One step closer to bomb-sniffing cyborg locusts
Study found locusts can quickly discriminate between different
explosives' smells

Date:
August 14, 2020
Source:
Washington University in St. Louis
Summary:
Research has determined that locusts can smell explosives and
determine where the smells originated -- an important step in
engineering cyborg bomb-sniffing locusts.



FULL STORY ==========================================================================
If you want to enhance a locust to be used as a bomb-sniffing bug,
there are a few technical challenges that need solving before sending
it into the field.


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Is there some way to direct the locust -- to tell it where to go to do
its sniffing? And because the locusts can't speak (yet), is there a way
to read the brain of these cyborg bugs to know what they're smelling?
For that matter, can locusts even smell explosives? Yes and yes to
the first two questions. Previous research from Washington University
in St. Louis has demonstrated both the ability to control the locusts
and the ability to read their brains, so to speak, to discern what it
is they are smelling. And now, thanks to new research from the McKelvey
School of Engineering, the third question has been settled.

The answer, again: 'yes.' In a pre-proof published online Aug. 6 in
the journal Biosensors and Bioelectronics: X, researchers showed how
they were able to hijack a locust's olfactory system to both detect
and discriminate between different explosive scents -- all within a few
hundred milliseconds of exposure.



==========================================================================
They were also able to optimize a previously developed biorobotic sensing system that could detect the locusts' firing neurons and convey that information in a way that told researchers about the smells the locusts
were sensing.

"We didn't know if they'd be able to smell or pinpoint the explosives
because they don't have any meaningful ecological significance," said
Barani Raman, professor of biomedical engineering. "It was possible that
they didn't care about any of the cues that were meaningful to us in this particular case." Previous work in Raman's lab led to the discovery
that the locust olfactory system could be decoded as an 'or-of-ands'
logical operation. This allowed researchers to determine what a locust
was smelling in different contexts.

With this knowledge, the researchers were able to look for similar
patterns when they exposed locusts to vapors from TNT, DNT, RDX, PETN
and ammonium nitrate -- a chemically diverse set of explosives. "Most surprisingly," Raman said, "we could clearly see the neurons responded differently to TNT and DNT, as well as these other explosive chemical
vapors." With that crucial piece of data, Raman said, "We were ready to
get to work. We were optimized." Now they knew that the locusts could
detect and discriminate between different explosives, but in order to
seek out a bomb, a locust would have to know from which direction the
odor emanated. Enter the "odor box and locust mobile."


==========================================================================
"You know when you're close to the coffee shop, the coffee smell is
stronger, and when you're farther away, you smell it less? That's what
we were looking at," Raman said. The explosive vapors were injected
via a hole in the box where the locust sat in a tiny vehicle. As the
locust was driven around and sniffed different concentrations of vapors, researchers studied its odor-related brain activity.

The signals in the bugs' brains reflected those differences in vapor concentration.

The next step was to optimize the system for transmitting the locusts'
brain activity. The team, which included Shantanu Chakrabartty, the
Clifford W.

Murphy Professor in the Preston M. Green Department of Electrical &
Systems Engineering, and Srikanth Singamaneni, the Lilyan & E. Lisle
Hughes Professor in the Department of Mechanical Engineering & Materials Science, focused the breadth of their expertise on the tiny locust.

In order to do the least harm to the locusts, and to keep them stable
in order to accurately record their neural activity, the team came up
with a new surgical procedure to attach electrodes that didn't hinder the locusts' movement. With their new instrumentation in place, the neuronal activity of a locust exposed to an explosive smell was resolved into a discernible odor- specific pattern within 500 milliseconds.

"Now we can implant the electrodes, seal the locust and transport them
to mobile environments," Raman said. One day, that environment might be
one in which Homeland Security is searching for explosives.

The idea isn't as strange as it might first sound, Raman said.

"This is not that different from in the old days, when coal miners
used canaries," he said. "People use pigs for finding truffles. It's a
similar approach -- using a biological organism -- this is just a bit
more sophisticated."

========================================================================== Story Source: Materials provided by
Washington_University_in_St._Louis. Original written by Brandie
Jefferson. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Debajit Saha, Darshit Mehta, Ege Altan, Rishabh Chandak, Mike
Traner, Ray
Lo, Prashant Gupta, Srikanth Singamaneni, Shantanu
Chakrabartty, Barani Raman. Explosive sensing with insect-based
biorobots. Biosensors and Bioelectronics: X, 2020; 100050 DOI:
10.1016/j.biosx.2020.100050 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200814142934.htm

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