Biomedical Engineering Reference
In-Depth Information
TABLE 2.1
Frequency Ranges of Various Biopotential Signals
Application
Frequency Range
Action potentials detected with transmembrane
dc-2 kHz
pipette electrodes
Electroneurogram
(ENG): nerve bundle potentials
10 Hz-1 kHz
detected with needle electrode
Electroretinogram
(ERG): potentials generated
0.2-200 Hz
by retina in response to a
fl
flash of light; detected
with implanted electrodes
Electrooculogram
(EOG): eye potentials used
dc-100 Hz
to measure eye position; detected with surface electrode
pairs: left/right and above / below eyes
Electrogastrogram
(EGG): stomach potentials detected
0.01-0.55 Hz
with surface electrodes placed on abdomen
Electroencephalogram
(EEG): rhythmic brain potentials
Delta waves
0.5-4 Hz
detected with surface electrodes placed on head
Theta waves
4-7.5 Hz
Alpha waves
7.5-13 Hz
Low beta waves
13-15 Hz
Beta waves
15-20 Hz
High beta waves
20-38 Hz
Gamma waves
38-42 Hz
Brain evoked potentials
: brain potentials evoked by stimuli;
Visual evoked potential (VEP)
1-300 Hz
detected with surface electrodes placed on head
Auditory evoked potential (AEP)
100 Hz-3 kHz
Somatosensory evoked
potential (SSEP)
2 Hz-3 kHz
Electrocardiogram
(ECG): heart potentials detected with
Heart rates (R-R intervals)
0.5-3.5 Hz
surface electrodes placed on chest, back, and/or limbs
R-R variability due to
thermoregulation
0.01-0.04 Hz
R-R variability due to barore
fl
ex
dynamics
0.04-0.15 Hz
R-R variability due to respiration
0.15-0.4 Hz
P,QRS,T complex
0.05-100 Hz
Ventricular late potentials
40-200 Hz
Bandwith requirement for
clinical ECG/rate monitors
0.67-40 Hz
Clinical cardiac electrophysiology
: analysis of cardiac
Intracardiac electrograms
10 Hz-1 kHz
potentials detected with catheter electrodes placed in
Monophasic action
contact with the myocardium
potentials (MAPs)
dc-2 kHz
Electromyogram
(EMG): muscle potentials detected
Surface EMG
2-500 Hz
with surface electrodes or indwelling needle
Motor unit action potentials
5 Hz-10 kHz
electrodes
Single
fi
fiber electromyogram
500 Hz-10 kHz
Galvanic skin response
(GSR): battery potentials
dc-5 Hz
produced by sweat on skin electrodes
current limiters are used for redundant protection of the subject from leakage currents. C25,
C27, and C26 are used to protect the ampli
er from high-frequency currents, such as those
used in electrosurgery and ablation procedures. R21 and R24 limit the impedance of each
input to 10 M
fi
referred to the circuit's isolated ground. These resistors provide enough bias
to maintain high immunity to common-mode signals without the need of a patient ground
electrode. Diodes D7-D10 are used to protect the inputs of IC5 from high-voltage transients
such as those expected from de
Ω
fi
brillation and electrostatic discharge.
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