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ELECTRICAL AND COMPUTER ENGINEERING 4EL3 DAY CLASS Dr. H. de Bruin DURATION OF EXAMINATION: 3 hours McMaster University Final Examination April 2005 -------------------------------------------------------------------------------------------------------------THIS EXAMINATION PAPER INCLUDES 2 PAGES AND 2 QUESTIONS. YOU ARE RESPONSIBLE FOR ENSURING THAT YOUR COPY OF THE PAPER IS COMPLETE. BRING ANY DISCREPANCY TO THE ATTENTION OF YOUR INVIGILATOR -------------------------------------------------------------------------------------------------------------SPECIAL INSTRUCTIONS: In your answers, make use of diagrams whenever possible. The CASIO-FX 991 only is permitted -------------------------------------------------------------------------------------------------------------1. Answer five of the following (10 marks each) (I) Describe, using diagrams, the electrical activity of the heart and how the electrical events are related to the mechanical activity (i.e. generation of blood pressures and flow). Your explanation should include how the heart’s electrical events generate the Lead I ECG signal. (II) Describe how Doppler-shift ultrasound can be used to estimate blood flow in an artery lying near the skin surface (e.g. carotid artery). Describe the continuous Doppler-shift instrumentation used to obtain this estimate. What ultrasound frequency would you pick for this application and why? (III) Describe the physical basis of a piezoelectric crystal transducer, and give the equivalent circuit of such a transducer attached to an amplifier. Sketch the output voltage/input force response vs frequency and indicate the usable frequency range for force measurement. (IV) List four possible sources of noise in an ECG signal and briefly describe how good instrumentation or experimental design can remove each noise. (V) Describe what happens during heart fibrillation and how it can be corrected. Describe a typical defibrillator including its principle of operation, simplified circuit, output waveform and energy. (VI) Discuss electrical safety in a patient environment. How do we design patient instrumentation to make it safe (e.g. standards, layout, etc)? Why does clinical equipment have more stringent (safer) standards than other electrical equipment such as data processing or domestic equipment? continued on page 2 2 (VII) Describe the single electrode demand/inhibit (synchronous) pacemaker. Why is it the most common form of pacemaker used? Give the block diagram representation of the pacemaker, describing each block. 2 Answer two of the following (25 marks each) In your answers use block schematics and present the details for each block including a brief description of the theory of operation of your system where necessary. If your designs include transducers (sensors) describe these in detail and where they are placed in/on the body. Also consider patient safety and comfort, equipment reliability, cost and noise immunity in your design. (I) Using strain gauge technology design a system to continuously measure blood pressure and heart rate in a patient undergoing surgery. The system should also measure the depth of anaesthesia as shown by the EEG signal power in the delta band relative to the total EEG power. The blood pressure, heart rate and relative delta power should be measured and recorded for each 20 seconds over a maximum of 4 hours. How will the data be displayed? (II) A researcher wants to measure whether sensory nerve conduction in patients with sensory neuron disease is dependent on the temperature of the skin over that nerve. These patients have very low amplitude (4 μvolt, 20 Hz – 2 KHz) sensory nerve signals. The sensory nerve potential is contaminated by noise and the start point cannot be measured directly. Design a measurement system that stimulates the sensory nerves at the finger, obtains the nerve signals at the wrist and elbow and calculates the conduction velocities over time as the arm is allowed to warm up and displays the results (every 30 sec). The hand and arm should first be immersed in a water bath at 10O C. The average skin temperature should also be measured for each time interval. (III) Patients who have had a heart attack usually go through a period of rehabilitation during which they exercise and their tolerance is measured. Design a system to measure the heart rate, pedaling rate in revolutions per minute and peak pedal force for a subject who is pedaling a stationary bicycle. The pedaling resistance of the bicycle is gradually increased from 0 to a maximum over a 10 min period. The system should calculate the average for each variable for each 10 sec time interval in the 10 minute period. THE END