Handheld devices improve bio and chemical threat detection

The colorimetric detection assay is printed with several dozen indicator chemicals arranged in a grid of small dots.

Army researchers are working to bring chemical and biological detection down to size, with small, 3D-printed devices that can quickly detect the presence of harmful agents and report those results up the chain of command.

One such device being developed by the Army's Edgewood Chemical Biological Center (ECBC) at Aberdeen Proving Grounds, Md., is called the VOCkit system. Adapted from commercial technology, it uses a postage stamp-sized colorimetric detection assay printed with a grid of several dozen indicator chemicals with the ability to identify threats such as anthrax, sarin or mustard gas. The system can then transmit the results via soldiers’ Nett Warrior smartphones.

The detection assay, made with ECBC’s 3D printers, is placed in inside a disk-like cartridge. A plug on the cartridge can be removed to add a sample for testing, after which the assay’s grid of colored indicator chemicals react to reveal the sample’s composition, according to an Army release.

"You have almost one hundred reactions going on and the combination of those reactions gives you a unique signature," Peter Emanuel, ECBC's BioScience division chief, said in the release. "Some react, some don't ... some intensely. The signature, the collection of those dots, gives us a unique fingerprint for what that agent is."

Part of the trick is in developing a small system that can differentiate between harmful agents and everyday odors—such as those from cleaning fluids or bug spray—that might register similar reactions, researchers said. Testing has involved not only finding the signatures of harmful chemical and biological agents, but also the signatures of products soldiers regularly use—such as lotions, baby wipes, fuels, rifle cleaners and so on—in order to preemptively eliminate false positives.

"The problem is that common stuff confuses the strips," Aleksandr Miklos, a senior scientist at ECBC, said colormetric strips currently in use. "We know certain solvents will look a lot like [the nerve agent] VX. That's not particularly helpful."

While the VOCkit is being refined, ECBC also has tested a device called the SmartCAR, for "smart color-metric assay reader," a handheld device that uses electronics and a camera to read test strips. Unlike VOCkit, the SmartCAR can only test for one biological agent at a time, the Army said, but it works with strips that are already in wide use in the Army and was field-tested recently in South Korea during a biosurveillance demonstration that including scenarios involving anthrax and the plague.

The SmartCAR is an indication of how quickly handheld biological and chemical detection is advancing. ECBC engineer Colin Graham developed the device in six months, designing the circuit board and software and 3D printing the shell, the Army said.

And although it only tests for one agent at a time, the Army said soldiers in the field could each test for different agents simultaneously to present a complete picture. Like VOCkit, the SmartCAR connects with Nett Warrior phones so results can be shared.