Okay, I’ll admit this blew my mind, so I had to write about it, even though, as in the previous entry, I’m introducing a situation in which biology stands in direct competition with our much beloved e-nose.  Watch the video above and I promise, you will see “one of nature’s most sensitive detection platforms” in action — the honeybee!  Honeybee antennae have sensitivity thresholds of parts per trillion, comparable with dogs!

Can you believe this?  Scientists at the Los Alamos National Laboratory actually trained honeybees to detect explosives!  The bees are strapped inside specially prepared harnesses (yes, it gets stranger), trained to produce a conditioned response (they stick out their tongues upon contacting the substance in question), and then positioned inside a detection device which monitors the little guys for any display of their conditioned response!  With applications for detecting everything from illegal drugs to explosives, honeybees might actually become the weapon of choice in the detection game!

But wait!  The e-nose is not out of this fight!  Why would an electronic nose be a better option than honeybees?!  Well, for one thing, you have to train the bees for each new substance!  Thus, an e-nose would easily seem to outperform honeybees in terms of the range of substances that could be programmed for detection.  Each new substance has to be conditioned into the bees, whereas with an e-nose you just add the new substance into the machine’s parameters!  Certainly, with just this one example, the e-nose is proven a faster, more efficient means of detecting a wider variety of substances!

Such flexibility is definitely one reason why e-noses will eventually replace dogs and/or bees.  Indeed, any biological system would be slowed down by the necessity for training, whereas the upfront R&D for the e-nose is a one-time-only training cost that can’t be beat in terms of efficiency.

Ha ha ha.  The eternal battle between humans and machines seems to extend even to the realm of e-noses, judging by this article about water quality in The Los Angeles Times.

It seems that even finely tuned equipment can’t always discern the subtle qualities of taste that make for an aesthetically pleasing experience at the water fountain…

In fact, the Metropolitan Water District of Southern California employs a special flavor profile analysis panel to gauge the taste of their treated water.  Panelists receive a year of training and don’t even wear any perfume or aftershave while ‘on call.’  Between cleansing their palates with unsalted crackers and mineral water, the panelists check samples of the District’s outgoing tap water for any unusual odors or tastes, and then rate the offensive characteristic on a scale from 1 to 3.  Problems like blue-green algae can lend a distinctive, musty taste to even the most thoroughly treated water.  While such irregularities pose no health risk, water officials are constantly aiming to produce the ideal water — tasteless, odorless, even bland — yet still refreshing.

So why not use e-noses for this job?

“A lot of times there are off-flavors and odors that our equipment can’t detect.  No matter how complex our instrumentation, the [human] nose is better,” said Bart Koch, the head of Metro Water District’s water lab.

Will e-noses ever outperform the human nose?  As I pointed out last October, all kinds of advances in e-nose technology are in the works, but it seems that communication is the real issue here.  Until someone can invent a translator so the e-nose can rate a ‘chalky’ taste on a scale from 1 to 3, the noses on the flavor profile analysis panel will remain entirely human!

The other day, I noticed a short “shout out” to the e-nose online at exploratorium.edu.  Nothing major, but pretty cool, nonetheless.  Apparently, in 2001 (ancient, by e-nose technology standards), scientists wanted to determine what Antarctica smells like, hence the e-nose.

Once they climbed the rim of the active crater on Mt. Erebus, Geophysicist Jessie Crain unpacked her e-nose, basically a pump-driven air filter, to sniff a plume of sulfuric volcanic gas.  Her intent was to collect radioactive particles and to determine the origin of the volcano’s lava.

If you visit the link, be sure to enlarge the image of Crain’s bionic nose.  It looks pretty primitive by today’s standards, since e-noses are increasingly starting to resemble the sleek hardware seen in science fiction films.

Everyone is familiar with the concept of a fingerprint, but it turns out that our bodies also emit a signature odor.  As reported by Andrea Thompson yesterday on livescience.com, this odor remains largely unaffected by diet.

Referred to as odortypes, these specific body odors are genetically determined, and are characteristic of mammals.  Apparently, gene makeup in a genomic region known as the major histocompatibility complex (MHC) is largely responsible for determing an individual mammal’s unique odortype.

