Geodesic Sensor Net - Page 59

6: Applying the GSN
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Geodesic Sensor Net Technical Manual S-MAN-200-GSNR-001 • January 31, 2007
• HydroCel HS (without sponge insert) : For extended (12-hour) recordings, this is
a hydrogel formulation that requires individual electrode filling. The HydroCel
HS comes in powder form and must be mixed with water before using. No
shampoo is required for cleanup.
Use these solutions only on EGI Geodesic EEG Systems. The GSN 200 and the
HCGSN with sponge inserts use only the HydroCel Saline; the HCGSN without
sponge inserts uses only the HydroCel HS.
HydroCel Saline
The HydroCel Saline is EGI’s classic potassium chloride electrolyte solution designed
for standard (2-hour) recordings.
1 Place 10 cc. (2 teaspoons or 11 grams) of granular or powdered potassium
chloride (KCl) into the electrolyte/rinse bucket.
2 Add 1,000 cc. (1 liter or 4.23 cups) of warm distilled water, no warmer than 37° C.
3 Add 5 cc. (1 teaspoon) of Johnson’s Baby Shampoo.
4 Stir the ingredients vigorously, until the KCl is completely dissolved.
HydroCel HS
The HydroCel HS is EGI’s hydrogel-based formulation designed for extended
(12-hour) recordings. An HCGSN without sponge inserts can use this formulation. A
syringe must be used to load the electrolyte into each spongeless pedestal.
The HydroCel HS packet contains 1.0 gram of the HydroCel HS powder. The
formulation is biodegradable and nontoxic.
1 Add 250 cc. (or mL) of warm, distilled water, no warmer than 37° C into the
small HydroCel HS bucket provided with the Net.
2 Open the HydroCel HS packet and slowly stir the contents into the water. If
lumps develop, press them against the side of the container to break them up. If
the solution remains lumpy, let the solution sit for one hour to hydrate properly.
3 The solution is ready when the powder is completely dissolved.
Do not allow the
HydroCel HS solution
to sit for too long (e.g.,
several hours), or the
solution will become
runny. If this occurs,
mix up a new batch of
HydroCel HS.