I want advantages and disadvantages of smart material please give answer ....

Smart materials have properties that react to changes in their environment. This means that one of their properties can be changed by an external condition, such as temperature, light, pressure or electricity.
- Change is reversible and can be repeated many times.
- There are a wide range of different smart materials
- Each offer different properties that can be changed.


Thermochromic liquid crystals/film

Thermochromic (TC) products predominantly change color in response to temperature fluctuations.


There are two primary types of TC’s,
- liquid crystals
- leuco dyes.

Thermochromic liquid crystals/film
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Liquid crystals are used in many products, including forehead thermometers, room thermometers; game pieces, stress testers, and other applications.






- liquid crystal TC’s are extremely capable materials
- they are difficult to work with
- they require highly specialized manufacturing techniques.

Liquid Crystals are generally used for higher precision applications since the temperature response point can be tightly engineered. Uses include:
- Forehead Thermometers
- Medical devices
- Game pieces

Thermochromic leuco dye
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The other type of TC is called a leuco dye and is commonly used
- advertising
- consumer packaging
- product labels
- security printing
-novelty applications such as temperature sensitive plastics and mugs, promotional items, toys and textiles.


Leuco dyes are
- less precise
-easier to work with
- commonly used for packaging, product labeling/graphics, toys and novelty applications
Thermochromic permanent change ink
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A third one is Thermochromic permanent change ink is a high temperature activated, permanent change pigment.

It offers a gradual color change that becomes denser as the temperature increases.

Inks are available in the range of 60 to 200ºC and in two standard colors: white to magenta and white to black.


Applications include, but not limited to, high temperature alerts, security images, pharmaceutical control , safety / engineering warnings and receipt /check validation to name a few.
http://colorchange
TASK:
Explain how Thermochromic liquid crystals can be used as a forehead thermometer. (2+ marks)







Piezoelectric crystals
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Piezoelectricity background

Piezoelectricity is the charge that occurs in certain solid materials (notably crystals certain ceramics and biological matter such as bone and dna) in response to applied mechanical stress.The word piezoelectricity means electricity resulting from pressure. It is derived from the Greek piezo or piezein which means to squeeze or press, and electric orelectron (ήλεκτρον), which stands for amber, an ancient source of electric charge.


The Piezoelectric Effect
Certain crystals such as quartz are piezoelectric. That means that when they are compressed or struck, they generate an electric charge. It works the other way as well: If you run an electric current through a piezoelectric crystal, the crystal changes shape slightly. This property makes piezoelectric crystals useful in many applications.

Smart materials are reactive materials. Their properties can be changed by exposure to stimuli, such as electric and magnetic fields, stress, moisture and temperature.
Smart colours

Smart colours are pigments which can be incorporated into paints, dyes, inks and plastics.
thermochromic pigments react to changes in temperature
photochromic pigments react to changes in light levels
Photochromatic materials are used in the manufacture of sunglasses. Exposure to sunlight causes the lens of the glasses to darken to protect the eye.