Multichannel Systems MPA8I Manual - Manual (Page 9)

Welcome to the MPA8I
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2 Welcome to the MPA8I Miniature Preamplifier
The 8-channel miniature preamplifier MPA8I is connected to the microelectrodes for providing
the initial tenfold amplification stage.
It has additional common ground and reference electrode inputs. The reference electrode is
ideally identical to the recording electrodes and placed into a comparable but inactive area or tissue.
Background or noise signals that are picked up by both the reference electrode and the recording
electrodes are removed.
The metal case provides electrical shielding. Electrode damage is prevented by the very low bias
current. The high input impedance ensures stable long-term recordings: Ideally, the input
impedance would be infinite. As low voltages are generally recorded, a high current would flow
if the input impedance were low. As a result, the amplifier would not be able to deliver the current,
and the voltage would break down. The miniature preamplifier has a high input impedance to avoid
this problem.
Adapters for all standard microelectrodes such as NeuroNexus probes (NeuroNexus
Technologies) for acute and chronic implantations ensure a close proximity to the probe to minimize
signal loss and cross talk. Adapters are not included in the standard scope of delivery and have to be
ordered separately. For custom adapters, please ask your local retailer or contact Multi Channel
Systems MCS GmbH.