Tag Archives: explosives

Grasshopper-computer hybrids built to sniff out explosives

New research at the Washington University in St. Louis, Missouri, is sniffing out explosives — with insects.

Image credits Baranidharan Raman / Washington University, St. Louis.

The bomb-sniffing American grasshoppers (Schistocerca americana) were created in the lab of Dr. Barani Raman, an Associate Professor at the Washington University’s Department of Biomedical Engineering. In order to tap into their tiny insect noses, the team implanted electrodes into the olfactory centers of their brains.

Cyborg grasshoppers

Insect antennae house olfactory (smell) receptors that the animals use to find food and detect threats. Data from these receptors is sent to an area of their brain known as the antennal lobe, which performs many of the same functions as our olfactory areas. Information from each of the grasshoppers’ antennae, the team explains, is fed to around 50,000 neurons in the antennal lobe. This, the researchers suspected, would make them much better at sniffing out explosives than any device we’ve yet designed.

In order to tap into their ability, the team implanted tiny electrodes into the insects’ antennal lobes and puffed vapors of different explosive materials. The team used dynamite (TNT) and its precursor 2,4-dinitrotoluene (DNT), along with hot air and benzaldehyde (the primary component in the oil of bitter almonds) as controls. The team measured the patterns of neural activation each of the compounds produced in the grasshoppers’ brains. With some practice, they eventually learned how to distinguish between the different vapors just by looking at the insects’ brain activity.

The last step was to fit grasshoppers with a sensor ‘backpack’ which would record and transmit their neural activity in real-time to a computer, where it would be interpreted.

All in all, these mechanized insects were able to successfully detect explosive compounds for up to seven hours after the electrodes were first implanted; after this time, however, the insects died. The whole procedure also immobilized the grasshoppers, so the team had to mount them on a wheeled, remote-controlled platform for testing.

The authors report that the insects’ sense of smell was sensitive enough that they successfully detected the areas with the highest concentration of explosives as they were being moved between various points at the testing location. Individual insects had an average explosive-finding accuracy of 60%, they add; used in groups of seven, they yielded accuracies of 80%. However, the team did not test them in settings where multiple odors were present at the same time.

The project was funded by the US Office of Naval Research and the researchers believe the grasshoppers could be used for homeland security purposes.

The paper “Explosive sensing with insect-based biorobots” has been published in the preprint server bioRxiv.


U.S. Army designs more powerful, less toxic explosive to replace TNT

The U.S. Army is designing a new explosive to replace TNT. The new compound forgoes the catchy name in favor of more powerful boom-booms and less toxicity for soldiers.


Oxadiazole has a calculated detonation pressure 50% higher than that of TNT.
Image credits LANL.

Research at the Los Alamos National Laboratory and the U.S. Army Research Laboratory in Aberdeen, Maryland has resulted in a new “melt-cast” explosive to replace Trinitrotoluene (TNT). The material, bis(1,2,4 oxadiazole)bis(methylene)dinitrate, should be more reactive (i.e. make bigger explosions) than TNT while being less toxic.

More boom for your buck

“The Army and the Laboratory, through the Joint Munitions Program, have been looking for a TNT replacement,” said David Chavez, an explosives chemist at Los Alamos. “Something with non- or low-toxicity that has the right melting point so it can be liquified and cast, for use in a variety of munitions.”

The molecule is a nitrogen-containing compound, which the team refers to as bis-oxadiazole. Chaves used his decade-long experience of developing nitrogen-rich explosive compounds at Los Alamos to develop the material — which has a low explosive sensitivity (won’t go boom when it’s not supposed to) for temperature, pressure, and friction. It also boasts good environmental properties (won’t poison people).


The molecular structure of the new explosive.
Image credits C. Johnson et al., 2018, OPR&D.

One major challenge the team had to overcome was designing a material that would detonate with more force (aka ‘yield‘) than TNT while being stable enough to melt-cast. The two properties tend to butt heads — stable compounds generally make for poor explosives (fast and energetic reactions).

