Multichannel Systems MEA-IT Manual - Manual (Page 24)

Impedance Testing Device MEA-IT Manual
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4.2.3 Running a Measurement
Note the serial number and type of the MEA, and mount it in the correct orientation
in the MEA-IT device (please read chapter "Mounting the MEA").
Open the MEA-IT software and click the button "Measure" in "Main Controls" to start
a measurement. The "Select MEA" dialog appears.
Please type the serial number of the MEA into the "MEA-ID" in the drop down box.
The program will save the ID and you can select it from the drop down menu, when
measuring the same MEA again.
Please select a MEA "Layout" from the drop down menu. This is important, because the
diameter of an electrode has a major influence on its impedance: Smaller electrodes have
a higher impedance than bigger electrodes. For example, electrodes with 30 μm have an
impedance of about 30 - 50 kOhm and smaller electrodes with a diameter of 10 μm have
an impedance of about 250 - 400 kOhm. The impedance of an electrode also depends on
the hydrophilic properties of the electrode. If an electrode is hydrophobic, the measured
impedance will be too high.
The selection in “Layout” also defines the appearance of the virtual MEA layout. If the MEA
is already present in the database the "Layout" and the "Time of Initial Operation" will
be set automatically.
When testing a MEA with internal reference (iR), please activate the check box "Internal
Reference". The reference electrode is much bigger than the recording electrodes, that is
why the impedance should be very low. The MEA-IT software will therefore use different
reference values to evaluate the reference electrodes than the regular recording electrodes.
The "Time of Initial Operation" is the date that should be entered at the first measurement
of each MEA. It will be saved with the MEAs database file and helps the user to keep track on
the age of an array. The content of the "Comment" window will also be saved together with
the measurements.
The drop down menus "MEA-ID" and "Layout" are labeled with an asterisk *. They are required
to start a measurement.