The Arduino seems the ideal platform for making your own medical monitoring system. Your temperature, heart rate, respirations, blood pressure, weight and O2 content of the blood are all measurable and loggable. Here are a few links to get you started, but email me at sspence@green-trust.org with more links to this application.
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http://www.wonderhowto.com/how-to-make-infrared-heart-sensor-286365/
http://danjuliodesigns.com/sparkfun/hrmi.html
http://jdesbonnet.blogspot.com/2010/05/using-arduino-duemilanove-as-quick-and_25.html
I wrote an article recently on Medical Monitors – http://voices.yahoo.com/medical-monitor-emotional-stress-indicator-11584826.html?cat=5
In the article, I mention that Arduino could be used. I hope you find the article interesting.
Let me know if you want to chitchat about this…or if I can help you in any way.
Thanks!
Drop me a line at kk4hfj@arrl.net, I'm intrigued.