Piezoelectric pressure transducers utilize the piezoelectric properties of certain crystalline and ceramic materials to generate an electrical signal when pressure is applied. They consist of a diaphragm that transmits pressure to a piezoelectric crystal, which generates a signal amplified by a charge amplifier. They are self-generating, have a good frequency response, and show almost zero deflection, making them well-suited for medical, aerospace, and nuclear instrumentation applications. However, they cannot measure static pressure and their output is affected by temperature changes.

1. PIEZOELECTRIC PRESSURE
TRANSDUCER

2.  TRANSDUCERS
A TRANSDUCER MAY BE DEFINED AS A DEVICE THAT
CONVERTS ENERGY FROM ONE FORM TO ANOTHER
FORM.
ENERGY TRANSMISION CAN BE ELECTRICAL ,
MECHANICAL , CHEMICAL B, OPTICAL , THERMAL ,
NUCLEAR , ACOUSTICAL OR A COMBINATION OF ANY
TWO OR MORE .
IT
IS
OFTEN
VERY
CONVENIENT
TO
MAKE
MEASUREMENTS IN TERMS OF ELECTRICAL QUANTITIES
SUCH AS VOLTAGE OR CURRENT AND EASE IN

3.  PIEZOELECTRIC PRESSURE
TRANSDUCERS
• THESE DEVICE UTILIZE THE PIEZOELECTRIC
CHARACTERISTICS OF CERTAIN CRYSTALLINE
AND CERAMIC MATERIALS (SUCH AS QUARTZ) TO
GENERATE AN ELECTRICAL SIGNAL.

4.  PRINCIPLE
WHEN PRESSURE IS APPLIED ON CRYSTAL , AN ELECTRICAL
CHARGE IS GENERATED.
SOME OF THE PIEZOELECTRIC MATERIALS ARE BARRIUM
TITANATE SINTERED POWDER , CRYSTAL OF QUARTZ ,
TOURMALINE, AND ROCHELLE SALTS.

5.  CONSTRUCTION AND WORKING
oCONSTRUCTION
 IT CONSISTS OF A DIAPHRAGM BY WHICH PRESSURE IS
TRANSMITTED TO THE PIEZOELECTRIC CRYSTAL Y1. THIS
CRYSTAL GENERATES AN ELECTRICAL SIGNAL WHICH IS
AMPLIFIED BY A CHARGE AMPLIFIER.
 A 2ND PIEZOELECTRIC CRYSTAL Y2 IS INCLUDED TO

6.  APPLICATIONS

PRESSURE SENSOR IN THE TOUCH PADS OF MOBILE
PHONES.
TO MEASURE PRESSURE INSIDE THE CYLINDER OF
GASOLINE ENGINE.
IN VARIOUS APPLICATION SUCH AS MEDICAL
,AEROSPACE , NUCLEAR INSTRUMENTATION.

7.  ADVANTAGES
I. THE TRANSDUCER NEEDS NO EXTERNAL POWER
AND IS THEREFORE SELF GENERATING.
II. IT HAS A VERY GOOD HIGH FREQUENCY
RESPONSE.
III. THOUGH PIEZOELECTRIC SENSORS ARE
ELECTROMECHANICAL SYSTEMS THAT REACT
TO COMPRESSION , THE SENSING ELEMENTS
SHOW ALMOST ZERO DEFLECTION.

8.  DISADVANTAGES
I. THIS TYPE OF TRANSDUCER CANNOT MEASURE
STATIC PRESSURE.
II. THE OUTPUT OF THE TRANSDUCER IS
AFFECTED BY CHANGES IN TEMPERATURE.
THEREFORE TEMPERATURE COMPENSATING
DEVICES HAS TO BE USED.