Miniaturized eight-channel telemetry system for long-term EEG registration of humans and laboratory animals.

According to the increasing importance of telemetric EEG registration, a miniaturized telemetry system for AC and DC transmission has been developed. The basic model has been constructed for the demands of experiments with small rodents. The transmitter is 19 X 13 X 5 mm in size and weighs 5 g including two 1.5 V batteries. The transmission of AC or DC potentials can be chosen for each channel separately. In the case of eight-channel transmission, the bandwidth ranges from 0.8 to 100 Hz, and in the case of using only one channel, signals up to a frequency of 17 kHz may be registered. Semimicroelectrodes with an electrode impedance of about 10 M omega, as well as conventional surface electrodes can be applied. In case of long-term EEG registration of humans the total amplification at V = 1,000 has to be enlarged by using an extension module. This module consists of an additional amplification stage, a modified HF oscillator to enlarge the omnidirectional transmission sphere and external batteries to increase the operation time of the transmitter. Small dimensions, light weight and multifunctionality plead for the attractivity of this construction according to various clinical and experimental demands.