Sound Transducers

1.  Recentdevelopments in temperature
measurement have encouraged
researchers to develop
 low-cost
 simple structure
 computerized generic transducers for
environmental monitoring
 industrial process control.

2. Acoustic
Temperature
Transducer
QUITEVIS, Mary Francis(Enguero)

3. Agenda
Definition
Principle
Sensor Technology
Application

4. ATT?
Device based on the
characteristics of sound waves
in a wave- guided media, in
which sound wave is guided
physically

5. Basic Principle
 Speed of sound is proportional to the
absolute temperature, which is also
related to the frequency of the sound
wave, assuming existence of a constant
wavelength.
C = f . λ
 v = 331m/s + 0.6m/s/C * T

6.  Speed of
Sound
358.0 m/s
343.6 m/s
330.4 m/s

7. Status Quo:
Problem?
 Predominant market need for sensors
that are
 competitively priced due to mature and
established manufacturing methodologies
 inherently rugged because of the
implementation of advanced packaging
techniques
 very sensitive and intrinsically reliable.

8. Greater Problem?
 Sensors need to be of a
 very small size, not influenced by magnetic fields,
 contribute to emerging market needs of being able
to support data
 monitoring functions wirelessly
 complementing additional functionalities such as
low power requirements
 being passively and wirelessly interrogated (no
sensor power source required).

9. Solution:
ATT
Abilityto fulfill the above market
requirements
 high performance
 small size
 high reproducibility

10. Fig. 1. ( а ) Diagram of the experimental setup for detecting
heated bodies placed in biological media; (b) result of
detection of the heated body placed in gelatine.

11. Distinction
 The acoustic temperature sensor
provides temperature measurement
that is independent of wafer
emissivity conditions and lamp
radiation levels.
 It does not require thermal contacts
on the wafer and is compatible with
the reactive conditions of rapid
thermal processing.

12. Fig. 2. Two-dimensional tomogram of a heated sample placed in
water. The tomogram was obtained by antenna focus scanning
in depth and along the transverse coordinate.

13. Importance of
Acoustic Techniques
 Used to monitor the temperature of
silicon wafers during rapid thermal
processing from room temperature to
1000 C with tolerance 5 C accuracy.
 Acoustic transducers are mounted at
the bases of the quartz pins that
hold up the silicon wafer during rapid
thermal processing.

15. Security System
 Abilityto detect the range of the person
way from the sensor
 Effective monitoring system enabling the
knowledge of a moving body’s
prescence

16. Telecommunications
Industry
Largest volume application -
accounting for filters and
oscillators in mobile cell phones
and base stations.

17. SAW?
 Surface acoustic wave devices and
 Function as band-pass filters in both the
radio frequency and intermediate
frequency sections of the transceiver
electronics..

18. Applications
 Automotive applications (tire pressure
and oil condition monitoring sensors)
and industrial and commercial
applications (temperature in
ovens, pressure in tanks).

22. References
 http://www.directindustry.com/prod/dytra
n-instruments/acoustic-sensors-37504-
342307.html
 http://www.processindustryinformer.com
/Editorial-Feature-Archive/WIRELESS-
TEMPERATURE-SENSING-BY-
ACOUSTIC-WAVE-SENSORS
 http://www.sensorsportal.com/HTML/DI
GEST/august_2010/P_656.pdf