This document discusses the use of piezoelectric sensors and ultrasonic transmitters/receivers. It begins by explaining the direct piezoelectric effect where a piezoelectric material generates an electric potential when subjected to mechanical stress. It then defines a piezoelectric sensor as a device that uses this effect to measure changes in pressure, acceleration, temperature, strain, or force by converting them to an electrical charge. The document goes on to describe how an ultrasonic transmitter/receiver circuit uses a transmitter and receiver operating at the same frequency to detect motion. It provides several examples of applications for piezoelectric sensors and ultrasonic devices in areas like sonar, materials testing, microphones, medical devices, and

1. TRANSMITTER/RECIEVE
R USING
PIEZOELECTRIC
SENSOR
A presentation by
Subham Goyal
Engineering 40 AEIE
Heritage Institute Of Technology

3. Direct Piezoelectric Effect
Piezoelectric Material will generate electric potential
when subjected to some kind of mechanical stress.

4. Piezoelectric sensor?
 A piezoelectric sensor is a device
that uses the piezoelectric effect,
to measure changes in pressure,
acceleration, temperature,
strain, or force by converting
them to an electrical charge. The
prefix piezo- is Greek for 'press' or
'squeeze'.

5. Ultrasonic transmitter/reciever
 The
Ultrasonic Transmitter and Receiver
circuit comprises of transmitter
and receiver, that operates at
the same frequency.
 When something moves in the
area covered the fine balance
of the circuit is troubled and
the alarm is activated.
 The ultrasonic transmitter is
designed with 2-NAND gates
wired as inverters and they
make a multivibrator the o/p of
that drives the transducer.

6. Developing theories…
 Pierre and Jacques Curie predicted and
demonstrated the piezoelectric effect using
tinfoil, glue, wire, magnets, and a jeweler’s saw.
 They showed that crystals of tourmaline, quartz,
topaz, cane sugar, and Rochelle salt generate
electrical polarization from mechanical stress.
 The converse effect was mathematically
derived by Gabriel Lippman in 1881 using
fundamental thermodynamic principles and
was later experimentally confirmed by the
Curies.

7. Sonic and Ultrasonic Applications
 Sonar with Ultrasonic
time-domain
reflectometers
 Materials testing to
detect flaws inside cast
metals and stone
objects as well as
measure elasticity or
viscosity in gases and
liquids
 Compact sensitive
microphones and
guitar pickups.
 Loudspeakers

8. Pressure Applications
 Transient pressure measurement to
study explosives, internal
combustion engines (knock
sensors), and any other vibrations,
accelerations, or impacts.
 Piezoelectric microbalances are
used as very sensitive chemical
and biological sensors.
 Transducers are used in electronic
drum pads to detect the impact of
the drummer's sticks.
 Energy Harvesting from impact on
the ground
 Atomic force and scanning
tunneling microscopes.
 Electric igniters and cigarette
lighters

9. Consumer Electronics
Applications
 Quartz crystals resonators
as frequency stabilizers for
oscillators in all computers.
 Phonograph pick-ups
 Accelerometers: In a
piezoelectric
accelerometer a mass is
attached to a spring that is
attached to a piezoelectric
crystal. When subjected to
vibration the mass
compresses and stretches
the piezo electric crystal.
(iPhone)

10. Motor Applications
 Piezoelectric elements can be
used in laser mirror alignment,
where their ability to move a
large mass (the mirror mount)
over microscopic distances is
exploited. By electronically
vibrating the mirror it gives the
light reflected off it a Doppler
shift to fine tune the laser's
frequency.
 The piezo motor is viewed as a
high-precision replacement for
the stepper motor.
 Traveling-wave motors used for
auto-focus in cameras.

11. Our Experiment

12. Procedure
1) Attach a mirror to the piezoelectric buzzer. Position that laser
so that the beam can reflect off of the mirror and hit the
wall across the room.
2) Connect the function generator to the Piezoelectric device.
Find the resonant frequency of the device by slowly
increasing the frequency at 10Vp-p. The laser will vibrate the
most at the resonant frequency.
3) Measure the diameter of the laser without any signal. Then
measure the diameter of the laser with the AC signal
applied.
4) Calculate the displacement of the laser and divide it by two
to get the amplitude of the magnified change in volume for
the piezoelectric material.
5) Measure the distance from the piezo to the wall and to the
laser. Also measure the height of the laser and reflected
beam in relation to the piezo.
6) Calculate the change in volume for the piezoelectric
material.