1. RESISTIVE, CAPACITOR, INDUCTIVE, PIEZOELECTRIC SENSOR 2006200401 Tae-eui, Kim

2. Resistive Sensor ① Strain gage : changes in ② Force sensing resistor : changes in A ③ Thermistor : change in T ④ Potentiometer changes in L

3. Forcing Sensing Resistive

4. Thermister ceramicR NTC(Negative Temperature Coefficient) Thermister cf) PTC(Positive Temperature Coefficient)

5. (A) Voltage Divider (B) Inverting Amplifier

6. (C) Bridge Circuit (D) Linearization Linear region

7. Capacitive Sensor Most capacitive sensors are based on changes in

8. Inductive Sensor ① Self Inductance ② Mutual Inductance ③ Differential Inductance

9. Inductive Sensor ① Self Inductance

10. Inductive Sensor ② Mutual Inductance Don’t know where it is

11. Inductive Sensor ③ Differential Inductance LVDT(Linear variable Differential Transformer) a b c d e f Primary coil

12. Inductive Sensor (a) When core is at ; cancelled out

13. Inductive Sensor (b) When core is at

14. Inductive Sensor (c) When core is at Adventage of LVDT ; You have wide of range of measuring

15. Problem 13

16. Rectifier + LPF

17. Problem 13 Rectifier + LPF

18. Problem 13 phase – sensitive demodulation

19. Problem 13 phase – sensitive demodulation

20. Problem 14

24. Piezoeletric Sensor ifthen Piezoelectric sensor has no dc response You cannot measure static, but dynamic Microphone, pulse

25. Piezoeletric Sensor

26. ② Charge Amplifier

27. Piezoeletric Sensor If you plan to use the piezoelectric sensor for measuring pulse, the lowest frequency of pulse signal is assumed to be 0.1Hz