Technologies

Synthetic diamond

2008-03-19T07:03:00.000-07:00

Synthetic diamonds (also known variously as lab-created, manufactured, lab-grown or cultured diamond) is a term used to describe diamond crystals produced by a technological process, as opposed to natural diamond, which is produced by geological processes.

Synthetic diamond is not the same as diamond-like carbon, DLC, which is amorphous hard carbon, or diamond simulants, which are made of other materials such as cubic zirconia or silicon carbide. The properties of synthetic diamond depend on the manufacturing process used to produce it, and can be inferior, similar or superior to those of natural diamond

Because it can be made for less than it costs to mine and process natural diamond, synthetic diamond is used in many industrial applications. Reduced costs and the ability to engineer its physical and electrical properties give synthetic diamond the potential to become a disruptive technology in many areas, such as electronics and medicine.

History

The idea of making less expensive, gem-quality diamonds synthetically is not a new one. H. G. Wells described the concept in his short story "The Diamond Maker," published in 1911 [2]. In Capital Karl Marx commented, "If we could succeed, at a small expenditure of labour, in converting carbon into diamonds, their value might fall below that of bricks".[3]

Ever since the discovery that diamond was pure carbon in 1797 many attempts were made to alter the cheaper forms of carbon - generally with little success. One of the early successes reported in the field was by Ferdinand Frédéric Henri Moissan in 1893. His method involved heating charcoal at up to 4000 °C with iron in a carbon crucible in an electric furnace, in which an electric arc was struck between carbon rods inside blocks of lime. The molten iron was then rapidly cooled by immersion in water. The contraction generated by the cooling supposedly produced the high pressure required to transform graphite into diamond. Moissan published his work in a series of articles in the 1890's.

Many other scientists tried to replicate his experiments. Sir William Crookes claimed success in 1909. Ruff claimed in 1917 to have reproduced diamonds up to 7 mm in diameter, but later retracted his claims. In 1926, Dr. Willard Hershey of McPherson College read journal articles about Moissan's and Ruff's experiments and replicated their work, producing a synthetic diamond. That diamond is on display today in Kansas at the McPherson Museum. Despite the claims of Moissan, Ruff, and Hershey, many other experimenters had enormous difficulty in creating the required temperatures and pressure with similar equipment, leading some to contend that the early successes were the result of seeding by good-willed co-workers.

The most definitive duplication attempts were performed by Sir Charles Algernon Parsons. He devoted 30 years and a considerable part of his fortune to reproduce many of the experiments of Moissan as well as those of Hannay but also adapted processes of his own. He wrote a number of articles -- one of the earliest on high-pressure/high-temperature (HPHT) diamonds -- in which he claimed to have produced small diamonds. However in 1928 he authorized C.H Desch to publish an article in which he stated his belief that no synthetic diamonds (including those of Moisan and others) had been produced up to that date. In fact he found that most diamonds produced so far were more likely than not synthetic Spinel.

The GE diamond project

The first person who grew a synthetic diamond according to a reproducable, verifiable and witnessed process was Howard Tracy Hall while working for General Electric in 1954. He received a gold medal of the American Chemical Society in 1972 for his work. In 1941 an agreement was made between General Electric, Norton and Carborundum to further develop diamond synthesis. However this project soon thereafter ended because of the Second World War. They were able to heat Carbon to about 3000 °C (5432 °F) under a pressure of half a million psi, for a few seconds.

In 1951 the project was resumed at the Schenectady Laboratories of GE and a high pressure diamond group was formed with F.P. Bundy, H.M. Strong, and shortly afterwards joined by H. T. Hall and others. Following on the work done by Percy Bridgman (who received a Nobel prize for his work in 1946) Bridgman's Anvils were further improved first by Bundy and Strong and later by Hall. The GE team used a tungsten carbide "anvil" within a hydraulic press to squeeze the carbonaceous sample held in a catlinite container, the finished grit being squeezed out of the container through a gasket. It was believed that on occasion a diamond was produced, but since experiments could not be reproduced, such claims could not be maintained.

Finally Tracy Hall managed the first commercially successful synthesis of diamond on December 16, 1954 (announced on February 15, 1955). Hall's breakthrough was using an elegant "belt" press apparatus which raised the achievable pressure from 6 to 18 GPa and the temperature to 5000 °C, using a pyrophyllite container, and having the graphite dissolved within molten nickel, cobalt or iron, a "solvent-catalyst". Hall was able to have co-workers replicate his work and the discovery was published in Nature. The largest diamond produced by Hall was 150 micrometres across, clearly unsuitable for ornamentation but very useful in industrial abrasives.

Later developments

Another successful diamond synthesis was produced on February 16, 1953 in Stockholm, Sweden by the QUINTUS project of ASEA (Allemanna Svenska Elektriska Aktiebolaget), Sweden's major electrical manufacturing company using a bulky split sphere apparatus designed by Baltzar von Platen and the young engineer Anders Kämpe (1928–1984). Pressure was maintained within the device at an estimated 83,000 atmospheres (8.4 GPa) for an hour. A few small crystals were produced, but not of gem quality or size. The work was not reported until the 1980s.

During the 1980s a new competitor emerged in Korea named Iljin Diamond, followed later by hundreds of Chinese entrants. Iljin Diamond allegedly accomplished this by misappropriating trade secrets from GE via a Korean former GE employee in 1988.

Synthetic gem-quality diamond crystals were first produced in 1970 (reported in 1971) again by GE. Hall had continued to work for GE, developing the tetrahedral press with four anvils. Large crystals need to grow very slowly under extremely tightly controlled conditions. The first successes used a pyrophyllite tube seeded at each end with thin pieces of diamond and with the graphite feed material placed in the centre, the metal solvent, nickel, was placed between the graphite and the seeds. The container was heated and the pressure raised to around 55,000 atmospheres. The crystals grow as they flow from the centre to the ends of the tube, the longer the process is extended the larger the crystals - initially a week-long growth process produced gem-quality stones of around 5 mm and one carat. The graphite feed was soon replaced by diamond grit, as there was almost no change in material volume so the process was easier to control.

The first gem-quality stones were predominantly cubic and octahedral in form and, due to contamination with nitrogen, always yellow to brown in color. Inclusions were common, especially "plate-like" ones from the nickel. Removing all nitrogen from the process by adding aluminium or titantium produced a colourless 'white' stone, while removing the nitrogen and adding boron produced a blue. However removing nitrogen slows the growth process and impairs the crystals properties, so most stones are still yellow. In terms of physical properties the GE stones were not quite identical to natural stones. The colourless stones were semi-conductors and fluoresed and phosphoresed strongly under SWUV but were inert under LWUV - in nature only blue stones should do this. All the GE stones also showed a strong yellow fluorescence under X-rays. De Beers Diamond Research Laboratory has since grown stones of up to 11 carats, but most stones are around 1 to 1.5 carats for economic reasons, especially with the spread of the Russian BARS apparatus since the 1980s.

Following on from work by John Angus and Boris Spitsyn researchers at the National Institute for Research in Inorganic Materials in Tsukuba produced diamonds at less than one atmosphere of pressure and only 800 °C through Chemical Vapour Deposition (CVD). The Japanese had begun their research in 1974 and reported their success in 1981.

Properties of synthetic diamond

The gem diamond is just one of many different forms that diamond can take. Natural gem diamond is a single crystal diamond with low levels of impurities. This homogeneity is what allows it to be clear, while its material properties and hardness are what make it a popular gemstone. Most natural diamond removed from the earth's crust does not have the high purity or high crystallinity necessary to be a quality gemstone. Following are some important properties by which various types of diamond are described.
Crystallinity
A mass of diamond may be one single, continuous crystal or it may be made of up many smaller crystals ("polycrystalline"). Single crystal diamond is typically used in gemstones, while polycrystalline diamond is commonly used in industrial applications such as mining and cutting tools. Within polycrystalline diamond the diamond is often described by the average size of the crystals that make it up, called the "grain size." Grain sizes range from hundreds of micrometers to nanometers, usually referred to as "microcrystalline" and "nanocrystalline" diamond, respectively.
Hardness
A diamond's hardness can vary depending on its impurities and crystallinity. Nanocrystalline diamond produced through CVD diamond growth, for instance, can have a wide range of hardness from 30% to 75% of single crystal diamond, and the hardness can be controlled to be used in specific applications. Some single crystal diamonds grown through chemical vapor deposition have been shown to be harder than any known natural diamond.
Impurities and inclusions
No crystal is absolutely pure[citation needed]. Any substance other than carbon found in a diamond is an impurity, and may also be called an inclusion, due to the way these impurities fall in the crystal lattice. While inclusions can be unwanted, they can also be introduced on purpose to control the properties of the diamond. For instance, while pure diamond is an electrical insulator, diamond with small amounts of boron added is an electrical conductor, possibly allowing it to be used in new technological applications.

