at89s52

3ATmega16A [DATASHEET]Atmel-8154C-8-bit-AVR-ATmega16A_Datasheet-07/2014

1. Pin Configurations

Figure 1-1. Pinout ATmega16A

(XCK/T0) PB0(T1) PB1

(INT2/AIN0) PB2(OC0/AIN1) PB3

(SS) PB4(MOSI) PB5(MISO) PB6(SCK) PB7

RESETVCCGND

XTAL2XTAL1

(RXD) PD0(TXD) PD1(INT0) PD2(INT1) PD3

(OC1B) PD4(OC1A) PD5(ICP1) PD6

PA0 (ADC0)PA1 (ADC1)PA2 (ADC2)PA3 (ADC3)PA4 (ADC4)PA5 (ADC5)PA6 (ADC6)PA7 (ADC7)AREFGNDAVCCPC7 (TOSC2)PC6 (TOSC1)PC5 (TDI)PC4 (TDO)PC3 (TMS)PC2 (TCK)PC1 (SDA)PC0 (SCL)PD7 (OC2)

PA4 (ADC4)PA5 (ADC5)PA6 (ADC6)PA7 (ADC7)AREFGNDAVCCPC7 (TOSC2)PC6 (TOSC1)PC5 (TDI)PC4 (TDO)

(MOSI) PB5(MISO) PB6(SCK) PB7

RESETVCCGND

XTAL2XTAL1

(RXD) PD0(TXD) PD1(INT0) PD2


2. OverviewThe ATmega16A is a low-power CMOS 8-bit microcontroller based on the Atmel AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the ATmega16A achieves throughputs approaching 1MIPS per MHz allowing the system designer to optimize power consumption versus processing speed.

2.1 Block Diagram

Figure 2-1. Block Diagram


The Atmel AVR core combines a rich instruction set with 32 general purpose working registers. All the 32 registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two independent registers to be accessed in one single instruction executed in one clock cycle. The resulting architecture is more code efficient while achieving throughputs up to ten times faster than conventional CISC microcontrollers.

The ATmega16A provides the following features: 16Kbytes of In-System Programmable Flash Program memory with Read-While-Write capabilities; 512bytes EEPROM; 1Kbyte SRAM; 32 general purpose I/O lines, 32 general purpose working registers; a JTAG interface for Boundary-scan; On-chip Debugging support and programming; three flexible Timer/Counters with compare modes; Internal and External Interrupts; a serial programmable USART; a byte oriented Two-wire Serial Interface, an 8-channel; 10-bit ADC with optional differential input stage with programmable gain (TQFP package only); a programmable Watchdog Timer with Internal Oscillator; an SPI serial port; and six software selectable power saving modes. The Idle mode stops the CPU while allowing the USART; Two-wire interface; A/D Converter; SRAM; Timer/Counters; SPI port; and interrupt system to continue functioning. The Power-down mode saves the register contents but freezes the Oscillator, disabling all other chip functions until the next External Interrupt or Hardware Reset. In Power-save mode, the Asynchronous Timer continues to run, allowing the user to maintain a timer base while the rest of the device is sleeping. The ADC Noise Reduction mode stops the CPU and all I/O modules except Asynchronous Timer and ADC, to minimize switching noise during ADC conversions. In Standby mode, the crystal/resonator Oscillator is running while the rest of the device is sleeping. This allows very fast start-up combined with low-power consumption. In Extended Standby mode, both the main Oscillator and the Asynchronous Timer continue to run.

The device is manufactured using Atmels high density nonvolatile memory technology. The On-chip ISP Flash allows the program memory to be reprogrammed in-system through an SPI serial interface, by a conventional nonvolatile memory programmer, or by an On-chip Boot program running on the AVR core. The boot program can use any interface to download the application program in the Application Flash memory. Software in the Boot Flash section will continue to run while the Application Flash section is updated, providing true Read-While-Write operation. By combining an 8-bit RISC CPU with In-System Self-Programmable Flash on a monolithic chip, the Atmel ATmega16A is a powerful microcontroller that provides a highly-flexible and cost-effective solution to many embedded control applications.

The ATmega16A is supported with a full suite of program and system development tools including: C compilers, macro assemblers, program debugger/simulators, in-circuit emulators, and evaluation kits.


2.2 Pin Descriptions

2.2.1 VCC

Digital supply voltage.

2.2.2 GND

Ground.

2.2.3 Port A (PA7:PA0)

Port A serves as the analog inputs to the A/D Converter.

Port A also serves as an 8-bit bi-directional I/O port, if the A/D Converter is not used. Port pins can provide internal pull-up resistors (selected for each bit). The Port A output buffers have symmetrical drive characteristics with both high sink and source capability. When pins PA0 to PA7 are used as inputs and are externally pulled low, they will source current if the internal pull-up resistors are activated. The Port A pins are tri-stated when a reset condition becomes active, even if the clock is not running.

2.2.4 Port B (PB7:PB0)

Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port B output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port B pins that are externally pulled low will source current if the pull-up resistors are activated. The Port B pins are tri-stated when a reset condition becomes active, even if the clock is not running.

Port B also serves the functions of various special features of the ATmega16A as listed on page 57.

2.2.5 Port C (PC7:PC0)

Port C is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port C output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port C pins that are externally pulled low will source current if the pull-up resistors are activated. The Port C pins are tri-stated when a reset condition becomes active, even if the clock is not running. If the JTAG interface is enabled, the pull-up resistors on pins PC5(TDI), PC3(TMS) and PC2(TCK) will be activated even if a reset occurs.

Port C also serves the functions of the JTAG interface and other special features of the ATmega16A as listed on page 59.

2.2.6 Port D (PD7:PD0)

Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port D output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up resistors are activated. The Port D pins are tri-stated when a reset condition becomes active, even if the clock is not running.

Port D also serves the functions of various special features of the ATmega16A as listed on page 62.

2.2.7 RESET

Reset Input. A low level on this pin for longer than the minimum pulse length will generate a reset, even if the clock is not running. The minimum pulse length is given in Table 27-2 on page 282. Shorter pulses are not guaranteed to generate a reset.

2.2.8 XTAL1

Input to the inverting Oscillator amplifier and input to the internal clock operating circuit.


2.2.9 XTAL2

Output from the inverting Oscillator amplifier.

2.2.10 AVCC

AVCC is the supply voltage pin for Port A and the A/D Converter. It should be externally connected to VCC, even if the ADC is not used. If the ADC is used, it should be connected to VCC through a low-pass filter.

2.2.11 AREF

AREF is the analog reference pin for the A/D Converter.

3. ResourcesA comprehensive set of development tools, application notes and datasheets are available for download on http://www.atmel.com/avr.Note: 1. Data retention

4. Data RetentionReliability Qualification results show that the projected data retention failure rate is much less than 1 PPM over 20 years at 85C or 100 years at 25C.

5. About Code Examples This documentation contains simple code examples that briefly show how to use various parts of the device. These code examples assume that the part specific header file is included before compilation. Be aware that not all C Compiler vendors include bit definitions in the header files and interrupt handling in C is compiler dependent. Please confirm with the C Compiler documentation for more details.

