I was having a friend over for a cup of coffe when I realized I could do an ECG on him. He's a bit overweight and has a slightly bad heart. He has some Mitral Insufficiency, exactly the disease my grandfather had (until he got reconstructive surgeri for his heart valves). It comes and goes but we did see a negative peak of the QRS segment. THIS IS HUGE. It means that this device can detect cardiovascular disease.

Also, it seems that I've found a way to characterise these problems and devellop an algorythm to analyze the output from the ECG.

First of all: ECG patterns are very rhythmic. The timings are very strict and don't vary with the number of beats per minute or with blood pressure. So a table of timing values could be kept in a non-volatile memory (flash) and compared with the current heartbeat. The heartbeat timings could be easily found with interrupt conditions. Either rising or falling edges could be traced in order to find the specific parts of the Pulse complex. These parts would be timed and correlated with eachother as ratios rather than correlating them with a set of timing values as I've said vefore. The stored timing values would be usefull for determining said ratios for a healthy heart. If the readings differ with more than, say, 5%, an alarm would be triggered.

By the way, this thing will be able to fit in a box 30mm by 30mm by 15 along with a bluetooth module and LiPo battery. All that remains is to start the work on a box, the T-shirt and the code.

The concept's done, though.

I'll keep you posted