The Body Electric – Personal Area Network (PAN).

By Bruce Schechter

Personal Area Network Technology Permits Individuals to Pass Identifying Information to Other People and to Machines Simply by Touching Them
In Brief:
Technology under development at IBM’s Almaden Research Center is designed to pass digital information between two individuals or between an individual and a device via a simple touch. To develop such personal area networks, or PANs, Almaden scientist Thomas G. Zimmerman developed technology that, in effect, transforms the human body into a copper cable. Zimmerman foresees initial use of PANs to identify people to devices that they own, such as automobiles and telephones.

A gentle touch. A firm handshake. A pat on the back. A lingering caress. All can communicate an enormous amount of emotion, understanding and compassion from one person to another. Now, Thomas G. Zimmerman, a scientist at IBM’s Almaden Research Center, has demonstrated how a touch can also be used to communicate unemotional digital information.

When businessmen equipped with Zimmerman’s technology shake hands, tiny computers in their pockets automatically exchange business cards across a fleshy personal area network, or PAN. As part of a PAN, a person would be instantly known to properly equipped cars or telephones, eliminating the need for keys or coins. Merely touching the telephone receiver or the car’s door handle would establish a data link across which identifying information could flow.

“Imagine a world,” Zimmerman says, “where everything is open to you and available to you.” PANs make this a possibility by allowing the human body to be a network across which electronic devices can freely communicate.

Wacky world of electronic invention
Zimmerman has been musing about the interaction of humans and computers since 1982 when, as he puts it, he “first surfaced in the wacky world of electronic invention.” His debut invention was spectacular: the data glove, the staple of virtual reality that first allowed humans to reach into cyberspace. He worked for Atari for a while before going off to found several companies, including the virtual reality pioneer VPL Research, which he started up with Jaron Lanier. Eventually, he was drawn to MIT’s Media Lab, where “all these cool things were happening under one roof.” There, he would be serendipitously led to the invention of the personal area network.

Some of the coolest things, Zimmerman soon discovered, were taking place in Neil Gershenfeld’s Physics and Media Group. Gershenfeld had been working with the renowned cellist Yo Yo Ma on ways in which technology could expand the expressive capabilities of his instrument. Gershenfeld was searching for a way to measure the details of Ma’s bowing and fingering without interfering with his instrument.

Gershenfeld hit on a method known as near-field coupling. In essence he placed electrical antennas on Ma’s cello and bow. Pairs of these antennas formed capacitors. As Ma moved his bow across his instrument, he changed the capacitance of the circuit. By measuring the capacitance it was possible to determine the position of Ma’s bow accurately.

In effect, Gershenfeld converted Ma’s bow into a computer mouse. The only problem was that a hand placed between the antennas also affected the capacitance, interfering with the position measurement. The interference problem had Gershenfeld baffled. At this point Zimmerman joined the group and discovered the source of the interference. With the help of a rubber glove stuffed with hamburger meat, he demonstrated that some of the signal was passing through the human body.

This human interference proved advantageous when the magicians Penn and Teller came to the Media Lab looking for some high-tech tricks. Penn wanted to baffle his audiences by playing a set of “air drums.” Zimmerman and Gershenfeld decided to use Penn’s body as one of the antennas in the system by having him sit on a chair with an electrode built into its seat. Four antennas suspended in front of the chair allowed Penn to play 128 different, invisible drums. The audience was amazed.

Making devices communicate
The final inspiration came when another group at the Media Lab asked Zimmerman and Gershenfeld to help develop a network that could connect all the devices a gadget-hungry person might carry. As electronic devices have become steadily smaller and cheaper, many people now walk around adorned with a half dozen or more information and communication devices – pagers, cell phones, personal digital assistants (PDAs), wristwatches and electronic games.

“None of these devices can talk to any of the others, which is both inconvenient and inefficient. A page comes in and the silicon-laden recipient has to reach into a pocket, read the number, perhaps punch it into a PDA to find out who is calling and then punch it into a cellular phone. In effect, he or she is devoting considerable mental capabilities to emulating an extremely low-bandwidth communication network.”

Zimmerman and Gershenfeld saw that modulating the electrical signal flowing through Penn’s body in the air drum trick – for example, turning it on to represent a 1 and off to represent a 0 – could enable the body to carry digital information. Using low frequency and low power would ensure that the signal would not propagate very far beyond the body; thus, only devices worn by the user, or by people or devices in direct contact with the user, could detect it. The current involved is extremely tiny and totally unnoticed by the user, whose body has been transformed into a meaty version of a copper cable: a personal area network.

“The near-field effect used to make PAN possible has many advantages over other methods of short-range wireless communication. Even low-powered radio waves travel far enough to make eavesdropping and interference a real problem. Since the human body acts like a bag of salt water and shadows radio waves, a device on your lapel might not be able to communicate with one in your back pocket. In addition, the radio spectrum is already crowded, and the licensing requirements for radio communications are complex and vary from country to country. Infrared communication is limited by line of sight.”

