The dispersal of scent takes place via the thermal and light-like behavior of the fragrant particles in the air. Thousands of points, letters, and words are positioned in each and every air particle. Each molecule is created in a form to carry sounds, sights, and odor. Millions of sound waves, scents and images are being transported and translocated into each of the trillions of air particles without deforming or mixing. As our knowledge pertaining to this transport grows, new technological products that will enable the transport of odors will be offered to the service of mankind.

Our sense of smell occurs in the brain. The chemical molecules exiting a lemon peel stimulate the odor receptors in the nose, which are then transmitted to brain to be interpreted as electric signals. Our olfactory system can easily distinguish more than ten thousand scents. This has inspired scientists to design similar devices. These models are called “electronic noses.”

A series of chemical receptors are utilized in the electronic nose instead of the receptor proteins of the human nose. Each of these is designed to sense various scents. These devices are difficult to produce, as the cost grows for a more sensitive device. The signals that sensors collect from the environment are converted into binary codes via electronic systems and then sent to a computer. The role of human nerve cells in charge of sensing odor is replaced by the electronic systems of a computer.

Mostly in their early phases, electronic noses are beginning to be used in various sectors, primarily those involving foods and perfumes, as well as the medical and chemical industries.

How does odor transportation take place?

As I already mentioned, the aromatic molecules transported via air particles in their gaseous state are detected by the smell sensor system and converted into electric signals. Quite a few different materials are used as conductors: conductive polymers, semi-conductive metal oxides, a quartz-crystal micro-balance (QMB), surface acoustic wave (SAW) sensors, pellistors, and infrared sensors.

Once the electric signals are converted into binary, the odor information is determined via a software program in which algorithms such as artificial nerve networks and support vector machines are employed. This information is then transmitted to a remote medium via lines of communication, such as a computer network, the internet, or another form of mobile communication. The odor type is received in the target computer. This detection stage can be completed in the target PC when necessary.

Today’s technology can only permit the transmission of odor data. In order to perceive the transmitted information at the target location as smell, the scents must be present as stored in containers and must be triggered via received odor data to be dispersed. The research in this field is limited, with ongoing pilot studies.

How can diseases be diagnosed with odors?

The natural functions of the human body, such as sweat, blood, urine, and feces, can be used to help diagnose diseases. The odor of the gases in human breath holds significant information regarding body health. There are between two hundred and four hundred different gases found in human breath. Furthermore, the number of gas types detected and described in the breath can exceed three thousand. While blood gets cleaned in the lungs, the gases of the used blood pass to the breath via the alveoli. Therefore, many critical pieces of bodily information are present in the breath.

The gases exhaled through our breath are composed of various alkaline and aromatic compounds. Each of these is a potential indicator that provides information about a disease. The gases and their ratio in the breath of a healthy person are well established. Since the ratio of the gases in the breath gets altered depending on the cause of an illness – such as diabetes (Type I and II), cancer of the ear-nose-throat, tuberculosis, and women’s reproductive diseases – can be diagnosed by utilizing the electronic nose.

There are other uses for the technology, too. NASA is developing a highly sensitive artificial nose for space research. This device will almost be able to distinguish every type of chemical compound, making more sensitive measurements than a human nose. With this device, the detection of harmful substances in the space station will be possible.

Google has announced that significant progress has been made regarding the “Google nose” which helped revolutionize searching for aromas. The Google Aroma database (http://www.google.com.tr/intl/tr/landing/nose/) stores more than 15 million kinds of scent. The days when we will be able to smell the scent of any product through our internet based devices do not seem to be too distant. To make this possible, sound waves would be converted into odor signals. There is a partially-imaginary video prepared to show how this can feel.

New technologies will change our relationship with smell, which has always been deeply important to humanity. Reference is made of this in the Qur’an, especially when the Prophet Jacob of Canaan sensed the fragrance of his son, Joseph, who was hundreds of miles away. The verse, from the chapter of Joseph, reads, “Surely, I sense the fragrance of Joseph, unless you would consider me a dotard. “It shows how valuable scent is to us, as anyone who has had a long lost memory triggered by an unexpected smell understands. As the verse suggests, losing our sense of smell is akin to losing our minds. Research has borne this out, as one of the first symptoms of Alzheimer’s disease is the loss of smell. In fact, monitoring loss of scent has helped with the early detection and prevention of Alzheimer’s. This is yet another way that our body has been perfectly calibrated to cue us in to its messages. In this regard, as with many, technology is still trying to catch up to nature.

Many people probably would agree that the transistor was the greatest technological invention of the twentieth century. The first transistor, invented by Jack Kilby and Robert Noyce in 1958, was made from silicon. Even though integrated circuit technology has advanced to the level of putting millions of transistors on a fingernail-sized chip, transistors are still made from silicon. Now, however, both the scientific community and the high-tech industry are very excited about something new: plastic electronics. For many of us, this might sound like an oxymoron, for we know plastic only as an insulator. So how can a protective substrate or a carriage box to the actual electronic device be converted into an electronic device?

The story of plastic electronics started late 1970s with Alan Heeger, Alan Macdiarmid, and Hideki Shirakawa. These scientists demonstrated that the molecular structure of certain polymers (plastics) can be manipulated and then used as conductors. The Swiss Academy of Sciences was somewhat slow in recognizing their work, for they were awarded the Nobel prize in chemistry only in 2000. Nevertheless, the scientific community did not wait for the Nobel committee’s recognition of plastics. Since 1977, plastic has become probably the most common material in our daily lives.

Silicon versus plastic

All computer chips are made out of silicon (semiconductor) and aluminum (metal). Silicon is a great material for integrated circuits, because it is available, can be acquired in an extremely pure state (single crystal or amorphous), and has a very high mobility (the speed that electrons can travel through material). This mobility, in turn, determines the device’s switching speed. However, silicon has one important drawback: It is not easy to process.

Integrated circuit technology can deposit millions of silicon transistors on a single chip. However, the procedure for making these devices usually requires facilities worth billions of dollars, for silicon has to go through complicated photolithography procedures under clean room conditions before it can be incorporated into a device. But is it really worthwhile to spend billions of dollars on such facilities? The answer probably looks obvious, since Intel remains one of the world’s largest companies. However, we do not really need such a high quality in many of the applications for which silicon is used. So if there is something cheaper that can do the job perfectly, why not use it? Plastic is far cheaper, but not so sophisticated an alternative.

Plastic is cheap because billion-dollar facilities are not required to convert it into a device. In fact, the technology needed to process plastic into an electronic device is only slightly more advanced than an ink-jet printer. Electronic circuits are printed on an insulating polymer, and then certain parts of the polymer are exposed to UV light in order to convert the insulating polymer into a conducting polymer. The result is a device in which only the parts that we want to conduct are conducting. Moreover, these conducting parts sit on a protective insulating sheet of plastic. That is pretty much all we need for many applications.