Gem-quality diamonds grown in a lab can be chemically, physically and optically identical to naturally occurring ones although they can be distinguished by spectroscopy in infrared, ultraviolet, or X-ray wavelengths. The DiamondView tester from De Beers uses UV fluorescence to detect trace impurities of nickel or other metals in HPHT diamonds, or hydrogen in some LP CVD diamonds.

Manufacturing technologies

There are two main methods to produce synthetic diamond. The original method is High Pressure High Temperature (HPHT) and is still the most widely used method because of its relative low cost. It uses large presses that can weigh a couple of hundred tons to produce a pressure of 5 GPa at 1,500 degrees Celsius to reproduce the conditions that create natural diamond inside the Earth. The second method, using chemical vapor deposition or CVD, was invented in the 1980s, and is basically a method creating a carbon plasma on top of a substrate onto which the carbon atoms deposit to form diamond.

High pressure, high temperature

The GE method is called HPHT (High Pressure, High Temperature). There are two main press designs used to supply the pressure and temperature necessary to produce synthetic diamond. These basic designs are the belt press and the cubic press. There are a number of other designs, but only belt press and cubic press are used for industrial scale manufacturing.

The original GE invention by H. Tracy Hall, uses the belt press, wherein upper and lower anvils supply the pressure load and heating current to a cylindrical volume. This internal pressure is confined radially by a belt of pre-stressed steel bands. A variation of the belt press uses hydraulic pressure to confine the internal pressure, rather than steel belts. Belt presses are still used today by the major manufacturers at a much larger scale than the original designs.

The second type of press design is the cubic press. A cubic press has six anvils which provide pressure simultaneously onto all faces of a cube-shaped volume. The first multi-anvil press design was actually a tetrahedral press, using only four anvils to converge upon a tetrahedron-shaped volume. The cubic press was created shortly thereafter to increase the pressurized volume. A cubic press is typically smaller than a belt press and can achieve the pressure and temperature necessary to create synthetic diamond faster. However, cubic presses cannot be easily scaled up to larger volumes. To illustrate, one could increase the pressurized volume by either increasing the size of the anvils, thereby increasing by a great factor the amount of force needed on the anvils to achieve a similar pressurization, or by decreasing the surface area to volume ratio of the pressurized volume by using more anvils to converge upon a different platonic solid (such as a dodecahedron), but such a press would be unnecessarily complex and not easily manufacturable.

Chemical vapor deposition
Main article: Chemical vapor deposition of diamond

Chemical vapor deposition of diamond is a method of growing diamond by creating the environment and circumstances necessary for carbon atoms in a gas to settle on a diamond substrate in diamond crystalline form. This method of diamond growth has been the subject of a great deal of research since the early 1980s, especially due to its potential applications in the cutting tool, semiconductor and diamond gem industries.

In their pioneering work in the area, the Japanese passed a mixture of carbon-containing gas (methane in their case) and hydrogen into a quartz tube at a pressure of 0.05 atmospheres. Using microwaves the mixture was heated to 800 °C, disassociating both the methane and hydrogen into elemental forms. The carbon is deposited on a substrate, the majority as graphite but a very small proportion as diamond crystal. the graphite is 'removed' by the hydrogen leaving a thin layer of diamond, initially the layer was around 25μm in thickness.

Applications

Given the extraordinary set of physical properties diamond exhibits, diamond has and could have a wide-ranging impact in many fields.

Machining

Diamonds have long been used in machine tools, especially when machining non-ferrous alloys. While natural diamond is certainly still used for this, the amount of synthetic diamond is far greater. The most common usage of diamond in cutting tools is done by distributing micrometer-sized diamond grains in a metal matrix (usually cobalt), hardening it and then sintering it onto the tool. This is typically referred to in industry as poly-crystalline diamond (PCD). PCD tipped tools are often used in mining and in the automotive aluminium cutting industry.

For the past fifteen years work has also been done in the hope of using CVD diamond growth to coat tools with diamond, and though the work still shows promise it has not significantly displaced traditional PCD tools.

Electronics

CVD diamond also has applications in electronics. Conductive diamond is a useful electrode under many circumstances. University of Wisconsin-Madison chemistry professor Robert Hamers developed photochemical methods for covalently linking DNA to the surface of polycrystalline diamond films produced through CVD. In addition, the diamonds can detect redox reactions that cannot ordinarily be studied and in some cases degrade redox-reactive organic contaminants in water supplies. Because diamond is almost completely chemically inert it can be used as an electrode under conditions that would destroy traditional materials. For such reasons waste water treatment of organic effluents as well as production of strong oxidants, have been published. A number of companies produce diamond electrodes.

Diamond shows great promise as a potential radiation detection device. Diamond has a similar density to that of soft tissue, is radiation hard and has a wide bandgap. It is employed in applications such as the BABAR detector at Stanford.

Diamond also has potential uses as a semiconductor. This is because the diamonds can be "doped" with impurities like boron and phosphorus. Since these elements contain one more or one less valence electron than carbon, they turn the diamonds into p-type or n-type semiconductors. Diamond transistors are functional to temperatures many times that of silicon and are resistant to chemical and radioactive damage. While no diamond transistors have yet been successfully integrated into commercial electronics, they show promise for use in exceptionally high power situations and hostile environments.

CVD diamond growth has also been used in conjunction with lithographic techniques to encase microcircuits inside diamond. Researchers at Lawrence Livermore National Laboratory and the University of Alabama, Birmingham use this process to create designer diamond anvils as a novel probe for measuring electric and magnetic properties of materials at ultra high pressures using a Diamond Anvil Cell.

HPHT "type IIa" diamonds are, as of 2007, approaching the very high purity and crystallographic structure perfection required to replace silicon in applications like X-ray tomographic imaging at synchrotrons;[they will be able to sustain the increased intensities of next generation light sources.

Gemstones

Several companies currently produce gems made through HPHT technology. They are grown in split sphere high-pressure, high-temperature (HPHT) crystal growth chambers that resemble washing machines. The device bathes a tiny sliver of natural diamond in molten carbon at 1500 °C and 58,000 atm (5.9 GPa). This produces a rough diamond which can be cut down to a polished size close to half its original carat weight. Gemesis diamonds have an orange tint that is rare in natural diamonds. The yellow tint occurs when approximately one out of each 20,000 carbon atoms in the diamond crystal lattice are replaced with nitrogen atoms. Adia Diamonds produces diamonds in various shades of yellow and orange as well as blue and white (colorless). The blue color comes from doping the diamond with boron, rather than nitrogen, during the growth process. White diamonds must be grown in an environment free of nitrogen and boron, which makes them very difficult to produce. Yellow diamonds are more profitable because they can be made more quickly and cost less to manufacture than blue or colorless diamonds. The largest synthetic diamond crystal grown to date via this method was a 34-carat yellow stone[citation needed]. Apollo Diamond is a company that currently produces gem diamond through chemical vapor deposition and sells clear diamond gemstones.

The mined diamond industry is evaluating marketing and distribution countermeasures to these less expensive alternatives. The three largest distributors have made public statements about selling their diamonds with full disclosure and have implemented measures to laser-inscribe serial numbers on their gemstones.

LifeGem is a company offering to synthesize diamonds from the carbonized remains of people or pets.

Transhumanism

2008-03-19T06:58:00.000-07:00

Transhumanism (sometimes symbolized by >H or H+),[1] a term often used as a synonym for "human enhancement", is an international intellectual and cultural movement supporting the use of new sciences and technologies to enhance human mental and physical abilities and aptitudes, and ameliorate what it regards as undesirable and unnecessary aspects of the human condition, such as stupidity, suffering, disease, aging and involuntary death. Transhumanist thinkers study the possibilities and consequences of developing and using human enhancement techniques and other emerging technologies for these purposes. Possible dangers, as well as benefits, of powerful new technologies that might radically change the conditions of human life are also of concern to the transhumanist movement.

Although the first known use of the term "transhumanism" dates from 1957, the contemporary meaning is a product of the 1980s, when a group of scientists, artists, and futurists based in the United States began to organize what has since grown into the transhumanist movement. Transhumanist thinkers predict that human beings will eventually be transformed into beings with such greatly expanded abilities as to merit the label "posthuman". Transhumanism is therefore sometimes referred to as "posthumanism" or a form of transformational activism influenced by posthumanist ideals.

