Through a combination of careful theoretical modeling and precise micro-manufacturing, a team of engineers and scientists has developed a new type of ultra-thin, self-adhesive electronics device that can effectively measure data about the human heart, brain waves and muscle activity–all without the use of bulky equipment, conductive fluids or glues.
The researchers have created a new class of micro-electronics with a technology that they call an epidermal electronic system (EES). They have incorporated miniature sensors, light-emitting diodes, tiny transmitters and receivers and networks of carefully crafted wire filaments into their initial designs.
The technology is presented–along with initial measurements that researchers captured using the EES–in a paper by lead author Dae-Hyeong Kim of the University of Illinois and colleagues in the Aug. 12, 2011, issue of Science.
The EES device was developed by collaborators from the University of Illinois at Urbana-Champaign, Northwestern University, Tufts University, the Institute of High Performance Computing in Singapore, and Dalian University of Technology in China.
“Our goal was to develop an electronic technology that could integrate with the skin in a way that is mechanically and physiologically invisible to the user,” says corresponding author John Rogers, a professor in materials science and engineering department at the University of Illinois at Urbana-Champaign. “We found a solution that involves devices we designed to achieve physical properties that match to the epidermis itself. It’s a technology that blurs the distinction between electronics and biology.”
While existing technologies accurately measure heart rate, brain waves and muscle activity, EES devices offer the opportunity to seamlessly apply sensors that have almost no weight, no external wires and require negligible power.
Because of the small power requirements, the devices can draw power from stray (or transmitted) electromagnetic radiation through the process of induction and can harvest a portion of their energy requirements from miniature solar collectors.
The EES designs yield flat devices that are less than 50-microns thick–thinner than the diameter of a human hair–which are integrated onto the polyester backing familiar from stick-on tattoos.
The devices are so thin that close-contact forces called van der Waals interactions dominate the adhesion at the molecular level, so the electronic tattoos adhere to the skin without any glues and stay in place for hours.
The recent study demonstrated device lifetimes of up to 24 hours under ideal conditions.
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