Zimmerman understood that security is a serious problem for PANs. Touching a person equipped with a PAN is like tapping a phone line. This is an advantage when an exchange of information is desired, but a problem when privacy is important. Since coming to IBM in 1995, Zimmerman has collaborated with Almaden’s Prabhakar Raghavan and Don Coppersmith of the Thomas J. Watson Research Center to develop a security method using encryption that makes the PAN data look like a stream of random bits to would-be eavesdroppers.

CEOs holding hands
The version of the PAN that Zimmerman has been showing off is about the size of a pack of cigarettes. On the back of the PAN devices are metal plates, one of which must face the body while the other faces outward to establish a ground connection with the earth. The bandwidth of the PAN is relatively small, about that of a low-speed modem. That’s not sufficient to transmit video but more than enough to carry identification, financial or medical information.

At a recent show, Zimmerman enlisted several CEOs from some of the world’s largest corporations to hold hands, forming one of the highest-priced data networks in history. Information on the card of the CEO on one end of the network flowed through the intervening bodies and was detected by the card at the far end.

High-tech business cards are unlikely to be the first applications of PANs. For that to catch on, it will be necessary for almost everyone to be equipped with the cards. Instead, Zimmerman believes that PANs will be used to identify people to devices. “Imagine a thing like this,” he says, fishing a credit-card-sized device from his pocket. “It just sits in my wallet and I never take it out. I pick up a pay phone and it autodials my calling card number. So I dial the phone just as if it were my home phone. An ATM machine is just my top drawer at home with the cash in it. You just grab your car door and open it. It’s really locked; but as soon as you grab it, the PAN uploads your ID, the car acknowledges that it’s you and it unlocks.”

Information, in Zimmerman’s vision, will become contagious, flowing freely from person to person and computer to computer. By doing so, it will give a new twist on what it means to keep in touch.

Bruce Schechter is a science writer based in Los Angeles. He is currently writing a book on the life and times of Paul Erdös.

Check also this article

Propagation Characteristics of Intra-body Communications for Body Area Networks


Human body as a communication medium : DigInfo


µ-Chip. The World’s smallest RFID IC – Radio Frequency Identification Intergated Circuit

Electronic Numbering of Products and Documents using the “µ-Chip” (or mu-chip) supported by a Networked Database unleashes new Business and Life Style Applications that facilitate innovative Manufacturing, Distribution, Consumption, Tracking and Recycling operations.

*Size compared to a human fingertip

The RFID, wireless semiconductor integrated circuit that stores an ID number in its memory, was proposed about a decade ago as an alternative to the barcode. Its use, however, has so far been limited to a few applications where its advantages offset its relatively high cost.

The µ-Chip is Hitachi’s response to resolving some of the issues associated with conventional RFID technology. The µ-Chip uses the frequency of 2.45GHz. It has a 128-bit ROM for storing the ID with no write-read and no anti-collision capabilities. Its unique ID numbers can be used to individually identify trillions of trillions of objects with no duplication. Moreover with a size of 0.4mm square, the µ-Chip is small enough to be attached to a variety of minute objects including embedding in paper.

Manufacturing, distribution and tracking systems can be built or enhanced using the µ-Chip with an event-driven accumulation of, and on-demand access to, information stored in a database through the network. By coupling this database with the versatility of the µ-Chip new business and life styles applications can now be brought to reality. These new applications allow manufacturing, commerce and recycling processes to be operated in a way that has not been possible before.


September 2, 2003

Hitachi Develops a New RFID with Embedded Antenna µ-Chip
–Makes Possible Wireless Links that Work Using Nothing More Than a 0.4mm X 0.4mm Chip, One of the World’s Smallest ICs–

Tokyo, September 2, 2003-Hitachi, Ltd. (TSE: 6501) today announced that it has developed a new version of its RFID µ-Chip embedding an antenna. When using Hitachi’s original µ-Chip, one of the world’s smallest RFID ICs measuring only 0.4mm X 0.4mm, an external antenna must be attached to the chip to allow external devices to read the 128-bit ID number stored in its ROM (Read-Only-Memory). This newly developed version, however, features an internal antenna, enabling chips to employ the energy of incoming electrical waves to wirelessly transmit its ID number to a reader. The 0.4mm X 0.4mm chip can thus operate entirely on its own, making it possible to use µ-Chip as RFID IC tags without the need to attach external devices. This breakthrough opens the door to using µ-Chips as RFID IC tags in extremely minute and precise applications that had been impractical until now. For example, the new µ-Chip can be easily embedded in bank notes, gift certificates, documents and whole paper media etc.

The µ-Chip, announced by Hitachi in July 2001, is one of the world’s smallest IC chips at 0.4mm X 0.4mm. The chip data is recorded in read-only memory during the semiconductor production process, and therefore cannot be rewritten, thus guaranteeing its authenticity. Applications of the µ-Chip include a system for managing the SCM materials on sites, and entrance tickets for Expo 2005 Aichi Japan which opens on March 25, 2005.