Transhumanist foresight of a profoundly transformed future humanity has attracted many supporters and detractors from a wide range of perspectives. Transhumanism has been described by one outspoken opponent as the world's most dangerous idea, while a proponent counters that it is the "movement that epitomizes the most daring, courageous, imaginative, and idealistic aspirations of humanity".

Bioethics

2008-03-19T06:45:00.001-07:00

Bioethics is the philosophical study of the ethical controversies brought about by advances in biology and medicine. Bioethicists are concerned with the ethical questions that arise in the relationships among life sciences, biotechnology, medicine, politics, law, philosophy, and theology.

Scope

While scientific research has produced social benefits, it has also posed some troubling ethical questions. Public attention was drawn to these questions by abuses of human subjects in biomedical experiments, especially during the Second World War. During the Nuremberg War Crime Trials, the Nuremberg code was drafted as a set of standards for judging physicians and scientists who had conducted biomedical experiments on concentration camp prisoners. This code is often credited with jump starting the interdisciplinary field now called bioethics.

On July 12, 1974, the National Research Act (Pub. L. 93-348) was signed into law in the United States, thereby creating the National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research. One of the commission's charges was to identify the basic ethical principles that should underlie the conduct of biomedical and behavioral research involving human subjects, as well as to develop guidelines. After nearly five years of discussion and collaboration, these guidelines were published. In 1979, a statement of basic ethical principles and guidelines to assist decision-makers in resolving the ethical problems that surround the conduct of research with human subjects appeared in the Federal Register. This became known as the Belmont Report. The report centered around the following three important principles, or general prescriptive judgments:
Respect for autonomy of the Persons
Beneficence
Justice

Later principle of non-maleficence has been added to this list. To apply the general principles to the conduct of research involving humans, the Belmont Report suggested that the following requirements be considered: informed consent, risk/benefit assessment, and the just and fair selection of subjects of research. The Belmont Report remains a touchstone for many bioethicists.

With new challenges in public health and health policy, and with advances in bio-technology, today bioethics is a fast-growing academic and professional area of inquiry. Since the early 1980s, the field has generated at least a dozen English-language journals. In addition, many academic medical centers and some schools of law, engineering and the liberal arts offer degree programs with a specialization in bioethics. Such programs train physicians and nurses, attorneys, philosophers, theologians, health services researchers and even bench scientists.

As a field of inquiry, bioethics received another boost when President Clinton created an Advisory Committee on Human Radiation Experiments, chaired by Ruth Faden of the Johns Hopkins Berman Institute of Bioethics. The committee sought to analyze the following questions:

What is the federal government's responsibility for wrongs and harms to human subjects as a result of experiments with ionizing radiation? What remedies are appropriate for those wronged or harmed? And what lessons learned from studying research standards and practices in the past and present can be applied to the future?

President Clinton directed the Advisory Committee to uncover the U.S. history of human radiation experiments during the period 1944 through 1974. It was in 1944 that the first known human radiation experiment of interest was planned, and in 1974 that the U.S. Department of Health, Education and Welfare adopted regulations governing the conduct of human research, a watershed event in the history of federal protections for human subjects. In addition, the Advisory Committee examined cases in which the government had intentionally released radiation into the environment for research purposes. The Advisory Committee also identified ethical and scientific standards for evaluating these events, and made recommendations to help ensure that wrongdoing could not be repeated.

Today, the field of bioethics struggles with its proper scope. Should it concern itself with the ethical evaluation of all questions involving biology and medicine? Some bioethicists would narrow ethical evaluation only to the morality of medical treatments or technological innovations, and the timing of medical treatment of humans. Others would broaden the scope of ethical evaluation to include the morality of all actions that might help or harm organisms capable of feeling fear and pain, and include within bioethics all such actions if they bear a relation to medicine and biology.

The purpose of bioethics

The issues raised by bioethics as a distinct area of academic inquiry are largely answered by the needs of institutions. Bioethicists today are not hired or engaged in conversation (and thus "named") because of their opinions or because they have special skills of reasoning, but because they know and can put to work the enormous body of research and history of discussions about bioethics in a fair, honest and intelligent way, using tools from the different disciplines that "feed" the field. Training programs in bioethics differ in skill sets of faculty and size of program, but across the US, and increasingly globally, they do seem to share a commitment to that goal with few exceptions.

As a result, bioethics has been distinctively created, by institutions, specifically the multi-million dollar commitment of major and minor medical centers to the study of medical ethics as part of the development of curriculum and research efforts. Today it is all but impossible to create a major medical research effort without ethicists to assist. First in the regulatory review of research, the responsibility of the IRB, which can be staffed by persons not trained in ethics in any rigorous way, or trained specifically in the ethical and regulatory aspects of research with human subjects, rather than more comprehensively in bioethics. The second form of assistance is by those who can think in advance of the onset of research about its social, ethical and economic implications

Ideology and methodology

Bioethicists often focus on using philosophy to help analyze issues, and philosophical ethicists such as Peter Singer tend to treat the field as a branch of moral or ethical philosophy. However, this approach is sometimes challenged, and bioethics is becoming increasingly interdisciplinary. Many bioethicists come from backgrounds outside of academic philosophy, and some even claim that the methods of analytic philosophy have had a negative effect on the field's development. The percentage of bioethicists with professional backgrounds in health care, especially physicians, has been steadily increasing over time. In fact, the last two Presidents of the primary academic society for bioethicists in the U.S. (the American Society for Bioethics and Humanities) have been physicians. Some bioethicists, especially those who perform ethics consultation in clinical settings, emphasize the practical aspects of bioethics, and view the field as more closely related to clinical practice or public health than philosophy.

Religious bioethicists have developed rules and guidelines on how to deal with these issues from within the viewpoint of their respective faiths. Many religious bioethicists are Jewish, and Christian scholars. Since the Indian traditions of Hinduism, Buddhism, and Jainism considers the sanctity of all life, there is much literature related to the philosophy and ethics related to life in each of these traditions. A growing number of religious scholars from Islam have also become involved in this field. There has been some criticism by liberal Muslims that only the more religiously conservative voices in Islam are being heard on this issue.

Although there are a number of eminently qualified philosophers who approach bioethics from a religious perspective, some Western secular bioethicists are critical of the fact that religious bioethicists are often religious scholars without an academic degree or training in disciplines that pertain to the issues, such as philosophy (wherein the formal study of ethics is usually found), biology or medicine. From the standpoint of bioethicists whose work is secular, the central cause for caution as regards religious bioethics work is that tools and methods should be brought to bear on problems, rather than starting with conclusions, and then looking for justifications. Of course, this criticism does not apply solely, of even to all, forms of religious bioethical work.

In the case of most non-Western cultures a strict separation of religion from philosophy does not exist. In many Asian cultures, there is a lively (and often less dogmatic, but more pragmatic) discussion on bioethical issues. The discussion often refers to common demographic policies which are criticised, as in the case of China. Buddhist bioethics, in general, is characterised by a naturalistic outlook that leads to a rationalistic, pragmatic approach. Buddhist bioethicists include Damien Keown. In India, Vandana Shiva is the leading bioethicist whose speaks from the Hindu tradition. In Africa, and partly also in Latin America, the debate on bioethics frequently focus on its practical relevance in the context of underdevelopment and (national or global) power relations.

HAPPY NEW YEAR

2007-12-31T04:06:00.001-08:00

Betabiotics: antibiotics of the future

2007-12-04T08:19:00.000-08:00

An alarming number of infectious diseases are becoming increasingly difficult to treat with existing antibacterial drugs. This is due primarily to the rate at which bacteria becomes resistant to standard antibiotics. As a result there is a growing concern that an 'antibiotic crisis' is looming.

CSIRO scientists have identified and patented a new antibacterial drug target named 'Beta' that may address this problem.

This was followed by the development of an assay that helps researchers identify molecules that interfere with the normal function of Beta.

These new drug candidates offer a starting point for researchers and industry to develop new classes of antibiotics with improved resistance profiles.

Invisibility Made Easier

2007-12-04T08:16:00.000-08:00

In the past year, the media have been abuzz with talk of an exotic class of materials, called metamaterials, that could be used to make flat and distortion-free lenses, powerful microscopes, and even cloaking devices that make objects invisible. But versions of the materials suitable for practical applications have been difficult to make. Now researchers at Princeton University have demonstrated metamaterials that are both higher performing and much easier to manufacture, perhaps bringing these applications closer to reality.

