Welcome to the Internet of Skin

The average adult has between 1.5 and 2.0 square-meters of skin—all of it feeling all of the time. Skin offers a continuous monitoring of outside conditions and fills a sensory role that is even a bit hard to pin down. Touch: the body's wilderness of nerve endings. There is temperature and pain and pressure, of course, but also the delicate narcotic of another's fingers lightly brushing against it. Touch is what's between us and everything else, for better or for worse

It should be no surprise to learn that engineers are fascinated by skin and its sensory potential. A new paper published in the IEEE's Nanotechnology Magazine outlines the concept of "smart skins" and their fabrication using ink-jet printing—a cheap and "green" alternative to conventional electronics manufacturing. The ink: a solution of carbon nanotubes, particles highly desirable for their malleable electrical conductivity and chemical sensitivity.

"Because of their large surface area, carbon nanomaterials have the ability to physically and chemically absorb the chemicals on their surface," the authors, led by Georgia Tech electrical engineering professor Manos M. Tentzeris, write. "These carbon nanomaterials then alter their properties, which is the foundation for the chemical sensor applications."

Tentzeris and co. explain that it should be possible to print these carbon-based inks at enormous scales, perhaps using substrates (paper, likely) multiple kilometers in length. The group's prototype technique consists of graphene-oxide printed onto Kodak photo paper, which is then cured and imprinted with a different, silver nanoparticle-based ink, which forms the skin's external circuitry. Finally, an RFID integrated circuit is connected. This skin is wireless.

That last part is where things get really interesting. Tentzeris' skin is connected to a wireless identification and sensing platform (WISP), which is available as an off-the-shelf technology—read: an inexpensive technology—capable of harvesting power from its environment, sensing (obviously), on-board signal processing, and transmitting signals back to an RFID reader on-demand.

"Their light weight, low cost, outstanding electrical conductivity, and ease of fictionalization targeted for a broad range of chemicals make these carbon materials ideal candidates for the development of a wide spectrum of portable and wearable sensors," Tentzeris' group writes.

The promise, according to the current paper, is nothing less than sensing ubiquity. Indeed, this is more or less the definition of the Internet of Things—everything connected, always—which has been projected to be a $15 trillion industry in just a few years time. Already there are several billion sensors online, but the industry Vision is of over a trillion.

"In short," the Georgia Tech group concludes, "these smart skins could prove to be the ultimate sensing tool that could potentially allow for the mass implementation of a perpetual wireless network even in extremely rugged environments."