I have been working on setting up the Epileptic Seizure Detector. I tried wearing it for a while, and simulating the shaking associated with a tonic-clonic seizure. Some example spectra collected on the memory card are shown below:
This shows that the background noise level is at about 4 counts.
Wearing the accelerometer on the biscep gives a peak up to about 8 counts at 7 Hz, but it is not well defined.
Wearing the accelerometer on the wrist gives a much more well defined peak at 6-7 Hz. (and it raised an alarm nicely).
I have also tried an ADXL345 digital accelerometer. The performance is similar to the analogue one, but I think it may be slightly more sensitive. Example spectra with the accelerometer attached to the biscep are shown below. ONe is a simulated fit. The other is a false alarm going down the stairs. Not that much difference!
Therefore I think there is scope for this set up to work if it is worn as a wrist watch, but just attaching it to other parts of the body may not be sensitive enough.
I wonder if I could make a wrist sensor that is watch sized, with a wireless link to a processor / alarm unit?
Not sure if I will be able to persuade Benjamin to wear a wrist sensor though....Might have to think about microphones.