Myoware Muscle Sensor noise in the ER

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xykudyax

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Hi everyone,

I'm trying to acquire data from Myoware Muscle sensor either using RAW or SIG values (currently using RAW).
I'm using it inside the ER room and there are a lot of other machines there EEG, ECG...
My problem is that I'm getting a lot of noise...

Captura de ecra? 2017-10-20, a?s 11.22.15.jpg

... right now this information is useless!!
When I try the device in my home the data is perfectly clean.
What do you suggest what could be the problem I'm facing?
I tried changing the cables (I was using the electrode cables) and replace them by thin coaxial cables...
but no big improvements were seen.

I'm now trying to buy smaller electrodes (I'm trying to read eye muscle.. which is very small).
Does using SIG change my problem in any way?! also I need to be precise because this is a medical device,
so SIG does have some filtering applied to it... what is it?! and also the gain resistor (tends to change just by handling the device)...
rendering the acquired data useless again (because of gain fluctuations)
 
How quickly did you capture the data? Is the sampling jitter low?

Maybe try running a FFT over sections of the data and look if the interference has any strong spectrum, like maybe 50 or 60 Hz (and harmonics)?
 
As others have pointed out, it sounds like there is more ambient electrical noise at the ER than your home. I'm assuming you're using the Cable Shield and external cables with the sensor. That being the case, there's a few things you can try before switching to shielded cables.

1) Braid the cables. This helps make the noise common to both input lines which will then get removed by the CMRR of the instrumentation amplifier.
2) Coil Extra Length. The cables unfortunately make great antenna (which is why the new design has embedded electrodes). Making the "antenna" smaller by coiling any extra length in the cables can help in this regard.

Is there any other difference in your setup between your house and the ER? Using a laptop with the power cord plugged in to power the sensor?

As for the SIG output, this output won't resolve the noise you're seeing because all the noise removing circuitry is common to both the RAW and SIG outputs. The SIG output simply has rectification and integration tacked on.

When you say the gain potentiometer is fluctuating just by handling it... are you measuring it when the sensor is powered on? Also, the adjustable gain is only for the SIG output and doesn't affect the RAW output.
 
Could you post a pic of what it looks like when it appears to be working?

The amplitude seems too small to expect that you would capture anything physiologic or even external noise: ~0.1uV

It looks like some digitization noise to me.

What eye muscle or movement are you trying to capture?
 
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