The team’s earliest attempts only managed a meager 4% yield — far, far too little for an explosive. Several iterations later, Chaves explains, they were up to 44% yield. The final material is a 24-atom molecule packed full of nitrogen, which has 1.5 times the explosive performance of TNT, according to the team.

Another area where bis-oxadiazole should outshine TNT is toxicity, the team writes. The Environmental Protection Agency has listed TNT as a possible carcinogen. Exposure to the material has also been linked to disorders of the blood, such as anemia, and abnormal liver function, according to the Centers for Disease Control.

TNT was first synthesized by Julius Wilbrand, a German chemist, in 1863, to be used as a yellow dye. It took a few years for people to understand that TNT could also explode — up until 1891 — as the material was very stable and not that powerful as an explosive. TNT’s stability, however, made it ideal for pouring into shells and other casings. It became the explosive of choice for ammunition, artillery shells, landmines and all manner of explosive military implements starting in 1901.

Next, Chaves’ team plans to produce a few kilograms of the material to use in explosive testing and toxicity studies.

The paper “Bis(1,2,4-oxadiazole)bis(methylene) Dinitrate: A High-Energy Melt-Castable Explosive and Energetic Propellant Plasticizing Ingredient,” has been published in the journal Organic Process Research & Development.

Plants embedded with electronics can detect explosives, dopamine, and a slew of other chemicals. Credit: Juan Pablo Giraldo / MIT

Spinach doped with carbon nanotubes turns into explosive detector

Plants embedded with electronics can detect explosives, dopamine, and a slew of other chemicals. Credit: Juan Pablo Giraldo / MIT

Plants embedded with electronics can detect explosives, dopamine, and a slew of other chemicals. Credit: Juan Pablo Giraldo / MIT

Popeye’s favorite superfood was turned into an explosive detector after researchers at MIT enhanced the plant’s natural sensing abilities with nanotechnology. When explosive molecules bind to the plant’s leaves, these emit a telltale infrared signal that can be read with cheap equipment — even a smartphone with the right camera. This is one of the first demonstrations of “plant nanobionics” — engineering electronics inside plants — something that we’ll hear about more often in the near future because of the immense potential this technology has for detecting virtually anything: explosives, CO2, droughts, even neurotransmitters like dopamine. The possibilities could be endless.

Borg plants

Previously, in 2014, the team led by Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT, worked with a common lab plant called Arabidopsis thaliana. Back then, they also showcased plant nanobionics technology by using nanoparticles to enhance photosynthesis, but this time they wanted to use spinach because it’s so common and ubiquitous. Seeing how it worked with spinach, it should work with right about any plant, the researchers reckon.

Strano and colleagues first developed carbon nanotubes — a tube-shaped material, made of carbon, having a diameter measuring on the nanometer scale — which can sense a wide range of molecules, including TNT, sarin nerve gas or hydrogen peroxide.

Using a technique known as vascular infusion, the researchers applied a solution of these nanoparticles to the underside of the spinach’s leaves. This allows the plant to detect nitroaromatics, which are often used in landmines and other explosives. When one of these chemicals binds to the tubes, it alters their fluorescence.

Another set of carbon nanotubes was embedded in the plant which emits a constant fluorescent signal. This serves as a reference to compare the explosive-detection fluorescent signal against a background and drastically speeds up detection. If there are any explosives in groundwater, for instance, the spinach bomb detector can draw them in under 10 minutes, as reported in Nature Materials.

Diagram of the plant-nanotech sensing setup. Credit:  Juan Pablo Giraldo / MIT

Diagram of the plant-nanotech sensing setup. Credit: Juan Pablo Giraldo / MIT

To read the signal, a laser is shone onto the leaf prompting the leaves to emit near-infrared fluorescent light. Then, a small infrared camera connected to a cheap computer, like a $35 Raspberry Pi, can be used to monitor the signals. A smartphone whose infrared filter from the camera is removed can also be used with accuracy.

