Adventures in the Skin Trade

NTT Lab wants to build commercial technologies using its RedTacton technology, which enables devices to communicate by using the electrical fields on the human skin.

This month, NTT Labs, the research and development wing of Nippon Telegraph and Telephone Corporation, plans to start conducting field trials for a radical new "human area networking" technology called RedTacton that uses the naturally-occurring electrical fields of human skin to transmit data.

The slim, PCMCIA-based RedTacton transceiver combines an optical receiver circuit equipped with a super-sensitive photonic electrical field sensor and a crystal to transmit data over the surface of human body at up to 10 megabits per second between wearable devices.

Linked only by touch, the transceivers can also connect to similar transceivers worn by other users or embedded in any objects in real space, such as turnstiles or consumer electronics. Promising better security and far less interference than short-range wireless technologies such as Bluetooth, ZigBee and Near-Field Communications, RedTacton will likely be targeted for use in applications such as wireless headphones, wearable medical devices, security applications, and point-of-sale interactions.

RedTacton may be new, but the guiding principles behind it have been around for almost a decade. In 1996, MIT Media Lab researchers Thomas Zimmerman and Neil Gershenfeld published a paper that quickly engaged the mainstream media. The team developed a prototype of an intra-body communication network that exploited minute electrical fluctuations along the surface of the human skin to transmit data between devices. Penn and Teller used the technology for a magic trick in which a musical instrument was played without it being touched. IBM Almaden Research Center, which had backed the project, quickly snapped up Zimmerman and the technology for wearable-computer networks.

To date, though, no applications have seen the light of day. In fact, since then, there are has been little more heard on the subject. Further research was done at MIT, The University of Washington, The University of Tokyo, Microsoft, Sony, and Matsushita, but nobody seemed to be able to overcome the basic barriers of distance (measured in centimeters) and limited bandwidth (low double-digit kilobits per second). The dream of having two people shake hands and exchange anything more than the contents of a business card between wrist-mounted computers seemed nowhere in sight.

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Enter Mitsuru Shinagawa, a Distinguished Technical Member of NTT's Smart Devices Laboratory. Several years ago, Shinagawa had been working with the latest electro-optical sensors for a project on integrated circuit probes when he decided to apply the gizmos to the old intra-body problem. Replacing the electrical sensors of a Media Lab-style system with faster lasers and electro-optic sensors showed dramatic results.

"The first breakthrough was the idea to apply EO sensors," says Hideki Sakamoto, senior manager for NTT's R&D Strategy Department. "We accidentally realized that highly sensitive integrated circuit probes could be used for communication over the human body."