EMG acquisition by USB 6218

[kbakal]

Hi!

I am using an the NI USB 6218 to acquire a sEMG signal on labview 2010.

To get the sEMG signal, I have a ME6000 from megawin but I want to save it directly with my VI.

I have found the EMG analysis start up kit but it seems to lack of some VI (https://decibel.ni.com/content/docs/DOC-8206).

So I programmed my own VI using DAQ assistant. My electrode are plugged on AI17 and AIGND and I configured a RSE signal in the DAQ.

My problem is the signal I watch: it is not changing when I contract my muscle or not.

I tried to post-process my signal with De Luca method (get rid of the offset, applying a 20hz HP filter, whitening) and also by just using a BP filter (20 - 500 Hz).

If you have any suggestion to improve my signal/noise rate, I'ld be happy to ear.

Thanks,

Karim

[kahenneberg]

Dear Karim

As I understand from your posting you are trying to amplify and EMG signal directly with the instrumentation amplifier in the NI USB 6218.

And, it seems to me that you are using a single ended technique in the sense that you ground the patient and record the signal with just one electrode (connected to AI17). That won't work.

You need tree electrodes, one for connecting the patient to amplifier ground, and two for making a differential recording.

I would recommend that you try to amplify the signal with a separate instrumentation amplifier and then feed the signal from that to the NI USB 6218.

How do you establish patient isolation with your setting?

K. Henneberg

Technical University of Denmark

[kbakal]

Thank you for your answer.

I think I didn't explain my problem very well : I'm using 3 electrodes system ( + / gnd / - ). With the ME6000, the differential is already done. So I just have to plug on AI17 and AIGND to get my signal.

My problem was to have a proper signal on Labview. I found that I have to first launch a measure on the ME6000 to get a real EMG signal with muscle contraction.

Karim