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The idea of incorporating the acute sensitivity of the human nose in an instrument for measuring and identifying smells has the commercial allure of an expensive fragrance. Such a device could monitor manufacturing processes, track pollution, even sniff out contraband drugs and explosives.
For nearly a decade, a group of companies has been hotly pursuing that scent. Almost all the developers of artificial noses have tried to duplicate the sense of smell by combining biochemical coatings with silicon chips to produce arrays of sensors to detect the various components that make up an aromA: But the success of these so-called eNoses has been limited by their sheer complexity: To work well, they require enormous numbers of individual sensors to discern the thousands of aromatic hydrocarbons that waft through our noses every day.
One inventor, Edward J. Staples, took a radically different approach. He developed a device that can characterize virtually any smell -- with only one sensor. Its method of detection? Sound. At the heart of the instrument is a quartz crystal that vibrates in response to an electrical current, just like those that count the seconds in a typical wrist watches.
TIMED RESPONSE. It works like this: The chemical constituents of a sample separate as they travel along a specially coated tube. Each substance alters the vibration of the crystal as it passes over the sensor. By measuring the time required for each chemical to reach the sensor and the amount it effects the crystal's vibration, both the identity of the substance and the quantity in which it is present can be calculated by software incorporated in the instrument. The entire process takes only 10 seconds.
Staples, who calls his device the zNose, began his career as a research scientist in the R&D laboratories of Texas Instruments and Rockwell International. In 1983, he and two business associates formed a California research corporation they called Amerasia Technology (AMT). It was there that ZNose technology was eventually invented and patented. These days Staples is managing director of Electronic Sensor Technology. The company, based in Newbury Park, Calif., was set up in 1995 with support from private investors to commercialize products based on research at AMT.
In early December, Staples presented a report on the development of the zNose at an annual meeting of the Acoustics Society of AmericA: He also found time to discuss his invention with Business Week Online contributing Science & Technology Correspondent, Alan Hall. Here are edited excerpts of their conversation:
Q: There seems to be a great deal of interest in creating an artificial nose. Why?
A: For the first time, it will allow researchers and quality-control engineers to measure the chemistry of vapors in near real time. We are surrounded by hydrocarbons that our noses sense as "smells." The ability to identify and quantify them has an almost infinite number of applications.
Q: Aren't other companies also making instruments that can measure the components of smells?
A: More than 13 companies, which include Agilent and Perkin Elmer, have attempted to produce instruments -- but their approach is based upon arrays of sensors that simulate the biological sensors in our nose membranes. These electronic, or eNoses, are limited by the number of sensors they contain, and none can both identify the chemical and also measure its quantity.
Q: What is different about the zNose?
A: The zNose is a big departure from other technologies. The zNose can separate and measure the concentration of each chemical in an aromatic product, or the ingredients of that product, in about 10 seconds. Because it is based on a single acoustical sensor, it can be calibrated to detect virtually any hydrocarbon, even if they are only present in concentrations of parts per trillion. Because zNose can also calculate the amount of a chemical, it is the only instrument approved by the Environmental Protection Agency.
Q: Does that indicate that it's superior to the human nose?
A: The answer depends on the intent. Humans cannot quantify or speciate chemicals, but they do give perceptions, which instruments do not. Also humans do not smell everything equally, and sometimes they cannot smell hazardous chemicals at all. Humans can get colds and are not very reliable. For quantification of the chemicals in a fragrance or vapor, the instrument is far superior.
In some industries, like foods and beverages, the human nose determines the ultimate acceptance of the product. Smell and taste panels are used extensively as the judge. In these industries, the human nose can never be replaced, however, the zNose becomes simply another member of the taste panel with the ability to quantify the ambiguous human perceptions.
Q: What are the major applications for artificial noses?
A: The largest is quality control in the food-and-beverage industry. For example wineries and breweries are now using the zNose to monitor quality. We recently matched the zNose against human experts in detecting a taint in wine known as corkiness. The culprit is a chemical called TCA, which smells like musty newspapers. Even the tiniest amount can destroy a good bottle of wine. We tested wines judged by California wine experts to contain TCA contamination. We could measure the concentration of TCA in every case, in amounts consistent with the threshold for a human experts nose -- between 5 and 10 parts per trillion.
Q: Doesn't an instrument that sensitive produce a mind-boggling amount of data? How do quality-control technicians cope with the flood of information?
A: We have developed something we call VaporPrint images. These are olfactory images unique for particular smells, and humans can recognize them quite easily. To demonstrate, we made images of 12 different Campbell's soups. Each generates a unique and easily recognizable image. In effect, we have transferred the olfactory response to a visual human response. Even if you cannot smell, you can recognize visual images.
Q: What other industries are using zNoses?
A: There are many others including pharmaceutical, chemical-process control, environmental, and even medical. It can detect environmental pollutants in air, water, and soils. Chemical industries, like plastics, can monitor the quality of plastic packages based upon the chemical vapors they produce. I like to speculate that in 10 years, every doctor's examination room will have a zNose to probe the chemicals emitted from wounds, tumors, cancers, and infectious diseases of the body.
Q: Have you estimated the size of the potential market?
A: The market for an artificial nose which only replicates the human response is small. Current eNose companies, which have been around for about eight years, are not doing well, and suggest their market is $25 million in yearly sales. But we believe the market for a quantitative instrument suitable for quality control is in the billions.
Q: A small company like yours will need some real marketing muscle to make inroads into a market that size.
A: We are currently offering a private placement, and we hope to go public next year. Our company has just completed negotiations of an OEM [original equipment manufacturer] contract with Hitachi in Japan. Under the terms of the contract, Hitachi will distribute and market zNose technology exclusively in Japan under its own label. Also, negotiations are under way with several major companies in Europe.
Q: Where is zNose technology headed?
A: zNose technology will merge with other electronic technologies. For example, the zNose has been integrated with global positioning satellite receivers for remote operation. This means every time you capture the chemical signature of an odor and measure the concentrations, you also link the result to a time, latitude, longitude, and altitude. The data can be entered directly into mapping software showing the location on local maps down to streets and even addresses. Also, we can now operate the zNose over the Internet in real time. I could literally see smells from around the world.
Q: As an inventor, what do you find most gratifying?
A: The most exciting thing to me is how our customers are talking. A favorite expression we hear is that zNose gives them "one eye in the kingdom of the blind." Organic chemists say they are fascinated by the ability to now see, and measure, the chemistry of odors and fragrances that surround us.
With volume will come economies of scale, and ultimately, even consumers may have the opportunity to own a zNose. Just pause and reflect the next time you use your nose at home to assess the status of a dish cooking in the oven, or when you smell the milk to see if it's sour before you pour it on your breakfast cereal.
Copyright 2000, by The McGraw-Hill Companies Inc. All rights reserved.
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