"It's quite an important step," says Igor Smolyaninov, a research scientist at the University of Maryland who works with metamaterials. "It's much less expensive than anything else that people are doing."

Light passing from one ordinary material into another bends slightly--think of how a straight stick in water looks bent--but light passing into a metamaterial bends in the opposite direction. Metamaterials thus have what's called a negative index of refraction. A lens made from such a material wouldn't have to be curved. (It's the curvature of an ordinary lens that enables it to focus incoming light.) Metamaterials could also be used to route electromagnetic waves around an object, rendering it invisible. Already, researchers have demonstrated a cloaking device that makes objects invisible to microwaves, and others have created materials that negatively refract electromagnetic waves in the visible part of the electromagnetic spectrum. But until now, metamaterials have had to be patterned with intricate shapes smaller than the wavelength of light they're meant to manipulate. Consequently, materials that work with light of microscopic wavelengths, such as infrared and visible light, have been difficult to make. Because of the way they produce negative refraction, existing metamaterials have also had a strong tendency to absorb light, making them impractical for use in optics.

The materials developed at Princeton retain the property of negative refraction, yet they're much easier to make. Rather than requiring intricate structures, such as the split rings used in the microwave cloaking device, the materials can be made simply by stacking up extremely thin layers of semiconductor material. What's more, that stacking can be done by the same tools now used to make semiconductor materials for lasers used in telecommunications, says Claire Gmachl, the Princeton researcher who led the work. The new materials consist of alternating layers of indium gallium arsenide and aluminum indium arsenide, and they're tuned to work in the infrared region of the spectrum.

Like other metamaterials, the new materials affect light differently than ordinary materials do because they are made of structures significantly smaller than the wavelength of the light passing through them. In this case, however, it is the layers of semiconductors themselves that are thinner than the wavelength of light. Consequently, a wave passing through the material encounters multiple layers at once, responding to them as if they were a single material with properties quite unlike those of either semiconductor in isolation.

What makes the new materials different from previous metamaterials is that rather than changing two aspects of the way light moves, they change only one. If light is thought of as a wave, the wave front is perpendicular to the direction the light is moving. Imagine an ocean wave crashing ashore: it's moving in just one direction, but the wave front is a huge wall of water. Previous metamaterials changed the direction of light beams passing through them, and the wave front remained perpendicular to the direction of the beam. In the new materials, the light beam changes direction, but the wave fronts don't, giving the impression that they are slipping to the side rather than moving forward. (See image below.)

When a light beam moves through an ordinary material, it moves in the same direction the light waves are facing (top part of image). When a light beam enters a new type of "metamaterial," it changes direction, but the waves remain facing the same way, seeming to slip sideways (see bottom half of image). This image is from a computer simulation.
Credit: Anthony Hoffman, Princeton University

The overall effect on the direction of the light beam is the same as in the earlier metamaterial, but the new materials are simpler to create, and they absorb far less light, making them more attractive for use in optics.

The first application the Princeton researchers are developing is a flat lens for chemical-sensing devices, an application for which materials that work with infrared light are particularly well suited. Gmachl says that the current optical setups for such devices are bulky because they use conventional lenses. "The first application would be using that material to miniaturize optical setups" by replacing curved lenses with flat ones, she says.

Another early application could be in night-vision devices, which also work with infrared wavelengths. "For people who want to improve night-vision devices, this could be quite interesting," Smolyaninov says.

Terabyte Storage for Cell Phones

2007-12-04T08:08:00.000-08:00

A new type of memory technology could lead to thumb drives or digital-camera memory cards that store a terabyte of information--more than most hard drives hold today. The first examples of the new technology, which could also slash energy consumption by more than 99 percent, could be on the market within 18 months.

"It's a radically new technology," says Michael Kozicki, a professor of electrical engineering at the Arizona State University, whose group is one of several working on a version of the new memory. "If it really works as well as everybody thinks it could, it could genuinely revolutionize the memory and storage industry."

The new type of memory, called programmable-metallization-cell (PMC) memory, or nano-ionic memory, has been under development at the Arizona State University and at companies such as Sony and IBM. It's one of a new generation of experimental technologies that are bidding to replace hard drives, the nonvolatile "flash" memory used in portable electronics, and the dynamic random-access memory (DRAM) in personal computers. The first ionic-memory prototypes were far too slow for practical use. But recently, researchers have demonstrated that materials structured at the nanoscale could yield ionic-memory devices that are much faster. Nano-ionic memory is significantly faster than flash memory, and the speed of some experimental cells has rivaled that of DRAM, which is orders of magnitude faster than flash.

The memory could also prove easy to make. Recently, the Arizona group published work demonstrating that nano-ionic memory can be made from materials conventionally used in computer memory chips and microprocessors. That could make it easier to integrate with existing technologies, and it would mean less retooling at factories, which would appeal to manufacturers.

Another reason that ionic memory is attractive is that it uses extremely low voltages, so it could consume as little as a thousandth as much energy as flash memory. In theory, it could also achieve much higher storage densities--bits of information per unit of surface area--than current technologies can.

These attractions are largely the result of a new mechanism for storing information. Flash memory stores bits of information as electrical charge, but the smaller the memory cells that hold the bits, the less charge they can hold, and the less reliable they become. The new memory stores information by rearranging atoms to form stable, and potentially extremely small, memory cells. What's more, each cell could potentially store multiple bits of information, and the cells can be layered on top of each other, increasing the memory's storage density to the point that it might rival that of the densest form of memory today: hard drives.

Each memory cell consists of a solid electrolyte sandwiched between two metal electrodes. The electrolyte is a glasslike material that contains metal ions. Ordinarily, the electrolyte resists the flow of electrons. But when a voltage is applied to the electrodes, electrons bind to the metal ions, forming metal atoms that cluster together. These atoms form a virus-sized filament that bridges the electrodes, providing a path along which electrical current can flow. Reversing the voltage causes the wire to "dissolve," Kozicki says. The highly resistive state of the electrolyte and the other, low-resistance, state can be used to represent zeroes and ones. Because the metal filament stays in place until it's erased, nano-ionic memory is nonvolatile, meaning that it doesn't require energy to hold on to information, just to read it or write it.

A thumb drive that stored a terabyte of information, however, would have to take advantage of two other characteristics of nano-ionic memory, Kozicki says. First, it would have to store more than one bit of information per memory cell. Once the wire inside the cell forms, it's possible to apply a voltage again, causing more atoms to form, thickening the wire and further decreasing resistance. Successive jolts will thicken the wire yet more, and the different states of resistance could be used to store multiple bits of information per wire.

What's more, this type of memory can be stacked up in layers, since it's not necessary for each cell to be in contact with a base layer of silicon, as is the case with some other types of memory. Combining multiple bits per cell with multiple layers could make it possible to form extraordinarily dense memory, Kozicki says.

William Gallagher, a senior manager for exploratory nonvolatile-memory research at IBM Research, says that nano-ionic memory is one of several promising next-generation memory technologies. These include MRAM, which stores information using magnetic fields, and phase-change memory, which stores information in a way similar to that used to store bits on DVDs. Gallagher says that ionic memory's competitors have a head start on it. MRAM chips are already sold for some special applications, such as devices that will be exposed to harsh environments. But MRAM may also prove better for high-speed memory applications than as a replacement for flash, so it may not compete directly with nano-ionic memory. Samsung, however, could be selling a phase-change-based flash-replacement memory within a year.

Still, nano-ionic memory may not be far behind. A few companies have licensed nano-ionic-memory technology developed at the Arizona State University. These include Qimonda, based in Germany; Micron Technologies, based in Boise, ID; and a Bay Area stealth-mode startup. The startup is well on the way to producing its first memory devices, which Kozicki says could be available within 18 months. These first chips, however, won't rival hard drives in memory density, he says.

The new technology could nevertheless have difficulty winning wide adoption. Flash-type memory continues to improve and may do so for a few more generations of products. Also, the best nano-ionic-memory prototypes have been made from materials that aren't used in conventional microchips, so manufacturing could be costly, at least initially. Kozicki's group recently demonstrated that ionic memory can be built from a combination of silicon dioxide and copper--materials that are compatible with conventional manufacturing. But these materials do not perform as well, which could make them less attractive than alternatives such as phase-change memory. For the new type of memory to succeed, it may be necessary to convince manufacturers to switch to new materials.

The World's Smallest Radio

2007-12-04T08:04:00.000-08:00

Researchers have fashioned the world's tiniest radio out of a carbon nanotube. The nanotube, placed between two electrodes, combines the roles of all the major electrical components in a radio, including the tuner and amplifier. It can tune in to a radio signal and play the audio through an external speaker.

