This handheld device, which looks sort of like an old-fashioned iron, is one of the most sophisticated artificial noses ever created. It's used in industrial settings where you need to "smell" chemical leaks or toxins to know when they've happened. The best part? This nose, called the ScenTrak, uses a smear of specially-treated human DNA to sense multiple odors. Once the DNA slide is exposed to the air, the machine looks at how the molecules have changed and can determine what the nose has been smelling. We've got images of the DNA slides and a cool patent diagram below.
Here's what's happening inside that metal box.
Inventor Joel White created the ScenTrak for his company Cogniscent, and has just published an article about how it works in PLoS Biology. He and his co-authors write:
Biological systems can provide engineering guidance on how evolution has solved particular problems. In the context of detecting chemicals in either the aqueous or vapor phase, two general biological approaches have emerged. The first relies on individual highly specific single receptors (sensors), each tuned to detect a single molecular species—examples include the receptors that mediate pheromone detection in insects or those that function in neurotransmission. Specificity is achieved by narrow band design. The second approach is implemented by arrays of receptors with relatively broad responses. In this case, specificity emerges from a constellation of receptor types that recognizes the molecule of interest—the canonical example here is the olfactory receptors in the main olfactory system of vertebrates. Specificity is achieved by a "one chemical-many broadly responsive detectors" paradigm. While trying to mimic the enormous odor coding ability of biological olfaction in an "artificial nose," we searched for molecules with the requisite combinatorial capacity to serve as odor detectors. Here we show that single-stranded DNA molecules tagged with a fluorescent reporter and deposited onto solid surfaces can respond to vapor phase odor pulses in a sequence-selective manner.
In other words, human noses can sense a wide variety of smells. And it turns out so can our DNA, if treated with the proper chemicals to make it (literally) light up in the presence of certain smells. This ScenTrak nose could become the future's "canary in a coal mine," the little device that provides advanced warning of toxic leaks or hazardous spills. Here you can see the device with its cartridges loaded up with DNA.
DNA Detects Volatile Compounds in Vapor Phase [PLoS Biology]