2ATmega32A [DATASHEET]Atmel-8155D-AVR-ATmega32A-Datasheet_02/2014

(XCK/T0) PB0(T1) PB1

(INT2/AIN0) PB2(OC0/AIN1) PB3

(SS) PB4(MOSI) PB5(MISO) PB6(SCK) PB7

RESETVCCGND

XTAL2XTAL1

(RXD) PD0(TXD) PD1(INT0) PD2(INT1) PD3

(OC1B) PD4(OC1A) PD5(ICP1) PD6

PA0 (ADC0)PA1 (ADC1)PA2 (ADC2)PA3 (ADC3)PA4 (ADC4)PA5 (ADC5)PA6 (ADC6)PA7 (ADC7)AREFGNDAVCCPC7 (TOSC2)PC6 (TOSC1)PC5 (TDI)PC4 (TDO)PC3 (TMS)PC2 (TCK)PC1 (SDA)PC0 (SCL)PD7 (OC2)

PA4 (ADC4)PA5 (ADC5)PA6 (ADC6)PA7 (ADC7)AREFGNDAVCCPC7 (TOSC2)PC6 (TOSC1)PC5 (TDI)PC4 (TDO)

(MOSI) PB5(MISO) PB6(SCK) PB7

RESETVCCGND

XTAL2XTAL1

(RXD) PD0(TXD) PD1(INT0) PD2


rr

rr


p p


r r

r r

3ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]Atmel-8271I-AVR- ATmega-Datasheet_10/2014

1. Pin Configurations

Figure 1-1. Pinout ATmega48A/PA/88A/PA/168A/PA/328/P

32 TQFP Top View

28 PDIP

32 MLF Top View

28 MLF Top View

Table 1-1. 32UFBGA - Pinout ATmega48A/48PA/88A/88PA/168A/168PA

1 2 3 4 5 6

A PD2 PD1 PC6 PC4 PC2 PC1

B PD3 PD4 PD0 PC5 PC3 PC0

C GND GND ADC7 GND

D VDD VDD AREF ADC6

E PB6 PD6 PB0 PB2 AVDD PB5

F PB7 PD5 PD7 PB1 PB3 PB4


1.1 Pin Descriptions

1.1.1 VCC

Digital supply voltage.

1.1.2 GND

Ground.

1.1.3 Port B (PB7:0) XTAL1/XTAL2/TOSC1/TOSC2

Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port B output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port B pins that are externally pulled low will source current if the pull-up resistors are activated. The Port B pins are tri-stated when a reset condition becomes active, even if the clock is not running.

Depending on the clock selection fuse settings, PB6 can be used as input to the inverting Oscillator amplifier and input to the internal clock operating circuit.

Depending on the clock selection fuse settings, PB7 can be used as output from the inverting Oscillator amplifier.

If the Internal Calibrated RC Oscillator is used as chip clock source, PB7...6 is used as TOSC2...1 input for the Asynchronous Timer/Counter2 if the AS2 bit in ASSR is set.

The various special features of Port B are elaborated in Alternate Functions of Port B on page 82 and System Clock and Clock Options on page 27.

1.1.4 Port C (PC5:0)

Port C is a 7-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The PC5...0 output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port C pins that are externally pulled low will source current if the pull-up resistors are activated. The Port C pins are tri-stated when a reset condition becomes active, even if the clock is not running.

1.1.5 PC6/RESET

If the RSTDISBL Fuse is programmed, PC6 is used as an I/O pin. Note that the electrical characteristics of PC6 differ from those of the other pins of Port C.

If the RSTDISBL Fuse is unprogrammed, PC6 is used as a Reset input. A low level on this pin for longer than the minimum pulse length will generate a Reset, even if the clock is not running. The minimum pulse length is given in Table 29-11 on page 305. Shorter pulses are not guaranteed to generate a Reset.

The various special features of Port C are elaborated in Alternate Functions of Port C on page 85.|

1.1.6 Port D (PD7:0)

Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port D output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up resistors are activated. The Port D pins are tri-stated when a reset condition becomes active, even if the clock is not running.

The various special features of Port D are elaborated in Alternate Functions of Port D on page 88.


1.1.7 AVCCAVCC is the supply voltage pin for the A/D Converter, PC3:0, and ADC7:6. It should be externally connected to VCC, even if the ADC is not used. If the ADC is used, it should be connected to VCC through a low-pass filter. Note that PC6...4 use digital supply voltage, VCC.

1.1.8 AREF

AREF is the analog reference pin for the A/D Converter.

1.1.9 ADC7:6 (TQFP and QFN/MLF Package Only)

In the TQFP and QFN/MLF package, ADC7:6 serve as analog inputs to the A/D converter. These pins are powered from the analog supply and serve as 10-bit ADC channels.


2. OverviewThe ATmega48A/PA/88A/PA/168A/PA/328/P is a low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the ATmega48A/PA/88A/PA/168A/PA/328/P achieves throughputs approaching 1 MIPS per MHz allowing the system designer to optimize power consumption versus processing speed.

2.1 Block Diagram

Figure 2-1. Block Diagram

The AVR core combines a rich instruction set with 32 general purpose working registers. All the 32 registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two independent registers to be accessed in one single instruction executed in one clock cycle. The resulting architecture is more code efficient while achieving throughputs up to ten times faster than conventional CISC microcontrollers.


The ATmega48A/PA/88A/PA/168A/PA/328/P provides the following features: 4K/8Kbytes of In-System Programmable Flash with Read-While-Write capabilities, 256/512/512/1Kbytes EEPROM, 512/1K/1K/2Kbytes SRAM, 23 general purpose I/O lines, 32 general purpose working registers, three flexible Timer/Counters with compare modes, internal and external interrupts, a serial programmable USART, a byte-oriented 2-wire Serial Interface, an SPI serial port, a 6-channel 10-bit ADC (8 channels in TQFP and QFN/MLF packages), a programmable Watchdog Timer with internal Oscillator, and five software selectable power saving modes. The Idle mode stops the CPU while allowing the SRAM, Timer/Counters, USART, 2-wire Serial Interface, SPI port, and interrupt system to continue functioning. The Power-down mode saves the register contents but freezes the Oscillator, disabling all other chip functions until the next interrupt or hardware reset. In Power-save mode, the asynchronous timer continues to run, allowing the user to maintain a timer base while the rest of the device is sleeping. The ADC Noise Reduction mode stops the CPU and all I/O modules except asynchronous timer and ADC, to minimize switching noise during ADC conversions. In Standby mode, the crystal/resonator Oscillator is running while the rest of the device is sleeping. This allows very fast start-up combined with low power consumption.

Atmel offers the QTouch library for embedding capacitive touch buttons, sliders and wheels functionality into AVR microcontrollers. The patented charge-transfer signal acquisition offers robust sensing and includes fully debounced reporting of touch keys and includes Adjacent Key Suppression (AKS) technology for unambiguous detection of key events. The easy-to-use QTouch Suite toolchain allows you to explore, develop and debug your own touch applications.

The device is manufactured using Atmels high density non-volatile memory technology. The On-chip ISP Flash allows the program memory to be reprogrammed In-System through an SPI serial interface, by a conventional non-volatile memory programmer, or by an On-chip Boot program running on the AVR core. The Boot program can use any interface to download the application program in the Application Flash memory. Software in the Boot Flash section will continue to run while the Application Flash section is updated, providing true Read-While-Write operation. By combining an 8-bit RISC CPU with In-System Self-Programmable Flash on a monolithic chip, the Atmel ATmega48A/PA/88A/PA/168A/PA/328/P is a powerful microcontroller that provides a highly flexible and cost effective solution to many embedded control applications.

