Plastic electronics

Plastic electronics

Plastic electronics is a branch of electronics that deals with devices made from organic polymers, or conductive plastics, as opposed to silicon. The basic substrate will be polyethylene terephthalate, commonly used to manufacture plastic bottles. Circuits will then be printed on to these sheets.

The highly conductive polymers needed for electronic devices were first discovered in the early 1960s. They are already used in some electronic devices.

The plastic chips will then be used as the "control circuits" behind large flexible "electronic paper" displays. These devices, currently being developed and sold by firms such as Panasonic and Sony, can hold the equivalent of thousands of books.

It is hoped that one day these devices will become as common as newspapers and books. How do these differ from traditional electronic devices? Traditionally, semiconductors have been manufactured from inorganic materials, such as silicon. However, this must be processed at high temperatures in expensive clean room facilities.

In contrast, polymers can be printed using traditional inkjet printers or techniques similar to those used to produce magazines and wallpaper. This means they are cheaper, easier and quicker to produce.

As the polymers can be printed onto flexible substrates they can also be used in totally new types of devices such as electronic paper. Plastic electronics are also more robust than delicate silicon devices.

Will plastic ever replace silicon in microchips? Not at the moment. High speed computer chips require ultra-pure materials and precision design.

Computer chips routinely use components which are nanometres (billionths of a metre) in size. But using the present printing techniques used in manufacturing plastic components has been able to create components which are only micrometers in size.

However, Plastic Logic (a company) say it is currently working on plastic circuits with components 60 nanometers in size. If these are incorporated into working devices it could mean that cheap, flexible electronic chips could be built.

One final obstacle could be performance. Although the plastic devices are suitable for electronic paper displays for example, the speed requirements of modern chips are very different. But teams are now working on overcoming these limitations. Are other companies working on developing plastic chips? US firm Lucent, Philips of the Netherlands, Samsung of South Korea and Japan's Hitachi are all interested in developing plastic chips.

Graphene:

The research carried out in 2004 by Andre Geim and Kostya Novoselov at the Manchester University, United Kingdom on the isolation of graphene, a single layer of graphite. Graphene is the first isolated 2D nanomaterial. Graphene is the name given to a single layer of carbon atoms densely packed into a benzene ring structure. Graphene is the basic structural element of some carbon allotropes including graphite, carbon nanotubes and fullerenes

.Graphene sheets are one-atom thick, 2D layers of sp2-bonded carbon and predicted to have unusual properties. The one atomic thick 2D graphene monolayer sheets are not only ultra-thin, but ultra-strong, can be made as highly-insulating or highly-conductive. Graphene is quite stable under ambient conditions.

Graphene is the building block for carbon materials of all other dimensionalities and therefore the mother of all graphitic materials. Thus, the 2D material can be wrapped up into 0D fullerenes, rolled into 1D nanotubes or stacked into 3D graphite.

Another interesting experimental observation on graphene is the anomalous quantum Hall effect (QHE). QHE is usually observed at very low temperatures, typically below -243 C. The astonishing observation of QHE in graphene at room temperature in 2007 opens up new vistas for graphene-based resistance standards and quantum devices.

Potentials uses The Manchester group has already developed a graphene-based gas sensor and electronic devices. In March 2006, Professor Walt de Heer at the Georgia Institute of Technology in U.S. produced graphene-based transistors, loop devices and electronic circuitry.

Graphene's high electrical conductivity and high optical transparency make it a candidate for transparent conducting electrodes, required for such applications as touchscreens, liquid crystal displays, organic photovoltaic cells, and Organic light-emitting diodes. Graphene Biodevices: Graphene's modifiable chemistry, large surface area, atomic-thickness and molecularly-gatable structure make antibody-functionalized-graphene-sheets excellent candidate for mammalian and microbial detection and diagnosis. Due to the incredibly high surface area to mass ratio of graphene, one potential application is in the conductive plates of ultracapacitors, where graphene could be used to produce ultracapacitors with a greater energy storage density than is currently available. Graphene layers less than 10 atoms thick can form the basis for revolutionary electronic systems that would manipulate electrons as waves rather than particles, much like photonic systems control light waves. The anticipation that graphene transistors will provide life to electronic devices after the death of silicon may not be an exaggeration after all.Thermal Imaging:

Infrared Thermography, thermal imaging, thermographic imaging, , is a type of infrared imaging science. Thermographic cameras detect radiation in the infrared range of the electromagnetic spectrum (roughly 90014,000 nanometers ) and produce images of that radiation, called thermograms. Since infrared radiation is emitted by all objects based on their temperatures, according to the black body radiation law, thermography makes it possible to "see" one's environment with or without visible illumination. Thermal infrared imagers convert the energy in the infrared wavelength into a visible light video display.When viewed by thermographic camera, warm objects stand out well against cooler backgrounds; humans and other warm-blooded animals become easily visible against the environment, day or night. As a result, thermography's extensive use can historically be ascribed to the military and security services.Uses:

They are used by the police and military for night vision, surveillance, and navigation aid.

The use of thermal imaging has increased dramatically with governments and airports staff using the technology to detect suspected swine flu cases during the 2009 pandemic. Firefighters use it to see through smoke, find persons, and localize the base of a fire. Electrical and Mechanical System Inspection can be used to detect flaws in materials or structures. Corrosion Damage (Metal Thinning): thermal imaging can be used to detect material thinning of relatively thin structures since areas with different thermal masses with absorb and radiate heat at different rates.

Some physiological activities, particularly responses, in human beings and other warm-blooded animals can also be monitored with thermographic imaging.Advantages of thermography

It shows a visual picture so temperatures over a large area can be compared

It is capable of catching moving targets in real time

It is able to find deteriorating, i.e., higher temperature components prior to their failure

It can be used to measure or observe in areas inaccessible or hazardous for other methods

It is a non-destructive test method

It can be used to see better in dark areas.Limitations of thermography:

Images can be difficult to interpret accurately when based upon certain objects, specifically objects with erratic temperatures, although this problem is reduced in active thermal imaging. Accurate temperature measurements are hindered by differing emissivities and reflections from other surfaces. Most cameras have 2% accuracy or worse and are not as accurate as contact methods.

Only able to directly detect surface temperatures.CT SCANING

A CT (computerised tomography) scanner is a special kind of X-ray machine. Instead of sending out a single X-ray through your body as with ordinary X-rays, several beams are sent simultaneously from different angles.

The X-rays from the beams are detected after they have passed through the body and their strength is measured.

Beams that have passed through less dense tissue such as the lungs will be stronger, whereas beams that have passed through denser tissue such as bone will be weaker.

A computer can use this information to work out the relative density of the tissues examined. Each set of measurements made by the scanner is, in effect, a cross-section through the body.

The computer processes the results, displaying them as a two-dimensional picture shown on a monitor. The technique of CT scanning was developed by the British inventor Sir Godfrey Hounsfield, who was awarded the Nobel Prize for his work.

CT scans are far more detailed than ordinary X-rays. The information from the two-dimensional computer images can be reconstructed to produce three-dimensional images by some modern CT scanners. They can be used to produce virtual images that show what a surgeon would see during an operation.

CT scans have already allowed doctors to inspect the inside of the body without having to operate or perform unpleasant examinations. CT scanning has also proven invaluable in pinpointing tumours and planning treatment with radiotherapy.