Voltaile organic compounds, which we’ve written about several times on this blog, are released when we sweat, and these VOCs carry with them odortype information that is specific to each of us. 

To test the theory of how much impact food choice has on body odor, researchers at Philadelphia’s Monell Chemical Senses Center trained “sensor” mice to detect differences between test mice with differing MHC genes and diets. The results indicate that these genetic odortypes remain consistent even with a changing diet.  Dietary changes did affect the odor profiles, but both the sensor mice and additional chemical analysis were able to detect the basic odortype profile unique to each mouse. 

Gary Beauchamp, a behavioral biologist at Monell, had this to say: “The findings using this animal model support the proposition that body odors provide a consistent ‘odorprint’ analogous to a fingerprint or DNA sample.” 

Essentailly, this means that e-noses can also be used to identify individuals by detecting thier biological odorprints. 

Last week’s Reuters featured a report by Alastair Sharp about the addition of $320 million from the U.S. towards combating avian flu. With this increase in funds came a clear message: the world must not grow complacent in it’s fight against the virus, for fear of facing a serious epidemic. These extra funds bring the total of North America’s aid to $949 million.

Since 2003, avian influenza has been responsible for 245 deaths in Asia, Africa, and Europe. In the event of a large-scale outbreak, over 70 million global deaths are estimated. Furthermore, the cost of combating such an epidemic would total $3 trillion and cause a 5 percent decline in world gross domestic product.

Paula Dobriansky, Under Secretary of State for Democracy and Global Affairs, had the following words of caution: “(There is) a growing feeling that the threat of an influenza pandemic has somehow diminished and that scarce resources could be better used elsewhere in the field of public health, in other words flu fatigue.”

Europe’s estimated 2009 contributions total around 140 million euros ($176.2 million), for an overall total of 413 million euros.

This is a step in the right direction from the U.S. Hopefully, other countries will follow suit. A new generation of e-noses is right around the corner, and they will likely prove a valuable resource in helping sniff out threats like avian influenza.

Today’s post is similar to last month’s post about  the role of zNoses in testing wine.  India is a culture that knows its tea, so it’s not surprising that the United Planters Association of Southern India (UPASI) has enlisted the e-nose to help it monitor tea leaf quality. 

The move comes in response to recent crises within India’s tea industry, largely due to poor quality tea.  The UPASI Tea Research Foundation entrusted the Center for Development of Advanced Computing to develop an “electronic tongue” for quality assurance testing.  The result?  A promising prototype unveiled at a workshop in Kolkata, India.

One cool aspect of this tea tongue is its ability to be trained by tea planters and tasters, thanks to an uncommonly flexible software setup. 

This tea-centric e-nose monitors unstable emission patterns during the fermentation process, detecting subtle odor changes.  Essentially, quality control teams can monitor the tea during the manufacturing process, a previously impossible feat.  This means that e-noses can help companies correct or avoid problems at their very inception, instead of having to discard inferior tea afterwords. 

Tea weenies of the world, rejoice!

An article from a a few years back about an Australian e-nose company raised a few interesting points worth discussing.

With much of this blog’s focus on threat detection,  disease monitoring, and food safety, the issue of air quality, and how it is negatively affected by large industries, hasn’t received a lot of attention.

This article suggests that e-noses can play a vital part in helping industries monitor the quality of the air in and around their buildings and factories, thus sparing nearby communities from unnecessary olfactory discomfort.

Whether the industry is organic farming, sewage and waste treatment plants, chemical plants, or even local traffic, the presence of unpleasant odors from air pollution is all too common.

Many such industries spend millions of dollars each year responding to public complaints about bothersome odors and unclean air: assigning specialists to investigate the complaint, documenting their findings, paying legal fees, and complying with EPA regulations are but a few of the potential financial hits companies can expect to take.  Considered on a national level, these fees approach the billions; globally, they approach the trillions.

Where clean air is concerned, it is of course vital to enforce corporate accountability.  E-noses will make it far easier for companies to police themselves, so that they detect problems before the EPA need intervene.

