Multichannel Systems MEA Manual - Manual (Page 60)

MEA Manual
60
9.4 Overall Noise / Unsteady Baseline
The baseline is unstable, signals are jumping or drifting.
Possible causes:
? Bath electrode is not connected to ground.
 Connect the internal or external bath electrode to one of the ground inputs of the amplifier.
? AgCl bath electrode needs is not well-chlorided.
 Rechloride the electrode or use a new one.
? 50 Hz hum: 50 Hz is the frequency of mains power in Europe. If the shielding and grounding of the setup
is not sufficient, electrical signals are picked up from the environment.
 Use a proper shielding. For example, you can place aluminum foil over the amplifier that is connected to
any metal part of the MEA amplifier. You can also use special shielding equipment like a Faraday cage.
The following screen shot shows a recording of a 60MEA200/30 without bath electrode and without
shielding. You see that the signals are so high that the amplifier gets saturated, and you see a very strong
50 Hz hum.
The next pictures show the same MEA with bath electrode (silver pellet), but without shielding.
The baseline is very unsteady and oscillates with a frequency of 50 Hz.