Guide to Conductive Thread

In this guide, we’ll discuss some properties of conductive thread, tips and tricks, and ways you might use this versatile material in your paper circuit projects.

What is it? How might you use it?

Conductive thread is a fiber that conducts electricity.  Because it is thin and flexible, like ordinary thread, conductive thread traces can take many shapes and connect to a variety of conductive materials and components. Conductive thread is particularly useful for creating sewn circuits (also known as soft circuits or e-textiles) in applications that combine circuitry and textiles with the use of a needle.

Although conductive thread is most commonly used to make wearable electronics, it may also be paired with paper and conductive tapes. While it is most commonly used for attaching sewable LEDs, sensors, microcontrollers, and battery holders into garments, it is also useful for creating interactive components such as switches and sensors (such as a tilt sensor) that partner well with paper circuits.

Conductive thread helps this paper fish swim.
Fluttering Concertina/ Spinning Accordion Project

Circuit Stickers sewn onto fabric
Light-up Strawberry Project

Tilt sensing bookmark & circuit sketch
Slide Deck: What is a Tilt Sensor?

Simple Paper Tilt Switch/ Sensor

A simple tilt switch/ sensor may be made from paper, conductive thread, conductive fabric tape, and a metal bead.

Using paper, conductive thread, conductive fabric tape, and a metal bead, you can make a tilt switch/ sensor.

A tilt switch/ sensor such as this can connect to a paper circuit, or even a Chibi Chip, to trigger a reaction in an actuator, such as an LED!

Tyvek from a recycled postal envelope, backed with double stick tape, reinforces the area where the thread sews through the conductive fabric tape & metal bead.
The switch pad, made from a square of foam tape wrapped in conductive fabric tape, needed to extend from the paper’s surface due to the shape of the bead.
A paper tilt sensor is connected to a Chibi Chip with conductive fabric tape clipped by alligator clips.
The tilt switch/sensor has closed the circuit in this image, illuminating the Circuit Sticker.
A paper tilt sensor made with conductive thread triggers a function on a Chibi Chip.

Types of Conductive Thread

There are different types of conductive thread, including some made from copper, tin, nickel and silver; but, most are made from spun stainless steel that have been tightly wound together. Unlike the thread coated with copper or silver, stainless steel conductive thread does not oxidize or lose its conductivity over time, making it an ideal choice for crafters. Stainless threads generally come in two textures. Some are smooth and springy, but others are hairy (or “toothy”) with an almost yarn-like finish. While both types may be used interchangeably for most applications, they have different properties that you may want to consider before choosing one.

3 Types of Stainless Threads/ Yarn
Image Courtesy of Adafruit: CC BY SA 3.0
Hairy Stainless Thread/ Thin Yarn
Image Courtesy of SparkFun CC BY 2.0

Smooth, 2-ply, Stainless Thread
Image Courtesy of Adafruit: CC BY SA 3.0

Properties of Conductive Thread

Before highlighting a few key differences between the smooth stainless steel type of thread and its hairy, more yarn-like counterpart, there are notable properties that most types of conductive thread share.

Advantages

  • It is thin, flexible, and portable.
  • It’s versatile; it works well with fabric and other materials that may be pierced or sewn through.
  • Conductive stitches may be easily concealed.
  • It’s stronger than copper tape.
  • It’s usually magnetic.

Disadvantages

  • It can be a little tricky to thread and knot.
  • It has more resistance than copper tape.
  • Conductive stitches often need to be insulated.
  • Knots can loosen over time.
  • It’s difficult to solder to.
  • It can tangle and fray.

In addition to having these traits in common, there are also important differences between the two types of stainless steel conductive thread.

Smooth Thread

Smooth stainless threads, which have a bit of sheen, are very strong.

Hairy, “Toothy,” Thread/Yarn

Some stainless steel threads have a dull texture closer to a thin yarn than a thread.

Ease of Use

Smooth stainless thread is more slippery & springy, making it more difficult to knot.It’s easier to pull out if you make a mistake.
Pulling it through beeswax helps reduce fraying at the ends. Because its springy, it is more difficult to keep it wound on a spool.
The toothy texture of the thread/yarn makes it easier to knot.It grips fabric & paper better.
It curls, frays, & tangles easily, if it isn’t run through wax.
Because it is fuzzy, it can be susceptible to short circuits.

Strength

Smooth stainless thread is exceptionally strong; it must be cut with scissors.
Stainless thread/yarn breaks easily if it’s pierced or pulled with too much force.

