Features - Geodesic Sensor Net Technical Manual

2: HCGSN
Quick Application, Extended Use
As with the GSN 200, pressure is evenly distributed across all sensors in the HCGSN.
The enhanced head fit, lower pedestal design, and new HydroCel HS formulation
allow the HCGSN to be worn for as long as 12 hours.
All sensors for recording are contained in the HCGSN's structure, making application
a quick, one-step process. Typical application times are less than 10 minutes—even
for 256-channel HCGSNs—with typical impedances in the 50–100 kΩ range. No
special scalp preparation is required.

Features

Sensors and Electrodes
Each HCGSN (except for the 32-channel models used with the GES 120 and 140)
contains an array of EEG sensors, plus a reference sensor and an isolated common
sensor. Each sensor corresponds to an amplifier channel. Sensor maps are shown in
Appendix B, "Net Sizing and Sensor Layouts."
(The 32-channel HCGSN for the GES 120 and 140 contains no separate reference
sensor because it is designed to interface with the Neurotravel amplifier. In this
HCGSN, the average signal on channels 1 and 2 [also known as Fp1 and Fp2] form
the reference.)
An electrode consists of three linked components: a silver chloride–plated carbon-fiber
pellet, connected by a 1-meter-long shielded wire to a Hypertronics-compatible, gold-
plated pin (Figure 2-5). The electrode pellet features a wide, flat base.
Electrode pellet Shielded lead wire Pin
Figure 2-5. Electrode
34
Geodesic Sensor Net Technical Manual
S-MAN-200-GSNR-001 • January 31, 2007