Law enforcement and military personnel rely on the sensitive noses of dogs to detect drugs and bombs, as well as track down missing persons. But these working dogs are expensive to train and maintain, and they can get tired.
Scientists at Duke University may have taken the first steps toward creating an artificial alternative to those dogs: a “robot nose” made from mouse stem cells. The prototype is based on odor receptors grown from mouse genes, which react to certain target odors—and could potentially be used to detect drugs and explosives. But the researchers ran into some considerable challenges as they developed the prototype.
"This idea of an artificial nose has been present for a long time," said Hiroaki Matsunami, professor of molecular genetics and microbiology at Duke University and senior author of the study. "The receptors were identified in the 1990s, but there are significant technical hurdles to produce all these receptors and monitor the activity so that we can use that in an artificial device."
Matsunami believes that a device based on odor receptors could perform much more effectively than the devices currently on the market, which use chemical compounds to identify smells but aren’t nearly as capable as a dog.
The first step in creating the artificial nose was finding the receptor cells that would respond to target odors. Matsunami’s team created a liquid medium with molecules that would light up when activated. They then copied odor receptors from mice and mixed them with seven target odor chemicals in the medium.
The researchers chose the receptors that triggered the most luminescence for the second step, which monitored receptor reaction in real time. They tested those receptors to see how well they detected two odor vapors. In principle, any variety of airborne odors could be used.
“We can monitor how different receptors respond differently to various smells, including ones that are similar to each other in chemical structure or ones that might be related to real-world use, like something associated to explosives or drugs," Matsunami explained.
The researchers know this is only the beginning of their work. An immediate problem to solve is determining the role of mucus in sensing odors—whether it enhances the sense or gets in the way.
“It’s not like our paper will be immediately applied to a portable device used in the airport soon, but this is an important step forward to show that it is possible,” Matsunami said. “We can more clearly see what kind of hurdles to pass in order for the community to create such a device.”
In the meantime, police, airport security and the military will keep relying on their canine companions to sniff out dangerous substances or locate people in need of help.
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