Resistance

Smooth stainless thread has less resistance than the thread/yarn, making it a better choice for circuits involving a lot of electrical components.
3-ply smooth stainless thread has less resistance than the 2-ply version.
Stainless thread/yarn typically has more resistance than smooth thread.
3-ply stainless thread/yarn has less resistance than the 2-ply version.

Cost

Smooth stainless thread costs a bit more than the thread/yarn.
Stainless thread/yarn is slightly less expensive than smooth stainless thread.

Ideal Uses

Smooth stainless thread is best for applications involving a sewing machine; the 2-ply thread can fit in a bobbin case and the 3-ply can be used with a cording foot.
Toothy, stainless thread/yard is a great choice for making DIY touch-screen gloves.

Useful Tools for Working with Conductive Thread

Needles with tall, narrow eyes (sizes #4 – #8) work well.
Needle threaders are helpful in a classroom setting.
Black & red Sharpie pens are useful for marking +/- leads of through-hole LEDs.
Needle nose pliers are useful for prepping (curling) the legs of through-hole LEDs.
Beeswax is useful for preventing thread from fraying, curling, and tangling.
Clear nail polish is useful for sealing & securing knots. Avoid getting it on conductive pads, as it is an insulator.
A glue gun is useful for insulating conductive thread traces on fabric. Avoid getting it on conductive pads, as it is an insulator.
Embroidery hoops are useful for keeping fabric taut while sewing .
A fine-tipped awl or thumb tack (backed by cardboard) is useful for enlarging the guide holes of Circuit Stickers.
Metal brads are useful for attaching conductive thread to paper.
A Japanese screw punch is useful for making small holes for conductive thread to pass through.
Disk (or ring) magnets (pictured here on both sides of a battery) are useful for prototyping & making switches.

Tips & Tricks

Prepping a Circuit Sticker for Sewing

Holes can be enlarged with a needle, thumb-tack or a fine-tipped awl.

Circuit Stickers have guide holes on each end, which may be used to sew through with conductive thread. Before sewing a Circuit Sticker, it’s helpful to use a fine-tipped awl, thumbtack, or needle to gently enlarge the holes. Doing this on top of a piece of cardboard or an old phone book may help prevent the sticker from bending.

If you use a tool that’s too thick, the metal pads can tear. 

Place the Circuit Sticker & its protective backing on top of a piece of cardboard when enlarging the guide holes.
The cardboard helps to support the Circuit Sticker as you prepare it for sewing.

Choose a needle with a long, narrow eye (sized #4- #8).
Avoid thick needles when prepping & sewing through Circuit Stickers.
The holes of this sticker were carefully enlarged using the fine tip of a thumbtack & a piece of cardboard.
Sew 3-5 times through each metal pad of your Circuit Sticker to ensure a secure physical & electrical connection.

Preparation

These are a couple of circuit diagrams, brainstorming a tilt sensing bookmark.

Sketching out your circuit before you sew is best practice. 

After sketching the location of your battery and components, sketch the ground bus that will connect them all; then sketch out the positive traces.

Needles

Choose a needle with a tall, narrow eye. Needles with tall, fat eyes can damage Circuit Stickers.

When choosing a needle, look for one with a tall, narrow eye (such as the .067 mm wide needles sold by SparkFun). In general, any needle sized #4-#8 will work well (as in this needle set by Adafruit).

You may also wish to check out the sewing section of your local craft store. Look for “embroidery sharps” with tall, narrow eyes.

While needles with wide eyes may be useful for sewing pieces of felt together, these types of needles can damage the metal pads of Circuit Stickers.

Cutting

When cutting conductive thread, do not do it over your workspace. The tiny fibers can be hard to detect & cause short circuits.

Avoid trimming conductive thread over your work space; the tiny, hairy, fragments can lead to short circuits that are difficult to locate and repair.

Conductive thread is made out of metal, which means that it will dull your good scissors if you use them. Keep your good scissors away from your work space and designate a sacrificial pair of snippers specifically for cutting conductive thread.

Waxing

Pulling the length of your conductive thread through beeswax a couple of times will tame frays & reduce curling.

Before threading your needle, run a sufficient length of thread through beeswax a few times to prevent fraying and twisting; this is especially important for the hairy thread/yarn.

Avoid using more thread than you need to keep it more manageable.

Use one hand to hold the wax and the other to pull the entire strand of thread through, including both ends.

If you don’t have beeswax, you can substitute candle wax or canning wax (such as paraffin). Paraffin comes in large blocks, which are useful in a classroom setting.

In a pinch, a touch of Chapstick might be used to help tame frayed tips to aid with threading, but it can leave a noticable residue if you are working with paper

Threading

Needle threaders can help guide conductive thread a needle’s eye.

