ELEC ENG 4BD4 Lecture 1

1. ELEC ENG 4BD4Lecture 1 Biomedical Instrumentation Instructor: Dr. H. de Bruin

2. Cochlear Implant

3. Advances in Vision (Retinal Stimulation)

4. Mini Gastric Imaging

6. Calendar Description: Principles of instrumentation; Noise and interference in electrical measurements; Generation and nature of bioelectric potentials; electrodes and other transducers; electrical safety; neuromuscular and cardiovascular instrumentation; ultrasonics for bio-measurements other than imaging; computer interfaces for data acquisition systems. Course Objectives: Students will be able to apply the principles of electronic circuits and devices to the use and design of instrumentation in the biomedical area. They will have gained a basic knowledge of the operating principles of electrical and other transducers, analog and digital instrumentation, applied signal acquisition and processing, electrical safety in the medical environment, electrical properties of nerve and muscle physiology; and instrumentation used in cardiopulmonary, neurological, surgical, and rehabilitation areas of medicine.

7. Outline of Topics • Lectures Topics • Measurement systems • Noise and coherent interference in measurements • Analog signal conditioning • Origin of Electrophysiological Signals • Measurement of Electrical potentials and Magnetic Fields from the Body surface • Electrodes; Half-Cell Potential; Equivalent Circuits • Biopotential amplifiers; Medical isolation amplifiers; • Electrical Functioning of the heart • The ECG; Electrode placement; • The ECG; Vector cardiography; Driven-Leg ECG amplifiers; Design Example: QRS complex segmentation • Muscle • The EMG; Design Example: • Brain • The EEG; Design Example: Auditory event related potentials • Other body surface potentials; EOG; Electroretinogram Design Example: Human Computer Interface using EOG signals

8. Sensors commonly encountered in biomedical applications • Temperature sensors – Design Example: ICU system for body temperature monitoring • Large displacement sensors • Motivation: Studying Muscle Activation and Fatigue during the propulsion of a wheel chair • LVDT • Mechano-optical sensors • Design Example: Studying Muscle Activation and Fatigue during the propulsion of a wheel chair • Small displacement sensors • Motivation: Respiratory gating for lung CT • Strain gauges • Piezoelectric transducers • Design example: Respiratory gating for lung CT • Pressure measurements – • Invasive blood pressure measurements • Automatic non – invasive blood pressure measurements • Design Example: Design a non-invasive blood pressure measurement system • Electro-chemical sensors – noninvasive blood gas sensing with electrodes • Optical sensors – Pulse Oximetry

9. Plethysmography; volume displacement; impedance Ultrasound - Doppler US for blood and tissue velocity measurements Stimulation of excitable tissues; Cardiac pacing and defibrillation Digital Interfaces in measurement systems; Sampling Theorem; Quantization Noise; Dithering; Digital to Analog converters; Analog to digital converters

10. Laboratory Sessions: Lab 1 : Differential amplifiers; DAQ / DSP / Statistical Analysis Key Concepts: Discrete Signals, Acquisition, Amplifiers, Frequency Domain Lab 2 : ECG / Heart Rate Key Concepts: Biopotentials, Electrocardiogram, Einthoven's Triangle, Noise Artifact, Bio-instrumentation amplifier for ECG Lab 3 : EEG Key Concepts: Alpha & Beta Waves (Alpha Blockers) – in phase or out of phase. Spectral and time analysis, Irregularities, Bio-instrumentation amplifier for EEG Lab 4 : EMG & Motor Control Key Concepts: Muscle twitches, rectification, averaging, RMS, Force vs EMG, Filtering effects on applications of EMG, Bio-instrumentation amplifier for EMG Lab 5 : EOG & Environmental Control Key Concepts: DC Signals, DC Amplifiers, Frequency component of blinking, Scaling of signals and creation of algorithms to make raw data into useful information, Bio-instrumentation amplifier for EOG

11. Textbooks (Optional): 1. Medical Instrumentation: Application and Design. John G. Webster 2. Custom Courseware, Lecture Notes posted on the class website Additional resources: Introduction to Instrumentation and Measurements; Second Edition; Robert B Northrop; Taylor and Francis; ISBN 0-8493-3773-9 Noninvasive Instrumentation and Measurement in Medical Diagnosis; Robert N. Northrop; CRC press; ISBN 0-8493-0961-1 Design and Development of Medical Electronic Instrumentation, D. Prutchi and M. Norri, Wiley-Interscience, 2005

12. Process of Measurement • Understand the event (variable) you are measuring • Is variable directly related to event? • Is variable indirectly related to event? • Is variable statistically related to event? • Is event itself random?

13. Process of Measurement (cont’d) • Is measurement biased (will final result have an offset, e.g. does it always read high)? • What are unavoidable sources of noise? • How much does this contaminate your measurement? • Maximize your signal-to-noise ration SNR

14. Measurement Specifications • What is amplitude range of selected variable • What is bandwidth of variable (does variable change rapidly or slowly)? • What is required resolution (smallest change you need to measure)? • What is required accuracy?

15. Conditions of Measurement • Biopotential signals are low amplitude (<1μv – 25 mv) • Biopotential signals are low bandwidth (d.c. – 15 kHz) • Body is volume conductor (specificity of signal source) • Noise is high in bandwidth of biopotential signal (60 Hz: 30 mv on skin)