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Topic: Piezo element for sensing heartrate/pulse (Read 1 time) previous topic - next topic

Has anyone have success with using piezo element to create a pulse sensor (essentially detects vibration from you pulse)?
I looked into Spooky Arduino site http://todbot.com/blog/bionicarduino/ and their setup and the coding doesn't give a consistent
reading of the pulse. I was wondering if anyone can give me some advice with making a pulse sensor for wearable technology.

Piezo Film
http://www.sparkfun.com/products/9196

Thank you.

MarkT

Firstly I'd say you'll need to do some experiments to find the right value of load resistance to get a reasonable output signal - a 'scope very useful for this.

Then you'll have to think about signal processing and detecting the wanted information from the noise...  Without seeing a typical signal its impossible to know how tricky that might be.
[ I won't respond to messages, use the forum please ]

Artem_F

in addition to the first answer:
if you don't have a scope then you may try the following methodology:
make several iterations with different R_load mentioned in the description
of the sensor: for example, 1K, 10K, 100K, 1M
At each iteration try to fill an internal array of ~15-20K with samples taken
about 100 times/second. After you've finished collecting the
data, send them via serial output to your computer
and study what you've measured.
If you see something with the period of about 1 sec then it's the
signal you are looking for. Then you can try playing with it
using standard data processing software on your computer and
when you identify what you need to do with the signal to
detect the pulse rate (averaging, sliding window, Fourier transform, etc)
then you can transfer the methodology to Arduino.



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