When threading your needle, you may want to try using a needle threader to help guide conductive thread through the eye. If you are not using one, pinching the waxed tip of thread between your fingertips to flatten it also works well (especially with practice).

Thread the needle on one end of the strand, leaving a 1-2 inch tail coming out of the eye. This tail will allow you to adjust the length of the thread as you sew.

Threading the needle on only one end of the thread, and leaving a long tail that you may adjust as you sew, will make it easier for you to remove the needle and stitches should you make a mistake. 

Insert the threader throught the needle’s eye.
Insert the thread through the wire tip of the threader.
Pinch the wire of the threader tight and pull the thread through the eye.
Leave a 1-2 inch tail coming out of the eye.

Knotting

Knot the end of the long tail, leaving a 1-2 inch short tail near the eye.

Leaving a 1-2 inch tail of thread coming out of the needle’s eye, pull the rest of the strand straight down, away from the needle, and make a knot at the bottom.

Unlike sewing with embroidery floss, where you might thread your needle, match up the two loose ends of thread, and then tie them into a knot to secure them together, conductive thread should always be left as a single strand.

Only knot one end of the thread to make it easier to remove the needle if you make a mistake while sewing.

Knotting only one end of the thread makes it easier to undo your stitches (without cutting them) should you need to troubleshoot.

Stitching

One way to make evenly spaced holes for a running stitch on paper is by using a sewing machine without the thread.

A running stitch is the most common stitch used for sewing conductive thread traces.

To keep the knot hidden from view, a running stitch enters the back side of a piece of fabric or paper and then passes through to the front.

Pull gently on the thread until the knot locks. Then enter the front side, and carefully pull the thread all the way through again.

Then, as the name “running stitch” implies, pass back through to the back side and keep going, in a series of sequential, repetitive stitches.

In order to avoid loose connections and short circuits, it’s wise to keep your stitches small and neat.

If using a sewing machine to mark your holes, choose the longest stitch possible. Short stitches will perforate your paper, causing it to rip easily.

To hide your knot, start a running stitch by inserting the needle from the back side of the project & pull the thread through as far as the knot will allow.
When pulling the thread through, pinch the eye of the needle to keep the short tail from slipping out.
You can sew a Circuit Sticker directly to paper, but it will likely need reinforcement.
Reinforcement rings were added prior to sewing, to help strengthen the paper.

Insulation & Bridging

Hot glue may be applied to the back of a project to help seal knots & keep positive & negative traces from touching one another.

It’s important to insulate conductive thread traces to keep positive and negative threads from touching, especially in areas where a component, such as a Circuit Sticker or LED, has been sewn down.

Hot glue and fabric paint, when dry, make good insulators for the back sides of circuits sewn onto fabric.

A piece of paper, fabric, or tape makes a good insulator for covering conductive thread traces on paper circuits.

On occasions when you may need to cross a piece of positive thread over a piece of negative thread while sewing, scraps of fabric, paper, or tape make good insulating bridges (barriers) between the threads.

Sewing a Circuit Sticker to Fabric

Insert your needle through a hole in your Circuit Sticker from the back side.
When pushing your needle through the sticker, support the sticker with your free hand, to keep it from bending.
Pull the thread through until the knot catches on back of the fabric; trim the loose tail later.
Enter the second hole from the front side, supporting the sticker with your free hand, & pull the thread to the back side..
Sew 3-5 times through each metal pad of your Circuit Sticker to ensure a secure physical & electrical connection.
When you are finished sewing, insert your needle through the knot on the back side.
Wrap the thread once around the tip of your needle.
Form a new knot by pulling the needle through the loop you just formed.
Apply a dab of clear nail polish to the knot.
Tighten the knot by pulling the tails apart; allow the polish to dry.
When you are finished sewing, trim the tails, leaving a little bit of clearance near the knot.
Ensure that the positive & negative threads do not touch one another.

Connections

Enlarged holes are easier to sew through with conductive thread.

It’s important to make a solid physical and electrical connection between the conductive thread and electrical components you are trying to secure; loose connections will result in wonky circuits.

When using conductive thread to secure a component, such as the legs of a through-hole LED, a battery terminal, or the metal pads of a Circuit Sticker, sew 3-5 firm stitches around the component.

In the image to the left, four stitches of stainless thread/yarn have been made to secure the negative and positive pads of a Circuit Sticker. It wasn’t necessary to enlarge or sew through all of the holes.