The ATmega48A/PA/88A/PA/168A/PA/328/P AVR is supported with a full suite of program and system development tools including: C Compilers, Macro Assemblers, Program Debugger/Simulators, In-Circuit Emulators, and Evaluation kits.

2.2 Comparison Between ProcessorsThe ATmega48A/PA/88A/PA/168A/PA/328/P differ only in memory sizes, boot loader support, and interrupt vector sizes. Table 2-1 summarizes the different memory and interrupt vector sizes for the devices.

Table 2-1. Memory Size Summary

Device Flash EEPROM RAM Interrupt Vector Size

ATmega48A 4KBytes 256Bytes 512Bytes 1 instruction word/vector

ATmega48PA 4KBytes 256Bytes 512Bytes 1 instruction word/vector

ATmega88A 8KBytes 512Bytes 1KBytes 1 instruction word/vector

ATmega88PA 8KBytes 512Bytes 1KBytes 1 instruction word/vector

ATmega168A 16KBytes 512Bytes 1KBytes 2 instruction words/vector

ATmega168PA 16KBytes 512Bytes 1KBytes 2 instruction words/vector

ATmega328 32KBytes 1KBytes 2KBytes 2 instruction words/vector

ATmega328P 32KBytes 1KBytes 2KBytes 2 instruction words/vector


ATmega48A/PA/88A/PA/168A/PA/328/P support a real Read-While-Write Self-Programming mechanism. There is a separate Boot Loader Section, and the SPM instruction can only execute from there. In ATmega 48A/48PA there is no Read-While-Write support and no separate Boot Loader Section. The SPM instruction can execute from the entire Flash

3. Resources A comprehensive set of development tools, application notes and datasheets are available for download on http://www.atmel.com/avr.Note: 1.

4. Data RetentionReliability Qualification results show that the projected data retention failure rate is much less than 1 PPM over 20 years at 85C or 100 years at 25C.

5. About Code Examples This documentation contains simple code examples that briefly show how to use various parts of the device. These code examples assume that the part specific header file is included before compilation. Be aware that not all C compiler vendors include bit definitions in the header files and interrupt handling in C is compiler dependent. Please confirm with the C compiler documentation for more details.

For I/O Registers located in extended I/O map, IN, OUT, SBIS, SBIC, CBI, and SBI instructions must be replaced with instructions that allow access to extended I/O. Typically LDS and STS combined with SBRS, SBRC, SBR, and CBR.

6. Capacitive Touch SensingThe Atmel QTouch Library provides a simple to use solution to realize touch sensitive interfaces on most Atmel AVR microcontrollers. The QTouch Library includes support for the Atmel QTouch and Atmel QMatrixacquisition methods.

Touch sensing can be added to any application by linking the appropriate Atmel QTouch Library for the AVR Microcontroller. This is done by using a simple set of APIs to define the touch channels and sensors, and then calling the touch sensing APIs to retrieve the channel information and determine the touch sensor states.

The QTouch Library is FREE and downloadable from the Atmel website at the following location: www.atmel.com/qtouchlibrary. For implementation details and other information, refer to the Atmel QTouch Library User Guide - also available for download from Atmel website.

The wonder material

A Report on the wonder material by-:

Saksham Agrawal Tanishq Jasoria

Graphene, millions of ultra-thin layers that stack together to form graphite commonly found in pencils, was first studied

as long ago as 1947.

That electric current would be carried by effectively massless charge carriers in graphene was pointed out

theoretically in 1984, and the name 'graphene' was first mentioned in 1987 to describe the graphite layers that had various compounds inserted between them. The term was used extensively in work on carbon nanotubes, which are rolled up graphene sheets. Attempts to grow graphene on other single crystal surfaces have been ongoing since the

1970s, but strong interactions with the surface on which it was grown always prevented the true properties of graphene

being measured experimentally.

If you've ever drawn with a pencil, you've probably made graphene. The world's thinnest material is set to revolutionize almost every part of everyday life.

Fascination with this material stems from its remarkable physical properties and the potential applications these properties offer for the future. Although scientists knew one atom thick, two-dimensional crystal graphene existed, no-one had worked out how to extract it from graphite. That was until it was isolated in 2004 by two Russian-born researchers at The University of Manchester, Andre Geim and Kostya Novoselov.

Graphene, the wonder material, continues to capture the imagination. A honeycomb of carbon atoms so thin it is considered two-dimensional, graphene is stronger than diamond, more electrically conductive than copper and more bendable than rubber.

In the decade since its discovery at the University of Manchester, tens of millions of pounds have been ploughed into researching the material. But efforts to put it to widespread use have been hampered by the expense of producing it at a large scale and its weaknesses, such as radial cracking.

Yet recently there have been signs that the graphene revolution is entering a new phase. Various scientists, including Shou-En Zhu and Catharina Paukner, are claiming to have discovered methods to bulk manufacture the material. Others are formulating hybrid graphene spin-offs new substances with special properties of their own.

This would not only make graphene more efficient, it could also make it more durable. And if commercially viable and better adapted, graphene has the potential to reshape the world we live in. Here are six ways graphene could extend the longevity of products.

The molecule is priceless but it is not a matter of cost a few hundred dollars per kilo. The value lies in its potential. The molecule in question is called graphene and the EU is prepared to devote 1bn ($1.3bn) to it between 2013 and 2023 to find out if it can transform a range of sectors such as electronics, energy, health and construction. According to Scopus, the bibliographic database, more than 8,000 papers have been written about graphene since 2005.

As its name indicates, graphene is extracted from graphite, the material used in pencils. Like graphite, graphene is entirely composed of carbon atoms and 1mm of graphite contains some 3 million layers of graphene. Whereas graphite is a three-dimensional crystalline arrangement, graphene is a two-dimensional crystal only an atom thick. The carbons are perfectly distributed in a hexagonal honeycomb formation only 0.3 nanometres thick, with just 0.1 nanometres between each atom.

This 100% pure carbon simplicity confers some remarkable properties on graphene, very close to the calculated theoretical ones, as observed by the authors of A Roadmap for Graphene published in Nature last year.

Graphene conducts electricity better than copper. It is 200 times stronger than steel but six times lighter. It is almost perfectly transparent since it only absorbs 2% of light. It

impermeable to gases, even those as light as hydrogen or helium, and, if that were not enough, chemical components can be added to its surface to alter its properties.

"Graphene is a platform, like a chessboard, on to which one can place the pawns you want. The subtlety lies in finding the right positions. There is a real beauty in its simplicity," explained Vincent Bouchiat, from the Institut Nel in Grenoble, part of the National Centre for Scientific Research (CNRS). "The future lies in pencil graphite!" said Annick Loiseau, from the National Office for Aerospace Studies and Research (ONERA), coining a slogan. She is the French representative to the executive office of Graphene Flagship, a research consortium funded by the EU for the next 10 years.

The project was officially launched last month. "We have already learnt a great deal but new results could emerge in certain situations only we don't yet know which ones," said Mark Goerbig, another CNRS researcher, who works in the solid physics department at Paris-Sud Orsay University.

