We’ve all seen those flashy, light-up tee shirts and hats in the malls, and perhaps the geekier of us have lusted after them. It may surprise some of you that the materials to make your own electronic wearables are readily available and that, in fact, many designs are not that difficult to make yourself. This project is a great one to make for Valentine’s Day or any day.

I'm still proud of this simple design, even 3 years later!

This project is a couple years old for me, as I took a little, one-day class at The Public School taught by Syuzi Pakhchyan, author of Fashioning Tech and owner of the blog by the same name, almost 3 years ago. Crafting a simple, light up tee-shirt during the class and learning about the fun new materials available for making wearable electronics was awesome, and I’m looking forward to trying my hand at it again. I’m doing my best to recreate this tutorial from the steps I followed all those years ago, so bear with me.

For the purposes of this tutorial, I’m going to go over the basic materials I used in the shirt plus a few extras that inspire me for my next project (whatever that will be), and then the basic techniques for putting together a simple, non-animated, LED design on a tee shirt. A basic understanding of simple electronic circuits is helpful, but that sort of information is easily searchable on the web if you need a refresher.

For this project, you will need the following:

Here are the smart materials I used, plus some conductive Velcro that looks fun to use.

• A cute, comfortable tee shirt, preferably in a neutral color (I got mine at a thrift store for cheap)
• 8 or more red LED lights (though, looking back i wish i had a smaller, flatter red LED bulb to use)
• Conductive tape (Check out LessEMF - scroll down to the Ni/Cu/Co FABRIC TAPE for their conductive tape with conductive adhesive. This tape has Nickle in it, which may be allergenic in some people. You can use other tapes, just be sure the adhesive is also conductive; it works better.)
• Conductive Thread – Available at LessEMF, on Etsy and other places around the web.
• Sew-on Snaps
• Stretchy fabric (for battery compartment)
• Interfacing material, or other thin fabric for insulation
• Pink and black embroidery thread for embellishing
• CR2032 3V Lithium Coin Cell Batteries

The steps are pretty easy. I started by tracing a heart shape onto my tee shirt with a normal graphite pencil, and then roughly embroidering the heart shape with pink embroidery thread. I had no experience with real embroidery at this time so i just went for a rough look here. Mine is about 9 inches wide and about 7 inches tall.

Then I thought about the front design a bit more. I wanted to see the circuit design as part of the tee shirt, so I decided to use conductive tape strips to layout a simple pattern that looked, to me, like a circuit board, within the confines of my embroidered heart shape. This is where you get to be creative (see the photo at the top for my design). The result is that the tape strips must all touch each other, and must radiate towards the edges of your heart design – this is where the LEDs will go. We are working in a parallel circuit, so there will be one side of the circuit on the front (outside) of your shirt, and one on the inside as well, and all your LEDs will be connected to both.

Once you have cut and laid down your tape-strip circuitry on the outside of your shirt, you will want to sew over the tape with conductive thread, to ensure the tape stays in place through washings and to provide a more secure path for your circuit. This is necessary because most threads will have a lower resistance than your commercially available tapes. ***Note: I’m in no way an expert on electricity or smart materials so feel free to do your own research. Syuzi over at Fashioning Tech has a much better grasp on this, so defer to her knowledge, or another expert’s, before me.

Anyway, you’ll need the thread to connect the LEDs to your tape circuit, so it’s a good idea to sew this all the way through your tape circuit. LEDs have one positive and one negative prong which would generally be soldered to a circuit board, but for our purposes must be sewn in to our design. It’s important to identify which prong is positive (the anode) and which is negative (the cathode). On the front of your shirt, the outside, you will want to use the anode prong and push the cathode through to the inside of the shirt. All LEDs must be oriented the same way or your circuit will not work.

See the loops of the anode prong? I used a round nose pliers for jewelry to twist the anode into that shape, then joined the loop to the circuit by sewing several loops of conductive thread to it.

I used a round nose jewelry pliers to create a ring in the anodes and cathodes of the LEDs after pushing the cathodes through the shirt, bending each ring at a 90-degree angle so that they lay flat against the shirt surface and pinning the LEDs to the shirt. As I said before, the LEDs should be at the end of each arm of your tape circuit, around the edge of your heart. My LEDs are just inside the embroidered boarder for ease of connecting them to the tape, but you may choose to  be creative with this as well.

