Wireless Technology Promises Smarter Packages

FRAMINGHAM (04/24/2000) - Just as the optical laser scanner revolutionized grocery shopping, a new technology from Motorola Inc. promises to take that kind of identification and control to a new level, applying it to nearly anything that can be printed or have a label stuck on it. The basic idea is a new take on wireless, radio-frequency identification (RFID), a technology that's been around for years.

How It Works: Old Style

Until now, RFID systems have used the electrical property called inductance and have required the RFID tag - or transponder - to contain three elements: a metal coil antenna to generate electricity; a computer chip containing a radio transceiver, an analog-to-digital converter, memory and a processor; and a core of air or ferrite rod. Some tags also have their own batteries.

In operation, the RFID reader generates a low-level radio-frequency magnetic field that resonates with the tag's metal coil and capacitor, creating an electrical signal that powers the computer chip, which then transmits its stored data back to the reader. The process works well, but the tags are expensive - as much as $200 each. In recent years, that cost has fallen to less than $1 per tag, but that's still too expensive for all but high-priced items.

A Better Way

BiStatix, a new technology from Schaumburg, Illinois-based Motorola, changes that equation dramatically. BiStatix tags have only a silicon chip that's attached to carbon ink electrodes printed on the back of a paper label. Tags are printed by any known printing technique on standard printing equipment, and the electrodes can be virtually any size and shape.

The RFID silicon is simply attached to the printed substrate, with no need for a special interconnect. Thus, it can be put directly on a package during manufacture, or it can be added later.

BiStatix works on a capacitive coupling principle. A BiStatix reader/writer generates an excitation field that serves as both the tag's source of power and its master clock. The tag cyclically modulates its data contents and transmits it to the reader's receiver circuit. The reader decodes the data signal and formats it for sending to a host computer for further processing.

One of the significant advantages of any RFID system is that many different items - such as the entire contents of a shopping cart or of a sealed carton - can be read all at once and without requiring physical contact.

The BiStatix technology also has several characteristics that make it suitable for a wide variety of new situations and applications.

First, it's cheap. BiStatix uses an elegantly simple manufacturing process that can be implemented at the point of printing or paper converting. Conventional printing processes replace expensive coil-winding, stamping and etching.

(Information on exact pricing was unavailable.)Second, it can be incorporated into or applied onto almost any object. BiStatix is physically flexible and can be applied to corners, curved surfaces and odd shapes without danger of antenna breakage. Any nonconductive material can serve as a substrate. BiStatix chips are less than 250 microns thin (0.010 in.), with a surface area of less than 3mm.

Thus, they can be easily used in an unobtrusive manner. For example, a roll of preprinted, BiStatix-enabled tickets could be programmed and dispensed from a printer because the system's low profile and flexibility allow it to be used in roller-driven devices.

Third, the system is relatively indestructible in the short term - the substrate can be torn, folded, spindled or mutilated, and the tag will still operate properly. Because there isn't a capacitor to charge up, the tags can't be detuned. Tears, folding or punched holes won't make the BiStatix tags inoperable, as long as the chip remains intact. Tags can be read without a clear line of sight, and their readability is unaffected by moisture, dirt, dust or paint.

Finally, BiStatix tags have read/write capability, so that an existing stock of tags can be reprogrammed after manufacture or initial application. The data they contain can be changed, updated and/or locked.

Taken together, these traits make the new system well-suited for a wide variety of short-term, high-volume applications, ranging from supermarket inventory and checkout control to hotel keys, hospital patient wristbands, theme-park admission tickets and more.

‘Smart Mail' Testing

The U.S. Postal Service has been experimenting with "smart mail," using BiStatix as an adjunct to bar codes for tracking individual pieces of mail en route by "smart-mail boxes" or for quickly locating a piece in a stack of envelopes or a warehouse full of packages. Luggage control and identification at airports is another area where BiStatix technology would be beneficial.

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