“This is a novel demonstration of how we have overcome the plant/human communication barrier,” says Strano.

Plants are already one of the best sensors in the world. If you ever thought plants are good listeners, you’re not far from the truth as they continuously monitor the air, soil, moisture, and water — otherwise, they couldn’t adapt to the slightest weather and climate fluctuations, perishing.

“Plants are very good analytical chemists,” Strano says. “They have an extensive root network in the soil, are constantly sampling groundwater, and have a way to self-power the transport of that water up into the leaves.”

Besides explosive detection, the MIT lab also engineered spinach plants that read dopamine, which can influence plant root growth. They’re also working on other sensors which can track chemicals plants use to convey information within their own tissues.

“Plants are very environmentally responsive,” Strano says. “They know that there is going to be a drought long before we do. They can detect small changes in the properties of soil and water potential. If we tap into those chemical signaling pathways, there is a wealth of information to access.”

Hurricane Matthews exposed a trove of Civil War cannonballs in South Carolina

Hurricane Matthews unearthed an unexpected trove of Civil War cannonballs on a beach near Charleston, South Carolina when it hit the state. An US Air Force Explosive Team was deployed this weekend to dispose of an unexpected threat.

On Sunday morning, a Charleston local reported finding 16 Civil War cannonballs on a Folly Island beach near Charleston, South Carolina which were exposed by the passing of Hurricane Matthews. The site lies just 20 km (12.8 miles) off of Fort Sumter in Charleston, a place of historical significance. This is the place where the fist recorded shots of the Civil War were fired, at the First Battle of Fort Sumter on 12 April 1861.

An US Air Force team was dispatched to the area and detonated most of the 150-year-old ordinance on-site with a small amount of explosives. The rest was transported to a local navy base for disposal.

“We had to wait until after 7[pm] for the tide to go down,” Watson told Mary Bowerman at USA Today. “When the tide receded, our guys and members of the US Air Force explosive team used a small amount of C-4 to detonate the cannonballs.”

“We call it ‘rendering safe’, and we did that right there on the beach front,” Eric Watson, a spokesman with the Charleston County Sheriff’s Office told the press. “They’re putting the dirt from the detonation back in the hole and they’re transporting the device to [Joint Base Charleston].”

Folly Island is an 18-square-kilometer (7-square-mile) stretch of land which was used as a Union fort and staging area for attacks on Confederate strongholds during the Civil War. So it’s not surprising to find artifacts from that era here — in fact, in 1987, construction workers stumbled upon the remains of 14 people here. They were later identified as soldiers from the 55th Massachusetts regiment of the US Coloured Troops. What was most disturbing about the find was that most of them were missing their heads.

“What was odd about the bodies discovered on the island was that 12 of them didn’t have skulls and were also missing other body parts,” says Wheeler.

“And, more importantly, they showed no signs of battle injury, according to an account in an official history of Folly Island. What happened to these men was then and still is a mystery.”

So Hurricane Matthews has been doing some archaeology itself. Who knows how many other artifacts are waiting to be found, unearthed by the storm?


Concept illustration of the microscale free-surface microfluidic channel as it concentrates vapor molecules that bind to nanoparticles inside a chamber. (c) University of California

Detecting explosives with an artificial dog nose

In an age where the developing world is shadowed by paranoia in face of waves of terrorist attacks, no measure of precaution is spared. Preventing terrorist attacks has been a top priority for governments for a long time, especially since 9/11, and detecting explosives at critical check-ins like airport and customs makes for the first line of the defense. While we’re nearing 2013, dogs are still the gold standard for explosive detection and no man-made device has managed to come close to canine sensing accuracy – until recently that is.

Mechanical and chemical engineers at University of California, Santa Barbara have designed a detector that uses microfluidic nanotechnology to mimic the biological mechanism behind the dog’s sensing apparatus. Basically, they’ve developed a mechanical bomb sniffer based on the dog’s nose, which they claim is not only accurate, but actually more precise than the canine nose. If the device catches on – the scientists have already obtained a patent and exclusive licence – than it could become just as common in potentially hazardous zones like smoke detectors.

