1. Origin and Characteristics of Bioelectric Signals
Unit I
Chapter
Origin and Characteristics of Bioelectric Signals
ECG, EEG, EOG, EMG, PCG
Electrodes and sensors

2. Origin of Bioelectric Signals

3. Na-K pump Vm

4. Cell membrane, channel proteines

5. Electrical and chemical gradients
at the semi-permeable cell membrane

6. Ion
Intracel.
extracel.
potassum K+
400 20
Sodium Na+ 50
440
Chlorid Cl-
108
560
organic Aniones
460
Electrical and chemical gradients
at the semi-permeable cell membrane

7. Nernst – equation (chemical potential):
R … Gas-Constant = 8,3143 J / (mol·K)
T … Temperature (Kelvin)
Goldman – equation (for different ions):
As a result, we get a membrane resting potential of about -70mV

8. Depolarization
Sodium Cations
rush in
Hyperpolarization
Potassom Cations
rush out

9. Maintaining the
Resting potential
Sodium/potassum
Ion pump

10. Voltage- and Time dependent activation of Ion Channels:
the physiological basis for action potentials
Sodium-Channel Potassum- Channel

11. Hodgkin - Huxley Model (1952)
● Researched the Giant Squid-Axon
● Used the Voltage-Clamp technique
-> Isolation of channel currents of
Na und K
● Developed a model for the function
of the channel proteines
Alan Hodgkin
Andrew Huxley

12. Sodium and Potassum conductance
Calculated by the Hodkin Huxley Model (curve), measured (dots)

13. Action potential: the result of Na and K Ion movement through the membrane

14. Action Potentials

15. Axo-dendritic
transmission of
action potentials,
Synaptic transduction

16. Synaptic coupling, release and uptake of neurotransmitters

17. Types of nerve cells, Synaptic coupling

18. Signal Pathways
in the central nervous system

19. Bioelectric Signals

20. ECG Electro-Cardiogram, Heart activity EMG Electro-Myogram, Muscle movement EOG Electro-Oculogram, Eye movement EEG Electro-Encephalogram GSR Galvanic Skin Response
● Measured with electrodes: skin-electrode interface: Ions <--> Electrodes
Breathing, temperature, movement etc.
● Measured with other sensors / transducers:
NTC, LDR, piezo-crystal, hall-sensor, Accelerometer, Goniometer, …

21. ECG - Electrocardiogram

22. ECG: Heart- vector, QRS Complex

23. ECG measurement: Goldberger (left) and Einthoven (right)

24. ECG measurement: Wilson

25. Origination of the QRS - Signal

26. ECG - applications ● Diagnostics ● Functional analysis
● Implants (pace maker)
● Biofeedback (Heartrate variability, HRV)
● Peak Performacne Training, Monitoring

27. EMG - Electromyogram

28. EMG surface (glue-) electrodes EMG - signal (up to 3mV, 1kHz)

29. EMG electrodes
(active)
EMG electrodes (passive)

30. EMG electrodes
(active)

31. Recording locations for facial EMG

32. Needle electrodes adhesive electrode

33. EMG activity: averaging absolute vaues

34. EMG - applications ● Rehabilitation ● Functional analysis
● active Prothetics, Orthesis
● Biomechanics, Sports medicine

35. EOG – Electro Oculogram

36. Electrooculogram (EOG), Eye Dipole

37. Saccadic eye movements to the left and right

38. EOG - applications ● Diagnostics ● Functional analysis
● Human Computer Interfaces

39. EEG - Electroencephalogram

40. EEG Electrode – cap locations of the 10/20 system

41. Unipolar measurement ( indifferential right ear electrode ) Bipolar measurement

43. EEG, dominant frequencies, < 300 uV

44. EEG, Alpha bursts when eyes closed, alpha desynchronisation when eyes opened

45. Quantitative EEG (QEEG), many EEG channels (up to 256) source / dipole localisation

46. Auditory Evoked
Potentials (AEP)
Trial averaging
Also:
VEP
SSEP

47. EEG artifacts: Eye blinks, muscle tension

48. EEG artifacts: movement, electrode drifting

49. EEG artifacts: mains interference, 50/60Hz noise

50. Intracortical / chronical electrodes

51. Active EEG- electrode Singe disk gold plated electrodes
Ear clip electrode

52. EEG - applications ● Diagnostics (Epilepsy, Oncology, ..)
● Cognitive Sciences
● Sleep Analysis
● Human Computer Interfaces (BCIs)
● Pharmacology
● Intensive Care, Monitoring

53. Other (nonelectric) Biosignals

54. Blood pressure sensor Infrared plethysmography
blood volume amplitude

55. Breathing Sensors (thermal / mechanoresistive)

56. Galvanic Skin response (GSR) Electrodermal Activity (EDA) Skin Conductance Level (SCL)
peripheral body temperature

57. Summary bioelectric signals
Frequency Amplitude (mV)
ECG ,2 – ,1 - 3
EEG DC – , ,2
EEG (cortical) – , ,3
EMG – ,1 - 5
EMG (needle) 10 – ,05 - 5
EOG – ,1 - 2
Intracell –