The case for plastic

Plastic has two advantages over silicon: price and flexibility. Like other inorganic elements, silicon has strong covalent bonds between its atoms. As these bonds are rigid, they cannot bend or stretch. Plastic has very loose molecular bonds that can tolerate a significant amount of bending and stretching. Flexibility combined with electronics implies applications like flexible displays that can be rolled up and taken somewhere else, reloadable electronic newspapers that can be bent like paper, disposable mobile phones, and many others.

So if plastic is that good, why is it not the electronics industry’s standard material? For one simple reason: Plastic’s loose molecular bonds, which make the material so flexible, make it more difficult for the electrons to travel through it. Thus, plastic devices are slower than silicon devices. Until several years ago, the mobility of a typical conducting plastic used to be around 0.1 cm2/volts, whereas crystalline (best) silicon could reach 1000 cm2/volts at room temperature. Recently, a new class of polymers (pentacene) has been found in which molecules tend to self-organize. As a result, the mobility has been pushed up to 3 cm2/volts. Scientist working on pentacene estimate a number close to 50 cm2/volts as the limit of achievable mobility for this special polymer.

These expectations are not just wishful thinking of some optimistic scientists. In fact, even now there are some significant outcomes of plastic technology.

Current developments

John Rogers and coworkers from Bell Labs (Lucent Technologies) have patterned 256 polymer transistors on the back-plane of a flexible optical display. Richard Friend and coworkers from University of Cambridge have produced thin film transistor circuits using a high-resolution inkjet printing. Dago de Leeuw and colleagues at Philips Research Laboratories in Eindhoven, The Netherlands, have developed a new technique called photochemical patterning. In photochemical patterning, a light sensitive-polymer is exposed to ultraviolet light through a mask shaped in the form of the desired circuit. The ultraviolet light changes the polymer from a conducting state to a non-conducting state. In this process, the polymer’s resistance can increase as much as 11 orders of magnitude (100000000000). The advantage of this technique over the patterning techniques used for silicon is that it does not need any vacuum and can be used on flexible substrates. The problems with photochemical patterning are that it is not significantly cheaper than photolithography and etching used for silicon, and it can be used only for light-sensitive polymers. Different research groups have developed various techniques that have pros and cons compared to photochemical patterning. However, many of the techniques cannot print features that are small enough for electronic circuits. The critical length is the distance between the transistor’s source and drain, typically 0.01 mm. This is the distance that the field-induced charges have to travel. As the drive current and switching speed of the device depend on this distance, having too large of a distance reduces the capabilities of the device. Another technique that pursues quite a different approach is microcontact printing. Developed by the Bell Labs group, microcontact printing with rubber-like stamps can make small enough features. Scientists have used this technique to make a flexible display in which a transistor controls each pixel. The key point in developing this technique was using gold pads, instead of a polymeric material, to deposit the transistor’s source and drain. Even though this device is not completely plastic, it is a step toward that goal. When a special kind of ink was applied to a thin film of gold, it formed some sort of self-assembled layer on the gold, which then produced well-defined patterns and sharp edges. This provided the required resolution to make small enough features necessary for an electronic device having a reasonable speed. These two techniques show two important aspects of the problem. In photochemical printing, we have a device that is completely plastic and so has the important advantage of flexibility. However, it is not as cheap as it could be and does not have the required resolution. In the second technique, the outcome is not a 100 percent plastic device, so it is not as flexible as a purely plastic circuit. However, it can be manufactured very cheaply and has a better resolution (and thus a higher switching speed).

Conclusion

Many other approaches are being employed to develop this new and exciting technology. If plastic electronics does become standard for at least some applications, it probably will be a hybrid of these different techniques. If the optimistic group of scientists working on plastic electronics prove to be right, one day we might see TV screens curling around the walls of our rooms and even reloadable electronic newspapers that can be folded and carried like regular newspapers. Who knows what new inventions will come with this new technology?

References

• Garnier, F., (et al). Science 265 (1994): 1684-86.
• Gelinck, G., T. Geuns, and D. de Leuw. Applied Physics Letters 77 (2000): 406-8.
• Levi, Barbara G. ‘New Printing Technologies Raise Hopes for Cheap Plastic Electronics.’ Physics Today (February 2001). Online at: www.physicstoday.org/pt/vol-54/iss-2/p20.html.
• Nobel Focus: Electricity through Plastic.’ Physical Review Focus (24 October 2000). Online at: http://focus.aps.org/v6/st18.html.
• Scott, Campbell. ‘Electronics Put It on Plastics.’ Physics in Action. (October 1998). Online at: www.physicsweb.org/article/world/11/30/3/1.
• Voss, David. ‘Cheap and Cheerful Circuits.’ Nature 407 (28 September 2000).

New Findings in Biology

Olfaction was long considered a uniquely mammalian trait. Scientists have disproven this by showing that many intertebrates can smell. For example, birds were thought to be unable to smell, although they have nostrils in their bills. John Audubon, a famous nineteenth-century bird artist, reached this mistaken conclusion by observing vultures confronted with a covered and an uncovered animal corpse, he concluded that they could not smell. The minute weight of the birds’ olfactory bulb consolidated this widespread misconception. Recent research shows that birds use smell when finding and distinguishing food, choosing proper nesting sites and mates, and following avian navigation routes. Ken Stager, an orinthogist at Los Angeles County Natural History Museum, used turkey vultures to disprove Audubon’s vulture experiment. Marine biologist Betsy Bang, who measured the olfactory bulbs and tissues in the brains of 151 bird species, calculated the olfactory bulb’s mass as being between 3% to 37% of the brain’s entire mass. This shows that the ratio, and not the weight, determines a bird’s ability to smell.

Other examples are as follows:

•Pigeons perceive small amounts of odorants. If their olfactory bulbs are blocked, they become lost.

•Certain seabirds (e.g., white chinned petrels) are sensitive to the chemical emitted by their main food (plankton), and so follow an olfactory path over the sea.

•European starlings smell the best region for their nesting site.

•Chickens detect inedible bugs (e.g., bright-colored bad-tasting caterpillars) through smell and sight.

•Salmon return to their hatching sites years later by using the unique olfactory memory of these sites left in their brains.

Smelling is far more developed in mammals, especially dogs and cats, which can sense parts per billion or trillion and can identify millions of different odorants. Science would benefit greatly if such abilities could be reproduced in sensors. But first, how does the human nose smell?

Perceiving Odors

Scientists divide human olfaction into steps. First, a potential odorant emits an odor’s basic elements: volatile organic compounds (VOCs). We perceive an odor when molecules are transformed into an odor by binding the receptor proteins.(1) After binding with certain types of VOCs, these receptor proteins cause depolarization. The electrical charges produce unique signals, which the epithelium’s sensory cells transmit to our neural network (axons).

These signals then are carried to a cluster of neural networks in the brain (glomeruli).(2) Ultimately, the impulse reaches the hypothalamus and describes the scent through a process of classification and identification.

