Ultrasonic Doppler Fetal Monitor...

Don't get all excited: I have no idea how to do this yet.

My wife has rented an ultrasonic pocket Doppler to keep an eye (ear) on our new additions. I would not be surprised if we can, and so feel challenged to try to, make Arduino do this for us.

Anyone have any relevant experience to relate that will help me to listen to my little guys' heartbeats?

I don't even know where to begin! A good place to start is theory and workable components, so I'm all ears if you can get me started.

Thanks so much, folks.

I am not a medical tech, so I ran this past a friend who is.

Like myself, he tends to be rather long winded in his explanations, so I have condensed his tutorial. ;)

Here is the gist of what he told me...


The wavelength of the ultrasound must be short compared to the size of the object being detected.

Readily available transducers operate at about 40 Khz. The corresponding wavelength, in soft tissue, is 4 to 5 cm.

That wavelength is not short enough to be effective in detecting objects as small as a fetal heart. Fetal dopplers operate at about 2.5 Mhz, with a wavelength in soft tissue of about 1 mm.

But if you can obtain suitable transducers, an FM detector can be used to recover the heartbeat.