Minimizing EMI artifacts in Open Ephys recordings during mechanical whisker stimulation

[Rebecca Huang]

Hi everyone,

I'm using Open Ephys to record from tungsten wire electrodes in mouse, with simultaneous whisker stimulation. My entire setup is inside a Faraday cage (see diagram).The stimulation and acquisition systems are electrically isolated, but whenever the servo motor moves, I see artifacts like the ones shown below. This is LFP with 0.5-60 Hz filter:

I've tried shielding the servo motor wires, the motor itself, and the headstage with aluminum foil — the artifacts persist. Switching to a solenoid (no PWM, just digital high/low) reduced but didn't eliminate the problem; I still see similar dips. Twisting the signal and reference wires together also had no effect.

Is there something fundamentally wrong with my setup? Or is there a better approach for mechanical whisker stimulation that introduces less EMI? Thanks so much!

Best,

Rebecca

[Josh Siegle]

Hi Rebecca,

It looks like this was already answered on the Discord – as Jon said, the main thing is to avoid connecting your headstage ground to the Faraday cage. The headstage ground should be connected to the animal ground (e.g. via a ground screw or saline bath above the brain), which should ideally be isolated from everything else on your rig. For example, the mouse should not stand on a conductive platform that's contacting a metal air table.

Moving the servo motor outside the Faraday cage may also help.

Best,

Josh

--
You received this message because you are subscribed to the Google Groups "Open Ephys" group.
To unsubscribe from this group and stop receiving emails from it, send an email to open-ephys+unsubscribe@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/open-ephys/5232cbc7-6391-4a01-9bb8-20bb91ca1c06n%40googlegroups.com.