This miracle material has come a long way. In theory, such a two-dimensional structure was believed to be unstable and therefore better rolled up, as observed in the 1990s with carbon nanotubes.

In 2004 two Russian-born scientists, Andre Geim and Konstantin Novoselov, along with others, published the first electronic measurements proving they had isolated graphene. They had removed carbon flakes from graphite using bits of sticky tape which ultimately led to them winning a Nobel prize for physics in 2010.

"The theory only really held true for two dimensions, but in actual fact the crystal grows in a three-dimensional space and the small surface fluctuations, like waves, stabilise the crystal," said Goerbig. Experiments rapidly confirmed the marvellous behaviour of this new material, which can be explained by a kind of sea of electrons on the surface that nothing can stop and that do not interact with each other. It's as though the electrons have no mass and move at a speed 300 times slower than light. The mathematical equation to describe them is closer to that for high-energy particles than for solid matter, hence this outstanding performance that suggests so many potential uses.

Being transparent as well as a good conductor, graphene could replace the electrodes in the indium used in touchscreens. Since it is light, graphene could be integrated into composite materials to eliminate the impact of lightning on aircraft fuselages. It is also waterproof and would be perfect to use in hydrogen reservoirs.

Since nothing can stop the electrons, graphene cannot be "switched off" so in theory it is of little use in transistors, which are the key components of modern electronic goods. However, research is being carried out into ways of creating an artificial band gap that would enable it to be switched off and therefore used for that purpose.

The European consortium has decided to focus on a number of applications. "Our goal is to support innovation in Europe but also to create a network of specialists in contact with companies for long-term R&D projects," said Stephan Roche, in charge of one section of the project, and a researcher at the Catalan Institute of Nanoscience and Nanotechnologies in Barcelona.

A piece of graphene aerogel - weighing only 0.16 milligrams per cubic centimeter - is placed on a flower.

The major steps in this process have already begun. Several start-up companies are already manufacturing graphene, mainly for laboratories, using a variety of techniques. The "historical" one with sticky tape has been replaced by chemical exfoliation. An alternative is to use a carbon and silicon substrate, which is heated to remove the silicon atoms, leaving a layer of graphene on the surface. Yet another method is to place carbon on the surface of copper which, after heating, catalyses the graphene formation reaction. A team from Rice University in the US has even used a cockroach leg as a source of carbon.

In Europe, Applied Graphene Materials (AGM) in the UK and Avanzare and Graphenea in Spain are the spearheads. "If we want graphene to become the equivalent of silicon in microelectronics today, it is important to control the material and its quality," said Etienne Quesnel of the French Alternative Energies and Atomic Energy Commission, in

charge of the energy aspect of Graphene Flagship, which also works with manufacturing specialists.

Industry giants are in the running too. IBM has produced several electronic component prototypes, while Samsung has produced a flat screen (70cm in the diagonal) with graphene electrodes. The tennis racket maker Head used tennis champions Novak Djokovic and Maria Sharapova to promote rackets made with graphene. BASF and Daimler-Benz have designed a concept electric car calledSmart Forvision that incorporates graphene in a conductive e-textile. In 2012, BASF produced a report on the future of graphene, forecasting a market worth $1.5bn in 2015 and $7.5bn in 2025.

It goes without saying that China is also in the race, with 2,600 articles published in Europe. And with more than 2,200 patents it has surpassed Europe and the US.

Last summer one start-up, Bluestone Global Tech, announced a partnership with a mobile phone manufacturer for the first graphene-based touchscreens to be launched on the Chinese market in the coming months. Nevertheless, mass applications are not yet in the pipeline.

"People are being sold graphene that is really graphite only more expensive," said Marc Monthioux, from the CEMES research centre in Toulouse at a conference on graphene-based composite materials held in Paris earlier this year. Strictly speaking, graphene is single-layered, but manufacturing processes may create stacks of several layers. When more than 10 layers are created, the properties change enormously and resemble graphite more than graphene. "To date graphene is not absolutely superior to carbon nanotubes," said Monthioux. According to Loiseau, "In composites it is necessary for the carbon, graphene or nanotube molecules to 'touch' each other to be conductive. That is easier for elongated nanotubes than for flake-shaped graphene, which explains the difference." It takes a long time to develop a composite material and nanotubes have the advantage of being the more mature material. Nanotube researchers were not happy to see graphene arrive and grab both attention and funding.

Nevertheless, accumulated nanotube experience is very useful to speed up work on graphene. "It took six years to produce the first transistors with nanotubes," said Loiseau. "With graphene, we had the first electric measurements in a year."

As far as its medical use is concerned, knowledge of one material serves for the other. A crucial aspect of the European project is devoted to how to protect the people working with graphene as well as end users, in addition to researching possible medial

applications. "At present we have studies showing no effect while others indicate a potential risk," said Alberto Bianco, CNRS head of research at the Institute of Molecular and Cellular Biology in Strasbourg, who co-heads the health and environmental aspects of the European project.

In fact, as with carbon nanotubes, the considerable diversity of types of graphene need to be taken into account. Size certainly matters, but so does the chemical state. The molecule may be oxidised to a greater or lesser extent, or contain different amounts of residual impurities as a result of how the graphene is synthesised, or how its layers are built up. There is no definitive answer. In an article published in April in Angewandte Chemie, scientific journal of the German Chemical Society, Bianco quoted several contradictory studies, some of which found toxic effects on micro-organisms where others did not. Nor has any light been shed on the way graphene could cause damage to cells. Does the graphene cut through the cell wall perpendicularly or does it coat the cell?

"One optimistic note is that chemistry may enable us to modulate the biological activity of this nanomaterial," said Bianco. For instance, by binding different chemical groups one might make the graphene more or less soluble, or guide it towards a given therapeutic target. Additional work is therefore required. The consortium will study the effects on different types of cells (cancerous, neuronal, related to the immune system etc)as well as on amphibians.

Another advantage of graphene is that is opens up paths to other two-dimensional materials as small as atoms. Boron nitride, molybdenum sulphateand tungsten or even 100% silicon sillicene are some of the peculiar sounding names that could become more common. Some isolate, others conduct. Piling up these molecules layer-by-layer would create new materials with new properties. The game is on.

WHAT GRAPHENE CAN DO?Graphene. The world's first 2D material. Since its isolation in 2004 it has captured the attention of scientists and researchers worldwide. It is ultra-light, yet immensely tough. It is 200 times stronger than steel, but is incredibly flexible. It is fire resistant yet retains heat. It is a superb conductor, but not even helium can pass through it. All this and more. Much more.

When graphene is used alone or combined with other materials or substances the possibilities are infinite. It is a young material with the potential to create incredible future technologies and vastly enhance existing products.

So where will graphene take us? How will it change our world? What benefits will it bring to mankind in the near future and the decades to come?

Graphene could revolutionise medicine. Nanotechnology is set to transform medical procedures. Drugs could be delivered to specific targeted cells. Graphene could pave the way for a step change in the treatment of cancer and conditions such as Parkinson's.

Graphene has enormous potential when used as a membrane to separate liquids. It could see huge progress in water purification and treatment in developing countries, and even provide more efficient desalination plants.

Graphene can make the world a safer place. In aircraft technology and cars. Through clothing for the defence industry.

