There’s a saying that was popular among some generals during the war in Iraq: every soldier is a sensor. It speaks the potential of soldiers to collect and relay information to help the broader effort. But the equipment soldiers carry can also serve as a sensor, absorbing data about the soldier’s external experience as well as the physical and mental state of the person in uniform.
The military has been pushing to outfit troops with sensors capable of reporting biophysical feedback on blasts, shocks and other events to which soldiers are exposed. Researchers at the University in California at Berkeley have discovered a way to — potentially — make future body sensors more flexible, cheap and useful by moving away from silicon to an organic carbon compound.
UC-Berkeley researcher Ana C. Arias, head of the Arias Lab, along with fellow researchers Claire M. Lochner, Yasser Khan and Adrien Pierre have created a biosensor made from carbon that functions very similar to more expensive and less flexible silicon.
Here’s how it works: traditional sensors that read oxygen levels in the blood as well as pulse, so-called oximeters, clip to the ear or fingertip. A light-emitting diode (LED) shoots red light and ultraviolet light through the skin. Blood (or rather hemoglobin in blood) that’s rich in oxygen will glow bright red. Oxygen deprived of blood absorbs red light. Based on the light redness level, a computer can calculate the oxygen level in the blood. Arias and her team replaced inorganic LEDs with organic red and green ones to get accurate oxygen and pulse readings.
Image by Yasser Khan via UC Berkeley
Conventional biosensors made from silicon are inflexible and silicon, refined for electronics, can start at $250 per 100g. An oximeter can start at $10.
“We showed that if you take measurements with different wavelengths, it works, and if you use unconventional semiconductors, it works,” Arias said in a press release. Because the material is far more flexible than silicon, it can be attached to the body at points besides the ear or the fingertip, allowing for better and more numerous readings. And because the material is organic and inexpensive, it’s disposable, as opposed to traditional oximeters that hospitals typically clean and reuse.
Arias and her team published their findings in a recent issue of Nature Communications.
Oxygen levels in the blood can speak to a person’s level of alertness as well as overall general health. But here’s why this small breakthrough could be big for the military beyond just blood oxygen level.
Body sensors are going to play a growing role the way soldiers interact with equipment like flak jackets. In the summer of 2012, the Army’s Rapid-Equipping Force outfitted more than 1,000 soldiers in Afghanistan with a special Integrated Blast Effect Sensor Suite, or I-BESS, that could collect and transmit data related to how soldiers experienced nearby shocks and blasts. The system consisted of four sensors, two in the front of a vest and two in the back, and an accelerometer to measure force.
“We don’t really know what is causing traumatic brain injury today, and there are different theories, all of which require collecting environmental data that we can link back to medical outcomes,” Brian Liu, a researcher with the Georgia Tech Research Institute that developed the system for the Army told The Wall Street Journal reporter Laura Landro.
But the military is looking at a much wider set of applications for body sensors than just recording data blast info, including but not limited to heart rate and blood oxygen levels, which can speak to how well a soldier is performing and what the soldier is experiencing. It’s all information that could make its way into future electronic medical records, an area where the military is leading while the private sector lags. Years of carefully (and cheaply) collected biophysical data from cheap organic sensors could help the military heath system much better take care of the veteran of 2030.
Bio-physical signals could give commanders a bird’s eye-view of every soldiers’ current physical and mental state, everything from how rested a soldier is to the possible presence of toxins in the air or in the blood. It’s data that the military could use as part of ongoing efforts improve performance across the force.
Some of the more futuristic potential datasets that future biosensors could yield include galvanic skin response, which can speak to an individual’s mood or level of arousal or fear, based on the phenomenon where in the skin becomes a slightly better conductor of electricity when someone is aroused. That could provide a secret signal when a soldier is in trouble.
We also tend to store information during heightened arousal a bit better, so data on galvanic conductivity could provide clues as to memory, even, with enough data, personality.
But that’s not possible until the sensors can get out there closer to the soldier, a development that’s slightly closer to today.