If you look carefully, you might notice a loose fiber of conductive thread/yarn, slightly to the left of the “Y.” Loose fibers such as this can cause short circuits & should be removed when discovered. To avoid encountering loose fibers, avoid cutting conductive thread over your projects and work space.

Connectors

Conductive thread may be sewn to conductive fabric & conductive fabric tape.

Conductive thread pairs well with conductive fabric tape, because it’s strong enough to sew through. While copper tape may be used to connect or reinforce a strand of conductive thread on a flat surface, like a piece of paper, piercing it will tear and weaken it.

In the image to the left, strips of conductive fabric tape were adhered to the back of a piece of felt and sewn to the positive and negative leads of a Circuit Sticker. The knots on the back were then sealed with clear nail polish and a dab of hot glue.

Conductive fabric tape can be used with alligator clips, or joined with copper tape.

Conductive fabric tape may also be applied on top of a sewn Circuit Sticker; although, this type of connection may need reinforcement over time.

In this example, conductive fabric tape strips have been sewn to a fabric-backed Circuit Sticker.
When sewing to the conductive fabric tape, watch out for excessively long tails of thread that might cause shorts if left untrimmed.
In this image, conductive fabric tape was layed on top of a sewn Circuit Sticker, rather than being connected to it with thread.
While the tails of thread on the back are long, they are not close enough to touch each other & the knots have been sealed with clear nail polish.
In this image, tails of conductive thread have been left long in order to do some prototyping.
The conductive thread on back has been knotted, reinforced with clear nail polish, & dabbed with hot glue.
Conductive thread may be sewn through a bare Circuit Sticker. Securing the knots with clear nail polish is a little more difficult when the sticker lacks a paper or fabric support.
The stitches on this sticker look loose. To reinforce the physical & electrical connection between the thread & metal pads, a conductive fabric patch would be useful..

In addition to using conductive thread and conductive fabric tape connectors, metal brads and magnets may also be used.

In this prototype, small disk magnets attached to both sides of a battery are holding the conductive thread traces in place.
In this prototype, a bare Circuit Sticker with conductive thread leads has been connected to conductive thread power & ground rails with help from tiny metal brads.
In this prototype, a fabric-backed Circuit Sticker with conductive thread leads has been connected to conductive thread power & ground rails with simple knots.
In this prototype, conductive fabric tape is adhered on top of conductive thread power & ground rails.

Rapid Prototyping

This experiment, in which conductive thread traces were “couched” on to the surface of a piece of paper, was designed to tinker with different connection techniques.

One way to learn more about using conductive thread in your projects is by doing some rapid prototyping to try a few different experiments, to see what works and what doesn’t.

During this “couching” exploration, a sewing machine with a cording foot was used to create power and ground rails on top of a piece of watercolor paper; although, any sturdy paper, such as poster board, Bristol, or cardstock would work.

Using a zigzag stitch sewn with regular cotton thread, the two pieces of smooth 3-ply stainless conductive thread were secured at the top and bottom of the paper, leaving ample space between them for experimentation.

To keep the conductive thread from slipping through the zigzag stitch (which happened on the bottom row) clear tape was used to secure the loose thread tails on one end of the paper. The tails on the other end, which were left longer, were connected to a coin cell battery using disk magnets.

To create power & ground rails from conductive thread on heavy paper, 3-ply smooth stainless thread has been sewn down using a cording foot, zigzag stitch, & ordinary cotton thread.
Circles were removed with a die cutter & holes were poked with a screw punch.
In this prototype, conductive fabric tape connected to the back of a piece of fabric wraps around a piece of paper to connect with the ground rail on the opposite side.
Disk (or ring) magnets (pictured here on both sides of a battery) are useful for prototyping & making switches.

Through prototyping, you might discover a new technique that’s useful for something from your imagination. The paper fish below was attached to a ground rail of conductive fabric tape using a metal brad, after a successful experiment sparked an idea.

This paper fish is suspended by conductive thread & secured with a metal brad.
A Circuit Sticker was sewn to a sturdy piece of watercolor paper. Glue dots were used to diffuse the LED & attach the fish overlay. Notice the running stitch?
A small metal brad was inserted. Conductive thread was pulled to the back & tied around the brad in a figure eight pattern before being knotted, using a needle.
This is the back of the fish. Notice the Tyvek reinforcement. Conductive fabric tape was applied on top of the metal brad as extra reinforcement for the circuit.
This paper fish is securely attached to the power & ground using conductive thread, a metal brad, & conductive fabric tape.

Battery Holders

In this prototype, small disk magnets attached to both sides of a battery are holding the conductive thread traces in place.

There are many different ways to connect conductive thread to a battery.