Graphene conducts. It means advanced paints could both reduce corrosion and increase energy efficiency.

Graphene detects. It could create sensors that can detect even minute traces of gases or dangerous chemicals, or sustainable food packaging that can let you know when food has gone off.

Graphene absorbs light and retains it as energy. Add this to its strength and flexibility and bendable mobile phones and cameras with enormous battery life are ever closer. So are wearable electronics, clothing that communicates. These are future technologies which are becoming realistic in our present.

Graphene has low weight and high strength. Harnessed with polymers and composites it could make numerous forms of transport safer and more fuel efficient.

This is only the start. These are only the first steps. The potential of graphene is limited only by our imagination.

IS GRAPHENE INVISIBLE?Graphene is the world's thinnest material one atom thick. To put this into context, it is almost one million times thinner than a human hair. Therefore, on its own it is not visible to the human eye. However, single-layer graphene can be seen under the microscope and millions of layers of graphene can be put together to create applications. Graphene samples can also be transferred onto wafers, made from silicon and similar materials, or in soluble solutions so they can be seen clearly by the human eye.

WHEN IS IT HITTING THE MARKETS?Graphene was isolated in 2004, so its an extremely new material. We expect to see the first products, likely to be graphene screens for mobile phones and e-paper devices, on general sale in 2015. This will mean from extraction to application in just over 10 years. This is a remarkably quick turnaround for a new material. Further applications may take several years to develop, for example, bio and medical applications such as drug delivery would need to be subject to clinical trials, laboratory experiments and further research.

GRAPHENE VS. CARBON NANOTUBESCarbon nanotubes are, in fact, simply rolled up tubes of graphene. Their potential uses have been widely discussed, but few, if any, applications have yet been made. It is considered that many of the current and potential applications of carbon nanotubes may be taken by graphene as it displays enhanced properties but with greater ease of production and handling. It is graphenes combination of superlatives that give it its 'wondermaterial' title. Other materials individually have superb qualities, but graphene has several all in one. It is these characteristics that provide expectation that graphene will lead to real-life applications of the future. In addition, the isolation of graphene paved the way for a series of other 2D materials, all of which can be combined with graphene to create novel applications as yet only a figment of our imagination.

IS GRAPHENE DANGEROUS?

There are no proven dangers to consumers. However, if you were to inhale or ingest a nanomaterial such as graphene it could potentially be toxic and so producers engaged in the manufacturing process have to act with caution.

THE MANUFACTURING PROCESSTechnically, every time you write with a pencil, graphene is produced. One of the most beguiling and fascinating aspects of the isolation of graphene is the remarkable simplicity of how it was extracted from graphite.

Andre and Kostya used humble Scotch tape to painstakingly peel layers from a stick of graphite. And, believe it or not, some of our researchers still use this method to produce graphene, because of the high-quality of the material created.

On an industrial scale, however, production methods have advanced greatly. There are a few ways to mass-produce graphene, including Chemical Vapour Deposition, where a gas containing carbon (such as Methane) is broken down and reassembled on a hot metallic surface into a sheet of graphene, and Solution Exfoliation, where graphite is blasted into small fragments of graphene using ultrasonic energy.

A NEW APPROACH

Graphene was discovered by Konstantin Novoselov and Andre Geim. Strong, chemically inert, transparent and thermally and electronically conductive, the material had so much potential for use in a variety of applications. The problem is, graphene is difficult and expensive to produce. All that could change, however, as a researcher discovers a means of making production faster for the material, bringing costs down by a thousand fold.

Shou-En Zhu is a PhD candidate from the Delft University of Technology in the Netherlands. In his thesis, which he will be defending in March, Zhu detailed a process of producing graphene that will not only hasten the process but will also be dramatically cheaper than current costs. Researchers have studied graphene well enough to sing praises to the material. Unfortunately, translating all that potential to an actual material is more difficult than it sounds.

When Novoselov and Geim produced graphene, they used scotch tape and pencil markings, repeatedly sticking tape against a pencil mark to thin out the graphite layer until it was just a single carbon sheet. There are several means of making graphene but Novoselov and Geim's way, known as the exfoliation method, is the best way to produce the material with the highest level of electron mobility and the lowest number of defects. Unfortunately, making graphene perfectly through this method costs over $1,000 for a flake about the size of a hair.

Zhu's method calls for a low-pressure mix of argon, methane and hydrogen over a sheet of copper heated to 1,832 degrees Fahrenheit. With the copper acting as catalyst, hydrogen is stripped from methane, leaving a layer of pure carbon sticking to the sheet.

This deposition process will typically need 10 hours to accomplish but Zhu has found a way to reduce that to one hour. This is possible by splitting the quartz tube in the oven. After deposition, the furnace is slid away to facilitate cooling.

But is graphene made through Zhu's way good enough? A demonstration took place showing graphene the size of a millimeter was indeed a single crystal by moving electrons freely around it. Free-moving electrons were pushed into circular trajectories without scattering, proving the flawlessness of the synthetic graphene.

"I want to make graphene real and bring it into daily life. Bring it into products anyone can touch," Zhu said of his future research goals. Though just as thick as one atom, graphene is 200 times stronger than steel, as flexible as rubber and more conductive compared to copper.

TYPES OF GRAPHENE

Graphene a single-atom-thick sheet of hexagonally arranged, bonded carbon atoms, either freely suspended or adhered to a substrate. The dimensions of graphene can vary from several nanometers to the macroscale. Monolayer (single-layer) graphene is the purest from available and is useful for high-frequency electronics. Bi- and tri-layer graphene, two and three layers respectively, display a range of different qualities as the number of layers increase, as well as becoming progressively cheaper as the layers multiply.

Few-layer graphene (FLG) or multi-layer graphene (MLG) a 2D,sheet-like material, either as a free-standing flake or substrate-bound coating, consisting of a small number (between two and about 10) of well-defined, countable, stacked graphene layers of extended lateral dimension. Individual flakes should still maintain a high aspect ratio. Few-layer graphene or graphene oxide dispersions can have a defined thickness distribution. MLG is useful for composite materials, and as a mechanical reinforcement.

Graphene oxide (GO) chemically modified graphene prepared by oxidation and exfoliation. Graphene oxide is a monolayer material with a high oxygen content. Thin membranes that allow water to pass through but block off harmful gases are a major use for GO.

Reduced graphene oxide (rGO) graphene oxide (as above) that has been reductively processed by chemical, thermal, microwave, photo-chemical, photo-thermal or microbial/bacterial methods to reduce its oxygen content. Conductive inks are just one potential use for rGO.

Graphite nanoplatelets; graphite nanosheets; graphite nanoflakes; 2D graphite materials with a thickness and/or lateral dimension of less than 100 nanometres. The use of nanoscale terminology here can be used to help distinguish these new ultrathin forms from conventional finely milled graphite powders, whose thickness is typically more than 100 nanometres. Excellent for electrically conductive composites

APPLICATIONS

Graphene-based micro battery could power biotelemetry implants Scaling down electronics isnt only important when building consumer devices, it also has a hufe impact on the world of implantable medical devices. However, as with all things technological, batteries just arent keeping up with all the other components. It is possible to build incredibly small sensor packages that can be injected into the body, but the tiny silver oxide watch batteries most devices use just dont allow for long-term study. This problem might be solved by everyones favorite form of carbon, graphene. A new type of graphene micro battery could kick off a new age of long-term biotelemetry.

