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/