For prototyping purposes, it’s possible to connect a battery directly to conductive thread by using disk or ring magnets. Since coin cell batteries and conductive thread are magnetic, a magnet placed on top of a strand of thread, sandwiching it between the magnet and a coin cell battery, can hold the thread in place to test a connection or light an LED.

Scotch tape, copper tape, and conductive fabric tape may also be used to construct paper battery holders, such as an origami battery holder, that pair well with conductive thread.

There are also a variety of commercially manufactured, sewable, battery holders that are designed for connecting to conductive thread.

These come in a variety of form factors. Some have tiny holes (which are more difficult to sew), some have large holes (which connect well to alligator clips), and some even have built-in switches. More information about these battery holders may be found in the Sourcing section below.

Organization

Smooth stainless 3-ply thread is springy, causing it to easily unravel from its bobbin.

Keep your thread neat to avoid tangles. One way to do this is by keeping it wound. To prevent it from springing free, it’s helpful to insert the loose end of the thread through a hole in the side of the bobbin to keep it secure.

It may also be wrapped around a piece of cardstock or stored in a small ziplock bag with the loose end held in place when it’s zipped.

To keep your thread from unraveling when not in use, pull a loose end through a hole in the bobbin to secure it.
Wrapping thread around cardstock, or keeping the bobbin in a small bag can help keep it tidy.

Additional Support

Notice how I’m supporting the LED by holding one leg under my thumb while sewing through the other leg. You’d need to do this for a Circuit Sticker, too, to avoid bending it.

An embroidery hoop is useful for sewing an LED onto fabric, such as this through-hole LED which has had its legs curled to make it easier to sew.

Embroidery hoops are most useful when sewing large pieces of fabric that might otherwise flop around.

By allowing you to keep the fabric taut, you won’t have to worry as much about having too much slack in your stitches.

Notice how close the stitches of conductive thread are to the curled metal leg of the LED. As is the case with sewing a Circuit Sticker, it’s important to sew 3-5 loops around components to ensure a secure physical and electrical connection.

Cool Hack

You can make touch screen gloves with conductive thread.

Did you know that conductive thread sewn to your winter gloves will transform them into “DIY Touch Screen Gloves“?

Basically, the trick is to sew the thread all the way through the tips of your gloves, so that the thread comes into contact with your hands on the inside.

The fuzzy thread/yard is especially good for this.

If you’d like to see some very imaginative uses for conductive thread (staring another pair of gloves), check out the incredibly inspiring video below, titled, “Connecting Thoughts.”

Inspiration

The creator of this video owns the copyright. It is being featured on this site in accordance with Educational Fair Use doctrine. 

Kandenko, a Japanese infrastructure company, paired with a conductive thread manufacturer (Smart-X) to create the aspirational video, titled “Connecting Thoughts.”

In this video, a tiny city lights up and reacts in surprising ways, all resulting from clever contraptions and connections that use conductive thread.

To learn more, visit “The Kids Should See This.”

Bonus: How might the gloves in this video work?

.

Sourcing

While Chibitronics does not make or sell conductive thread or sewable battery holders, both are available from reputable retailers such as Adafruit and SparkFun.  Lectrify also sells a switched coin cell battery holder that is popular with educators.

Adafruit

SparkFun

Resources for Further Exploration

Curriculum, Facilitator Guides, & Tutorials

Sew Electric

Gettings Hands-On With Soft Circuits:  A Workshop Facilitator’s Guide 

Stitching the Loop: An Electronic Textiles Unit in Exploring Computer Science 

Stitching the Loop: E-Textiles Technical Guide

Light Stitches: E- Textiles Project Resources Book

Light Stitches Book 1: Electronic Textiles Teacher’s Resources

Exploring Computer Science Projects

Instructable: Light-up LED Cuff with Magnetic Switch (classroom tested project)

Maker Camp: Sew the Circuits (classroom projects)

Wearables:  First Steps (useful materials and activities)

Chibitronics Tutorial: Light-up Sphere Card

Chibitronics Tutorial: Flying Concertina Accordion Book Tutorial

Chibitronics Tutorial: Light-up Spinner Card

Chibitronics Tutorial: Light-Up Strawberry Tutorial

Product Guides

Spark Fun:  LilyPad Basics: E-Sewing

Adafruit:  Conductive Thread

Adafruit Video: Conductive Thread 10 Tips

Sensors Using Conductive Thread

Spark Fun:  Sewable Electronic Sensors

Stroke Sensor 

Sticky Tape Bend Sensor

Kokobant Tilt Sensor

Becca Rose Tilt Sensor

Slide Switch with Coins and Thread

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