This LEGO Box Could Be Key to Detecting Deadly Nerve Gas

Vivian Abagiu, University of Texas at Austin
Vivian Abagiu, University of Texas at Austin

Researchers at the University of Texas at Austin have developed a new way to detect deadly nerve gases, and it involves LEGO.

The new detection device, described in a study published in the journal ACS Central Science, uses chemical sensors, a box made out of LEGO bricks, and a cell phone to identify the presence of odorless, tasteless nerve agents like VX and sarin.

Chemical weapons like sarin are extremely dangerous—even at low concentrations, a direct whiff of sarin can kill you in just minutes. So being able to identify them in the field is vital, and it has to be done fast.

The chemical-identifying sensors, developed by UT Austin chemist Xiaolong Sun and his colleagues, fluoresce in different colors and brightnesses to indicate which nerve agents are present in the air, and in what concentrations. Unfortunately, depending on where these tests are taking place, it’s not always easy to see how bright the fluorescent glow is. Expensive equipment designed to detect these changes in the lab just isn’t feasible on the battlefield or in a war-torn region.

An open black LEGO box sits in the lab in front of a chemical test plate.
Vivian Abagiu, University of Texas at Austin

The 320-brick LEGO structure, meanwhile, is portable and quick to assemble. It acts as a black box that blocks out light around the sensors. The top of the box has a hole in it, over which the user places a smartphone’s camera lens. Using a standard lab test plate and a UV light inside the box, the fluorescent changes can be photographed with the phone and analyzed with UT Austin's free software to determine what type and concentration of nerve agents are present in the sample.

While 3D printing could produce a cheap equivalent of the LEGO box, the toy bricks may be more accessible. Not everyone has access to a 3D printer or the same printing materials as researchers might use in the lab—but LEGOs are available across the world for a relatively low price. The software necessary to analyze the samples is available for free on GitHub, and the researchers include the LEGO assembly directions within their study.

What Caused Pangea to Break Apart?

iStock.com/alfimimnill
iStock.com/alfimimnill

Emily Devenport:

There's another way to look at this question. People tend to think in terms of supercontinents forming and then breaking up again due to convection currents in the mantle, hot material rising and causing rifts in weaker spots, possibly in old sutures where the continents were shoved together—but what is really happening is that ocean basins are opening and closing, and the ocean has an active role in subduction.

The opening and closing of an ocean basin is called a Wilson Cycle. It begins when hot material rising from the mantle stretches the overlying crust. As molten material rises, a rift is formed. The rift is widened as material continues to squeeze into it. If that rifting goes on long enough, through a broad enough swath of a continent, ocean water will eventually flow into it, and an ocean basin begins to form. The upwelling of hot material will continue to rise through that thinner area of crust, pushing the plates apart. The Atlantic Ocean is an example of a basin that is well along in the Wilson Cycle; eventually subduction is going to begin at its margins, and the whole shebang will pivot.

This will happen because at the edge of continents, sediments accumulate. The weight of those sediments, combined with the weight of the water, drives the heavier, denser edge of the oceanic plate under the continental crust, which is fatter and lighter. Eventually subduction begins, and the basin begins to close again. The Pacific Ocean is an example of a basin that's closing.

If you look at a map of the oceanic rift zones, you'll notice that the one in the Atlantic is pretty much in the middle of that ocean, but the Pacific rift zone has been pulled all the way over to North America above Central America. Subduction is actively occurring on all margins of that plate.

The simple picture is that the continents are moving toward each other across the Pacific Ocean while the Atlantic Basin continues to widen. The truth is more complicated. When plates subduct, the water in the crust lowers the melting point of those rocks, so partial melting occurs. The partially melted material begins to rise through the overlying rocks, because it's less dense, and decompression melting occurs. Eventually, the upwelling of hot material forms plutons and volcanoes above the subduction zones. Fore-arc and Back-arc [PDF] basins can form. As the oceanic crust is pulled under the continental plate, island chains and other chunky bits get sutured to the edge of the continent along with sediments, making it larger. Our world is ~4.6 billion years old, so our continents are really large, now. They're unlikely to rift through the ancient cratons that formed their hearts.

What will happen if subduction begins on the eastern side of North America before the Pacific Basin closes? The margin next to California is a transform fault; it's not subducting. Will it eventually push itself under that part of North America again, or will the transform zone get bigger? The hot spot that was driving the ancient Farallon Plate under North America was eventually overridden by the southwestern states (Arizona, New Mexico, etc.) forming a rift zone. Will it continue to rift or poop out?

There are computer models predicting what supercontinent may form next. They will continue to change as our understanding of tectonic processes gets more accurate.

This post originally appeared on Quora. Click here to view.

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