Infra Red Heartbeat Monitor with IPhone connection

For the wearable project I used the following:
1) Arduino Duemilanove.
2) Infrared Emitters and Detectors.
3) 10k and 220k resistors.
4) The Arduino and processing environment.
5) touchOSC - for communication with the iPod touch.
6) Misc wires and other fun tools.

I have been interested in combining the quality of the Apple iPhone/iPod Touch family of products with medical devices with the goal to produce affordable medical devices that could be used anywhere in the world during natural disasters or in rural areas that do not have full clinics.

I put together a infra red heartbeat monitor that used the arduino to power the led and receive data from the ir detector. I purchased the matched InfraRed Emitter and detector from Sparkfun and after some research on how the circuit should work I connected it using the bread board and used the following code to read data from the emitter and send it to the computer.



I followed the posts of Charles Martin with a couple of exceptions. He used the Arduino to process the information coming from the emitter, I found the arduino wasn't fast enough to do both translate the analog data and compute whether it was a real heartbeat or some anomaly in the emitter signal from the detector.



I used processing to do the calculations as it is running on a 64bit Mac Book Pro, I then used the touchOSC interface to sync with the Touch. After having some real difficulty in getting any kind of feedback from the emitter, the I eventually burned it out. To check if an infrared emitter or led is working I just looked at it through the LCD screen on my digital camera.

I tried using the emitter detector package from Radio Shack but it either wasn't sensitive enough to detect the variations in the size of the capillaries in my finger or it was to bright. I ordered a new set of emitter and detector from Sparkfun and was far more careful about heat and power when wiring them together.

I was able to get everything together on the bread board and working in a satisfactory manor, so I put it together in a package that could be presented. I used a electrical extension box to hold the Arduino and allow for the the wire to the emitter/detector to be plugged in easily, I stripped a standard 4 wire phone cable for this and soldered the emitter and detector to the wires and soldered the resistors in the circuit inside the box.



I cut some holes for the USB plug for the Arduino and phone connection into the box(only sliced my finger once) and put everything together. Fortunately it worked, when I get an opportunity I will get some video of it running and post the code. What I would do differently would be to put a variable resistor in the emitter circuit so that when you put the clip on your ear it works, I think the emitter is to bright and just shows through the ear not allowing for variations in the capillaries to be picked up.