Quantifying Scents

Human odor panels or gas chromatography and mass spectroscopy (GC/MS) are used to identify odors. Such quantification is problematic, however, because it is hard to quantify the VOC’s perception in the nose as a unit of odor. Quantifying mass, volume, temperature, light intensity, and the molecular concentration of a soluble substance in a solution are reasonably objective and can be measured as a multiple of a standard unit.

But a standard olfactory measure does not exist, for it varies according to time and environment. Odor concentration is expressed as a multiple of a threshold: 50% of human “sniffers” must detect-not necessarily identify-it. This threshold is defined by the American Society for Testing and Materials (ASTM), and is accepted as the absolute threshold of odor perception. It takes 5 or 10 odor units for the human panel to identify the odor. GC/MS also can identify the odor’s chemical composition.

Electronic Nose

After developments in electronic sight and hearing, scientists sought similar progress in odor perception. Research began at the University of Warwick (Coventry, England) in the 1980s. Its participants coined the term “electronic nose,” now commonly known as “e-nose.”(3) Their progress made it a commercial commodity with many applications.

E-noses have moved from being metal oxide devices, to conducting polymers, and now to laptop-size or pocket-size odor sensors. The Swiss Federal Institute of Technology (Zurich) has made one the size of a wrist-watch. However, current e-nose use is largely restricted to labs and military applications. Scientists are trying to match or surpass the human sense of smell’s accuracy and sensitivity, after which they will work on surpassing that of the canine species.

Uses and Advantages

E-noses have a wide application in agriculture. Since they can detect minute differences, an e-nose using polymer materials can determine whether a tomato is sun-ripened, picked green, or internally damaged, and whether apple juice comes from a concentrate or is authentic but pasteurized.

Volunteers often test such products. But who wants to determine if corn oil is rancid or canola oil is oxidized? E-noses, having no such “qualms,” detect changed odors in oil samples and provide far more accurate reports.

In animal science and poultry, e-noses provide detailed reports about spoiled food. Judy Arnold, a microbiologist in Athens, GA, researches food quality for the Agricultural Research Service (ARS).

In 1998, researchers discovered that e-noses can detect gases produced by spoiled poultry products. They claim that an e-nose can determine freshness, period of time in a refrigerator, and the amount of fat in white meat. Such an objective evaluation benefits poultry farmers and producers by eliminating returns of “funny-smelling” poultry. E-noses also can detect meat’s decay rate and bacteria, overall quality and freshness, the composition of mixed meat-part products (e.g., processed meat), and how long a ham has been dry-cured. Given this, the e-nose’s ability to examine a bundle of scents makes it very useful. It can perform hundreds of preliminary assessments that would occupy a chemist for months.

The military uses e-noses to detect land mines and traces of chemical-biological weapons. This is important, for over 100 million land mines litter 62 war-torn countries. Although dog-sniffers are useful, this practice is inhumane (dogs are often injured) and impractical (they need lots of training).

E-noses also are better than metal detectors and ground-penetrating radar and infrared imaging-the former detects even tiny pieces of metal, whereas the latter often images pebbles. As e-noses can identify traces of TNT or similar explosives to the 100 parts per quadrillion level, their detection rate is far more accurate and efficient. Nomadics, a Still-water, OK-based company, produces a cigar-box-sized e-nose for this purpose. Tufts University produces an optical e-nose that is designed and functions much like a mammalian nose.

Environmentalists use e-noses to analyze air. For instance, e-noses can report the chemical makeup of odors emitted by a farm’s store of manure, detect the compounds causing that odor, help minimize leaks, and determine a new diet that will decrease such odors. With their ability to detect toxic VOCs and compounds leaking from a factory’s or waste site’s storage areas, e-noses will help environmentalists force industry to change its practices. The major difficulty here remains sampling, as concentrations vary with time and place.

Caltech has used Department of Defense funding to develop a device that identifies odors in seconds. Its 32 components swell like sponges when exposed to a particular vapor, and its resistance (hence conductivity) changes accordingly. As it can detect any type of odor, doctors at the Children’s Hospital in Los Angeles are studying medical applications. Currently, it is applied to patients’ breath to help diagnose upper respiratory infections.

The major advantages of e-noses over human noses in these areas are objectivity; ability to measure odors over long real-time periods; and immunity to fatigue, infection, mental state, hazardous material, and adaptation (gradual loss of sensitivity).

How E-noses Work

E-noses have three functional components: a sample handler, a gas sensor array, and a signal processing system. Its output identifies the odorant, estimates its concentration, and relates its characteristic properties. A sensor recognizes different types and concentrations of odors through its arrays, each of which has a different sensitivity. The resulting combination provides the response pattern that enables the e-nose to identify odorants.

In a typical e-nose, a vacuum pump pulls the first air sample into the tube housing the electronic sensor arrays. The air sampling unit exposes the odorant to the sensor, after which VOCs interact with the surface and the sensor’s active material until reaching a steady state. The sensor’s response is recorded and transmitted to the signal-processing unit. When completed, a washing gas cleanses the sensor. After the reference gas is applied to the unit, the sensor is ready to measure again.

E-nose Technologies

The sensor is the e-nose’s key element, and the sensor type is its defining characteristic. There are 5 types of e-nose sensors, as follows:

Optical sensors: Optical fiber sensors work through fluorescence and chemoluminescence. The tube’s glass fibers contain a thin encoated active material in their sides and at both ends. As VOCs interact with the organic matrix’s chemical dyes, the dye’s fluorescent emission changes the spectrum. These changes then are measured and recorded for different odorous particles.

Fiber arrays with different dye mixtures can be used as sensors. These are fabricated by dipcoating (binding a plastic solution to a substrate), micro electromechanical system (MEMS), and precision machining. The main advantage is that this adjustable tool can filter out noise. Also, since many dye forms are available in biological research, sensors are cheap and easy to fabricate. But the instrumentation control systems are complex, which adds to the cost, and have a limited lifetime due to photo bleaching (the sensing process slowly consumes the fluorescent dyes).

Optical sensors are sensitive and can measure low ppb (parts per billion); however, they are still in the researach stage of development.

Spectrometry-based Sensors: This group consists of a molecular spectrum-based gas chromatography (GC), an atomic mass spectrum-based mass spectrometry (MS), and a transmitted light spectrum-based light spectrum (LS). The first two can analyze the odor’s components accurately, which is a plus. However, their use of a vapor trap to increase concentration can alter the odor’s characteristics. LS devices do not consume the sample, but do require tunable quantum-well devices. GC and MS devices are commercially available, while LS devices are only at the research stage. All spectrometry-based sensors are fabricated by MEMS and precision machining, and can measure odors to a low ppb level.

The GC tube decomposes the odorant into its molecular constituents, and MS forms a mass spectrum for each peak. The spectra then is compared to a large precompiled database of spectral peaks to classify and identify odorants.