If a doctor or scientist needs to track some aspect of a persons health, they either need to be hooked up to an external machine, or there needs to be something implanted in the patients body for example blood glucose and cardiac monitors. These devices are usually very short lived or much larger than they would otherwise be due to power requirements. Work on miniaturizing implantables relies on smaller, more efficient batteries like the graphene cell created by researchers at Pacific Northwest National Laboratory (PNNL).

The PNNL battery was developed for an experiment following the development of adolescent salmon. Existing implantable sensors didnt last long enough to keep relaying data over the course of the fishs migration, so the researchers looked into building something better. In the process of chasing the perfect implantable fish sensor, the team designed a so-called jelly roll micro battery based on a graphene cathode.

The form of graphene used in the PNNL battery is known as fluorinated graphene. The application of fluoride to graphene enhances its electrochemical properties allowing it to retain higher voltages and discharge more efficiently. The micro battery design is referred to as a jelly roll because the various components are laid out flat in a stack during construction. There is the fluorinated graphene cathode and a lithium-based anode, each with separating layers in between. The entire stack is then rolled up into a cylinder and sealed, thus a jelly roll.

This design allows for a significant increase in the total surface area of cathode and anode, meaning higher capacity. Even in this first iteration, the researcher managed to double the capacity of other micro batteries, and this cell is even smaller than most about the size of a grain of rice. The battery is capable of sending out a 744-microsecond pulse every five seconds for a month. Thats more than sufficient to gather biotelemetry data over the long term.

If these tiny batteries can be developed into a reliable component in human medicine, they could absolutely save lives. Patients with medical conditions that require monitoring could get real time updates, and may not need to spend as much time in the hospital. Having fewer people in hospitals simply for monitoring reduces the risk of nosocomial (hospital-acquired) infections.

However, there is still work to be done on the design of PNNLs batteries. Each one for the fish study was hand made from sheets of the individual components. Other teams are sure to look more closely at fluorinated graphene batteries now.

Graphene smart contact lenses could give you thermal infrared and UV vision

A breakthrough in graphene imaging technology means you might soon have a smart contact lens, or other ultra-thin device, with a built-in camera that also gives you infrared heat vision. By sandwiching two layers of graphene together, engineers at the University of Michigan have created an ultra-broadband graphene imaging sensor that is ultra-broadband (it can capture everything from visible light all the way up to mid-infrared) but more importantly, unlike other devices that can see far into the infrared spectrum, it operates well at room temperature.

As you probably know by now, graphene has some rather miraculous properties including, as luck would have it, a very strong effect when its struck by photons (light energy). Basically, when graphene is struck by a photon, an electron absorbs that energy and becomes a hot carrier an effect that can be measured, processed, and turned into an image. The problem, however, is that graphene is incredibly thin (just one atom thick) and transparent and so it only absorbs around 2.3% of the light that hits it. With so little light striking it, there just arent enough hot carrier electrons to be reliably detected. (Yes, this is one of those rare cases where being transparent and super-thin is actually a bad thing.)

Zhaohui Zhong and friends at the University of Michigan, however, have devised a solution to this problem. They still use a single layer of graphene as the primary photodetector but then they put an insulating dielectric beneath it, and then another layer of graphene beneath that. When light strikes the top layer, the hot carrier tunnels

through the dielectric to the other side, creating a charge build-up and strong change in conductance. In effect, they have created a phototransistor that amplifies the small number of absorbed photons absorbed by the top layer (gate) into a large change in the bottom layers conductance (channel). In numerical terms, raw graphene generally produces a few milliamps of power per watt of light energy (mA/W) the Michigan phototransistor, however, is around 1 A/W, or around 100 times more sensitive. This is around the same sensitivity as CMOS silicon imaging sensors in commercial digital cameras.

The prototype device created by Zhong and co. is already smaller than a pinky nail and can be easily scaled down. By far the most exciting aspect here is the ultra-broadband sensitivity while the silicon sensor in your smartphone can only register visible light, graphene is sensitive to a much wider range of wavelengths, from ultraviolet at the bottom, all the way to far-infrared at the top. In this case, the Michigan phototransistor is sensitive to visible light and up to mid-infrared but its entirely possible that a future device would cover UV and far-IR as well. There are imaging technologies that can see in the UV and IR ranges, but they generally require bulky cryogenic cooling equipment; the graphene phototransistor, on the other hand, is so sensitive that it works at room temperature.

Now, I think we can all agree that a smartphone that can capture UV and IR would be pretty damn awesome but because this is ultra-thin-and-light-and-efficient graphene were talking about, the potential, futuristic applications are far more exciting. For me, the most exciting possibility is building graphene imaging technology into smart contact lenses. At first, you might just use this data to take awesome photos of the environment,

or to give you you night/thermal vision through a display built into the contact lens. In the future, though, as bionic eyes and retinal implants improve, we might use this graphene imaging tech to wire UV and IR vision directly into our brains.

Imagine if you could look up at the sky, and instead of seeing the normal handful of stars, you saw this:

Graphene body armor Graphene, the wonder material that should rejuvenate almost every sphere of science and technology in the next decade or so, can add another application to its already exceedingly long list: bulletproof armor. US researchers have found that, by stacking sheets of graphene on top of each other, it has between eight and 10 times the stopping power of steel.

I know, I know at this point, its hardly surprising that graphene would make the ideal material for thin and light bulletproof armor. Its still pretty awesome, however, that all ofgraphenes properties from being the most electrically conductive material in the world, to being super-strong, to allowing for transparent brain implants all derive from a one-atom-thick layer of carbon atoms arranged in a honeycomb structure.

This new research, carried out by Rice University and the University of Massachusetts, is notable for being one of first examples of actually testing graphene out. Usually, a lot of graphene research is simulated or theoretical or extrapolated. In this case, the US researchers actually fired tiny gold bullets at sheets of graphene, and then measured the results.

The researchers tested between 10 and 100 layers of graphene between 10 nanometers and 100 nanometers thick, respectively. They focused a laser on a gold filament, vaporizing it into a projectile bullet that traveled at 3,000 meters per second or more than twice the muzzle velocity of a high-powered rifle. As the tiny (micrometer-sized) bullets slammed into the graphene armor, it showed around twice the stopping power of Kevlar, or about 10 times the stopping power of steel plate.

As expected, the impact of the bullets caused the graphene to deform into a cone shape and then cracking radially. These cracks are somewhat problematic, but they could be easily solved with a composite structure (a ceramic plate, perhaps), or just by using more graphene. Remember, graphene is so thin and light that you can basically keep stacking layers of it indefinitely without incurring any significant bulkiness or mass; a million layers of graphene would be on the order of 1 million nanometers or 1 millimeter thick.

Moving forward, we yet again return to the linchpin of the impending graphene revolution: Producing large quantities of the stuff, at a high enough quality for commercial applications. As it stands, we have processes that can produce fairly large quantities of low-grade graphene, or tiny quantities of high-grade graphene, but were still waiting for the Goldilocks method that does it all. And then and then well be taking rides on a space elevator, equipped with transparent, bendy smartphones, with batteries that last a week and lightweight graphene body armor, just in case someone shoots you, or youre hit by a stray piece of space debris. Doesnt the future sound grand?