For example, according to the article, in Australia, the current method for identifying and evaluating a potentially problematic environmental odor is a laborious one: “it consist(s) of drawing air into clean non-adsorbent plastic bags, from various parts of the site or downwind from it. The air is then taken, within 30 h, to a lab where chemical analysis is performed…The trained human panel of 6 to 8 people sniff systematically diluted samples of the original air sample, to determine how many times a unit volume of that air has to be diluted before it can no longer be detected. The effort and cost required to obtain these numbers means that not many numbers can be obtained, either over time or over a wide area…timely action to minimize a possible complaint is practically impossible.”

To detect the problem before it spreads, an optimal air-monitoring technology must posses four characteristics: sensitivity, reliability, temporal resolution (quickness), and robustness.  If you’ve been reading this blog, you know that e-noses are engineered with these four traits in mind, making them ideal tools to assist companies in preventative air-quality monitoring.

Today’s post is a follow up to last week’s post, which discussed the potential of GMR in enabling self-sufficient, portable biolabs.

It’s worth mentioning how incredibly sensitive the computer chips in these devices are.  A few of the prototypes currently detect substances with a concentration level of fewer than one part in a million billion!  Two researchers claim that the devices can even detect individual molecules.  These devices are so sensitive that they might even be able to detect individual strands of DNA.

In addition to being extremely sensitive, GMR-powered scanning devices are also able to filter out a lot of background noise, be it in the form of light or odor.

One real-world application of the GMR chip occurred at Stanford, where researchers used a tiny (smaller than a postage stamp) GMR chip to detect carcinoma-embryonic antigen and human papilloma virus.  This ability makes GMR-based scanners incredibly useful for early detection of cancer.  Additionally, researchers at the Naval Research Laboratory have used shoebox-sized GMR chip devices to detect ricin, staphylococcal enterotoxin B, and other dangerous substances likely to be used as bioweapons.   Finally, Austin-based Seahawk Biosystems is using the chip to carry out environmental applications and food testing.

In the U.K., plans are afoot to introduce a hand-help drug-testing scanner in 2009.  It would be used by police to scan drivers’ breath for illegal drugs, producing conclusive results in under one minute.

Probably the coolest, and most sci-fi sounding idea though, is the possibility of combining nanomagnets and GMR sensors into a kind of comprehensive biocard.  Imagine going to your doctor, swiping your own personal “wellness card” through a specialized card reader, and instantly receiving a complete, guesswork-free health assessment.  Very cool!

A few days ago, economist.com featured an article about quantum mechanics, and how it might enable full-scale analytical laboratory capabilities in portable scanning devices.  The relevance of this for e-noses is obvious.

This jump in technology is thanks to a quantum-mechanical effect called giant magnetoresistance (GMR, for those in a rush).

Here’s a quick summary of GMR:  Spin valves (made from interleaving thin sheets of magnetic and non-magnetic metals into a “sandwich” of nanometer-thick layers) alter their electron spin and their electrical resistance when exposed to a magnetic field, and this reaction is easy to detect.  These valves are placed in the heads of hard-disk readers.  Essentially, GMR forms the basis of the computer hard drive within the sensor device.

Twenty years ago, David Baselt, researcher at the U.S. Naval Research Lab, realized that these spin valves could also function as biosensors.  Researchers would need to magnetize a biological material sample, which would easily be accomplished by sprinkling magnetic nanoparticles coated with the desired antibody or DNA onto the target sample.  At that point, the spin valve can “read” the sample, since it will react to the magnetic charge. All this technology is housed on silicon wafers, which are divided into chips.

Basically, what this all means is that e-noses have the potential to become far more robust in their capabilities, possibly enough so that they can act as portable full-service scientific labs. This increased capability would be a boon to program’s like Google’s Predict and Prevent Initiative.

There’s a good deal more detail throughout the remainder of the article, and we might cover it in next week’s blog posts.

P.S.- If you skipped the tech speak in this summary, don’t worry.  Here’s the shorthand: The Star Trek Tricorder- coming soon to disaster site near you.