MOSFET (Metal-oxide-silicon field-effect-transistor): The basic principle here is capacitive charge coupling. In other words, VOCs react with the catalytic metal and thereby alter the device’s electrical properties. The device’s selectivity and sensitivity can be fine-tuned by varying the metal catalyst’s thickness and composition. MOSFETs are micro-fabricated and commercially available, but can measure only parts per million. They can be manufactured by electronic interface circuits, which minimizes batch-to-batch variation. However, the gas produced by the VOC-metal reaction must penetrate the MOSFET’s gate.

Conductivity Sensors: The sensor types used here are metal oxide or conducting polymer. Both operate on the principle of conductivity, for their resistance changes as they interact with VOCs. Metal oxide sensors are common, commercially available, inexpensive, and easy to produce (they are micro-fabricated). Their sensitivity ranges from 5-500 ppm. However, they only operate at high temperatures (200°C to 400°C).

In conducting polymer sensors, VOCs bond with the polymer backbone and change the polymer’s conductivity (resistance). They are micro-fabricated together with electroplating and screen printing, are commercially available, and can measure from .1 to 100 ppm. They operate at room temperature, yet are very sensitive to humidity. Moreover, it is hard to electropolymerize the active material, which makes batch-to-batch variation inevitable. Sometimes VOCs penetrate the polymer chain, which means that the sensor must be returned to its neutral and reference state-a very time-consuming process.

Piezoelectric Sensors: These devices, which measure any change in mass, come in two varieties: quartz crystal microbalance (QCM) and surface acoustic wave (SAW) devices.

QCM sensors have a resonating disk and metal electrodes on each side. While applying the gas sample to the resonator’s surface, the polymer surface absorbs VOCs from the environment. Thus its mass increases, which increases resonance frequency. As the U.S. Navy has long used QCMs, this technology is familiar, developed, and commercially available. A QCM sensor is fabricated by screen-printing, wire bonding, and MEMS. Althoug it can measure a 1.0 Ng mass change, its MEMS fabrication and interface electronics is a major disadvantages. QCM sensors are quite linear in mass changes, their sensitivity to temperature can be adjusted, and their response to water can vary for the material used.

MEMS techniques should be handled carefully, for the surface-to-volume ratio increases drastically as dimensions approach the micrometer levels. Measurement accuracy is lost when the increasing surface-to-volume ratio begins to degrade the signal-to-noise ratio. This problem occurs in most micro-fabricated devices. SAW devices have much higher frequencies. Since 3-D MEMS processing is unnecessary, SAW devices are cheaper. As with QCM devices, many polymer coatings are available. The differential devices can be quite sensitive. However, interface electronics require more complex electronics than those of conductivity sensors for both QCM and SAW sensors. Also, as the active membrane ages, resonance frequencies can drift and so must be detected for frequency by time. SAW devices are commercially available and sensitive to mass changes at the 1.0 pg level.

Pattern Recognition

Any e-nose’s primary task is to identify an odorant and perhaps measure its concentration. After the signal processing step comes the crucial step of pattern recognition: preprocessing, feature extraction, classification, and decision-making. A database of odors must be formed for comparison purposes.

Preprocessing accounts for sensor drifts and reduces sample-to-sample variation. This can be done by normalizing sensor response ranges, manipulating sensor baselines, and compressing sensor transients.

Feature extraction involves dimensionality reduction, a crucial step for statistical data analysis, since the database’s examples usually are subject to financial constraints. The higher dimensionality caused by sensor arrays is reduced to relevant pattern-recognition information and thus extracts only significant data. As most dimensions are correlated and dependent, it is better to reduce dimensionality to a few informative axes.

Feature extraction usually is accomplished by classical principal component analysis (PGA) or linear discriminant analysis (LDA). PCA is a linear transformation that finds the maximum variance projections and the most widely used technique for feature extraction. But as PCA ignores class labels, it is not an optimal technique for odor recognition.

LDA seeks to maximize the distance between class label examples and minimize the within distance, and thus is a more appropriate approach. LDA is also a linear transformation. For instance, LDA might better discriminate subtle but crucial odor projections, whereas PCA can remove the high variance random noise in a projection.(4)

The classification stage identifies odors. Classical classification techniques are KNN (k nearest neighbors), Bayesian classifiers, and ANN (artificial neural networks]. KNN with, say, 5 nearest points will find the 5 closest matches from the precompiled database. The closest match will be assigned as the tested material’s odorant class.

Bayesian classifiers first assign a posterior probability to the classes in the lower dimension and then pick the class that maximizes the predetermined probability distribution. ANN is closer to biological odor recognition. After being trained by the odor database, it is exposed to the unknown odorant in order to recognize the largest applicable response odorant class. The classifier estimates the class and places a confidence level on it.

In decision-making, risks and application-specific knowledge are considered in order to modify the classification. All decisions are reported-even a nonmatch.

Conclusion

As this article indicates, we can expect great progress in this area. And with each step forward, science and technology will continue to point toward the Greatest Artist’s most subtle designs and allow us to appreciate them better.

Footnotes

1. There are over 100 million receptor proteins of about 1,000 different types.
2. A human olfactory bulb contains approximately 2,000 glomeruli.
3. The terms “electronic nose” and “e-nose” are incorrect, for these devices cannot be considered “real” noses. The correct terminology should be “electronic arrays for chemical sensory and identification.” However, “e-nose” has gained wide acceptance in the literature since it first appeared during a 1991 NATO workshop in Reykjavik, Iceland.
4. Such nonlinear transformations as Sammon nonlinear maps and Kohonen self organizing maps also are used in feature extraction. These preserve the distance between pairs of examples when reducing dimensionality to 2 or 3.

References

• Baltes, Henry, Dirk Lange, and Andreas Koll. “The Electronic Nose in Lilliput.” IEEE Spectrum (Sept. 1998): 35-38.
• Barinaga, Marcia. “Salmon Follow Watery Odor Home.” Science 286 (22 Oct. 1999): 705-6.
• http://csmt.jpl.nasa.gov/enose.html.
• http://faculty.washington.edu/chudler/nosek.html.
• Malakoff, David. “Following the Scent of Avian Olfaction.” Science 286 (22 Oct. 1999): 704-5.
• Mamberts, Peter. “Seven-Transmembrane Proteins as Odorant and Chemosensory Receptors.” Science 286 (22 Oct. 1999): 707-10.
• Perkins, Sid. “Eau, Brother! Electronic Noses Provide a New Sense of the Future.” Science News 157 (19 Feb. 2000): 125-27.
• Schiffmann, Susan, and H. Troy Nagle. “The How and Why of Electronic Noses.” IEEE Spectrum (Sept. 1998): 22-32.
• Stern, Peter and Jean Marx. “Making Sense of Scents.” Science 286 (22 Oct. 1999): 703.
• Wolfgang, Gopel, and Tilo Weiss. “Design for Smelling.” IEEE Spectrum (Sept. 1998): 32-34.
• www.planetee.com/planetee/servlet/DisplayDocument?ArticleID=6899.
• www.sfn.org/briefings/smell.html.

