glue. Mind the direction (+/-) when attaching LEDs.
Note :Using conductive thread on Brother machine is out of guarantee, so please use it on your own risk.
Step 5: Application Example
Attached picture shows embroidery pattern of 2.8" x 2.8" at the hem of T-shirt. This example mounts LEDs on the inner fabric and made the pocket lights so that circuit embroidery is hidden.