1. Blood Pressure and Sound (1)
Dept. of Biomedical Engineering
YOUNHO HONG

2. What kinds of devices? BP ( Blood Pressure ) Invasive BP ( IBP )
Noninvasive BP ( NIBP )
Tonometry
Stethoscope

3. Tonometry P = F/A When we blow some air to
ball M
F=Mg
contact area = A
P = F/A
eye P
LED
blow air
air ject
photo sensor
(photo diode
or photo TR)
When we blow some air to
eye by air ject, The eye will be
pressed and then the reflection
degree of the light that is from LED
will be changed.

4. NIBP (noninvasive blood pressure)
Cuff
Cuff Pressure
(systolic
pressure)
120mmHg
90mmHg
(diastolic
Pa (arterial pressure) t
We can’t measure the wave
precisely by NIBP.

5. NIBP (noninvasive blood pressure)
(systolic
pressure)
120mmHg
90mmHg
(diastolic t P
korotkoff sound
Cuff pressure
slope (-2 ~ -3 mmHg/s)
180mmHg
Threshold
“ Oscillometric Method”
As cuff pressure is getting smaller, the pressure that sensor measures
is getting bigger at first. And then the pressure is getting smaller in the
middle until cuff pressure reachs to the diastolic pressure.

6. Phase-Sensitive Demodulation
# From Problem 8 (HW2)
(1) Add noise Cn to x(t). And do phase-sensitive demodulation.

7. Phase-Sensitive Demodulation

8. Phase-Sensitive Demodulation
(2) Add random noise to x(t). And do phase-sensitive demodulation.

9. Phase-Sensitive Demodulation

10. Thank You.