own electronic sewing kit
(no previous electronics knowledge or soldering required)
left: a shirt decorated with LEDs and fabric switches.
right: a homemade headlamp with LEDs sewn into a stretchy headband.
what you will need:
Where to get electrical supplies: You can get LEDs, batteries, battery holders, wire strippers, pliers, multi-meters, soldering irons, and other electronic supplies from your local RadioShack. In the back of most stores there's an electronic hobby selection. Ask a salesperson if you have trouble finding it. A salesperson should also be able to help you find all the electrical supplies on this list. For a larger selection of LEDs and other electronics check out Digikey online.
left: Light Emitting Diodes (LEDs).
right: a battery holder for 2 AA batteries and snap-on leads.
some of the other supplies you'll need: pliers, wire strippers, scissors, needles and conductive thread.
a little about circuits and LEDs
If you are completely new to circuits, you should read enough to understand how a basic circuit works before embarking on this project. Introductions to electricity and circuits can be found at: Electronics Club - Electricity and the Electron and Doctronics - Circuits.
Light Emitting Diodes (LEDs) are special types of lights. An LED shines when electricity passes through it in the correct direction. LEDs usually have two "leads" or wires coming off of them. One lead is the positive (+) end of the LED, called the "anode", and one lead is the negative (-) end of the LED, called the "cathode". In the picture above, you can see that for each LED one lead is longer than the other. The longer lead is usually the anode lead. If you are new to LEDs, you should read the first section of the page at: Electronics Club - Light Emitting Diodes (LEDs) before proceeding.
A note about LEDs and resistors. Generally, you have to be careful not to attach an LED directly to a power supply. Attaching an LED directly to a power supply can cause the LED to burn up as too much electrical current flows through it. Normally, you have to attach an LED to a power supply through an electrical component called a resistor. However, for the project described here we will not need resistors because we will use a fairly weak power supply of 2 AA batteries (these will supply 1.5 volts + 1.5 volts = 3 volts) and the conductive thread we will use to sew out our circuit has some natural resistance and thus functions like a resistor. IF YOU USE A DIFFERENT POWER SUPPLY FOR THIS PROJECT OR DO ANY OTHER ELECTRICAL PROJECTS INVOLVING LEDs YOU NEED TO USE RESISTORS IN YOUR CIRCUITS TO PREVENT BURNING UP YOUR LEDs! For more information on resistors and LEDs see Electronics Club - Light Emitting Diodes (LEDs).
1. Pick a garment or piece of fabric to sew on.
2. Design your circuit. Decide on the number of LEDs you want and their placement. Also decide where you're going to put your power supply. I decided to sew four LEDs and four fabric switches into a tank top and to place my power supply close to the edge of my shirt so that I could carry the batteries around in my pocket. Whenever a switch is pressed, the LED attached to it will turn on. (For a simpler design, remove the switches - then all four LEDs will be on all of the time) Here's my design:
left: my design for a tank top with four LEDs. (click on the image for bigger picture.)
right: a schematic diagram of the design.
to learn how to read schematics check out Electronics Club - Circuit Symbols.
left: a parallel circuit. the + lead of each LED is attached directly to the + end of the battery and the - lead of each LED is attached directly to the - end of the battery
right: a series circuit. the LEDs are all in a row. the - lead of one LED is attached to the + lead of the next LED
1. Sew your circuit, following the design you traced. If you have a sewing machine, this will go more quickly, but you can also do it by hand. If you are using a sewing machine, wind a bobbin of conductive thread and put it in the bobbin of your machine. Some conductive thread is too large to be used as top thread in a sewing machine, so this is your best bet. Follow the lines you made on your garment to stitch out the conductive traces. Again, be careful to leave space for your LEDs and other components.
left: conductive thread should be placed in the bobbin of your machine.
right: sewing out the traces.
