Flexible electronic sensors, worn like temporary tattoos on the skin, could be used to detect everything from blood flow to cognitive function, according to a new study published in Nature Materials, led by John Rogers, who is also the cofounder of wearable sensor company MC10.

Rogers, a University of Illinois at Urbana-Champaign professor who has been working on flexible electronic sensors for several years, said he was initially approached by NIH temperature researchers after the publication of his original electronic sensor article in Science in 2011.

"When we were first approached by the NIH guys, temperature to me didn't seem to be a very compelling or interesting parameter. It turns out that it is, if you can measure it with extreme precision," he told MobiHealthNews. "If you can determine it to the third decimal place and accurately track the change at that level, it provides a lot of deep insight into physiological health."

The wearable sensors in the study were accurate to the same degree as the "gold standard" technology, a $250,000 infrared camera. But unlike the camera, the patch can do continuous monitoring without the need to maintain a line of sight.

Using just the temperature sensors, Rogers and his team were able to see when a subject was working out math problems in his or her head, based on minute changes in metabolism. He said this functionality could potentially be used for lie detectors. They were also able to track small physiological changes -- a patch on a subject's left hand could detect the subject rubbing his or her thumb and forefinger together on the right hand.

The electronics in the sensors could also convert them into actuators, generating one to two degrees of heat. Using a combination of actuators and temperature sensors, researchers could assess blood flow and skin conductivity, and extrapolate things like hydration.

Although this study was not officially affiliated with Cambridge, Massachusetts-based MC10, the company's BioStamp flexible sensors do build on Roger's work. He told MobiHealthNews that temperature sensors could be built into wearable devices along with other sensors.

"Imagine adding precision temperature to a suite of sensors," he said. "Use this along with accelerometry, blood oxygen, ECG. I think it adds into a pool of measurement modalities that could be really valuable."

Currently, the sensors are being used in a six-person pilot study at a Chicago hospital affiliated with Northwestern University. The hospital is using the sensors to monitor wound healing in post surgical patients. Although the sensors are currently being applied periodically, they are compatible with MC10 electronics which could allow them to monitor continuously and provide early warnings of infection, Rogers said.