May 5, 2049

E-Nose knows!
By Staff Writer Melissa Engelbrecht

In space, there are many hazardous airborne chemicals, such as ammonia. In our underground community here at the Peak of Eternal Light, gases flow through pipes below and around our living space helping to keep our living environment habitable. These gases must be closely monitored. Rest assured, we have plenty of e-noses sniffing the air and keeping it safe at all times.

For instance, ammonia is a poison, and if it leaks, the inhabitants of the Peak of Eternal Light community will need to know about the leak right away. Ammonia becomes dangerous at a concentration of a few parts per million (ppm), but humans can't sense it until it reaches about 50 ppm. Ammonia is just one of about fifty compounds necessary in the space community. But these compounds cannot be allowed to accumulate in the community.

As always, fire is a huge hazard. Before an electrical fire breaks out, increasing heat releases a variety of signature molecules which humans can't sense until concentrations become high. The e-nose will be able to detect the fire before it gets out of hand, thus allowing the workers to put a stop to it.

And what if molds, which are naturally present nearly everywhere, start growing and cause unappealing and unusual flavors? Some molds are capable of producing toxins, which are hazardous to human health. Who needs a stinky, green tortilla for dinner? Not me!

Fortunately for the inhabitants of the Peak of Eternal Light community, the E-Nose is quietly monitoring the air they are breathing. The E-Nose is based on the same mechanisms that allow humans to detect and differentiate smells.

Here's how it works. Imagine a sponge as thin as a human hair. Putting water onto that sponge would cause it to swell up. Imagine putting particles of carbon, similar to pencil lead, into the sponge, just like blending garlic into butter. When the water makes the sponge expand, the distance between the garlic flakes gets bigger. Carbon particles conduct electricity, but the farther apart the particles, the harder to pass the electrical current from particle to particle.

E-Nose smells hazardous airborne chemicals.

If you hook up the sponge to a meter that measures electricity, you can tell whether the sponge is swollen with water or not by how easily the electricity passes through it. Thus the sponge can “smell” water. So, mixing carbon particles into sponges made of different materials that swell up in the presence of different substances, enables us to recognize different odors. In the same way that we have different finger prints, each odor has a different “smell print”.

The E-Nose that NASA developed can learn to recognize almost any compound or combination of compounds. The E-Nose is amazingly versatile and much more sensitive than a human nose. The E-Nose contains 32 thin polymer carbon composite film sensors on a very small chip. These sensors expand or contract depending on the elements in the air. The reaction of the individual polymers creates a pattern or smell print, which scientists can evaluate using software. Like the human brain, the E-Nose is trained to recognize these patterns and smells.

So, during you stay at the Peak of Eternal Light community, you can enjoy your food, work hard and sleep peacefully, knowing that the E-NOSE is monitoring the air that you are inhaling.