Bio Signal Processing Introduction Biological signals or biosignals

Bio. Signal Processing

Introduction Biological signals or biosignals v. 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 analyzed. v. 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.

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

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

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

Physiological Origins of Biosignals v. Bio magnetic Signals (cont. ) ØMagnetoencephalography (MEG) - monitor magnetic activity from the brain ØMagnetoneurography (MNG) – monitor peripheral nerves ØMagnetogastrography (MGG) – monitor gastrointestinal tract ØMagnetocardiography (MCG) – monitor the heart

Physiological Origins of Biosignals v. Biochemical Signals ØContain information about changes in concentration of various chemical agents in the body ØOxygen concentration ØDetermine levels of glucose, lactate and metabolites ØProvides information about the function of various physiological systems

Physiological Origins of Biosignals v. Biomechanical Signals ØProduced by the mechanical functions of biological signals such as: • motion, displacement, tension, force, pressure, and flow ØBlood pressure measurement

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

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

Characteristics of Biosignals v Biosignals can be classified according to various characteristics: ØWaveform Shape ØStatistical Structure ØTemporal Properties v 2 broad classes of signals: ØContinuous ØDiscrete

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

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