=========================preview======================
(ELEC383)[2008](f)final~ee_jmx^sol_10328.pdf
Back to ELEC383 Login to download
======================================================
ELEC383 2008 fall Final Exam Solution
Solution:
For signal average, the noise level is inversely proportional to the square root of the
number of sample taken:
For SNR to be 10:1, signal should be averaged by 100 times.
For SNR of 100:1, signal should be averaged by 10000 times. However, once the number
of sampling is too large, it is impractical to implementation.
Solution: (i).
(ii). 9 electrodes.
(iii). The QRS complex primarily by ventricular depolarization.
(iv). Tthe direction of this dipole moment more likely orient the direction of lead II.
Solution:
(i). The integrated semiconductor sensor uses a silicon substrate for the structural membrane of the diaphragm. The gages are diffused directly to the diaphragm. The sign of tangential stress component at edge is opposite to that of central area.
(ii). Silicon strain-gauge pressure sensor can be placed on the tip of a catheter and inserted directly into the blood, resulting in more accurate measurements and faster response times.
(iii). Silicon strain-gage element is more temperature sensitive and inherently more nonlinear than metal strain gages because the piezoresistive effect varies with strain.
(iv). Use a blood pressure cuff stethoscope, and mercury manometer to generate a controllable pressure and record the corresponding value of semiconductor sensor.
Solution:
(i). The sphygmomanometer cuff is inflated by a hand bulb to pressures above the systolic level. Pressure is then slowly released, and blood flow under the cuff is monitored by a microphone or stethoscope placed over a downstream artery. The first Korotkoff sound detected indicates systolic pressure, whereas the transition from muffling to silence brackets diastolic pressure.
(ii). Oscillometric method employ a calibrated semiconductor pressure sensor to transfer the pressure signal to electronic signal. Then a differential amplifier is used to enhance the SNR of the recorded signal. Then the diastolic and systolic pressure value could be calculated.
Solution: (i). The measurement of PH value and PCO2 uses a PH sensitive fluorescent dye. The excitation peak wavelength for the acidic form of the dye is 410nm, whereas the excitation peak wavelength for the basic form of the dye is 460nm. It is also apparent that emission spectra for both the acidic and the basic forms of the dye have a peak at 520nm.
Carbon dioxide comes to an equilibrium with a mixture of a pH indicator in bicarbonate buffer. There is a direct relationship, based on the Henderson-Hasselbach equation, between the pH change in a bicarbonate solution and the CO2 concentration in that solution. Thus a change in pH in an isolated bicarbonate buffer with a changing PCO2 is measured.
PO2 sensor makes use of the principle of fluorescence or luminescence quenching of oxygen. Whit oxygen present, these molecules provide collision paths and transfer of energy to the oxygen molecule, which competes with the energy de