The majority of deaths on the battlefield occur within half an hour after injury--often too quickly for a soldier to get to a medic, let alone a hospital. But a collaboration between researchers at the University of California, San Diego (UCSD), and Clarkson University, in New York, aims to change all that with a chip that could detect injuries and treat them almost instantly.

At the center of the research is a sensor, still in development, that could be used to continuously monitor a soldier's blood, sweat, or even tears for biomarkers. All of these fluids contain glucose, oxygen, lactase, and the hormone norepinephrine, which fluctuate depending on a person's health and activity levels. Specific, collective changes in these markers can indicate the presence of an injury. And once the sensor picks that up, it could transmit the information elsewhere on the chip, or to another chip, and trigger release of an appropriate medication. That, at least, is the idea; the reality, however, could take a little while to develop.

The head of the project, Joseph Wang, is a nanoengineering professor at UCSD whose office is packed with electronic sensors of every shape but only two sizes: small and even smaller. Wang, who previously helped develop a noninvasive glucose monitor that samples sweat, is no stranger to continuous sensing. But rather than picking up just one signal, the new sensor will need to differentiate among multiple markers and interpret the results.

To do this, Wang is collaborating with Clarkson's Evgeny Katz, who recently created a system that uses an enzyme-based logic gate to not only measure a combination of biomarkers but also use the results to make a limited diagnosis. Katz's system is based on enzyme-driven reactions: in the presence of certain enzymatic products, one set of "gates" is unlocked and triggers a specific chain reaction; other products trigger a completely different set of gates. The end result is a logic chain that has the potential to identify certain medical conditions.

So far, Katz's enzyme logic diagnostics work only in solution. But Wang and Katz envision a system that would use an electronic sensor, one containing enzymes, to detect the presence or absence of the four biomarkers mentioned above: glucose, oxygen, lactase, and norepinephrine. In different combinations, these biomarkers can indicate different injuries, such as brain trauma or shock. Depending on the injury, the electrodes would translate the enzymatic results into a code that activates signal-dependent membranes to release the appropriate medication. If a soldier were to go into hemorrhagic shock, for example, the electrode would detect rising levels of lactate, glucose, and norepinephrine. As the electrode enzymes' product mixture begins to change, the reaction would trigger the logic gate unique to shock and, potentially, signal for the release of the appropriate medication. "We want to build a smart, intelligent sensor that can distinguish between different injuries, make the decision to treat, and, once it recognizes the injury, treat appropriately," Wang says.