An invisible patch placed on the skin much like a temporary tattoo can pick up and transmit physiological signals, such as heart rate, brain waves and muscle activity, which can bend, wrinkle and stretch similar to properties of human skin.

The researchers demonstrated their concept through a diverse array of electronic components mounted on a thin, rubbery substrate, including sensors, LEDs, transistors, radio frequency capacitors, wireless antennas, and conductive coils and solar cells for power.

“We threw everything in our bag of tricks onto that platform, and then added a few other new ideas on top of those, to show that we could make it work,” said John Rogers, a professor of materials science and engineering at the University of Illinois Urbana-Champaign.

The epidermal electronic system (EES) improves on existing products and processes, many of them borrowed from Silicon Valley and the semiconductor industry.

"Our goal was to develop an electronic technology that could integrate with the skin in a way that is invisible to the user,” Rogers, who led the study, told BBC News on Thursday.

The EES might also form the basis of a "smart" Band-Aid in the future, by using electrical stimulation to accelerate wound healing.

BBC News reports that there are also tiny solar cells which can generate power or get energy from electromagnetic radiation. The device is small, less than 50 micrometers thick - less than the diameter of a human hair.

The sensor is mounted on to a water-soluble sheet of plastic, so it is attached to the body by brushing with water, just like a temporary tattoo, the British news wire reported.

"I can't feel its presence," said John Rogers, senior author of a paper on the patch published in the Aug. 12 issue of Science, who demonstrated the two-inch-square device on his forearm during a Wednesday teleconference.

"The distinction between electronics and the skin is blurred. It's much like a temporary transfer tattoo, though this has high-quality electronics embedded," said Rogers.

The EES has an antenna, and is functional.

The researchers' next challenge is make all the different elements work as a coherent system, to add Wi-Fi and to figure out the best power sources, such as batteries, wireless coils and solar cells.

"This is not [yet] a fully integrated system with all the bells and whistles we hope to achieve. The story doesn't end here," Rogers said.

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