While the practical application of the radio is uncertain, it could be used in biological and environmental sensors. Researchers are now developing microelectromechanical (MEMS) sensors to measure blood sugar levels or cancer markers in the body. Instead of researchers using a stamp-size radio-frequency identification tag, a nanotube radio could be packaged with the MEMS-based sensor and injected directly into the bloodstream, says Alex Zettl, an experimental physicist at the University of California, Berkeley, who is leading the development of the nanotube radio. Once in the body, the radio could provide wireless communication between the tiny biological sensors and an external monitor. To do that, however, the nanotube radio would have to work as a transmitter. Right now, it is only configured as a receiver, but Zettl says that "the same physics would work as a transmitter."

The nanotube radio works differently than a conventional radio does. Conventional radios have four main functional parts: antenna, tuner, amplifier, and demodulator. Radio waves falling on a radio antenna create electric currents at different frequencies. When someone selects a radio station, the tuner filters out all but one of the frequencies. Transistors amplify the signal, while a demodulator, typically a rectifier or a diode, separates the data--the music or other audio--that has been encoded on a "carrier" electromagnetic wave.

Zettl's team used one carbon nanotube for all these functions. Because of their unique electrical properties, carbon nanotubes have been previously used to make electronic components such as diodes, transistors, and rectifiers. "It was a revelation that all of this could be built into the same [nanotube]," Zettl says.

The nanotube is grown sticking out from a tungsten surface, which acts as a negative electrode. The tip of the carbon nanotube is also negatively charged. A vacuum separates the nanotube from a positive copper electrode. The researchers use an external battery to apply a voltage between the two electrodes. Electrons jump out from the negative nanotube tip to the positive electrode, creating what is called a field emission current.

Zettl explains that the "nanotube does not act as an antenna in the conventional sense." That is, instead of picking up electromagnetic waves electrically, it picks them up mechanically. This happens because of the nanotube's natural resonance frequency. As soon as it encounters radio waves that match the frequency, the nanotube starts vibrating in step with the waves, effectively tuning in only to that radio signal. The nanotube's vibrations change the field emission current, and the mechanical vibrations are converted into an electrical signal. An external battery powers the field emission current and amplifies the radio signal. The field emission is naturally asymmetrical--it allows current to flow only in one direction, just like the diodes and rectifiers used in demodulators. So the nanotube also acts as a demodulator and detects the music encoded onto the carrier wave.

To tune to a different radio station, the researchers change the resonance frequency of the nanotube. They do this by changing the voltage applied across the electrodes. "It's like tuning a guitar string," Zettl says. "The electric field pulls on the nanotube." With the same nanotube, the researchers can cover the entire FM radio band.

Cees Dekker, a nanotube researcher at the Delft University of Technology, in the Netherlands, calls the new radio "an appealing demonstration that very simple devices can be used for everyday [tools]." Whether or not the device is used for sensors remains to be seen, he says, but for now, the simple demonstration is a good start.

Announcing the world's first 40G silicon laser modulator!

2007-12-04T01:28:00.000-08:00

In this blog, I would like to share with you our recent breakthrough in Silicon Photonics research at Photonics Technology Lab of Intel, a laser modulator that encodes optical data at 40 billion bits per second. Here I am holding a packaged device:

As you may know, a photonic integrated circuit (PIC) could provide a cost-effective solution for optical communication and future optical interconnects in computing industry. PICs on silicon platforms have attracted particular interest because of silicon’s low cost and high volume manufacturability. Competition in this arena is intense as many players in both academia and industry have been aggressively pursuing research into completely integrated CMOS photonics. The DARPA-initiated Electronic & Photonic Integrated Circuits (EPIC) program has also been supporting several Universities and startups to develop capabilities in this area.

One of the key components needed for silicon PICs is the high-speed silicon optical modulator, which is used to encode data on optical beam. Today’s commercially available optical modulators at 10 Gbps are based on more exotic electro-optic materials such as lithium niobate and III-V compound semiconductors. These devices have deployed at speeds up to 40 Gbps. Our goal to achieve similar performance in silicon has been very challenging, because crystalline silicon does not exhibit the linear electro-optic (Pockels) effect used to modulate light in these materials. Engineers are forced to rely on the free-carrier plasma dispersion effect, in which silicon’s refractive index is changed when the density of free carriers (electrons/holes) is varied, to modulate light in silicon.

In 2004, we published in Nature the first silicon modular to reach gigahertz speeds, 50x times faster than previous attempts in silicon. Since then, we scaled the device to 10Gbps, brining silicon modulation speed to a level comparable to most commercial devices. In January 2007, we designed and fabricated a new type of silicon optical modulator scalable to >>10 Gbps and demonstrated data transmission at 30 Gbps (see Optics Express, 22 January 2007, pp. 660-668). The modulator still relies on the free-carrier effect, but its high speed is the result of a unique device design with traveling-wave drive scheme.

This is the new chip . With a similar device configuration, the modulator performance has been further improved by better device packaging to reduce the parasitic effect, better traveling-wave electrode with lower RF attenuation, and better modulator termination circuitry. In the conference of Integrated Photonics and Nanophotonics Research and Applications, Salt Lake City, Utah, July 9-11, 2007, I presented our world record results in a silicon modulator to a small group of scientists. We have finally reached the goal of data transmission at 40 Gbps speed, matching the fastest devices deployed today using other materials.

The Intel modulator is based on a Mach-Zehnder interferometer with a reverse-biased pn junction in each of the arms (Figure 1a). When a reverse voltage is applied to the junction, free carriers – electrons and holes resulting from the n- and p-dopants – are pulled out of the junction, changing its refractive index via the free-carrier effect. The intensity of the light transmitted through the Mach-Zehnder interferometer is modulated by modulating the phase difference between the interferometer’s two arms. This modulation can be very fast, because free carriers can be swept out of the junction with a time of approximately 7 ps. The modulator speed is thus limited by the parasitic effects such as RC time constant limit.

To minimize the RC constant limitation, Intel researchers adopted a traveling-wave drive scheme allowing electrical and optical signal co-propagation along the waveguide. The traveling-wave electrode which is based on a coplanar waveguide was designed to match the velocity for both optical and electrical signals, while keeping the RF attenuation small. To operate the traveling-wave modulator, the RF signal is fed into the transmission line using a commercially available driver from the optical input side and the transmission line is terminated with an external resistor (see Fig. 1a). After packaging the modulator on a printed circuit board, the researchers demonstrated that the modulator has a 3 dB bandwidth of ~30 GHz (Fig. 2a) and data transmission capability up to 40 Gbps (Fig. 2b).

The high-speed silicon modulator could find use in various future applications. For example, a highly integrated silicon photonic circuit may provide a cost effective solution for the future optical interconnects within computers and other devices. With the demonstration of the 40 Gbps silicon modulator and the electrically pumped hybrid silicon laser, it will become possible to integrate multiple devices on a single chip (Fig. 3) that can transmit terabits of aggregate data per second in the near future – truly enabling tera-scale computing.

ATM with EyE

2007-11-24T19:14:00.001-08:00

There is an urgent need for improving security in banking region. With the advent of ATM though banking became a lot easier it even became a lot vulnerable. The chances of misuse of this much hyped ‘insecure’ baby product (ATM) are manifold due to the exponential growth of ‘intelligent’ criminals day by day. ATM systems today use no more than an access card and PIN for identity verification. This situation is unfortunate since tremendous progress has been made in biometric identification techniques, including finger printing, facial recognition, and iris scanning.

This paper proposes the development of a system that integrates Facial regognition and Iris scanning technology into the identity verification process used in ATMs. The development of such a system would serve to protect consumers and financial institutions alike from fraud and other breaches of security

INTRODUCTION
The rise of technology in India has brought into force many types of equipment that aim at more customer satisfaction. ATM is one such machine which made money transactions easy for customers to bank. The other side of this improvement is the enhancement of the culprit’s probability to get his ‘unauthentic’ share. Traditionally, security is handled by requiring the combination of a physical access card and a PIN or other password in order to access a customer’s account. This model invites fraudulent attempts through stolen cards, badly-chosen or automatically assigned PINs, cards with little or no encryption schemes, employees with access to non-encrypted customer account information and other points of failure.

Our paper proposes an automatic teller machine security model that would combine a physical access card, a PIN, and electronic facial recognition. By forcing the ATM to match a live image of a customer’s face with an image stored in a bank database that is associated with the account number, the damage to be caused by stolen cards and PINs is effectively neutralized. Only when the PIN matches the account and the live image and stored image match would a user be considered fully verified. A system can examine just the eyes, or the eyes nose and mouth, or ears, nose, mouth and eyebrows, and so on.

