Building on others' work, I came up with this little device to go and measure my heart rate. Now, I knew it was fitting to go and make a heart shape from LEDs and so, I did. Not having any template, I was quite clueless. A bit of experimentation led me to find a heart that seemed decent looking. I didn't have much time to draw up plans of any sort as I came up with this on the 13th. It turned out really good and quite successful. Some people even asked if the LEDs went faster along with my heart when I went by a person I liked :-)

Here it is.

Step 1: Parts

You will need:

18 Red LEDs (I used some nice diffused ones but any ones will do.)
1 Arduino
1 Large Piece of Perforated Circuit Board (I used this one)
1 Pulse Sensor (I got mine at World Maker Faire but you can get yours here or here)
Some Male and Female Headers (I used a three pin female header for the pulse sensor itself)
Some Wire

Step 2: Program.

Follow the guide here for setup.

Basically, set up an LED on digital pin 5 of the Arduino that goes to the ground pin as well. The sensor connects to positive 5 volts (or 3.3 volts if you changed it to work with 3.3 volts),ground and Analog 0.

Leave a comment if something doesn't work.

Step 3: Assemble the Heart.

Of course, this is Instructables and most people reading this make stuff often so why don't you go and design your own heart from LEDs? Post in the comments below if you do. Skip the next part if you do design your own.

No? Well, I won't leave you hanging so I will tell you this:

Cut a 15*14 hole piece of perforated circuit board (Position it so that the vertical axis is 14 holes and the horizontal is 15)
Following, these coordinates, build your heart: (remember, go across and then up and down):

LED # (Clockwise) Positive or Anode(+) Coordinates Negative or Cathode(-) Coordinates
1 Top Center (9,3) (8,2)
2 (7,1) (6,1)
3 (5,1) (4,1)
4 (3,1) (2,2)
5 (2,3) (2,4)
6 (3,5) (3,6)
7 (4,7) (4,8)
8 (5,9) (5,10)
9 (6,11) (7,12)
10 (8,13) (9,13)
11 (11,11) (10,12)
12 (12,9) (12,10)
13 (13,7) (13,8)
14 (14,5) (14,6)
15 (15,3) (15,4)
16 (14,1) (15,2)
17 (12,1) (13,1)
18 (10,2) (11,2)

Next, solder you positive leads together and your negative leads together. In this case, all my cathodes or negative leads are in the center. All my positives were connected raised off the board. (See pictures).
Then, solder two wires and those are going to connect to digital pin 5. The first time I hooked it up, I was nervous that it was not going to turn on because the Arduino could not drive so many LEDs at once. It did so...success!

Step 4: Assemble the Rest.

This step is more optional but I made a DoAnything shield and so, I use it in almost every project. I just soldered the connections to give them more solidity. (See pictures)

Step 5: Done.

I usually use a small binder clip to clip it to my sweatshirt (over/near over my heart) and then I put the Arduino and batteries in my sweatshirt pocket.

There is the whole thing. Hope you liked it.