Multichannel Systems HiClamp Manual - Manual (Page 26)

HiClamp Manual
20
5.2 Electrode Alignment
Mounting and adjusting the electrodes
First, mount the provided glass capillaries on the measuring head. Use a binocular and adjust
the tip distance between 300 and 400 μm. Also be careful to align the tips to be at about the
same height. Then, fill the capillaries with either 3 M KCl or with a mixture from KCl and KAc
which reduces crystallization (1 M and 1.5 M, respectively). Filling should not exceed about
70 % of the capillary length.
Try to insert the filling needle or micro loader as close as possible to the tip region. Try to avoid
to have any air bubbles in the capillary after filling. The tip region usually fills by itself, because
the capillaries have a filament inside, but this takes sometimes a few minutes. Be patient and
wait until the tip region fills spontaneously. Tipping against the capillary in order to speed up
the process very often ends up in having many small air bubbles in the tip region making the
capillary unusable.
After filling, insert the provided AgAgCl wires. A small drop of mineral oil can be finally added
on the top of each electrode opening to prevent evaporation.
Please put the oil on top of each glass capillary after inserting the electrode wires! Otherwise
the AgAgCl coating will soak up the oil and destroy the electrical properties of the electrode.
Important: The recommended electrode resistance is in the range of 100 kilohms to 1 megaohm.
The electrode resistance also limits the maximum gain that may be used. It is considered a normal
behavior of electrodes that the resistance increases over time. It is recommended to use only
high-quality oocytes (with high membrane potential and low leak current) to avoid blockade
of the electrode tips. For an optimum clamp performance of the TEVC amplifier, the electrode
impedance should not exceed the recommended range.
Warning: Use only a well-chlorided silver wire for all electrodes. Use a diameter of 0.4 mm
if you plug the wire directly into the connectors of the vertical axis in order to avoid
damaging the vertical axis. We recommend the use of the provided connectors for
a better handling.
Once the measuring unit is installed on the HiClamp it is necessary to adjust the maximal depth
at which the electrodes will be moved during oocyte impalement. Please use the camera for
optical control of this alignment.