I would like to focus briefly on the twentieth century in terms of technological innovations and their impact on the human soul. The Industrial Revolution radically changed our traditional lifestyle. Modern technology engendered many improvements in such areas as production and transportation. These changes were reflected in the literature and art of the period as well.

Views of Technology

In 1909, for instance, the Italian writer Marinetti published The Manifesto of Futurism, a great example of how intellectuals were affected by technology. He states that the world’s magnificence has been enriched by this new beauty, the beauty of speed: We stand on the last promontory of the centuries! Why should we look back? What we want is to break down the mysterious doors of the impossible. Time and space died yesterday. We already live in the absolute, because we have created eternal, omnipresent speed. We will destroy the museums, libraries, academies of every kind, will fight moralism, feminism, every opportunistic or utilitarian cowardice.(1)

This approach is very understandable, because its adherents assumed that modern technology would provide opportunities they had never experienced. The prospects of technology amazed them. But looking back, we see that technology shaped a new type of people who are dependent on machines. Producing tools and making money became cornerstones of modern life. These views threaten cultural values and traditional relationships among people who feel alone in these technologically separated environments. We ask: How much do machines dominate humanity, and why do people feel so deeply abandoned?

We can look at two perspectives from that period. The first is technology as a magical and wonderful creation, promoted by Marinetti and other futurists. The other is characterized by people like Charlie Chaplain who, in one of his movies, shows a worker who screws bolts every day as eventually starting to see everything as a bolt. This is the worst effect of twentieth-century technology: People have begun to feel like machines or parts of machines.

Do people need and deserve more than this? Of course, they do.

The latest version of modern technology is cyberspace, a place where people can find all sorts of information. Locating information and sharing experiences is easier than ever before. The Internet, for example, has become the information superhighway on which people can find almost everything. The Internet and other technological tools have helped create the expression being digital, which refers to people who use a lot of technology. Is this the illusion of technological globalization(2) or electronic democracy will be the end of participatory democracy?(3) Even though this digital medium provides a new source of information, we have not figured out how best to use it or what information to trust on it.

Issues

At this point, we must learn how to use modern technology and regulate information, because we cannot ignore them. These scientific and technological advances will play important roles in future developments. Science and technology in and of themselves are not the problem, nor have they ever been. The real problem is that science and technology are developed, deployed, and controlled by the predatory system of pancapitalism. The mainstream development of knowledge and technology is guided by increased efficiency in militarized production of violence and/or by potential corporate profits in civilian markets.(4)

There is another significant point here: Modern technology has been trying to create a cyberbody. In the future, scientists will be able to produce digital flesh to enhance our abilities. So here is the problem we have to solve: People who have these enhancements installed may begin to wonder if they are humans or robots. We already have seen that people can adjust their bodies in many ways: laser surgery to correct their vision, or synthetic material to replace their teeth.

Cyberfeminism focusing on women’s role in cyberculture is another interesting example of changing the human body. This already has caused some problems. The challenge here is rather how to combine the recognition of postmodern embodiment with resistance to relativism and a free fall into cynicism.(5)

Technology has limited privacy. When we are born, we get a birth certificate that quickly goes online. Educational files, social security files, insurance files, criminal files, consumption files, and so on are all in cyberspace. The Internet has become an on-line marketplace and is continuing to grow.

On the other hand, even though we are so connected, our social relationships with others have fallen apart. Every relationship between teachers and students, buyers and sellers, parents and children, for example, will be changed radically in the next few decades.

The most important question is how can we find a good balance that gives happiness and hope for both our bodies and our souls? We are not just bodies that need to eat, sleep, and rest, among other things; our souls must be nourished. In this technological age, this has led to a conflict”the crisis of modernity”between religious and metaphysical ideas. Nietzsche said that God was dead. Of course he was wrong, because he, like other philosophers, could not have realized that spiritual needs would become so important in modern times.

Today, we still are seeking for something to feed modern society’s spiritual hunger. We will have to find or build a way of thinking that will include metaphysical ideas, scientific innovations, and religious thought. After that, we will be able to put ourselves in a place where people can regulate their spiritual and physical needs. Otherwise, we will never feel that we are free

Footnotes

1 F. T. Marinetti, The Manifesto of Futurism, Le Figaro (February 20, 1909).

2 Steve Gibson, www.kk.kau.se/mct/MCTO199/steve/ right.html.

3 An Interview with Paul Virilio, www.nettime.org/ nettime.w3archive/199904/msgn00456.html.

4 Critical Arts Ensemble Staff, Critical Art Ensemble, The Flesh Machine: Cyborgs, Designer Babies, and New Eugenic Consciousness (Autonomedia: 1998), 7-8.

