Removing
electrodes from the protective box
To
remove an electrode from
the box, first, spread the slot in the foam and grasp the uninsulated
shaft of
the
electrode with forceps or fingers, then gently lift
it out. Fit into headstage or coupler (e.g. NL04).
It is advisable to
use
watchmaker’s forceps to handle the electrode, however avoid touching the
glass as it can fracture if pressure is applied there by forceps.
You
may also use fingers, but it is advised to operate with great care,
minimising any damage to the electrode shank; in particular, the
electrode tip is extremely delicate and easily damaged.
Avoid storing
electrodes outside of boxes; the tip will be damaged, rendering the
electrode unusable.
If you suspect tip
damage, examine the electrode tip
under light microscope with
x200 or
higher magnification and check the electrode impedance.
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Fitting
electrodes
into tubing or NL04 holder
These
microelectrodes easily fit into 25G, 26G or
27G hypodermic needle tubing. The uninsulated end of
the electrode requires slight bending (e.g. 20deg,
5mm from the electrode end),
and then can be carefully inserted into the tubing. This prevents the
electrode from
slipping out of the holder and ensures optimal electrical contact with
the
holder. We recommend electrode holder: NL04.
The
microelectrodes can also
be soldered into any of above stainless steel tubings. Soldering
tungsten onto stainless steel can be a difficult process; it is
strongly
advised to
use a professional soldering station and stainless steel flux.
The
microelectrodes can be
also crimped within any of above stainless steel tubings or within any
commercially available type of pin holder. It is strongly recommended
to use
a professional crimping tool to avoid any personal accident/injury or
electrode
damage.
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Optimal
electrode use
Our
short-tip electrodes are intended
for single-unit spike recordings and have impedances of several MOhms — this results in high selectivity. It is advised to use
precise
micropositioners with minimum advancing steps of 0.5-2µm for reliable
cell
isolation
(smaller cells require finer searching step).
Best
signal-to-noise ratio is obtained when using an
electrode preamplifier (as close as possible to probing electrode)
with
an input impedance at least one order of magnitude higher than the
electrode impedance. Moreover, consider
avoiding shielding of concentric cables connecting electrode to
preamplifier,
which can significantly reduce the SNR due to its capacitive shunting
effect.
It is strongly
recommended to
perform the experiment in shielded/grounded cabinets (e.g.
sound
booth, Faraday cage) with internal equipment being battery-powered to
minimise the mains hum. Otherwise, recordings will be contaminated
with mains frequency (50Hz/60Hz).
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Cleaning
electrodes
For
longevity, it is best to clean electrodes
immediately after removing from the tissue. The electrodes
can be
cleaned by sonication, e.g. in 30% sodium
hypochlorite for 5 minutes, then should be thoroughly agitated in
distilled
water and then ethanol. Once cleaned, it is advised to check
the condition of electrode
tip under microscope and to measure its impedance.
If tissue remains at the tip after cleaning, repeat the
cleaning/testing
procedure.
Dust particles from
surrounding
air easily adhere to electrode
tips. Thorough rinsing
with distilled water usually removes all dust deposits. However,
electrodes stored for extended periods of time may need sonication
cleaning in distilled water.
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Disposing of used electrodes
Our
electrodes are not
harmful to the environment and can be disposed of as a sharp item.
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