ECE4552: Medical Electronics By Ijlal Haider Intro to Biosignals ECE4552: Medical Electronics By Ijlal Haider

BioSignals Human body is a complex system comprising many Electrical, Mechanical and Chemical subsystems The electrical, chemical, and Mechanical activity that occurs during these biological event often produces signals that can be measured and analyzed. These signals are space, time, or space–time records of a biological event such as a beating heart or a contracting muscle. They contain useful information that can be used to understand the underlying physiological mechanisms of a specific biological event or system, and which may be useful for medical diagnosis.

Major Systems of Human Body Neuromuscular (Electromechanical & Electrochemical) Information processing, control & communication Cardiovascular (Electromechanical) Transportation, blood is the carrier Digestive (Chemical) Respiratory (Chemical) Lymphatic (Chemical) Reproductive (Chemical) Endocrine (Chemical) Also controls several mechanisms

Information from Biosignals Functional Information Electrical EEG EMG ECG Other MEG fMRI fNIRS Structural Information (Images) X-Ray CT Scan Ultrasound MRI

Bioelectric Signals Traditional Non Traditional EMG, ENG: Muscles ECG (or EKG): Heart EEG, ECoG: Brain Non Traditional EGG: Stomach EOG: Eyeball ERG: Retina GSR: Skin Some other signals such as breathing, temperature, movement etc.

Neuromuscular System Nervous Subsystem Muscular Subsystem Central Brain, Spinal Cord Peripheral Nerves (motor, sensory) Muscular Subsystem Muscles

EMG - Electromyogram

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

EMG electrodes (active) EMG electrodes (passive)

EMG electrodes (active)

Recording locations for facial EMG

Needle electrodes adhesive electrode

EMG activity: averaging absolute vaues

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

EOG - Electrooculogram

Electrooculogram (EOG), Eye Dipole

Saccadic eye movements to the left and right

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

EEG - Electroencephalogram

EEG Electrode – cap locations of the 10/20 system

Parts of Brain and Functions 3 Major Parts The Medulla Oblongata helps in control of Autonomic Functions, Relay of Nerve Signals Between the Brain and Spinal Cord Coordination of Body Movements The Cerebellum is involved in the coordination of voluntary motor movement, balance and equilibrium The Cerebrum is the newest (evolutionarily) and largest part of the brain as a whole.  It is here that things like perception, imagination, thought, judgment, and decision occur (consists of many lobes, links on next slide)

Cortical Areas

Motor & Somatosensory Cortices

Further Readings For interesting information on different parts of brain and their functions, visit http://www.brainhealthandpuzzles.com/brain_parts_function.html http://webspace.ship.edu/cgboer/genpsycerebrum.html (for Cerebrum in detail how it controls )

Configuration of Electrodes Needs a standard configuration of electrodes on the brain 10-20 system is accepted worldwide The top of head is divided into grids of 20%, 20% and 10% from the center to the sides

10-20 System

Configuration of Electrodes

Unipolar measurement ( indifferential right ear electrode ) Bipolar measurement

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

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

EEG artifacts: Eye blinks, muscle tension

EEG artifacts: movement, electrode drifting

EEG artifacts: mains interference, 50/60Hz noise

Intracortical / chronical electrodes

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

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

ECG - Electrocardiogram

ECG: Heart- vector, QRS Complex

Origination of the QRS - Signal

Composition of ECG Signal

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

ECG measurement: Wilson

12 (and beyond) Lead ECG

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

Other (nonelectric) Biosignals

Electrogastrogram (EGG)- Gastric Myoelectric Activity

Electroretinogram (ERG)

Blood pressure sensor Infrared plethysmography blood volume amplitude

Galvanic Skin response (GSR) Electrodermal Activity (EDA) Skin Conductance Level (SCL)

Summary bioelectric signals Frequency Amplitude (mV) ECG 0.2 – 300 0.1 - 3 EEG DC – 100 0.005 - 0,2 EEG (cortical) 10 – 100 0.015 - 0,3 EMG 10 – 1000 0.1 - 5 EMG (needle) 10 – 10000 0.05 - 5 EOG DC – 30 0.1 - 2