5 Rosi Braidotti, Cyberfeminism with a Difference, www.let.ruu.nl/womens_studies/library.html.Other Negative Effects The majority of electronic media content, especially TV programming, contributes to materialism and consumerism. Material well-being and possessions are viewed as lifes greatest values. The AAP labels child-directed advertisement as inherently deceptive and exploitive. Numerous studies conclude that children under the age of approximately 8 cannot understand the intent of advertisements. This vulnerability leads them to accept such advertisements as true,(11) which leads to unnecessary spending in some families and to childrens keen disappointment in others. Part of the reason for the Wests decreasing spirituality may be attributed to increased materialism via electronic media programming. The electronic media contributes markedly to obesity by displacing many more active alternative activities. Advertising also is a factor, as many of food advertisements are for unhealthy products. In particular, child-directed toy and food commercials may result in increased conflict between parents and children because of the parents inability or un-willingness to meet the childs demands. Most electronic media content glamorizes and normalizes alcohol, tobacco, and drug usage. The implicit message usually associates these substances with fun, prestige, humor, and excitement. But their negative consequences are usually depicted rather poorly or not at all. When Sweden banned alcohol advertising on TV in the mid-1970s, alcohol consumption decreased by 20 percent. If this was the result with a clearly stated message, we can expect the effect on an implicitly stated message to be even more dramatic. The implicit message concerning sexuality is roughly the same: Everybody, especially the young, is sexually active. There is nothing to worry about. The drawbacks and consequences of such depictions are rarely, if ever, mentioned. Abstinence is either not presented or is portrayed negatively. Another concern is the medias provision of ready-to-use gender, occupational, race, religious, and other stereotypes. Many viewers accept these passively and then generalize them. The impact is much greater on children than adults. Finally, the electronic media affects school and job performance. If we consider the people we know, we would find that academically or professionally successful people rarely invest much time in the electronic media. Similarly, many heavy users have accomplished nothing significant at school or on the job. Recent studies have pointed out that more than 1 to 2 hours per day of TV viewing has an adverse effect on academic performance, especially a childs reading and comprehension scores.(13) As we read in Drabman and Thomas: A socially interactive environment that stimulates curiosity and exploration enhances the development of an effective brain. Thus, excessive childhood involvement with electronic media that limit social interaction could hinder the development of a brains social system.(14) Heavy electronic media viewing might lead to attention deficit disorder (ADD) or a decreased attention span. A person with ADD cannot concentrate on any task for long, and so does not acquire the necessary persistence required both at school and at work to achieve something. Such children also may become accustomed to learning through visual images. But learning at school is primarily verbal, via teacher lectures, and contains few images. Thus they may be unable to learn as much, for this is not the way they have learned to comprehend. The impact also is seen in ones imagination, which may be considered a precursor for creativity. Carlsson-Paige and Levin conclude that before TV, children usually made up their own war-play themes. Today, most of it comes from imitating electronic media content.(15) Such imitative, in lieu of imaginative, play impairs the proper development of childrens cognitive systems. Media Literacy or Media Education One rather radical solution to counteract these negative effects is to remove all electronic media from our lives. However, this is not a realistic option for those with children. Electronic media has the potential to enhance peoples, especially childrens, knowledge, experience, and perception. Isolating children from its harmful effects is impossible, for they will be exposed thorough their school and friends. Such isolation may have an even more adverse effect. A more elaborate and sensible alternative is to improve critical electronic media usage skills through media education or literacy. Such strategies can be defined as eliminating negative effects while taking advantage of its benefits by educating children, adolescents, and adults. According to the AAP, a media-literate person should understand that(16): All media messages are constructions produced by people to be viewed Media messages shape our understanding of the world People interpret media messages uniquely Electronic and mass media have powerful economic implications. People can become more media literate if they: Get involved in sports, camping, hiking, reading, and other non-media activities. Provide immediate and elaborate content-related explanations to children and adolescents via content interpretation and explanation Ban all violent, offensive, and indecent electronic media content, including non-educational video games and cartoons Restrict electronic media usage to those with high educational content Have one TV per house Put the TV and other electronic media in the houses less-prominent areas Keep TVs, computers, video games, and so on out of childrens rooms Do not use the electronic media, especially TV, to babysit, punish, or reward Turn off all electronic media during meals, when most family interaction occurs Do not fight boredom by using more electronic media, for if directed properly, boredom may lead to creativity Prepare a weekly schedule of programs to watch Keep children under 2 years old away from the TV and other electronic media, for such children require a great deal of interaction for healthy brain growth and the development of appropriate social, emotional, and cognitive skills. For older children, limit it to 1 to 2 hours. Conclusion The electronic media has potential benefits. However, it also has negative, harmful effects, especially on children. As it cannot be banished, both parents and children should become media literate. Rather than waiting until unacceptable behavioral patterns are learned and then dedicating substantial resources to cope with them, it is far better to redirect efforts and resources toward early prevention programs, particularly for children and adolescents Footnotes 1 This is the American Academy of Pediatricss definition. 2 Judith Van Evra, Television and Child Development, Children, Youth, and Family Consortium (CYFC), (1990). 3 Pediatrics: Policy Statement on Impact of Music Lyrics and Music Videos on Children and Youth, American Academy of Pediatrics 98, no. 6 (December 1996): 1219-21. 4 Said Nursi, Letters: Seeds of Reality (Turkey: Sozler Nesriyat, 1994), 545. 5 Victor C. Strasburger, Children, Adolescents, and the Media: Five Crucial Issues, Adolescent Medicine: State of the Art Reviews 4, no. 3 (October 1993); Van Evra, Television and Child Development. 6 R. S. Drabman and M. H. Thomas, Does TV Violence Breed Indifference? Journal of Communication 25, no. 4 (1975): 86-89. 7 R. Sylwester, The Effects of Electronic Media on the Developing Brain, Media Literacy Online Project (College of Education, University of Oregon: 1994). 8 Surgeon Generals Scientific Advisory Committee on Television and Social Behavior, Television and Growing Up: The Impact of Televised Violence, Report to the Surgeon General, United States Public Health Service (Washington, DC: US Government Printing Office, 1972); D. Pearl, Television and Behavior: Ten Years of Scientific Progress and Implications for the Eighties, US Department of Health and Human Services, Publication No. ADM 82-1195, vol. 1, (Washington, DC: US Government Printing Office 1982); A. C. Huston et al., Big World, Small Screen: The Role of Television in American Society (Lincoln, NE: University of Nebraska Press, 1992). This book is the APA Task Forces report on television in society. 9 C. Anderson, Video Games and Aggressive Thoughts, Feelings, and Behavior in the Laboratory and in Life, Journal of Personality and Social Psychology 78, no. 4 (April 2000): 772-90. 10 C. Kalin, Television, Violence, and Children (M.Sc. Synthesis Paper, College of Education, University of Oregon, 1997). 11 Pediatrics: Policy Statement on Children, Adolescents and Advertising, American Academy of Pediatrics (February 1995); Surgeon Generals Scientific Advisory Committee, Television and Growing Up. 12 In the context of this article, spirituality is defined as implementing the requirements of religious orders in ones life. For instance, the size of the Sunday service congregations has been declining for several decades. 13 Victor C. Strasburger, Does Television Affect Learning and School Performance? Pediatrician 38 (1986): 141-47; M. Morgan, Television and School Performance, Adolescent Medicine: State of the Art Reviews 4 (1993): 607-22. 14 Drabman and Thomas, Does TV Violence Breed Indifference? 86-89. 15 Huston et al., Big World, Small Screen. 16 Pediatrics: Policy Statement on Media Education, American Academy of Pediatrics 104, no. 2 (August 1999): 341-43.

– Moive Review

Science Fiction/Fantasy and Action/Adventure

Rated R for sci-fi violence and language

Starring: Keanu Reeves, Laurence Fishburne, Carrie-Anne Moss, Hugo Weaving, Joe Pantoliano

Directed by: The Wachowsky Brothers

Produced by: Andrew Mason and Joel Silver

Written by: Andy Wachowski and Larry Wachowski

Distributor: Warner Brothers

In the year 1999. To be more precise, people believe it is the Year 1999. In facts we are well into the middle of the twenty-first century. In addition, this is not the only reality concealed from us. The “creators” of artificial intelligence were caught unprepared while they were drunk on the extent of their accomplishments. There has been a great revolution-machine revolted against humanity and conquered life. Now we do not even have a system about whose corruptness and shortcomings we can complain. Yet we continue to work from 8 a.m. to 5 p.m. in our daily shifts, eat hamburgers while watching television, and attend parties. Children are still being born, and the sun still rises and sets.

However, none of this really exists, for only the “Matrix” exists. This “Matrix” is the name of a dream from which we cannot awake. It also is a three-dimensional curtain pulled between reality and humanity. With your fork-actually your fork does not exist either-you can still feel the taste of a nonexistent slice of meat. Tiredness, disappointment, and sorrow are all possible, along with the signals they send to your brain, most of which they already own.

Unless you believe “ignorance is a virtue,” like someone who realizes the difficulty of “knowing” does after he or she has known, you would like to learn. Yet, you also realize immediately that knowing this particular truth does not exalt you. This is neither an auto-criticism nor a suggested solution, but rather a knowledge that you will not be able to relate to others with extravagant praise or mention in every meeting or social gathering.