Ultra-Sensitive graphene sensor that can detect cancer biomarkers

Sam Goodys technological pivot from vinyl to polycarbonate was one of the most sweeping changes of the guard that the Earth has ever seen. Not only did new optical CDs have the rewritable potential of the magnetic ribbon tape, they also had the nonrewritability of the record. While many imagine a similar takeover of silicon by

graphene may be just around the corner, those in the field of biosensing know that we have already rounded the bend. Case in point: Some researchers have now created a graphene sensor that can detect one of the genetic markers of cancer.

The good old graphene exfoliation techniques, where layers of graphene are peeled from graphite, do not generally create enough surface area for a sensitive detector. Even the more exotic graphene fabrication methods, like supersonic sprays from de Laval nozzles, just make simple uniform coatings. Researchers from Swansea University have now perfected a new graphene processing technique to build a detector of precancerous conditions that blows other technologies out of the water. They were able to grow graphene on silicon carbide substrates and then use more germane semiconductor processes to pattern them. Antibodies that could bind to a specific derivative of damaged DNA were then bound using fancy chemistry to functionalize the graphene.

The hallmark of several kinds of cancer is widely believed to be a molecule called 8-hydroxydeoxyguanosine, or simply 8-OHdG. Guanosine is one of the four genetic bases and its damaged hydroxy form ends up in the blood, saliva, and urine as it cycles naturally through the cellulo-physiological circle of life. The new graphene chip was able to detect this molecule at concentration of just 0.1 nanograms per milliliter. That is five times more sensitive and several times faster than any other method we have. This new device shifts the balance of power back to the hardware and puts the onus of relevance back on the plate of biology. In other words, medicine asked for the ability to easily detect 8-OHdG and they got it. Now the larger world can respond to medicine and biology with a resounding, show me that it really matters to my quality of life.

The amount by which your iPhone memory exceeds that of the computers on board the Apollo 11 is the perfect measure for how little the size of your bit matters compared to what you do with it. While the genetic bit that indicates you may have cancer tells you infinitely more than the one that holds the Nth color value of the last pixel in a sunset, the

real powers are in the devices that feed that bit. The answer to the actual relevance of myriad and frequently nebulous biomarkers like 8-OHdG is not yet in hand. Devices like the new Swansea graphene chip are exactly what we need to determine if they are mere technological lures, or end goals in themselves.

Transparent optogenetic brain implants

Transparency is the key to many technologies. Thin conductive films, like those made from ITO (indium tin oxide) for example, can carry currents or create electric fields critical for displays or solar panels without blocking all the light. The most powerful brain implants being built today have exactly this same requirement. Namely, they need to record fast electric signals with conductive arrays while permitting light to pass out through them for high-resolution imaging and just to take it up a notch let light pass in to permit optogenetic control directly under the implant for the icing on the cake.

Unfortunately, ITO is generally too stiff and too brittle for brain implants. Even if it could be made flexible, the high temperatures required to process it are incompatible with many of the materials (like parylene) that are used in the implants. Furthermore the transparency bandwidth of ITO is insufficient to fully exploit the wide spectrum of new UV and IR capable optogenetic proteins that have researchers fairly excited. The solution, now emerging from multiple labs throughout the universe is to build flexible, transparent electrode arrays from graphene. Two studies in the latest issue of Nature

Communications, one from theUniversity of Wisconsin-Madison and the other from Penn, describe how to build these devices.

The University of Wisconsin researchers are either a little bit smarter or just a little bit richer, because they published their work open access. Its a no-brainer then that we will focus on their methods first, and also in more detail. To make the arrays, these guys first deposited the parylene (polymer) substrate on a silicon wafer, metalized it with gold, and then patterned it with an electron beam to create small contact pads. The magic was to then apply four stacked single-atom-thick graphene layers using a wet transfer technique. These layers were then protected with a silicon dioxide layer, another parylene layer, and finally molded into brain signal recording goodness with reactive ion etching.

The researchers went with four graphene layers because that provided optimal mechanical integrity and conductivity while maintaining sufficient transparency. They tested the device in opto-enhanced mice whose neurons expressed proteins that react to

blue light. When they hit the neurons with a laser fired in through the implant, the protein channels opened and fired the cell beneath. The masterstroke that remained was then to

successfully record the electrical signals from this firing, sit back, and wait for the Nobel prize office to call.

The Penn State group used a similar 16-spot electrode array (pictured above right), and proceeded we presume in much the same fashion. Their angle was to perform high-resolution optical imaging, in particular calcium imaging, right out through the transparent electrode arrays which simultaneously recorded in high-temporal-resolution signals. They did this in slices of the hippocampus where they could bring to bear the

complex and multifarious hardware needed to perform confocal and two-photon microscopy. These latter techniques provide a boost in spatial resolution by zeroing in over narrow planes inside the specimen, and limiting the background by the requirement of two photons to generate an optical signal. We should mention that there are voltage sensitive dyes available, in addition to standard calcium dyes, which can almost record the fastest single spikes, but electrical recording still reigns supreme for speed.

One concern of both groups in making these kinds of simultaneous electro-optic measurements was the generation of light-induced artifacts in the electrical recordings. This potential complication, called theBecqueral photovoltaic effect, has been known to exist since it was first demonstrated back in 1839. When light hits a conventional metal electrode, a photoelectrochemical (or more simply, a photovoltaic) effect occurs. If present in these recordings, the different signals could be highly disambiguatable. The Penn researchers reported that they saw no significant artifact, while the Wisconsin researchers saw some small effects with their device. In particular, when compared with platinum electrodes put into the opposite side cortical hemisphere, the Wisconsin researchers found that the artifact from graphene was similar to that obtained from platinum electrodes.

At this point both groups are busy characterizing the performance of their new devices in exacting detail. If workable as more permanent brain implants they may offer a nice compliment to other new approaches we have recently seen flexible materials like silk for example. Where silk may offer biodegradability and reversibility, graphene may offer biocompatible permanence and reliability. The significant hype regarding optogenetics, well-founded in our opinion, seems to have died down for the moment. New advances like those just described may help refocus general attention on the huge potential benefit optogenetics holds for humans.

Flexible smart cards

In the UK, about 58m million credit and other bank cards were in circulation in February last year. Add the miscellaneous others which congregate in the average wallet and youll have an idea of the amount of plastic used annually.

A graphene smart card could change all this, as shown by the Spanish companyGraphenano. Imagine a single touch-activated card that held all your personal information credit cards, boarding passes, train tickets, Oyster cards in one. With everything updated from a computer, a smart card could eradicate enormous amounts of plastic waste.

Updatable foldable newspaper

Last September, the Cambridge Graphene Centre demonstrated the firstgraphene-based flexible display. It could be bent this way and that, while continuing to show digital content. It was a little moment of great significance.

A bendable screen could be used in any number of ways. Like the moving images in the Daily Prophet newspaper featured in Harry Potter , real newspapers could develop foldable graphene templates that are updated wirelessly each day, cutting paper waste dramatically. Updatable foldable Ordnance Survey maps could do the same.

Electric car batteries

Batteries have long been the Achilles heel of electric cars. Poor charge capacity means that people are less likely to rely on them, and with the lifespan of the battery linked to the lifespan of the vehicle, electric cars often become obsolete and need replacing.

