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(ELEC4810)[2010](f)final~=idkeaej^_93613.pdf
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Introduction to Biosensors and Bioinstrumentation

(ELEC 383)
FINAL EXAMINATION

DATE: December 15, 2010
TIME: 8:30 am -11:30 am

Venue: Room 3007

PLEDGE OF HONOR
On my honor as a student of Hong Kong University of Science and Technology, I have neither received aid from others nor given aid to others while taking this exam. All of the answers represent my own work.
Signature: __________________ Date: ________________
Student Name:



Student Number:

TOTAL: 50 pts + 6 pts bonus.
1. (4 pts.) Calculate membranes resting potential at room temperature based on the
kT
information in the figure below ( . .27mV , Pk : PNa : PCl = 5 : 0.1 : 2 ).
q

2. (12 pts.) (i) Explain why an action potential can be physically described as a traveling current dipole? (ii) Draw a typical ECG signal and explain the meaning of each peak. (iii) The EEG can be monitored with either a bipolar montage or a referential one. Explain the meanings of bipolar and referential montage. (iv)A large nerve fiber of 100m diameter is immersed in saline (salt water) and an electrode is located 5 mm away from the nerve fiber. Estimate the maximal potential signal that the electrode can pick up when an action potential travels

through the nerve fiber. ( i 0.2, resting potential, Vr -70 mV, action potential,

e
Va 50 mV).
3.
(8 pts) (i) For patient safety it is important to have electrically isolated instrumentation devices. Describe briefly the function of electrical isolation, and describe one technology to implement it. (ii) EMG is a stochastic signal. Why does it not have the same shape at each contraction? (iii) Sketch a block diagram of an instrumentation amplifier to measure the EMG signal from the biceps (arm) muscle which uses a driven right leg circuit. Describe briefly how the driven right leg circuit affects the common mode output of an amplifier?

4.
(10 pts) (i) Describe the mechanisms of blood pressure measurement based on Korotkoff's and oscillometric methods in Lab 2. (ii) An oscillometric blood pressure instrument is constructed based on an inflatable cuff on the arm. The cuff is inflated and slowly deflated and the cuff pressure measured and shown in the figure below (oscillations amplitudes are exaggerated from those in an actual system). From these data, estimate: a. systolic pressure, b. diastolic pressure, c. mean arterial pressure, and d. the heart rate. (iii) Describe one mechanical source of inaccuracies between the pressure in the inflatable cuff, and the arterial pressure in the arm.

5.
(10 pts.) (i)Explain the mechanism of ultrasonic flowmeter for the measurement of blood flow. (ii) Monitoring of babys heart beat rate is critical during pregnancy. Use your imagination to design an ultrasound device to monitor the heart beat rate of a baby in mothers belly. (iii) Assume the speed of sound in tissue is 1500 m/s. If the maximum blood velocity in baby's aorta (the largest a