2. Make your LEDs stitch-able. Get out your LEDs and pliers. Grasp one of the leads of an LED with the pliers. Using the pliers, twist the lead over on itself several times so that the lead now makes a loop. Be careful to leave some indication of which lead is + (usually the longer lead) and which is -. I do this by leaving a long tail on the + lead and clipping the tail on the - lead completely off. You can use wire cutters or a pair of strong scissors to snip off unwanted wire tails.
twisting the LEDs
3. Stitch in your LEDs. If you have not yet twisted your LEDs, you can hide the twisting loops on the back side of your garment or fabric. Align your LED where you want it on your garment being careful to align the + and - leads correctly with your traces. Push your LED through the fabric and twist the leads as was described above. Again, wire cutters or scissors can be used to trim off the excess wire once you're done twisting.
left: pushing an LED through the fabric.
right: LEDs which were pushed through the fabric and then twisted.
left: stitching in the LEDs.
right: close up of a stitched in LED.
When you have a good sturdy stitch, tie your thread in a knot and coat the knot with fabric glue before snipping your thread. Conductive thread will fray and come un-knotted easily, so this is a crucial step.
gluing a knot so that it won't fray.
Once you strip off the insulation, you should have about an inch of bare metal wires coming out of each of your leads. Twist each end to form a loop. Twist it several times so that you make a good strong loop. You will stitch these loops to your shirt to attach your battery, so they'll need to withstand some stress.
left: stripping the insulation off of the battery holder leads.
right: the snap on battery holder leads after the leads have been twisted into loops.
6. Add decoration and, if necessary, protective backings so that the twisted LED leads will not scratch your skin. I sewed patches of felt over my stitched on twisted LED leads. I also sewed felt frames around each of my LEDs for decoration.
left: a decorative LED frame.
right: protective backings on the inside of the shirt.
If your LEDs don't turn on, here are some common sources of error:
making a fabric switch (optional)
Note: This basic technique for building fabric switches was first described by Remi Post and Maggie Orth in their excellent paper E-Broidery: Design and fabrication of textile-based computing.
1. Cut out two patches from a thick springy material like heavy wool or felt. Cut the patches in the shape you'd like your switch to be in.
2. On each patch, sew a conductive region through the middle and leave a dangling conductive thread attached to your conductive region. Do not cover the entire patch with conductive stitching, you will need two non-conducting edges. See the picture below to get an idea of what these pieces should look like.
3. Cut out two pieces of netting roughly the size and shape of your patches, but a little bigger
left: components of a fabric switch.
right: sewing the switch together
Sandwich your pieces together and sew your sandwich together. Make sure that you take the conductive thread out of your sewing machine before you do this!
5 . Test your switch. Using a multi-meter in its "beeping" mode, attach a lead of the multi-meter to each of your dangling conductive threads. The multi-meter should be silent (read "open") when the switch is left alone and beep (read "short") when it's pressed.
6. Sew your switch into your design just like you stitched in your LEDs making sure that the two ends of the switch don't contact one another.
7. Plug in your battery and test your garment. If any of your LEDs don't work, see the last part of the previous section for details on a couple of common problems and how to fix them. Enjoy your electronic fashion!
Your sewn circuit is washable. Remove the battery and wash the garment by hand with a gentle detergent. Drip dry.
for more information:
For information on more sophisticated techniques, including instructions on how to attach microcontrollers to fabric, check out my make your own wearable LED display page.
Sewing Circuits: more information about the Craft Technology Group's electronic sewing workshops, a collaborative project with Nwanua Elumeze and Sue Hendrix.
SWITCH: Alison Lewis has a web broadcast of how tos intended to introduce girls to technology.
Electronic Jewelry Workshops Page: Elisabeth Sylvan conducts workshops where participants learn to make electronic jewelry
Electronics Club: an excellent electronics reference for beginners
Enlighted Designs: for inspiration, check out this site where you can order custom made LED clothing.
This material is based upon work supported by the National Science Foundation under Grant No. 0326054.
Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation (NSF).