At last, there are plans to introduce a new polymeric graphene battery in 2015. Especially suited to electric cars, this battery is said to have a lifetime four-times longer than conventional hybrid ones and allows vehicles to run as much as 1,000km on a 10-minute charge. Without the need to be replaced, the graphene battery may signal a new era for the electric car.

Indestructible smart phones

In America the average lifespan of a smartphone is just two years. Some models fall out of fashion, others are lost, smashed or drowned in water. According to extended warranty

service provider SquareTrade, as many as one third of smartphone users damage their handset in the first year of ownership.

For a prevalent product, this signifies enormous waste, yet graphenes tough properties could change this. A recent experiment published in the journal Science suggested graphene was twice as bullet-proof as Kevlar the standard material for ballistic armour. Imagine if such a strong material was integrated into smartphone design, replacing the glass or plastic components?

Paint

Not so eye-catching, but equally useful is graphenes use as a paint. Its tough exterior is useful to withstand the wind and rain in outdoor structures, but it also has useful lubricating properties that mean it works in other situations. Applied Graphene Materials in the USA are developing graphene paints that can be used on a ships hulls, halting the spread of underwater corrosion and stopping barnacles from adhering to metal.

A similar enterprise is underway in Spain, where Grapheano have mixed together graphene powder and ground limestone to make a paint that they call Graphenstone. In a publicity move they proposed to paint the Valencia opera house that had been damaged by wind erosion just eight years after its completion.

Solar panels

Standard solar panels have a lifespan of about 40 years, but become less efficient with time and often have to be replaced. One of the main challenges is exposure to all types of weather.

Scientists at the University of Exeter claim that solar panels could be made much more weather resistant if the indium tin oxide (ITO) currently used was replaced with GraphExeter. Formulated at The Centre for Graphene Science at the University of Exeter, GraphExeter comprises several layers of graphene sheets mixed with a separate layer of ferric chloride molecules.

According to a recent press release, GraphExeter is much tougher than ITO and improves on the properties of traditional graphene, able to withstand humidity of 100% and temperatures of up to 150C, all of which promises less waste and huge improvements for the solar panel industry.

Using Oxides to Flip Graphene ConductivityGraphene, a one-atom thick lattice of carbon atoms, is often touted as a revolutionary material that will take the place of silicon at the heart of electronics. The unmatched speed at which it can move electrons, plus its essentially two-dimensional form factor, make it an attractive alternative, but several hurdles to its adoption remain.

A team of researchers from the University of Pennsylvania; University of California, Berkeley; and University of Illinois at Urbana-Champaign has made inroads in solving one such hurdle. By demonstrating a new way to change the amount of electrons that reside in a given region within a piece of graphene, they have a proof-of-principle in making the fundamental building blocks of semiconductor devices using the 2-D material.

Moreover, their method enables this value to be tuned through the application of an electric field, meaning graphene circuit elements made in this way could one day be dynamically rewired without physically altering the device.

The study was a collaboration between the groups of Andrew Rappe at Penn, Lane Martin at Berkeley, and Moonsub Shim at Illinois. It was published in the journal Nature Communications.

Silicon is used for making circuit elements because its charge-carrier density, the number of free electrons it contains, can be easily increased or decreased by adding chemical impurities. This doping process results in p-type and n-type semiconductors, silicon that has either more positive or more negative charge carriers.

The junctions between p- and n-type semiconductors are the building blocks of electronic devices. Put together in sequence, these p-n junctions form transistors, which can in turn be combined into integrated circuits, microchips and processors.

Chemically doping graphene to achieve p- and n-type version of the material is possible, but it means sacrificing some of its unique electrical properties. A similar effect is possible by applying local voltage changes to the material, but manufacturing and placing the necessary electrodes negates the advantages graphenes form factor provides.

Weve come up with a non-destructive, reversible way of doping, Rappe says, that doesnt involve any physical changes to the graphene.

The teams technique involves depositing a layer of graphene so it rests on, but doesnt bond to, a second material: lithium niobate. Lithium niobate is ferroelectric, meaning thatit is polar, and its surfaces have either a positive or negative charge. Applying an electric field pulse can change the sign of the surface charges.

Thats an unstable situation, Rappe says, in that the positively charged surface will want to accumulate negative charges and vice versa. To resolve that imbalance, you could have other ions come in and bond or have the oxide lose or gain electrons to cancel out those charges, but weve come up with a third way.

Here we have graphene standing by, on the surface of the oxide but not binding to it. Now, if the oxide surface says, I wish I had more negative charge, instead of the oxide gathering ions from the environment or gaining electrons, the graphene says I can hold the electrons for you, and theyll be right nearby.

Rappe suggests using lithium niobate, as it is already commonly used in optical engineering and has properties that would lend themselves to creating p-n junctions. The researchers took advantage of the fact that a certain type of the material, periodically poled lithium niobate, is manufactured so that it has stripes of polar regions that alternate between positive and negative.

Because the lithium niobate domains can dictate the properties, Shim says, different regions of graphene can take on different character depending on the nature of the domain underneath. That allows, as we have demonstrated, a simple means of creating a p-n junction or even an array of p-n junctions on a single flake of graphene. Such an ability should facilitate advances in graphene that might be analogous to what p-n junctions and complementary circuitry has done for the current state-of-the-art semiconductor electronics.

Whats even more exciting are the enabling of optoelectronics using graphene and the possibility of waveguiding, lensing and periodically manipulating electrons confined in an atomically thin material.

Their experiments also involved adding a single gate to the device, which allowed for its overall carrier density to be further tuned by the application of different voltages.

By taking into account how the oxide balances out its surface charges on its own, or by

binding ions from the aqueous solution, the researchers were able to show the relationship between the polarization of the oxide and the charge carrier density of the graphene suspended over it.

And because the oxide polarization can be easily altered, the type and extent of supported graphene doping can be altered along with it.

You could come along with a tip that produces a certain electric field, and just by putting it near the oxide you could change its polarity, Martin says. You write an up domain or a down domain in the region you want it, and the graphenes charge density would reflect that change. You could make the graphene over that region p-type or n-type, and, if you change your mind, you can erase it and start again.

This ability would represent an advantage over chemically doped semiconductors. Once the atomic impurities are mixed into the material to change its carrier density, they cant be removed. Future research will investigate the feasibility of designing dynamic semiconducting devices with this technique.

We cant currently do that, but thats the direction we want to take it, Rappe says, There are some oxides that can be repolarized on the timescale of nanoseconds, so you could make some really dynamic changes if you needed to. This opens up a lot of possibilities.

FUTURE SCOPE

The progress of a technology from the moment of discovery to transformative product is slow and meandering; the consensus among scientists is that it takes decades, even when things go well. Paul Lauterbur and Peter Mansfield shared a Nobel Prize for developing the MRI, in 1973almost thirty years after scientists first understood the physical reaction that allowed the machine to work. More than a century passed between the moment when the Swedish chemist Jns Jakob Berzelius purified silicon, in 1824, and the birth of the semiconductor industry. So we expect that after 20 or 30 years we will flexible devices and batteries and superconductors at room temperature.

at89s52

Documents

asynchronous timer

overviewthe atmega16a

idle mode

programmable watchdog

lowpower consumption

adc noise reduction

serial programmable

internal oscillator