VICKSBURG, Miss. -- A simple scientific question by a fellow laboratory researcher led Research Physicist Dr. Benjamin Barrowes to invent the High Frequency Electromagnetic Induction instrument, now proving successful in detection tests of low and non-metallic improvised explosive devices known as Warfighter-threatening IEDs.
A 2018 patent recipient for this U.S. Army Engineer Research and Development Center-Cold Regions Research and Engineering Laboratory innovator, Barrowes’ invention was presented to the U. S. Patent Office by the ERDC’s Office of Research and Technology Transfer, and he was personally congratulated for his noteworthy achievement by ERDC Director Dr. David Pittman at ERDC-CRREL’s Town Hall in October 2018.
Barrowes’ inventive ideas began in 2014 when he was first approached with the initial problem of non-metallic unexploded ordnance on U. S. military ranges.
“Can you find ordnance with shells made from carbon fiber instead of metal?” asked ERDC-CRREL researcher Steven Grant, leading to the invention with assistance from Dartmouth Professor Dr. Fridon Shubitidze, whom Barrowes recognizes as instrumental in helping develop ideas for this patent, and ERDC Vicksburg researchers Janet Sims and Hollis “Jay” Bennett.
Using his Massachusetts Institute of Technology doctorate background in electrical engineering, Barrowes suspected that finding targets with conductivity in between metal and soils should be possible.
“Carbon fiber is more conducting than the ground but less conducting than metal. Thinking about what actually happens when we bring these frequencies close to metal, I realized that the electrons in less conducting targets needed to be pushed harder in order to respond like they do in metals, because it is difficult for electrons to move in less conducting targets, kind of like moving your hand through water as opposed to moving your hand through the air.
“The way to push electrons harder at these frequencies is to use a higher frequency, so that is the direction we went in, while maintaining the set of physical assumptions that we used in our models and our understanding,” Barrowes said.
Because carbon fiber is at least a thousand times less conducting than metal, Barrowes explained the need to develop a new sensor instrument that operates in the higher frequencies from 100 kHz up to 15 MHz.
“Our sensor was able to find carbon fiber shells in the ground. It was also able to find carbon rods and wires, which are typical constituent parts of improvised explosive devices.
“It was a joint effort between ERDC-CRREL and the Dartmouth Thayer Engineering School. We tested it on local soils and local targets in conjunction with our initial research funding as part of the 6.1 ERDC program, then continued from 2016 with the Office of Naval Research IED program. We went to Fort AP Hill, which has Night Vision and Electronic Sensors Directorate IED test lanes, to test our instrument. We were able to find carbon rods and wires associated with IEDs as well as voids in the soil which can indicate an ammonium nitrate IED,” Barrowes said.
With no current Department of Defense solution for finding less conductive targets like carbon fiber in the ground, Barrowes explained that his sensor is able to find these less conductive targets because it operates at higher frequencies than normal metal detectors.
“The current handheld IED detection system used by dismounted troops in theater combines two separate sensors into one form factor. The first sensor is a low-frequency electromagnetic induction sensor which excels at finding metallic targets.
“The second sensor is a ground-penetrating radar sensor which excels at finding disturbances under the soil, but it has trouble distinguishing different types of disturbances; for example, the difference between a rock and a metal target.
“Our high-frequency electromagnetic induction sensor bridges the gap between these two sensing modalities and enables the handheld sensor to find very thin metallic objects like wires, less conducting targets like carbon rods from D cell batteries, and voids in the soil that could indicate a nonconductive IED, such as an ammonium nitrate fuel oil IED.
“When the current handheld sensor incorporates higher frequency electromagnetic induction into the system, it will be better able to distinguish typical IED targets. The false alarm rate will go down, and the positive ID rate will go up, saving Soldiers’ lives,” Barrowes said.