In fact, you would prefer not to know it at all: Matrix is the name of a computer program that is animated as if it is “life.” In reality, our bodies are connected to metal basins, and cables of various sizes are plugged into us. Our life lasts only as long as (the lifetime of the “battery.” We are planted on electronic fields, harvested and fed “until we exhaust” the battery. We are walking around with large plap-ins,which provide our connection with the machine, located at the back of our heads. Only those few who were born naturally have seen the world in which real parents exist, known in the movie as “Zion,” and do not have plug-ins. Zion is the only place that the electronic barbarians cannot enter, which is why the ruthless guards of the Matrix are trying so hard to find its coordinates.

THE CHOSEN MAN

Thomas Anderson is a computer geek who works for a software company during the day and spends his nights as a computer hacker known as “Neo.” There is a truth that he has been trying to find for a long time: Is his life somehow being controlled? He is after “Morpheus,” whose name is usually uttered as if he were a terrorist. Neo feels that this man is somehow connected to his problems and can provide him some answers. Morpheus gets in touch with Neo through his assistant “Trinity.”

When they finally meet, Morpheus promises to show Neo “the truth,” of which even minute parts are invaluable. Now, faith is the power that reality cannot deny. Neglecting humanity’s fragile nature, men and women built the Machine and will defeat it to the extent that they can free their thoughts from it. Is Neo the awaited savior? If so, what will he promise to humanity? Unless they are killed at the instant they “awaken,” will he promise the underground breakfasts consisting of mossy oats at best? In place of a joyful but unreal world, can he promise a dark but real world?

ELECTRONIC SCIENCE FICTION

Finally, a science fiction movie that can be viewed with enjoyment and suspense, one that is graded “A” despite its shortcomings. In The Matrix, the dose of excitement, long and technical dialogues, and contrasts are properly blended. The fighting scenes, modeled after Asian action movies and modernized in a computer environment, have been transformed into a public demonstration by the aesthetic style of the Wachowsky brothers. They do not hesitate to use such scenes, for they know that even viewers who do not like such action and fighting scenes will appreciate the results. With cameras that can shoot 12,000 clips per second, with actors seemingly almost independent of gravity, these fighting scenes seem like dances conforming to the movie’s theme, rather than brutal fights.

The movie moves smoothly between prologue and awakening, development and meeting, result and struggle, and conclusion. Among the cool, black-clad men and women with sunglasses, Reeves, Fishburne, and Moss have peculiar facial expressions. But the movie itself has a power beyond its individual components. One example of this is how the camera approaches objects: In one scene, the camera is located right under the helicopter and window from which a gun is being fired. Both action areas can be seen, yet the focus is on cartridges seemingly suspended in the air and then gradually gliding to the ground

As a matter of fact, the question: “Seeing that this electronic mechanism fools man and condemns him to a virtual life, to a dream from which awakening is impossible, could not man be deceived by a better view of 1999 rather than the present one?” is answered before long. Agent Smith accidentally lets the cat out of the bag when he has cornered Morpheus: “We wished a better world for man, but man defines his essence with such misery and sorrow that these designs were rejected by human conscious in the experiments.”

The martial-art figures borrowed from Asia give the impression that this struggle to awaken humanity carries a deeper philosophy, yet only in the movie’s second half is this suspicion confirmed. But it is impossible not to notice the symbolic supports of the Bible and Greek mythology, which are layered one inside the other and pervade the movie’s life and imagery. The relationship of “Trinity” to the Bible is self-evident. Moreover, “Neo” (like his name, he also is “new”) ascends to his own “reality” under the protective wings of “Morpheus” (the Greek god of dreams), who heals the mental and physical harm caused by switching from one world to another. Trinity Morpheus, and Neo form a sacred trio who know the “truth” and partially own the mechanism to alter it. They are striving to benefit a humanity corrupted by its own faults, while at the same time being fully aware that they really do not have more than just their belief. Until he experiments with the limits of his powers to learn if he is the “Chosen One” or not, Neo continues to learn. A female soothsayer wants him to sacrifice himself. After all, is there any other savior for humanity, who became arrogant because of its accomplishments but lost the struggle against evil forces and was enslaved, other than a “Chosen One”?

A BROTHER TO LEM

I do not know how much of The Matrix is inspired by the science fiction work of Polish author Stanislaw Lem. But the theme of living in a fake world as if alive, which came to the public agenda with such books as Strangers by Day (by Vicki Malones, 1984) and movies as Dark City (written by Frank Lauria, 1998, the movie version released on February 27, 1998), or the theme of an existing dark reality contrary to the present make-believe world-in other words the theme of illusion-simulation-is not so new.

The Matrix’s story-line bears a considerable resemblance to a book written in the 1970s by Lem, who is considered to be the genius of science fiction. But rather than eulogies, Lem delicately criticizes science. He foresaw humanity’s misfortunes and degeneration years ago. He touches on the results of inventions and discoveries in his future tableaus, rather than becoming carelessly intoxicated by them, and analyzes our greed and inordinate desires via scientific diagnoses and terms. Lem fictionalizes a virtual world similar to The Matrix in his 1974 novel The Futurological Congress.

The story goes like this: After a space voyage, Ijon Tichy finds himself in an advanced twenty-first century civilization. He tries to understand the age in which he lives and what he missed while asleep in the shuttle. In this new age, people can assume any temperament they want via chemical stimulants, store in their brains any information they want to by means of drugs, torment those they hate in their virtual worlds, travel, and participate in any virtual fantasy. In this “democracy,” such serious social problems as prejudice and racial discrimination are solved by chemicals. Opportunities are endless. There are firms to decide things for you, fight your fights, even to satisfy your religious sentiments. In short, this society has an ultra-free market economy.

Ijon comes across a Professor Trottelreiner, whom he had known long ago and who was sent to sleep in a spaceship like himself. He shows Ijon more than he wants to know by giving him a bottle of fragrance to smell. The scent emitted from the bottle shows reality to Ijon. The eye-catching restaurant coated with Italian tile, and the palm trees are transformed into a coarse underground shelter. The pheasant they are eating is, in fact, a porridge that has a grayish-brown vomit-like color, because the last pheasant died 25 years ago. The palm tree is really the rubber underwear of the man living in the upper shelf, which in reality is too narrow. People inhabit an incredibly overcrowded world, and forks and knives are made of tin.

Worse than that, Ijon understands why people are always red and out of breath: There are no elevators, so people reach the ninth and tenth floors by climbing up elevator cords. The chemical empire has already started to transform them, for most people now have stained and discolored skins, longer ears, and scaly backs. All seen images and used chemicals conceal the already demolished system of the planet, on which more than 20 billion people live. The air we breathe is full of camouflage mascots, reality is hidden under layers of chemical products, and humanity is rescued superficially from the reality of poverty and misery!