Previously, we’ve seen some interesting concepts for detecting explosives, from cutting-edge projects employing graphene layers to quite eccentric projects that use bee venom. The present showcased device, however, seems the most promising.

The team of researchers were led by professors Carl Meinhart of mechanical engineering and Martin Moskovits of chemistry,

“The device is capable of real-time detection and identification of certain types of molecules at concentrations of 1 ppb or below. Its specificity and sensitivity are unparalleled,” said Dr. Brian Piorek, former mechanical engineering doctoral student in Meinhart’s laboratory and Chief Scientist at Santa Barbara-based SpectraFluidics, Inc

Concept illustration of the microscale free-surface microfluidic channel as it concentrates vapor molecules that bind to nanoparticles inside a chamber. (c) University of California

Concept illustration of the microscale free-surface microfluidic channel as it concentrates vapor molecules that bind to nanoparticles inside a chamber. (c) University of California

An artificial bomb sniffer puts dogs out of work

The technology works by combining two key principles  – free-surface microfluidics and surface-enhanced Raman spectroscopy (SERS) – to capture and identify molecules. One of the molecules they’ve targeted is 2,4-dinitrotoluene, the primary vapor emanating from TNT-based explosives. The substance comes in such a minute quantity that the human nose can not sense it, but dogs’ noses are sensitive enough to detect it. Inspired by the dog’s olfactory mucus layer, the scientists devised an artificial “sniffer”.

The device mainly consists of two parts – a microchannel, twenty times thinner than the human hair, which traps the target molecule for presenting it to the second part, a mini spectrometer power by a laser that detects the molecule. A computer database of spectral signatures identifies what kind of molecule has been captured, meaning that its uses are far from being limited only to detecting explosives; anything from noxious substances that can’t be senses otherwise to extremely sensitive sensors for scientific research could be employed.

“The technology could be used to detect a very wide variety of molecules,” said Meinhart. “The applications could extend to certain disease diagnosis or narcotics detection, to name a few.”

Moskovits added, “The paper we published focused on explosives, but it doesn’t have to be explosives. It could detect molecules from someone’s breath that may indicate disease, for example, or food that has spoiled.”

Their findings were published in the journal  Analytical Chemistry.


Bee venom

Bee venom could be used to detect explosives and pesticides

Bee venomA remarkable MIT research has found that by coating carbon nano-tubes with bee venom they can create incredibly faithful sensor detectors for explosives,  such as TNT, as well as at least two different types of pesticides.

The find came after MIT chemists, lead by Michael Strano, coated one-atom-thick tubes of carbon with protein fragments found in bee venom saw that the compound reacts with explosives. Not only this, the resulting sensors are actually hypersenstive to the explosives, in terms that each sensor can detect explosives on a molecular level. Also the sensor can also detect the chemical molecules of the explosives as they break down, which could provide experts with a foot print for each explosive and a better assesement of an explosion site.

“When it wraps around a small wire, that allows it to recognize ‘nitro-aromatics’,” Strano explains, the chemical class of explosives like TNT. That wire is a carbon nanotube, a mere one atom thick.

Its applications aren’t limited to explosives either, as the researchers found that the coated nanotubes can also detect two pesticides that contain nitro-aromatic compounds. Meaning that the bee venom detector could be applied in fields from military, to airport security, to agriculture.

Strano has filed for a patent on the sensor, while the team is still working out a compression system to ensure that any molecules in the air come into contact with the tubes and are therefore detected – an indispensable system. A commercial product of this bee venom derived sensor could very much prove to be successful, if it holds up to its claims and proves to be flawlessly reliable, as it is needed in explosive detection.

Strano and his team published their work Tuesday in the Proceedings of the National Academy of Sciences.