Once all your LEDs are sewn to your circuit on the front/outside of the shirt, go ahead and turn the shirt inside-out and look at the back of your design. On mine, I applied the interfacing before i sewed the circuit on the front, but part of the reason for the interfacing is to keep the front part and back part of your circuit separate, so really you should put the interfacing over the conductive thread to keep it from coming in contact with the back half of your circuit later.

Don't sew through the interfacing from the front side of the shirt like I did.

Cut your interfacing into the shape of the heart on the front side of your shirt and apply conductive tape around the outside edge, as shown in the photo. Push your LEDs through the interfacing and use the round nose pliers to again twist the prong of the LEDs (the cathode, if you’ve been following along) into your loop and crimp it at a 90-degree angle so it’s pressed against the inside surface of the shirt/interfacing. Although I didn’t (I think I was pressed for time at the class), again it’s a good idea to sew with your conductive thread through the conductive tape so that you have one unbroken circle of thread that you’re using to connect the LEDs. Once you have the LEDs sewn with this conductive thread, it’s time to make the battery compartment and attach it to your circuit.

There’s some bit of math to use to determine how many batteries you should use to power your shirt. I never bothered. One of these CR2023 coin cells should power your standard LED for a while without a problem, and the conductive threads and tapes we are using should provide adequate resistance in our circuit to keep our LEDs from shorting out so that you don’t need any additional resistors. I usually stack 2 or 3 of the coin cell batteries in my shirt’s battery holder, which keeps the LEDs bright-ish for a good amount of time. Fewer batteries will dim your LEDs quickly and will wear out quicker.

For your battery compartment, you’ll be using a few inches of stretchy fabric sewn into the inside of your shirt. In mine, I folded a small square of the material  and cut a small slit lengthwise in the fold. With one thin strip of conductive tape, I taped one “flap” of the folded fabric , being sure to fold that tape through the slit I made and around the backside of it. I used a separate thin tape strip to tape “sideways” along the inside crease of the folded material, making sure it extended to the outside edge of the fabric. This is confusing to explain, let me draw a little diagram…

The grey strips represent the conductive tape. Notice how the "top" one does not go to the edge, but it wraps around past the edge on the outside of the folded piece. The sideways piece of tape should go all the way to the edge of the fabric.

The sideways strip will go against the Positive side of the battery, and the part that goes through the slit will be for the negative side. You can see on your battery that there is a little lip of the “top” piece (which is the positive piece) and it curves around the sides of the “bottom” part of the battery, which is also the negative side. When you fold this pouch along the fold line pictured above, you will sew it shut by sewing around the outside of a battery that’s inside for testing purposes. You can see how i did mine, with the white thread in the following picture:

Here is the Battery pouch I made for my shirt. The slit is on the left side there, and the ends of the tape (right and bottom) are sewn with conductive thread.

You will insert your battery/ies (in my picture, the negative face of the battery would be facing up, or towards your skin if you were wearing the shirt) into the pouch through the slit. The elasticity of the fabric will allow the battery inside even though you should have cut the slit a bit smaller than your battery is wide, and hold it in place in contact with the tape. Sew this pouch on the inside of your shirt, near your circuitry but not over it.

Sew some conductive thread to the edge of the positive strip of tape, and then you will thread that through to the front/outside of your shirt. I embroidered a decorative bow in black embroidery thread on the front of the shirt, in front of where the battery pack is, to hide the stitching holding the pack in place. I then entwined the conductive thread into the embroidery thread and let a strand of this fall about 2 or 3 inches below the knot in my decorative bow. I tied/sewed the end of this tightly to one side of a sew-on snap. The other side of the snap, I sewed using conductive thread attached to the negative strip of tape, and also into the circuitry on the inside of the shirt. When the two pieces of the snap is snapped together, the shirt lights up, assuming the battery is in place.

Whew! That’s hard to describe! I hope you understood most of it. If you have questions feel free to ask them, and be sure to check out Fashioning Tech for more high tech fashion, and get the book for some easier-to-understand how-to’s for making your own wearables.