Geodesic Sensor Net Technical Manual page 33

Electrolyte Formulations
Long-term monitoring is enabled by both the HCGSN's pedestal design and EGI's
electrolyte formulations.
• For 12-hour recording, the HCGSN must contain no sponges and must use the
HydroCel HS. Individual electrode filling is required.
• For standard 2-hour recordings, the HCGSN must contain sponges and use the
HydroCel Saline. For recording with infants, see the "Caution" below.
Caution!: For very long-term monitoring (e.g., days), EGI recommends removing
and reapplying the HCGSN at least every 12 hours to improve comfort and to
decrease the risk of skin irritation or breakdown. Careful monitoring of the patient
is recommended.
For full descriptions of the electrolyte formulations, see "Preparing the Electrolyte
Formulation" on page 58.
Electrode Materials
The HCGSN's electrode is designed for low-noise electrophyiological recording.
Electrochemical noise, created by varying half-cell potentials at the electrode–
electrolyte interface, is minimized by a proprietary technology in which carbon fibers
are embedded within a plastic substrate, and then coated with a tough silver-chloride
surface.
The electrode leads, called HydroCel CleanLeads , have a Teflon-core coaxial design
that reduces movement artifacts from triboelectric noise (produced by the friction
between two objects). In addition, the coaxial shielding decreases the pickup of
environmental electromagnetic noise.
More information about the general electrode design is provided in "Features" on
page 34.
Geodesic Sensor Net Technical Manual
S-MAN-200-GSNR-001 • January 31, 2007
2: HCGSN
33