The sensors were built using existing technologies -- it's the algorithms in the hub that make the system unique, says Freund. For example, hydration is assessed by measuring how much water escapes from the bladder-style canteen. Based on an analysis of drinking patterns, the hub can tell the difference between a soldier's sips and slow, steady water loss to a leak. The hub will send out a "grey" signal if there is no heart rate or respiration for five minutes, but it knows when this occurs because the soldier has taken off his sensors, and will send a "blue" signal instead, for "unknown." Along with a health status report, the hub sends out a confidence rating -- "You know when you don't know," as Freund puts it -- so that medical resources won't be misdirected.

Currently, the hub sends and receives information using radio frequencies, but this could change, since its architecture is open-ended. Using internal radios, it currently works at short range up to 100 meters; for long-range uses, it connects to commercial or field radios. Data from the system have also been sent through a cell-phone text-messaging system for long distances in real time.

Michael Cima, MIT professor of materials science and engineering who works on medical devices and is associated with MIT's Institute for Soldier Nanotechnologies, is "very impressed" with the monitoring system. Because the system is modular, he says, it could easily be adapted for other uses in health care. Cima says he believes the Army research will lead to medical technologies for monitoring patients after they've left the hospital.

Actual deployment of the monitoring system will happen piecemeal. Buller says the sleep-monitoring watches are already being field-tested on pilots in Iraq. These devices use accelerometers to collect information about body movement -- information that can be analyzed to determine whether the wearer is awake or asleep. Every branch of the armed services won't want or need all the information the sensors are capable of generating. But the Army is collaborating with NASA, the Navy, and the Air Force, who are interested in using the system to create flight suits that respond to changes in G-force.

Home page image courtesy of the U.S. Army.