Smart materials
We will be considering the working properties, characteristics, application and advantages/ disadvantages of the following smart and modern materials;
thermo-ceramics, shape memory alloys (SMA), reactive glass, liquid crystal displays (LCD), photo-chromic materials, thermo-chromic materials, quantum tunnelling composites.
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.
We will be considering the working properties, characteristics, application and advantages/ disadvantages of the following smart and modern materials;
thermo-ceramics, shape memory alloys (SMA), reactive glass, liquid crystal displays (LCD), photo-chromic materials, thermo-chromic materials, quantum tunnelling composites.
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
![Picture](/uploads/1/1/1/3/11139306/165093000.jpg?457)
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
- 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
![Picture](/uploads/1/1/1/3/11139306/975966930.jpg?419)
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
![Picture](/uploads/1/1/1/3/11139306/929847918.png)
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.
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://www.colorchange.com/
TASK:
Explain how Thermochromic liquid crystals can be used as a forehead thermometer. (2+ marks)
Piezoelectric crystals
![Picture](/uploads/1/1/1/3/11139306/116543767.png)
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
In simples....press it and it creates electricity.... put in electricity and it moves!!
Uses..
Acoustic Uses
Piezoelectric devices can be used both to capture sound and to produce it. Piezoelectric pickups are commonly used for folk guitars and other acoustic instruments. A piezo pickup is a strip of piezoelectric material connected to two wires. The pickup is attached to the instrument. When the instrument is played, the sound makes it vibrate. These vibrations create an electrical current in the piezo pickup, which can be recorded or amplified as sound.
A piezo speaker works in the opposite way. Electricity flows into a sheet of piezoelectric material, making it bend back and forth. This creates pressure waves in the air, which we hear as sound.
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.
In simples....press it and it creates electricity.... put in electricity and it moves!!
Uses..
Acoustic Uses
Piezoelectric devices can be used both to capture sound and to produce it. Piezoelectric pickups are commonly used for folk guitars and other acoustic instruments. A piezo pickup is a strip of piezoelectric material connected to two wires. The pickup is attached to the instrument. When the instrument is played, the sound makes it vibrate. These vibrations create an electrical current in the piezo pickup, which can be recorded or amplified as sound.
A piezo speaker works in the opposite way. Electricity flows into a sheet of piezoelectric material, making it bend back and forth. This creates pressure waves in the air, which we hear as sound.
Piezo Lighters
One of the most visible applications of piezoelectricity is the piezo lighter. Pretty much any lighter with a push button is powered by piezoelectricity. When you push the button, it makes a small, spring-powered hammer rise off the surface of the piezo crystal. When the hammer reaches the top, it releases and strikes the crystal as the gas is turned on. The impact creates a large voltage across the crystal, which flows into two wires. This voltage is high enough to make a spark between the wires, which ignites the gas. Piezo igniters are used on most gas furnaces and stoves now as well.
One of the most visible applications of piezoelectricity is the piezo lighter. Pretty much any lighter with a push button is powered by piezoelectricity. When you push the button, it makes a small, spring-powered hammer rise off the surface of the piezo crystal. When the hammer reaches the top, it releases and strikes the crystal as the gas is turned on. The impact creates a large voltage across the crystal, which flows into two wires. This voltage is high enough to make a spark between the wires, which ignites the gas. Piezo igniters are used on most gas furnaces and stoves now as well.
Diesel Injectors
Task
Explain how a diesel injector could use piezoelectric crystals to inject diesel fuel into the engine. What would be the advantages?
Task
Explain how a diesel injector could use piezoelectric crystals to inject diesel fuel into the engine. What would be the advantages?
Radio frequency identification (RFID).
RFID stands for Radio-Frequency IDentification. The acronym refers to small electronic devices that consist of a small chip and an antenna. The chip typically is capable of carrying 2,000 bytes of data or less.
The RFID device serves the same purpose as a bar code or a magnetic strip on the back of a credit card or ATM card; it provides a unique identifier for that object. And, just as a bar code or magnetic strip must be scanned to get the information, the RFID device must be scanned to retrieve the identifying information.
RFID Works Better than Barcodes. A significant advantage of RFID devices over the others mentioned above is that the RFID device does not need to be positioned precisely relative to the scanner. We're all familiar with the difficulty that store checkout clerks sometimes have in making sure that a barcode can be read. And obviously, credit cards and ATM cards must be swiped through a special reader.In contrast, RFID devices will work within a few feet (up to 20 feet for high-frequency devices) of the scanner. For example, you could just put all of your groceries or purchases in a bag, and set the bag on the scanner. It would be able to query all of the RFID devices and total your purchase immediately!
The RFID device serves the same purpose as a bar code or a magnetic strip on the back of a credit card or ATM card; it provides a unique identifier for that object. And, just as a bar code or magnetic strip must be scanned to get the information, the RFID device must be scanned to retrieve the identifying information.
RFID Works Better than Barcodes. A significant advantage of RFID devices over the others mentioned above is that the RFID device does not need to be positioned precisely relative to the scanner. We're all familiar with the difficulty that store checkout clerks sometimes have in making sure that a barcode can be read. And obviously, credit cards and ATM cards must be swiped through a special reader.In contrast, RFID devices will work within a few feet (up to 20 feet for high-frequency devices) of the scanner. For example, you could just put all of your groceries or purchases in a bag, and set the bag on the scanner. It would be able to query all of the RFID devices and total your purchase immediately!
TASK
Compare an RFID and 2d barcode. (4+ marks)
Smart Ink
![Picture](/uploads/1/1/1/3/11139306/654307910.gif?848)
Sometimes known as electronic paper or e-paper, or electronic ink are display technologies which are designed to mimic the appearance of ordinary ink on paper. Electronic paper displays reflect light like ordinary paper and wider viewing angles than conventional displays, making it more comfortable to read. Contrast ratios are not high but atr generally better than that of newspaper. A quality e-paper display can be read in direct sunlight without the image appearing to fade.
Many electronic paper technologies can hold static text and images indefinitely without using electricity. Flexible electronic paper uses plastic substrates and plastic electronics for the display backplane.
Applications of e-ink include electronic pricing labels in retail shops, and digital signage time tables at bus stations electronic billboards, mobile phone displays, and e-readersable to display digital versions of books and e-paper magazines.
Applications of e-ink include electronic pricing labels in retail shops, and digital signage time tables at bus stations electronic billboards, mobile phone displays, and e-readersable to display digital versions of books and e-paper magazines.
The Future?????
TASK
Evaluate the use of E ink in supermarket labelling
(4+marks)
(4+marks)