In this paper , we will also look into an automatic teller machine security model providing the customers a cardless, password-free way to get their money out of an ATM. Just step up to the camera while your eye is scanned. The iris -- the colored part of the eye the camera will be checking -- is unique to every person, more so than fingerprints.

ATM SYSTEMS

Our ATM system would only attempt to match two (and later, a few) discrete images, searching through a large database of possible matching candidates would be unnecessary. The process would effectively become an exercise in pattern matching, which would not require a great deal of time. With appropriate lighting and robust learning software, slight variations could be accounted for in most cases. Further, a positive visual match would cause the live image to be stored in the database so that future transactions would have a broader base from which to compare if the original account image fails to provide a match – thereby decreasing false negatives.

When a match is made with the PIN but not the images, the bank could limit transactions in a manner agreed upon by the customer when the account was opened, and could store the image of the user for later examination by bank officials. In regards to bank employees gaining access to customer PINs for use in fraudulent transactions, this system would likewise reduce that threat to exposure to the low limit imposed by the bank and agreed to by the customer on visually unverifiable transactions.

In the case of credit card use at ATMs, such a verification system would not currently be feasible without creating an overhaul for the entire credit card issuing industry, but it is possible that positive results (read: significant fraud reduction) achieved by this system might motivate such an overhaul.

The last consideration is that consumers may be wary of the privacy concerns raised by maintaining images of customers in a bank database, encrypted or otherwise, due to possible hacking attempts or employee misuse. However, one could argue that having the image compromised by a third party would have far less dire consequences than the account information itself. Furthermore, since nearly all ATMs videotape customers engaging in transactions, it is no broad leap to realize that banks already build an archive of their customer images, even if they are not necessarily grouped with account information.

History

The first ATMs were off-line machines, meaning money was not automatically withdrawn from an account. The bank accounts were not (at that time) connected by a computer network to the ATM. Therefore, banks were at first very exclusive about who they gave ATM privileges to. Giving them only to credit card holders (credit cards were used before ATM cards) with good banking records. In modern ATMs, customers authenticate themselves by using a plastic card with a magnetic stripe, which encodes the customer's account number, and by entering a numeric passcode called a PIN (personal identification number), which in some cases may be changed using the machine. Typically, if the number is entered incorrectly several times in a row, most ATMs will retain the card as a security precaution to prevent an unauthorised user from working out the PIN by pure guesswork..

Hardware and software

ATMs contain secure cryptoprocessors, generally within an IBM PC compatible host computer in a secure enclosure. The security of the machine relies mostly on the integrity of the secure cryptoprocessor: the host software often runs on a commodity operating system.In-store ATMs typically connect directly to their ATM Transaction Processor via a modem over a dedicated telephone line, although the move towards Internet connections is under way.

In addition, ATMs are moving away from custom circuit boards (most of which are based on Intel 8086 architecture) and into full-fledged PCs with commodity operating systems such as Windows 2000 and Linux. An example of this is Banrisul, the largest bank in the South of Brazil, which has replaced the MS-DOS operating systems in its automatic teller machines with Linux. Other platforms include RMX 86, OS/2 and Windows 98 bundled with Java. The newest ATMs use Windows XP or Windows XP embedded.

Reliability

ATMs are generally reliable, but if they do go wrong customers will be left without cash until the following morning or whenever they can get to the bank during opening hours. Of course, not all errors are to the detriment of customers; there have been cases of machines giving out money without debiting the account, or giving out higher value notes as a result of incorrect denomination of banknote being loaded in the money cassettes. Errors that can occur may be mechanical (such as card transport mechanisms; keypads; hard disk failures); software (such as operating system; device driver; application); communications; or purely down to operator error.

Security

Early ATM security focused on making the ATMs invulnerable to physical attack; they were effectively safes with dispenser mechanisms. ATMs are placed not only near banks, but also in locations such as malls, grocery stores, and restaurants. The other side of this improvement is the enhancement of the culprit’s probability to get his ‘unauthentic’ share.

ATMs are a quick and convenient way to get cash. They are also public and visible, so it pays to be careful when you're making transactions. Follow these general tips for your personal safety.

Stay alert. If an ATM is housed in an enclosed area, shut the entry door completely behind you. If you drive up to an ATM, keep your car doors locked and an eye on your surroundings. If you feel uneasy or sense something may be wrong while you're at an ATM, particularly at night or when you're alone, leave the area.

Keep you PIN confidential. Memorize your Personal Identification Number (PIN); don't write it on your card or leave it in your wallet or purse. Keep your number to yourself. Never provide your PIN over the telephone, even if a caller identifies himself as a bank employee or police officer. Neither person would call you to obtain your number.

Conduct transactions in private. Stay squarely in front of the ATM when completing your transaction so people waiting behind you won't have an opportunity to see your PIN being entered or to view any account information. Similarly, fill out your deposit/withdrawal slips privately.

Don’t flash your cash. If you must count your money, do it at the ATM, and place your cash into your wallet or purse before stepping away. Avoid making excessively large withdrawals. If you think you're being followed as you leave the ATM, go to a public area near other people and, if necessary, ask for help.

Save receipt. Your ATM receipts provide a record of your transactions that you can later reconcile with your monthly bank statement. If you notice any discrepancies on your statement, contact your bank as soon as possible. Leaving receipts at an ATM can also let others know how much money you've withdrawn and how much you have in your account.

Guard your card. Don't lend your card or provide your PIN to others, or discuss your bank account with friendly strangers. If your card is lost or stolen, contact your bank immediately.

Immediately report any crime to the police. Contact the Department Of Public Security or your local police station for more personal safety information.

FACIAL RECOGNITION

The main issues faced in developing such a model are keeping the time elapsed in the verification process to a negligible amount, allowing for an appropriate level of variation in a customer’s face when compared to the database image, and that credit cards which can be used at ATMs to withdraw funds are generally issued by institutions that do not have in-person contact with the customer, and hence no opportunity to acquire a photo.

Because the system would only attempt to match two (and later, a few) discrete images, searching through a large database of possible matching candidates would be unnecessary. The process would effectively become an exercise in pattern matching, which would not require a great deal of time. With appropriate lighting and robust learning software, slight variations could be accounted for in most cases. Further, a positive visual match would cause the live image to be stored in the database so that future transactions would have a broader base from which to compare if the original account image fails to provide a match – thereby decreasing false negatives.

SOFTWARE SPECIFICATION

For most of the past ten years, the majority of ATMs used worldwide ran under IBM’s now-defunct OS/2. However, IBM hasn’t issued a major update to the operating system in over six years. Movement in the banking world is now going in two directions: Windows and Linux. NCR, a leading world-wide ATM manufacturer, recently announced an agreement to use Windows XP Embedded in its next generation of personalized ATMs (crmdaily.com.) Windows XP Embedded allows OEMs to pick and choose from the thousands of components that make up Windows XP Professional, including integrated multimedia, networking and database management functionality. This makes the use of off-the-shelf facial recognition code more desirable because it could easily be compiled for the Windows XP environment and the networking and database tools will already be in place.

Many financial institutions are relying on Windows NT, because of its stability and maturity as a platform.The ATMs send database requests to bank servers which do the bulk of transaction processing (linux.org.) This model would also work well for the proposed system if the ATMs processors were not powerful enough to quickly perform the facial recognition algorithms.

SECURITY

In terms of the improvement of security standards, MasterCard is spearheading an effort to heighten the encryption used at ATMs. For the past few decades, many machines have used the Data Encryption Standard developed by IBM in the mid 1970s that uses a 56-bit key. DES has been shown to be rather easily cracked, however, given proper computing hardware. In recent years, a “Triple DES” scheme has been put forth that uses three such keys, for an effective 168-bit key length. ATM manufacturers are now developing newer models that support Triple DES natively; such redesigns may make them more amenable to also including snapshot cameras and facial recognition software, more so than they would be in regards to retrofitting pre-existing machines .

