Multichannel Systems MEA Manual - Manual (Page 11)

MEA Manual
11
3.3 Electrodes, Tracks, and Insulation
Microfold structures result in a large surface area that allows the formation of electrodes with an excellent
signal to noise ratio without compromising on the spatial resolution.
TiN (titanium nitride) is a very stable material that, for example, is also widely used for coating heavy
equipment. All MEAs with TiN electrodes have a long life and can be reused several times if handled with
care. If used for acute slices, MEAs can be used for approximately one year. Additionally available are
EcoMEAs equipped with gold (Au) electrodes.
Long-time experiments with cell cultures and rigid cleaning methods shorten the MEA lifetime, but you
can still reuse a MEA about 30 times, depending on the coating, cell culture, and cleaning procedure.
All MEAs (except pMEAs) show excellent temperature compatibility and are stable from 0 °C to 125 °C,
that is, they can be autoclaved.
The impedance of a flat, round titanium nitride (TiN) electrode ranges between 30 and 400 kiloohms,
depending on the diameter. The smaller an electrode, the higher is the impedance. On one hand, lower
impedance seems desirable, but on the other hand, a smaller electrode and interelectrode distance results
in a higher spatial resolution.
Multi Channel Systems provides MEAs with TiN electrodes with sizes of 10, 20, or 30 μm and gold
electrodes with 100 μm, which all show an excellent performance and low noise level. The average
noise level of 30 μm and 10 μm electrodes is less than 10 μV and 15 μV peak to peak, respectively.
Gold electrodes (EcoMEAs) are only available with a low spatial resolution and are useful for medium
throughput screening, where costs are a limiting factor.
All planar TiN electrodes are positioned on a round pad with a diameter of 40 μm. If you like to check
the electrodes with a light microscope, you will need an upright microscope to see the MEA from above.
With an inverse microscope, you are only able to see the (bigger) pad from below, not the electrode itself.
The electrodes are embedded in a carrier material, usually glass. Standard tracks made of titanium (Ti)
or indium tin oxide (ITO) are electrically isolated with silicon nitride (SiN). Standard contact pads are made
of titanium nitride (TiN) or indium tin oxide (ITO). ITO contact pads and tracks are transparent, for a perfect
view of the specimen under the microscope.