The primary features of this revolutionary µ-Chip are as follows.

(1) A RFID IC chip measuring only 0.4mm X 0.4mm with built-in antenna

Despite its extremely small size, this µ-Chip has a built-in antenna to permit contactless communications (at very close proximity) with other devices without using an external antenna.

(2) No need for special manufacturing equipment

The antenna is formed using bump-metalization technology (used to create the electrical contacts of an IC), a process already widely used by semiconductor manufacturers, thus eliminating any need for specialized equipment.

(3) Complete compatibility with conventional µ-Chip

With ID numbers and support systems that are fully compatible with those of existing µ-Chip, the new chip is fully compatible with all systems that use current µ-Chip technology.

Hitachi plans to develop numerous markets for this chip that take full advantage of its outstanding features. Embedding the chip in securities, identification and other valuable documents such as vouchers offers a highly sophisticated means of preventing counterfeiting. Another high-potential application is agricultural products, where the chips can help ensure the safety of food by providing traceability of ingredients. Additionally, the chips can be embedded in business forms to automate logistics systems and many other business processes.

About Hitachi, Ltd.

Hitachi, Ltd. (NYSE: HIT), headquartered in Tokyo, Japan, is a leading global electronics company, with approximately 340,000 employees worldwide. Fiscal 2002 (ended March 31, 2003) consolidated sales totaled 8,191.7 billion yen ($68.3 billion). The company offers a wide range of systems, products and services in market sectors, including information systems, electronic devices, power and industrial systems, consumer products, materials and financial services. For more information on Hitachi, please visit the company’s Web site at

Technical Description

Specifications of µ-Chip

Simple Mechanism :

128-bit read only memory, no anti-collision control

Super-micro Chip: 0.4 mm x 0.4mm

Battery Less:

The µ-Chip a passive IC, that receives the microwave from the reader, generates electric power from the microwave, decodes its µ-Chip ID and transmits it back to the reader.

Unique ID (µ-Chip ID):

Each µ-Chip stores unique 128-bit data in its ROM as its ID, to distinguish it from the others.

Radio Frequency:

2.45 GHz

Maxmum Communication Length:

about 25 cm (with an external antenna) (Reader: 300mW, 4 Pach Antenna, Circular Polarization)

Response Time:



When the reader is activated by a terminal device (PC), it radiates microwave on to the µ-Chip attached to a carrying article and the µ-Chip returns its µ-Chip ID to the reader. The carrying article may be a tag, a label or a customers products.
Database Query:
The terminal device authenticates the µ-Chip ID and uses it to retrieve information from the database about the article carrying the µ-Chip. The result of the query can be displayed on the terminal device or used by a software application.
Database Construction:
The database may be located at the site server or at the central server and stores attributes of the µ-Chip carrying article. Information associated with the event of readout may be used to update the database.
Linking each µ-Chip ID to the carrying article is performed upon application of the µ-Chip to it.
The attributes of the article at this point comprise the basic entry to the database. For efficient, automated linking process, consultation and engineering services are available.

Printable Nanocircuits Promise to Make RFID Tags More Ubiquitous Than Bar Codes.

The product would also be the first to use printed nanotube transistors
Printable RFID Tags Here’s hoping to printable tags at a penny a pop Gyou-Jin Cho/Sunchon National University

Bar codes in the supermarket might face extinction sooner rather than later, if radio-frequency identification (RFID) tags can cost just a penny apiece, rather than the dime or more they currently run. Now South Korean researchers say they have the technology to print RFID circuits on plastic film, courtesy of nanotube-containing inks, Technology Review reports.

A version of the RFID tags slated to hit the market later this year would be the first product to use printed transistors based on carbon nanotubes. Printing means the application of different layers of antenna coils, nanotube inks, and capacitors and diodes.

The researchers at Sunchon National University in South Korea successfully printed out the plastic RFID tags using common industrial methods such as roll-to-roll printing, ink-jet printing, and silicone rubber-stamping.

These processes churn out tags for just three cents per piece, but the group ultimately hopes to pass the one-cent milestone by figuring out how to lay down all the nanotube ink layers in one go during the roll-to-roll printing. Many RFID tags today cost anywhere from 7 cents to 15 cents, if not more.

Cheap RFID: Pleasingly cheap, flexible, and cheap  Gyou-Jin Cho/Sunchon National University

But some hurdles remain before you’ll see these newer tags at checkout lines. The current prototypes are three times the size of a typical barcode, and can only store one bit of information — just enough to either give a yes or no response to an RFID reader. Such tags also only work with readers up to 10 centimeters away, because of their weak power signals. 

That should change with the 64-bit tag set to come out next year, and then ultimately a 96-bit tag, a real barcode-killer.

Even the pricier RFID tags today have already found use in EZPass highway tolls and as anti-counterfeiting devices.

[via Technology Review]