S.NAVEEN,ECEDEPT.,SRIT,PACCHAPALAYAM, COIMBATORE-010

PIEZO ELECTRIC MATERIALS AS SOURCES TO

SENSORS

ABSTRACT

• Piezoelectric crystals are versatile tools for the measurement of various purposes. They work on the principle of

piezoelectric effect. They are insensitive to radiations and emf enabling high performance at harsh conditions. Such a

material could be used in places where harvesting energy is much needed. Harvesting energy from random mechanical

process in various uncontrollable environment is an effective approach for powering wireless sensors to meet wide range of

applications in our day to day life. A Piezoelectric material is used to generate or harvest energy by vibration. When sensors

are used to study about various variable conditions the battery source plays a major role in that part. For example when

sensors are placed in animals to study about them battery sources powering the sensors has a limited lifetime. But sensors

powered by piezoelectric crystals may have a very long lifetime nearly an infinite lifetime. It may be a very good alternative

for common battery sources.

• When the sensors with piezoelectric sources are placed in animal’s body they are powered by the pressure or vibrations

created by the animal’s body movements such that the sensor is turned on. If they are used in sensors to study wildlife they

are powered even due to the air. Such a sensor may be regarded as an ideal one as it may create a new revolution in the field

of sensors

SENSORS

• A sensor is an object whose purpose is to detect events or changes in its environment, and then

provide a corresponding output. A sensor is a type of transducer; sensors may provide various types of

output, but typically use electrical or optical signals. For example, a thermocouple generates a known

voltage (the output) in response to its temperature.

• With advances in micromachinery and easy-to-use micro controller platforms, the uses of sensors

have expanded beyond the most traditional fields of temperature, pressure or flow measurement.

A GOOD SENSOR OBEYS THE FOLLOWING RULES:

• it is sensitive to the measured property,

• it is insensitive to any other property likely to be encountered in its application, and

• it does not influence the measured property.

BLOCK DIAGRAM

LITHIUM THIONYL CHLORIDE BATTERY

• Advantages of Lithium thionyl battery :

• 1.High cell voltage (3.6V) and high energy

density.

• 2.Wide temperature application: -55°C to 85°C.

• 3.Stable voltage plateau and long term reliability

in service for 10 years.

• 4.Low self-discharge for 2% max at 20°C per year.

• 5.TIG Arc / laser seal process.

• 6.Safety design.

ADVANCES IN SENSORS

Now the technology advancement is so fast that sensors have high tech

batteries. Nowadays even the battery sources in the sensors are designed in

such a way that the sensors are on/off based on the user’s desire. It has become

user defined. These batteries too have a long life time.

PIEZO ELECTRIC CRYSTALS

• Piezoelectric Crystals :

• Piezoelectric crystals are crystals that

work based on the principle of piezoelectric

effect i.e. they generate electricity due to

pressure on it or due to vibrations.

Some widely used crystals are :

• Quartz

• Berlinite

• Galium orthophosphate

• Equivalent circuit

ENERGY HARVESTING BY PIEZOELECTRIC CRYSTALS

• A dramatic consumption reduction of integrated circuits

related to the development of mobile electronic devices has

been reached over the past years, enabling the use of ambient

energy instead of batteries. The focus is here on the

transformation of ambient mechanical vibrations into

electrical energy. This paper compares the performances of a

vibration-powered electrical generator using PZT

piezoelectric ceramics associated to two different power

conditioning circuits. A new approach of the piezoelectric

power conversion based on a nonlinear voltage processing is

presented and implemented using a particular circuit.

Theoretical predictions and experimental results show that the

new technique may increase the power harvested by a factor

up to 4 compared to the Standard technique. The power

optimization problem is in particular examined in the case of

broadband, random vibrations.

ADVANTAGES OF USING PIEZOELECTRIC CRYSTALS

• High dielectric constant

• Spontaneous polarization

• Highly stable

• High temperature material

• Even small changes in environment is noted

REFERENCES

• Steven R Anton and Henry A Sodano, published on 18 may 2007,Materials and structures.

• Huidong Li, Chuan Tian and Z.Daniel Deng, pacific northwest national lab

• Dr.Harry Zervos,jan 10 2013,Energy harvesting and storage

• SP Beeby,MJ Tudor,published on 26 oct 2006,Energy harvesting Vibrating materials

• KA Cook,AM Sastry, published on 9 june 2008, Powering MEMS portable devices.

CONCLUSION

• I here by conclude by saying that even batteries like lithium thionyl chloride battery even have a life

time of 5 to 6 months but these sensors powered by piezoelectric crystals have nearly infinite life time

acting as an ideal source for sensors.

THANK YOU