An EEG is a procedure that detects abnormalities in your brain waves, or in the electrical activity of your brain.

1. Measurements from Nervous System:
Electroencephalogram (EEG)
Online Class
Subject : Biomedical Instrumentation
Presented By
Mr. Gaurav Pandey

2. EEG – Key Points
1. Records Electrical activity of the brain, by suitable placing
surface electrode on scalp.
2. Minimum of 25 electrodes inputs are used ( 21 on the scalp,the
system reference , ground and 2 extra).
3. EEG electrodes are arranged on the scalp according to a
standard known as the 10/20 system, adopted by American EEG
society.
4. Fast Fourier Transformation of the digitized EEG waveform is in
the form of spectrum is done.
5. Amplitude Analysis : Amplitude changes indicate clinical changes
and further signifies the result in changes of power.
6. Amplitude of EEG is in microvolt and power is in nanowatts or
picowatts.

3. 10-20 System of Placement of Electrodes

4. SCHEMATIC DIAGRAM OF AN EEG MACHINE

5. Brain Waves

6. • Interference problem is reduced by differential
amplifier(preamplifiers)
• Filter bank:- consists of appropriate filters to
select different types of brain waves.
• Output can be given to 8-channel pen recorder,
display unit, computer storage memory for
further processing.
• Evoked Potential:- Measure of the “disturbance”
in the EEG pattern that results from external
stimuli.
• Time delay between stimulus and response can
be measured in signal processing unit.
Key takes