1. BioSignal Processing

2. Introduction Biological signals or biosignals
Are space, time, or space–time records of a biological event such as a beating heart or a contracting muscle. The electrical, chemical, and Mechanical activity that occurs during these biological event often produces signals that can be measured and analyzed.
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.

3. Introduction Data acquisition Signal analysis
Digital processing methods
Data acquisition
Using stethoscope to listen to patient’s heart
Signal analysis
Retrieve useful information
Amplification
Filtering
Digitization
Processing
Storage

4. Physiological Origins of Biosignals
Bioelectric Signals
Generated by nerve and muscle cells as a result of electrochemical changes within and between cells
Can be measured with intracellular or extracellular electrodes
ECG, EGG, EEG, and EMG are results of the Bioelectric signals taken from the human body

5. Physiological Origins of Biosignals
Biomagnetic Signals
Different organs(heart, lungs & brain) generate weak magnetic fields
Measured from specific physiological activity that is linked to an accompanying electric field from a specific tissue or organ
Uses very precise magnetic sensors or SQUID magnetometers (Superconducting Quantum Interference Device)

6. Physiological Origins of Biosignals
Bio magnetic Signals (cont.)
Magnetoencephalography (MEG) - monitor magnetic activity from the brain
Magnetoneurography (MNG) – monitor peripheral nerves
Magnetogastrography (MGG) – monitor gastrointestinal tract
Magnetocardiography (MCG) – monitor the heart

7. Physiological Origins of Biosignals
Biochemical Signals
Contain information about changes in concentration of various chemical agents in the body
Oxygen concentration
Determine levels of glucose, lactate and metabolites
Provides information about the function of various physiological systems

8. Physiological Origins of Biosignals
Biomechanical Signals
Produced by the mechanical functions of biological signals such as:
motion, displacement, tension, force, pressure, and flow
Blood pressure measurement

9. Physiological Origins of Biosignals
Bioacoustic Signals
Are special subset of biomechanical signals that involve vibrations (motion)
Respiratory system, joints, and muscles generate distinct bioacoustic signals
Often measured at the skin using acoustic transducers such as microphones and accelerometers

10. Physiological Origins of Biosignals
Biooptical Signals
Generated by the optical, or light-induced, attributes of biological systems
May occur naturally or signals can be introduced to measure a biological parameter using an external light medium

11. Characteristics of Biosignals
Biosignals can be classified according to various characteristics:
Waveform Shape
Statistical Structure
Temporal Properties
2 broad classes of signals:
Continuous
Discrete

12. Characteristics of Biosignals
Continuous Signals
Defined over a continuum of time or space and are described by continuous variable functions
Produced by biological phenomena:
Like voltage measurements from the heart
Arterial blood pressure measurements
Measurements of electrical activity from the brain

13. Characteristics of Biosignals
Discrete Signals
Defined only at a subset of regularly spaced points in time and/or space
Commonly used in today’s clinical setting
Continuous signals from human body are converted to discrete signals that can be analyzed and interpreted by a computer