August 11, 2011. Copyright 2011, Graphic News. All rights reserved

Tattoo technology aids medical monitoring

LONDON, August 11, Graphic News: An ultra-thin electronic device that attaches to the skin like a temporary tattoo can measure heart rate and other vital signs without the bulky electrodes used in current hospital monitoring. The device could also potentially be used as an electronic bandage to speed up wound healing, burns and other skin conditions, and could even provide touch sense to prosthetic devices such as artificial legs or arms.

The complicated wiring involved in current hospital monitoring can be inconvenient and distressing for both patients and doctors. For example, a patient who may have heart disease is usually required to wear a bulky monitor for a month or more in order to capture abnormal but rare cardiac events. The current best electrodes are gel-coated adhesive pads. Many people, particularly those who have sensitive skins, can develop a rash.

The electronic skin sits on a layer of rubbery polyester engineered to have mechanical properties well matched to those of natural skin. The device sticks to the skin using "van der Waals" forces -- the molecular-level adhesion that gives a gecko the ability to hang on a glass surface using only one toe.

The epidermal electronic system (EES) incorporates miniature sensors, light-emitting diodes, tiny transmitters and receivers, and networks of carefully crafted wire filaments -- all squeezed into an ultra-thin layer about the thickness of a human hair. A wireless power coil draws electricity from stray or transmitted electromagnetic radiation through the process of induction.

"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 John Rogers, a professor in the 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."

The researchers tested the electronic skin on participants and showed that the device works for up to 24 hours or more on the arm, neck, forehead, cheek and chin, and that it doesn't irritate the skin. The team then used the device to take measurements of the electrical activity produced by the heart and leg muscles of the participants, and found that the device's signals matched signals taken simultaneously with the conventional setup of bulk electrodes, conductive gel and tape.

The results suggest that electronic skins could one day replace conventional hospital monitoring techniques. The device was developed by collaborators from the University of Illinois, Northwestern University, Tufts University, the Institute of High Performance Computing in Singapore, and Dalian University of Technology in China. The research appears in the August 12, 2011 issue of Science.
/ENDS