FACIAL RECOGNITION TECHNIQUE:

There are hundreds of proposed and actual implementations of facial recognition technology from all manner of vendors for all manner of uses. However, for the model proposed in this paper, we are interested only in the process of facial verification – matching a live image to a predefined image to verify a claim of identity – not in the process of facial evaluation – matching a live image to any image in a database. Further, the environmental conditions under which the verification takes place – the lighting, the imaging system, the image profile, and the processing environment – would all be controlled within certain narrow limits, making hugely robust software unnecessary .One leading facial recognition algorithm class is called image template based. This method attempts to capture global features of facial images into facial templates. What must be taken into account, though, are certain key factors that may change across live images: illumination, expression, and pose (profile.)
The natural conclusion to draw, then, is to take a frontal image for the bank database, and to provide a prompt to the user, verbal or otherwise, to face the camera directly when the ATM verification process is to begin, so as to avoid the need to account for profile changes. With this and other accommodations, recognition rates for verification can rise above 90%. A system can examine just the eyes, or the eyes nose and mouth, or ears, nose, mouth and eyebrows, and so on

The conclusion to be drawn for this project, then, is that facial verification software is currently up to the task of providing high match rates for use in ATM transactions. What remains is to find an appropriate open-source local feature analysis facial verification program that can be used on a variety of platforms, including embedded processors, and to determine behavior protocols for the match / non-match cases.

OUR METHODOLOGY

The first and most important step of this project will be to locate a powerful open-source facial recognition program that uses local feature analysis and that is targeted at facial verification. This program should be compilable on multiple systems, including Linux and Windows variants, and should be customizable to the extent of allowing for variations in processing power of the machines onto which it would be deployed.

We will then need to familiarize ourselves with the internal workings of the program so that we can learn its strengths and limitations. Simple testing of this program will also need to occur so that we could evaluate its effectiveness. Several sample images will be taken of several individuals to be used as test cases – one each for “account” images, and several each for “live” images, each of which would vary pose, lighting conditions, and expressions.

Once a final program is chosen, we will develop a simple ATM black box program. This program will server as the theoretical ATM with which the facial recognition software will interact. It will take in a name and password, and then look in a folder for an image that is associated with that name. It will then take in an image from a separate folder of “live” images and use the facial recognition program to generate a match level between the two. Finally it will use the match level to decide whether or not to allow “access”, at which point it will terminate. All of this will be necessary, of course, because we will not have access to an actual ATM or its software.

Both pieces of software will be compiled and run on a Windows XP and a Linux system. Once they are both functioning properly, they will be tweaked as much as possible to increase performance (decreasing the time spent matching) and to decrease memory footprint.

Following that, the black boxes will be broken into two components – a server and a client – to be used in a two-machine network. The client code will act as a user interface, passing all input data to the server code, which will handle the calls to the facial recognition software, further reducing the memory footprint and processor load required on the client end. In this sense, the thin client architecture of many ATMs will be emulated.

We will then investigate the process of using the black box program to control a USB camera attached to the computer to avoid the use of the folder of “live” images. Lastly, it may be possible to add some sort of DES encryption to the client end to encrypt the input data and decrypt the output data from the server – knowing that this will increase the processor load, but better allowing us to gauge the time it takes to process.

IRIS RECOGNITION:

Inspite of all these security features, a new technology has been developed. Bank United of Texas became the first in the United States to offer iris recognition technology at automatic teller machines, providing the customers a cardless, password-free way to get their money out of an ATM. There's no card to show, there's no fingers to ink, no customer inconvenience or discomfort. It's just a photograph of a Bank United customer's eyes. Just step up to the camera while your eye is scanned. The iris -- the colored part of the eye the camera will be checking -- is unique to every person, more so than fingerprints. And, for the customers who can't remember their personal identification number or password and scratch it on the back of their cards or somewhere that a potential thief can find, no more fear of having an account cleaned out if the card is lost or stolen.

How the system works.

When a customer puts in a bankcard, a stereo camera locates the face, finds the eye and takes a digital image of the iris at a distance of up to three feet. The resulting computerized "iris code" is compared with one the customer will initially provide the bank. The ATM won't work if the two codes don't match. The entire process takes less than two seconds.

The system works equally well with customers wearing glasses or contact lenses and at night. No special lighting is needed. The camera also does not use any kind of beam. Instead, a special lens has been developed that will not only blow up the image of the iris, but provide more detail when it does. Iris scans are much more accurate than other high-tech ID systems available that scan voices, faces and fingerprints.
Scientists have identified 250 features unique to each person's iris -- compared with about 40 for fingerprints -- and it remains constant through a person's life, unlike a voice or a face. Fingerprint and hand patterns can be changed through alteration or injury. The iris is the best part of the eye to use as a identifier because there are no known diseases of the iris and eye surgery is not performed on the iris. Iris identification is the most secure, robust and stable form of identification known to man. It is far safer, faster, more secure and accurate than DNA testing. Even identical twins do not have identical irises. The iris remains the same from 18 months after birth until five minutes after death.

When the system is fully operational, a bank customer will have an iris record made for comparison when an account is opened. The bank will have the option of identifying either the left or right eye or both. It requires no intervention by the customer. They will simply get a letter telling them they no longer have to use the PIN number. And, scam artists beware, a picture of the card holder won't pass muster. The first thing the camera will check is whether the eye is pulsating. If we don't see blood flowing through your eye, you're either dead or it's a picture

CONCLUSION:

We thus develop an ATM model that is more reliable in providing security by using facial recognition software. By keeping the time elapsed in the verification process to a negligible amount we even try to maintain the efficiency of this ATM system to a greater degree. One could argue that having the image compromised by a third party would have far less dire consequences than the account information itself. Furthermore, since nearly all ATMs videotape customers engaging in transactions, it is no broad leap to realize that banks already build an archive of their customer images, even if they are not necessarily grouped with account information.

Thermoelectric cooler

2007-11-24T18:53:00.001-08:00

INTRODUCTION

Thermoelectric cooler (TEC) is a solid-state heat pump which offers no-moving parts, ease of miniaturization, high reliability and flexibility in design. It makes use of Peltier effect of semiconductor material to provide a temperature difference when solid state P-N materials are connected electrically in series and thermally in parallel. The heating and cooling is almost instantaneous and the temperature can easily be controlled by an appropriate control circuit with proper heat sink for heat dissipation. Due to flexibility in design and fabrication, it is possible to integrate into devices that require precise temperature control

WORKING PRINCIPLES

The working principle of a TEC is based on two effects:-

1. SEEBECK EFFECT

The Seebeck effect is the conversion of temperature differences directly into electricity. This effect was first discovered, accidentally, by the German-Estonian physicist Thomas Johann Seebeck in 1821, who found that a voltage existed between two ends of a metal bar when a temperature difference ΔT existed in the bar.

The effect is that a voltage, the thermoelectric EMF, is created in the presence of a temperature difference between two different metals or semiconductors. This causes a continuous current to flow in the conductors if they form a complete loop. The voltage created is of the order of several microvolts per degree difference.

In the circuit,
S_A and S_B are the Seebeck coefficients (also called thermoelectric power or thermopower) of the metals A and B, and T₁ and T₂ are the temperatures of the two junctions. The Seebeck coefficients are non-linear, and depend on the conductors' absolute temperature, material, and molecular structure. If the Seebeck coefficients are effectively constant for the measured temperature range, the above formula can be approximated

thus, a thermocouple works by measuring the difference in potential caused by the dissimilar wires. It can be used to measure a temperature difference directly, or to measure an absolute temperature, by setting one end to a known temperature. Several thermocouples in series are called a thermopile.

This is also the principle at work behind thermal diodes and thermoelectric generators (such as radioisotope thermoelectric generators or RTGs) which are used for creating power from heat differentials.

The Seebeck effect is due to two effects: charge carrier diffusion and phonon drag.

Charge carrier diffusion :

Charge carriers in the materials (electrons in metals, electrons and holes in semiconductors, ions in ionic conductors) will diffuse when one end of a conductor is at a different temperature than the other. Hot carriers diffuse from the hot end to the cold end, since there is a lower density of hot carriers at the cold end of the conductor. Cold carriers diffuse from the cold end to the hot end for the same reason.

If the conductor were left to reach thermodynamic equilibrium, this process would result in heat being distributed evenly throughout the conductor (see heat transfer). The movement of heat (in the form of hot charge carriers) from one end to the other is called a heat current. As charge carriers are moving, it is also an electrical current.

In a system where both ends are kept at a constant temperature relative to each other (a constant heat current flows from one end to the other), there is a constant

diffusion of carriers. If the rate of diffusion of hot and cold carriers in opposite directions were equal, there would be no net change in charge. However, the diffusing charges are scattered by impurities, imperfections, and lattice vibrations (phonons). If the scattering is energy dependent, the hot and cold carriers will diffuse at different rates. This creates a higher density of carriers at one end of the material, and the distance between the positive and negative charges produces a potential difference; an electrostatic voltage.

