METAMATERIALSA GREAT ACHIEVEMENT OF MATERIAL SCIENCE

Sakti Prasanna Muduli

SCOPE What are Metamaterials Working principle Types Applications Limitations

INTRODUCTION

Metamaterials are artificial structures designed to have unique properties not found in common materials. Such as

Negative refractive index, elasticity, can modify sound waves, enhance radiated power etc.

NOTE:- “META”- above, higher, superior or beyond

What are Metamaterials ?

HISTORY

Winston E Kock developed material that had similar characteristics to that of metamaterial in 1940.

Russian Physicist Victor Veselago(1929) explained about the properties exact opposite to common materials in1967.

Prof. John Pendry(1943) suggested the practical method for making metamaterials in 1999.

Prof. John pendry Victor Veselago

INTERESTING ABOUT THE TOPIC:-

Interesting things about the topic are metamaterials can be used to make invisible cloak, super lenses beyond the diffraction limit, flexible electronic devices etc.

WORKING PRINCIPLE Like unit cell crystal structure of common materials,

unit component of metamaterial is called “Meta-atom” whose structure is just like a MOSFET. This goes under nano technology.

This is a metallic resonator structure whose dimensions allow the resonant oscillation of electromagnetic waves. Structure is shown in the above fig.

NEGATIVE REFRACTIVE INDEX

Magnetic permeability(µ) and electric permittivity(€) of a metamaterial can be –ve simultaneously ;which results in –ve RI. Graphically shown bellow

TYPES OF METAMATERIALS

Metamaterials are classified in to following types:

Electromagnetic Acoustic Seismic

1.ELECTROMAGNETIC METAMATERIALS

Common refractive material metamaterial

Light is an electromagnetic wave. Due to -ve RI light wave is treated by metamaterials as above

2.ACOUSTIC METAMATERIALS

Acoustic metamaterials control and direct manipulate the sound wave(a transverse wave).

This can be used in following : 1. Sound Proof Room 2. Sonar Blocking(Invisible

submarines)

3.SEISMIC METAMATERIALS

These metamaterials are designed to counteract the adverse effect of seismic waves like longitudinal surface waves.

1.volcanic vibration 2.Earthquake

APPLICATIONS We can describe the applications in following

points: Invisibility(cloaking device) Super lenses Small size Antennas Wave Absorber Seismic Protection

INVISIBILITY

Due to –ve RI of the material, It can bend the light wave tobackside of an opaque object and make it go in same direction as it falls on the object. As a result one can observe the absence of That object visually.

SUPER LENSES Super lenses consist of metamaterials to

achieve resolution beyond the diffraction limit. Which are able to view live viruses and may be even bits of DNA.

ANTENNAS As metamaterials can enhance radiated

power, Small size antennas like radars can be designed with improved performances.

ABSORBER Metamaterial can absorb large amount

of electromagnetic radiation by varying its magnetic permeability and electric permittivity.

SEISMIC PROTECTION As previously described metamaterials can

be used to manipulate seismic waves like destructive surface waves.

LIMITATIONS1. For smaller

wavelength ,smaller unit is required to design.

2. Different wavelengths require meta-atom of different dimensions.

3. Practically it does not work perfectly.

4.It is very expensive.

REFERENCES https://en.wikipedia.org/wiki/Metamaterial http://science.howstuffworks.com/invisible-tank1.ht

m http://phys.org/tags/metamaterials/ www.metamaterial.com/