The Matrix is a movie that should be seen more than once. The Wachowsky brothers took into consideration not only aesthetic styles, but also commercial worries by meeting the expectations of an average sci-fi viewer and then combining both issues on the same platform. After the Coen and Taviani brothers, it is possible to say that the Wachowsky brothers, who managed to attract interest with their previous movie Bound, have opened a respected room in the cinema for themselves with The Matrix. We can only hope that the sequels, already rumored to be coming soon, will be just as good.

The best side of the movie is the Matrix paranoia itself, which is even scary to say. The Matrix gains importance when the uncontrolled life is faced with the reality of existence, the purpose of which is almost forgotten. It gains importance by becoming the new name for alienation, enslavement, and enumeration. Everything is assigned a number, including people. Our identification and accomplishments, everything we do, is specified with statistics and numbers, which have more value than the individual in the twenty-first century.

Since the mid-1980s, there has been increasing interest in developing so-called “electronic noses” (e-noses), that is, electronic instruments that can detect and recognize simple and complex odors.1 And since the mid-1990s, nearly 20 years after the concept was originally published, the commercialization of e-noses has started to take place. The main reasons for this delay were the complex nature of the problem and the need for advanced technologies. However, the recent development of microsensor technology has led to low-cost integrated chemical sensors and application-specific microprocessing devices. This, coupled with our greater understanding of artificial intelligence, has allowed us to construct electronic instruments that perform in a manner similar to our own olfactory system.

E-noses are now being developed as systems for the automated detection and classification of odors, vapors, and gases. They are generally composed of a chemical sensing system (e.g., sensor array or spectrometer) and a pattern recognition system, such as an artificial neural network (ANN). At Pacific Northwest National Laboratory (PNNL), e-noses use ANN technology for the automated identification of volatile chemicals used in environmental and medical applications.2

The electronic nose works as follows. While a chemical vapor or odor is blown over a sensor array, sensor signals are digitized and fed into a computer. The ANN (implemented in software) then identifies the chemical. The benefits of e-noses include compactness, portability, real-time analysis, and automation.

FOOD INDUSTRY APPLICATIONS

Currently, the largest market for e-noses is the food industry. In some instances, e-noses can augment or replace panels of human experts and can reduce the amount of analytical chemistry performed in food production, especially when only qualitative results will do.

An electronic smelling device is a valuable tool for analyzing whether a product has gone bad. Potential applications of e-noses in the food industry are numerous: inspecting and grading food quality by odor; inspecting fish and beverage containers; controlling fermentation, automated flavoring, and microwave cooking; monitoring the ripening of cheese; verifying if orange juice is natural and/or fresh; testing plastic wrap for containing the odor of onions; and classifying grains and blueberry ripeness.

Using human odor panels to evaluate and control the quality of raw materials or finished products is extremely labor intensive, time consuming, expensive, and error prone. E-noses can quickly identify a characteristic odor classified as “good” or “bad” by the odor panel, thereby decreasing the workload, improving throughput, and reducing the cost of screening many samples at different stages of the manufacturing process. The system is applied easily to the manufacture and quality control of perfumes, cosmetics, and fine chemicals, as well as to packaging, monitoring environmental quality, the automotive industry, medical and diagnostic matters, and microbial classification.

ENVIRONMENTAL MONITORING

The PNNL is exploring the technologies required to perform cost-effective environmental restoration and waste management. This effort includes developing portable, inexpensive systems that can identify contaminants in the field in real time. Environmental applications of e-noses include identifying toxic wastes and household odors; analyzing fuel mixtures; detecting oil leaks; monitoring air quality, factory emissions, and hazardous chemicals; and testing ground water for odors.

MEDICAL APPLICATIONS

Since the sense of smell is important for physicians, an e-nose can be used as a diagnostic tool to examine bodily odors (e.g., breath, wounds, bodily fluids, etc.) and identify possible problems. Odors in the breath can indicate gastrointestinal, sinus, and liver problems, as well as infections and diabetes. Infected wounds and tissues emit distinctive odors, and odors coming from such bodily fluids as blood and urine can indicate liver and bladder problems. Currently, an e-nose for examining wound-related infections is being tested at South Manchester University Hospital.

In similar applications, ANNs have been used to track glucose levels in diabetics, determine ion levels in bodily fluids, and detect such pathological conditions as tuberculosis.

While the inclusion of visual, aural, and tactile senses into telepresent systems is widespread, the sense of smell has been largely ignored. PNNL recently proposed a more futuristic application of e-noses for telesurgery. In this application, an e-nose would identify odors in a remote surgical environment. These identified odors then would be transmitted electronically to another site, where an odor generation system would recreate them.

The next decade should see the cost of e-noses fall dramatically, with the result that they will be used not only in industry but also in everyday life. They can be used, for example, to detect tainted foods in the refrigerator, ensure clean clothes in the washing machine, detect poor air quality in the car, and perhaps even help us monitor our own health.

FOOTNOTES

1. J. W. Gardner and P. N. Bartlett, Electronic Noses (Oxford, UK: Oxford University Press, 1999).
2. http://www.ivanhoe.com/docs/backissues/electronicnose.html.

To chemically identify substances, scientists around the world are trying to develop artificial taste sensors that mimic the human tongue. Recently researchers at the University of Texas in Austin have developed an electronic sensor that has the potential to detect taste as well as to identify the chemicals of any substances.1 It has uses for food and beverage development as well as medical applications.

Besides the tongue, an electronic nose has also recently been developed to mimic the sense of smell, but it can only detect volatile molecules in the air. Since many chemicals of interest, such as those in food and beverages, are not easily transported into vapor phase, there needs to be a way of detecting a combination of them in solution, such as the electronic tongue.

A team of engineers and chemists in Austin has come up with a prototype of the artificial tongue which resembles the mammalian tongue in some ways. The surface of the human tongue contains cavities which hold chemical receptors known as taste buds. The artificial tongue consists of an array of tiny chemical sensors on a square-centimeter chip. The sensors are actually polymer microbeads placed inside micromachined wells on a silicon wafer which mimics real taste buds on a human tongue. Each bead responds to specific conditions (for example, high acidity or charged ions). A special camera records those colors, which the researchers can then monitor on a computer.

One obvious application of the electronic tongue is in the rapid testing of new foods and beverages; the results could be quickly compared with databases of known popular consumer tastes. When developed further, the electronic tongue should be able to analyze chemical processing streams, biological fluids and other complex mixtures without exposing human beings to possibly harmful substances such as antigens, toxins, and bacteria. For the tasting of ice cream, though, we will likely continue to use our own tongues.

FOOTNOTES

• J.J. Lavigne, S. Savoy, M.B. Clevenger, J.E. Ritchic, B. McDoniel, S.J. Yoo, E.V.
• Ansyln, J. T. McDevitt, J. B. Shear and D. Neikirk, J. Am. Chem. Soc., 1998, 120, 6429-6430.
• See also R. Dagani, Chem. & Eng. News, June 29, 1998, 12.