Download ELECTRICAL AND COMPUTER ENGINEERING 4UA3

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