DARPA is developing skin-adherent sensors are to monitor troops vital signs possibly in real time. Military scientists believe that using the device — preferably a tattoo — to track heart-rate, temperature or bio-electric response during various training situations will help them crack the code of combat fatigue. The solicitation, which opened last month, hopes new technologies can transcend the current paradigm of patient monitoring of needles, gels and electrodes. And advanced materials make it possible to integrate everything from the sensors to the transmitter into thumb-sized membranes that can stick to skin — like temporary tattoos.
Darpa is hoping that whichever company wins the research contract will be able to use a relatively new technology known as epidermal electronic systems (EES) to make sensors that are both unobtrusive and durable enough for modern combat training. Using state-of-the-art, highly flexible materials, researchers can coil sensors, electronics, and transmitters into serpentine shapes that form a stretchable net. “This innovative design contains all of the necessary components in an ultrathin layer about the thickness of a human hair,” writes Zhenqiang Ma, an electrical engineer at the University of Wisconsin, in a review of the technology.
They are nearly as flexible as hair, too, and adhere to the skin using strong molecular forces. According to research by EES’ inventors at University of Illinois at Urbana-Champaign, they can be pinched, poked, pulled, and stretched without damaging the device. In one experiment, researchers left a sensor tattoo attached to their subjects’ necks for over 24 hours before it wore off.
These tiny arrays combine the necessary sensor — be it EKG, heart rate, or temperature — with a short-wave antenna and transmitting capability. Using tiny power sources that collect solar energy or stray electromagnetic radiation, the data can be collected in real time and sent to handheld devices.