This electric field, however, opposes the uneven scattering of carriers, and equilibrium is reached where the net number of carriers diffusing in one direction is canceled by the net number of carriers moving in the opposite direction from the electrostatic field. This means the thermopower of a material depends greatly on impurities, imperfections, and structural changes (which often vary themselves with temperature and electric field), and the thermopower of a material is a collection of many different effects.

Typical thermoelectric devices are structured as alternating p-type and n-type semiconductor elements connected by metallic interconnects as pictured in the figures below. Current flows through the n-type element, crosses a metallic interconnect, and passes into the p-type element. If a power source is provided, the thermoelectric device may act as a cooler, as in the figure to the left below. Electrons in the n-type element will move opposite the direction of current flow and holes in the p-type element will move in the direction of current flow, both removing heat from one side of the device. If a heat source is provided, the thermoelectric device may function as a power generator, as in the figure to the right below. The heat source will drive electrons in the n-type element toward the cooler region, thus creating a current through the circuit. Holes in the p-type element will then flow in the direction of the current. The current can then be used to power a load, thus converting the thermal energy into electrical energy.

Phonon drag :

Phonons are not always in local thermal equilibrium; they move along the thermal gradient. They lose momentum by interacting with electrons (or other carriers) and imperfections in the crystal. If the phonon-electron interaction is predominant, the phonons will tend to push the electrons to one end of the material, losing momentum in the process. This contributes to the already present thermoelectric field. This contribution is most important in the temperature region where phonon-electron scattering is predominant. This happens for

where θ_D is the Debye temperature. At lower temperatures there are fewer phonons available for drag, and at higher temperatures they tend to lose momentum in phonon-phonon scattering instead of phonon-electron scattering.

This region of the thermopower-versus-temperature function is highly variable under a magnetic field.

1. Peltier effect:

The Peltier effect is the reverse of the Seebeck effect; a creation of a heat difference from an electric voltage.

It occurs when a current is passed through two dissimilar metals or semiconductors (n-type and p-type) that are connected to each other at two junctions (Peltier junctions). The current drives a transfer of heat from one junction to the other: one junction cools off while the other heats up; as a result, the effect is often used for thermoelectric cooling. This effect was obser

Where Π is the Peltier coefficient, Π_AB of the entire thermocouple, and Π_A and Π_B are the coefficients of each material. P-type silicon typically has a positive Peltier coefficient (though not above ~550 K), and n-type silicon is typically negative, as the names suggest.

The Peltier coefficients represent how much heat current is carried per unit charge through a given material. Since charge current must be continuous across a junction,

the associated heat flow will develop a discontinuity if Π_A and Π_B are different. This causes a non-zero divergence at the junction and so heat must accumulate or deplete there, depending on the sign of the current. Another way to understand how this effect could cool a junction is to note that when electrons flow from a region of high density to a region of low density, they expand (as with an ideal gas) and cool.

The conductors are attempting to return to the electron equilibrium that existed before the current was applied by absorbing energy at one connector and releasing it at the other. The individual couples can be connected in series to enhance the effect.

An interesting consequence of this effect is that the direction of heat transfer is controlled by the polarity of the current; reversing the polarity will change the direction of transfer and thus the sign of the heat absorbed/evolved.

A Peltier cooler/heater or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other. Peltier coolers are also called thermo-electric coolers (TEC).

COMPARISON OF COOLING TECHNOLOGY:

(TECs Vs COMPRESSORS)

The flow of heat with the charge carriers in the thermoelectric device is very similar to the way the compressed refrigerant transfer’s heat in the mechanical system. The circulating fluids in the compressor system carry heat from the thermal load to the evaporator, where the heat can be dissipated. With TE technology, on the other hand, the circulating direct current carries heat from the thermal load to some type of heat sink that can effectively discharge the he

TEC MATERIALS AND PROPERTIES

MATERIALS:

The materials that are of interest for TE applications are poor thermal conductors but at the same time good electrical conductors, i.e., they maximize the TE figure-of-merit, Z = S2/ρκ, where S, ρ, and κ denote thermoelectric power, electrical resistivity, and thermal conductivity, respectively. There is a large need for higher performance materials than those that currently exist.

Early TE materials were Bi2Te3 and Si-Ge systems. More recently, the focus on new materials development was shifted to skutterudites, superlattice structures and low-dimensional and disordered systems. Currently the best TE materials are artificial multilayered semiconducting alloys with low phonon thermal conductivity and large electronic mobility. The misfit-layered oxides like Ca₃Co₄O₉ accomplish a similar effect in naturally assembled crystals that play a dual role of being a “phonon glass” and an “electron crystal”. They attract now interest as candidates for high-temperature TE applications.

Peltier Effect coolers are almost always constructed with Bismuth Telluride (Bi₂Te₃) and used around room temperature and below. Seebeck Effect power generators are often constructed of PbTe or, SiGe as well as Bi₂Te₃ and are used at much higher temperatures.

THERMOELECTRIC PARAMETERS: Imax, Vmax, dTmax and Qmax

As current flows through a material, heat is generated. Thermoelectric material is no different. There is a point where the heat generated internally offsets the TECs ability to pump heat. Each TEC has a limit on how much heat that it can pump. This limit is referred to as Qmax. The current associated with Qmax is referred to as Imax. The corresponding voltage across the coolers is referred to as Vmax. If a TEC is completely insulated and isolated from the environment and running at Imax, it will produce its maximum temperature difference, dTmax. At this point it will also be pumping no heat whatsoever. As heat is applied to the cold side of the TEC, the temperature differential is suppressed. Effectively, one trades temperature differential for heat pumping. As such, if the temperature differential is 0, the corresponding heat load is Qmax. The coefficient of performance (COP) is defined as the amount of heat pumping one gets for each unit of electrical power supplied.

RATE OF TEMPERATURE CHANGE...

Peltier device cooling & heating speed - they can change temperature extremely quickly, but to avoid damage from thermal expansion control the rate of change to about 1 degree C per second.

POWER SUPPLY REQUIREMENTS...

A simple DC supply is fine if the AC ripple is not more than about 10% or 15%.

TEMPERATURE CONTROL...

Varying the power supply voltage works. Pulse width modulation can be used, but a frequency above 1 KHz (Marlow) or 2 KHz (Tellurex) is recommended (watch out for EMI!) It's best to use some kind of temperature sensor feedback (thermistor or solid-state sensor) and a closed-loop control circuit.

HEATSINK REQUIRED!...

Peltier devices don't cool by making heat magically disappear! They move the heat from one side to the other where you must remove it with a heatsink.

ADVANTAGES AND LIMITATIONS :

Advantages:

1. No moving parts

2. Small size and weight

3. Ability to cool below ambient temperature

4. High reliability

5. Ability to generate electrical power

6. Environment friendly

Limitations:

· High cost

· Can be applied on small areas only.

· Less efficient

· Moisture effect

TEC APPLICATIONS

1. Used in automobiles as coolers, heaters as well as generator applications in various ways to increase efficiency of the vehicle.

2. Used in satellites and spacecraft to counter the effect of direct sunlight by dissipating the heat over the cold shaded side

3. Photon detectors such as CCDs in astronomical telescopes or expensive digital cameras are often cooled down with Peltier elements.

4. Thermoelectric coolers can be used to cool computer components to keep temperatures within design limits without the noise of a fan, or to maintain stable functioning when overclocking.

at into the outside environment.

ved in 1834 by Jean Peltier, 13 years after Seebeck's initial discovery.

POTENTIAL AUTOMOTIVE APPLICATIONS:

1. Heating, ventilation and air conditioning (HVAC) systems.

2. Seats

3. Cup holders

4. Arm rests

5. Enable hot or cold appliances (ACs and Warmers)

6. Electrical power generation from waste heat conversion.

BARRIERS FOR AUTOMOTIVE APPLICATIONS:

1. High cost

2. No clear acceptance of a specific thermoelectric technology.

3. Material issues(thermal stress and temperature limitations).

4. Lack of volume production capability.

Lack of subsystem design using thermoelectrics

CONCLUSION:

A thermoelectric material has paved the way for many innovative applications in the field of opto-electronics and automobiles. Thermoelectric technology has made its mark in the field of automobiles, but it needs to be prove and tested thoroughly. If both domestic and industrial uses switch to thermoelectric coolers from the conventional air conditioners, we can prevent the emission of chloro-fluo-carcons into the earths atmosphere and thereby depletion of the ozone layer. With pollution increasing at an alarming rate, thermoelectric coolers have come to the rescue as these are environment friendly, compact and affordable.