This hoodie has an open heart kit on the chest that is removable using magnetic snaps. The kit is driven by a lilypad arduino and battery pack attached to the inside of the hoodie. It runs various patterns through the LEDs when the zipper connects the exposed conductive threads.

I was inspired by these instructables:
Open Heart LilyPad Brooch
TV-B-Gone Hoodie

The open heart kit was created by Jimmie Rodgers.

Step 1: Materials & Tools

Materials:
1 open heart kit
1 LilyPad Arduino
1 LilyPad power supply
1 hoodie with a nylon zipper and a metal pull. sleeves are optional.
1 spool of conductive thread
1 spool of regular thread
1 bottle of puffy paint
6 magnetic snaps
1 AAA battery
8 wires with alligator clips
some extra fabric

Tools:
soldering iron, solder, etc.
sewing machine or needle
scissors
needle nose pliers
dremel drill, hacksaw, or metal file
fabric marker or pencil

Step 2: Wiring Diagram

Creating a simple wiring diagram will save you a headache when you start sewing everything together. When wiring up the heart and lilypad keep in mind that they will be mounted back to back.

Try to choose pins on the lilypad that are closed to the pins on the heart. The best fit i found to match the hear to lilypad respectively was:
1 = 12
2 = 2
3 = 10
4 = 7
5 = 5
6 = 4

Connect the negative pin on the lilypad to one of the negative pins on the power supply. I used the one closest to the positive pin.

Connect the positive pin on the lilypad to the zipper. Connect the zipper to the positive pin on the power supply.

Step 3: Code

Attached is the code I used. It was adapted from Jimmie Rodger's original code.

There are a series of heart shaped patterns that are each displayed for "runspeed" number of times each time for "blinkdelay" milliseconds. Once all of the patterns have been displayed, the series will repeat itself.

    {0,0, 0,0,
   0,1,1,0,1,1,0,
   0,1,0,1,0,1,0,
     0,1,0,1,0,
       0,1,0,
         0},

Once you finish with the code upload it to the lilypad.

OpenHeart.pde
Download

Step 4: Prototype and Test

Assemble the open heart kit according to Jimmie Rodger's instructions.

Assemble the heart, lilypad, and power supply according to the diagram. Wires with alligator clips will really make this part easier. You do not need to use the zipper switch during testing. Upload the code and watch it go! This would be the time to work out any pin mapping issues before you start sewing. It is much easier to debug code and pin mapping errors if you are not worrying about thread being stitched too loose or crossing other threads.

Step 5: Sew the Circuit

Mark the pattern for the circuit with either a fabric pencil, tape, or contact paper. Once the circuit is sewn with conductive thread sew over it again with plain thread using a tight zig-zag stitch to help insulate the circuit. Be sure to leave the very ends of the conductive thread exposed. You will need to hand sew the components to these leads. Make decent size pads of conductive thread near the zipper.

File the side of the zipper pull. Be sure to remove all paint. You need clean metal to make contact to the pads.

Step 6: Add Magnetic Snaps for Heart

Bend one tab down on each magnet snap. This is the tab that will be soldered to the PCB. The other tab should be filed off so it is flush with snap. Solder each of the snaps onto the PCB. Be careful because the snap requires alot of heat for the solder to stick. I damaged one pin on the pCB by overheating it. Try heating the snap first and then heat the PCB, snap, and solder together.

Once the snaps are all soldered on, lay the PCB on the hoodie where you want it to be attached. Mark the location of the snaps on the fabric. Then push the tabs for the other half of the snaps through the fabric in those locations. You should be able to separate the fabric fibers enough to push the tabs through without cutting the fabric. Slide the backing plate on and bend the tabs down to secure the snap.

Step 7: Insulate and Attach Components

Attach a swatch of fabric to the back of the lilypad. Using the heart as a guide trace where the 6 snaps will be located on the back of the swatch. Hand sew the leads from the pins to the snap locations on the swatch. Make a small pad with the conductive thread at that point. (NOTE: I sewed the traces on the backside of the swatch. This caused shorts when the fabric crinkled. Covering the traces with puffy paint solved this problem. If I did it again I would probably sew the traces on the front of the swatch to help prevent this.)

Sew each of the conductive thread pads to their respective snap backing on the hoodie. Be sure to tie these connections tight. If they are too loose they could move and short when hitting a nearby snap.

Attach a swatch of fabric to the back of the heart. Loop thread around each snap near where it is soldered onto the PCB. Then trim excess fabric so that it follows the edge of the heart. I would suggest using fabric that either matches the hoodie or the PCB.

The power supply does not lay over top of any conductive thread traces so I you can probably get away without adding a swatch to the back of it. Double check that you are attaching the correct traces to the positive and negative pins.

Step 8: Power Up. Zip Up. Light Up.

You are now ready to try it out. Stand in front of a mirror or video camera. Put on the hoodie. Turn on the power supply. Zip it up until the zipper touches both conductive pads. Enjoy the show!

Here is a video of the completed hoodie: