1. MEDICAL INSTRUMENTATION II BIOIMPEDANCE MEASUREMENT
BIOMEDICAL ENGINEERING
TAE_EUI, KIM

2. Measurement of Resistor
Measured
known
CCS
No matter whether AC or DC,
Able to measure fixed R

3. Measurement of Impedance
Reactance
Resistor

4. Measurement of Impedance

5. Measurement of Impedance
Changed with Freq.
Resistance at Impedance
Reactance at Impedance

6. Measurement of Impedance
changed
Not changed
Both changed
R, C can be found
Two equations and Two unknown variables
We can calculate

7. Measurement of Impedance
Two equations and Three unknown variables
We can calculate at multi freq.

8. Phase-sensitive Demodulation
Our goal is to find
Voltage & Theta
We have two components,
We can separate by using Phase-sensitive Demodulation.

9. Measurement of Impedance - In phase component

10. Measurement of Impedance - Quadrature component

11. Measurement of Impedance

12. More Interpretation

13. Two-electrode Method Need to think about interface Electrode
Contact interface phenomenon
Skin

14. Two-electrode Method

15. Two-electrode Method
i(t)
v(t)
v(t) sin
v(t) cos

16. Four-electrode Method

17. Four-electrode Method
i(t)
v(t)
v(t) sin
v(t)c os

18. Three-electrode Method

19. Three-electrode Method
i(t)
v(t)
v(t) sin
v(t) cos

20. Noise Effect

21. Spectrum Analyser

22. Bio Impedance Spectroscophy