Multichannel Systems MEA2100-System Manual - Manual (Page 51)

Troubleshooting
47
6.5
MEA is defective
MEAs wear out after multiple uses or over a longer time of use, for example, for long-term
cultures. This is considered a normal behavior. MEAs are also easily damaged by mishandling,
for example, if wrong cleaning solutions or too severe cleaning methods are used or if the
recording area is touched. If you observe a bad long-term performance of MEAs, consider
a more careful handling.
Possible causes:
? The contact pads are contaminated.
Clean the contact pads carefully with a swab or a soft tissue and pure (100 %) alcohol.
? The contact pads or the electrodes are irreversibly damaged. You could have a look at the
electrodes under a microscope: If they appear shiny golden, the TiN is gone and the electrode
is irreversibly damaged. Electrodes may be damaged without changing their visual appearance,
though.
Pick one of the bad channels after the other and ground it. See the MEA amplifier's manual for
more information on grounding channels. In most cases, only one of the electrodes that appear
bad is actually defective, and the other ones are only affected by the single defective electrode.
Ground as many electrodes as you need for a good general performance. Grounded electrodes
show a noise level that is lower than that of good electrodes. If too many electrodes are defective,
use a new MEA.
6.6 Overall Noise / Unsteady Baseline
The baseline is unstable, signals are jumping or drifting.
Possible causes:
? Bath electrode is not connected to ground.
Check orientation of MEA with internal reference. The internal reference must be on the left side
of the MEA when it sits in the amplifier. If the MEA has an internal reference, use a Ag/AgCl bath
electrode.
? AgCl bath electrode 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 and / or under the
amplifier that is connected to the system ground (ground connectors of the headstage or ground
connector in the back of the interface board). You can also use special shielding equipment like
a Faraday cage.