To continue its research for optimizing protection against blast force head injuries and to advance the long-range goals of robust technological
capabilities and medical applications, the U.S. Army in July awarded contracts valued at a minimum of $17 million each for a quantity of
second-generation helmet sensors
. The Army has ordered enough of these improved sensors – at a cost of approximately $300 per unit – to equip six brigade combat teams (BCTs) beginning
in January 2011. With so many troops victimized by IEDs (improvised explosive devices such as roadside bombs), the U.S. military hopes to use data
retrieved from these sensors to better understand "the forces acting on the helmet and the forces translated to the soldier's head," phrasing used by a
spokesman for PEO Soldier, the Army's department that expedites and procures the
most advanced uniforms and protective equipment for our troops.
The Gen II helmet sensor, which will be mounted on the inside crown of the troops' Advanced Combat Helmet (ACH), features a number of
technological advances over the 7,000 Gen I sensors in use by seven brigade combat teams (BCTs) since March 2009. In addition to measuring the linear
acceleration and blast pressure as the first generation sensor did, the Gen II model will also capture rotation data (i.e., rotational acceleration).
The improved Gen II version will also have an LED indicator light that will begin blinking when the sensor detects a blast pressure that exceeds a
specified threshold. This is expected to be useful in identifying possible head trauma to military personnel who are dazed or confused by a blast and
continue on with their duties, disregarding the mild to moderate concussion they may have sustained. The ongoing data download protocol is also
expected eventually to help identify personnel who may have cumulative brain trauma that should addressed.
Other improvements have been implemented in the Gen II model with respect to battery power management, data storage capacity, and wireless data
exchange. While each combat team member with the Gen I sensor connected it manually to a computer with a USB cable, the Gen II sensors will be designed
to have their data retrieved wirelessly. You can imagine the possibilities this may have in future applications for triage and medical care management.
It is almost an understatement to say that IEDs have been devastating to military personnel who encounter them while
serving in the Iraq and Afghanistan war zones. Brain injuries are, in fact, a more common injury than we may want to believe. One study of soldiers
returning from Iraq found that fully 15 percent had sustained head injuries severe enough to cause them to lose consciousness, to exhibit mental
confusion, or both.
Looking to the future, the U.S. military has fast-tracked the implementation of helmet blast sensor technology with the hope that it will lead to
improved helmet design strategies.
The initial research used first-generation sensors manufactured by U.K.-based BAE Systems, a behemoth global military goods manufacturer. In fact, the research has been
conducted using two different helmet-and-sensor designs: one with a sensor mounted internally beneath the pad at the crown and one with a sensor
mounted externally at the back of the head. This battery-powered sensor made by BAE Systems stores the acceleration data it detects, such as when a
soldier may be thrown by a blast, and even if the helmet is dropped.
During this initial phase, the internal sensor helmets were issued to members of the 1st Brigade Combat Team (BCT), 4th Infantry Division deployed
in Iraq, while the external sensor helmets were issued to members of the 4th BCT, 101st Airborne Division deployed in Afghanistan. Each soldier or
Marine with a sensor-enhanced helmet downloaded its data for analysis to a computer monthly using a USB cable during the first year of research which
ended this spring.
BAE Systems' technology is formally known as HEADS (and
HEADS II), an acronym for Headborne Energy Analysis and Diagnostic Systems. The company, which produces its sensors in Phoenix, Arizona, is one of the
two firms awarded a contract to produce the Army's Gen II sensor.
Allen Vanguard, the other company awarded a contract to develop and sell high-tech helmet sensors,
will do so from its Ashburn, VA, facility. Allen Vanguard is a Toronto-based firm (now owned by Philadelphia-based Versa Capital Management) that is a leading producer of bomb suits and counter-IED technologies. As such, its
researchers worked with investigators at the Naval Research Lab (NRL) several years ago to conduct experiments with sensor-rigged, helmeted test
dummies, exposing them to varying blast pressures comparable to enemy IEDs. The tests produced some surprising, "paradoxical" results: under-helmet
shockwaves registered more pressure on the side of the head away from the blast, suggesting that the helmet actually functions as a focusing mechanism
for traumatic forces. According to a report presented to a meeting of physicists in late 2008 by NRL scientist David Mott, blast pressure waves
penetrate the gap between the helmet and the head and travel beneath the helmet to deliver a more powerful pressure to the side of the head facing away
from the blast. This force would, of course, be in addition to external force of shockwaves striking and wrapping around the outside of the test
dummy's helmet.
In addition to the design efforts of BAE Systems and Allen Vanguard, combat blast investigations continue at a third, more academically-oriented
R&D firm, Simbex LLC. Simbex is well-known for its state-of-the-art head impact telemetry (HIT), a patented technology that uses sensors within Riddell football helmets
and other sports helmets to measure, record, and analyze impacts in real time.
Engineers at Simbex have expanded their expertise in measuring the repeated blunt force impacts experienced by NFL and NCAA football players to
encompass the more complex types of blast impacts that combat personnel experience when they encounter an IED.
Simbex engineers are maintaining a sharp focus on detecting head acceleration (rather than helmet acceleration) by employing a more complex
placement strategy of multiple sensors mounted on springs or resilient foam inside the combat helmet. These sensors are designed to maintain contact
with the soldier's head to provide a more accurate measurement – at multiple points – of the forces acting on the brain that can result in concussion
or more serious injury.
Studies by Simbex engineers as well as published studies by other researchers have determined that there is no correlation between helmet
acceleration and head acceleration, so they contend that determining a threshold of when injury to the brain occurs is a complex problem. The force
(acceleration) that the victim's skull and the brain floating within it experiences can be affected by the location and strength of the pressure wave
as well as by the helmet shape and resonant frequencies. The HIT research that the Simbex engineers have done has been used and cited by researchers
from the University of North Carolina, University of Illinois, and Virginia Tech (for example) in numerous peer-reviewed, scholarly publications. In
analyzing the blunt force impacts in sports with its patented HIT technology over the years, Simbex has measured more than 1.3 million injuries.
The combat helmet research by Simbex is funded by a federal Small Business Innovation Research (SBIR) grant sponsored by the U.S. Department of
Defense. Simbex is based in Lebanon, New Hampshire, and was founded by Dartmouth engineering professor Dr. Richard Greenwald and entrepreneur Robert Dean, Jr. The company is staffed by a number of other
engineers with associations to DartmouthCollege's Thayer School of Engineering; Simbex also maintains close ties with Dartmouth's business school and
medical school.
