Madison, Wis. — The UW RFID Lab at the University of Wisconsin-Madison aims to solve the host of thorny problems that prevent radio-frequency identification technology from becoming a truly cost-effective tool. For supply chain managers and RFID tag users, those issues range from the physics of signal propagation right up to logistics.

Alfonso Gutierrez, who heads the lab, acknowledged that "we have a ways to go" before achieving workable levels of cost and reliability for RFID technology. The lab, which last month opened its doors to the public for the first time, was founded as a collaborative, noncommercial "industry/university" forum to "analyze the true capabilities and limitations of RFID technologies — what works and what doesn't work," Gutierrez said.

In putting RFID tags into actual products, the devil is in the details. Gutierrez cited the potential technical challenges for a beverage company that wants to track canned soda with RFID tags. It's a challenge because the radio waves that underlie RFID technology can go haywire when placed close to certain items containing liquid or metal. For example, liquids, like soda in a can, tend to absorb the electromagnetic energy needed to power the RFID chip. Meanwhile, the metal of the soda can tends to reflect this energy, bouncing it around in unpredictable ways. In either case, the RFID signal sent by a chip to the reader faces interference, thus dramatically reducing read rates for RFID tags.

Nevertheless, the RFID industry has made significant strides in bringing new standards and new silicon to market. The Electronic Product Code Generation 2 (EPC Gen2) standard is in the ratification stage at the International Organization for Standardization. The standard will ensure that any RFID tags based on it can be read anywhere in the world. Many chip vendors, including Philips Semiconductors, Texas Instruments and Impinj, are sampling EPC Gen2-compliant RFID chips to reader makers and label manufacturers.

Even with new standards and agreements, when it comes to real-world implementation issues, such as "how product contents, packaging and media affect RFID performance," many questions remain largely unanswered, said Gutierrez.

An RFID tag consists of a microchip strapped into an inlay, antenna and substrate. The quality of the antenna inside each RFID tag matters, because it has a dramatic impact on RFID system performance and its overall network architecture.

The industry needs "millions of tags to bring down the cost of RFID," said Gutierrez. And yet, the physics of RFID technology doesn't allow a "one-size-fits-all approach," he noted. The industry may eventually need an antenna that's custom-designed just for soda in a can, or figure out an entirely new RFID-friendly packaging design for canned soda, Gutierrez predicted.

Things like canned soda and bottled water represent only a fraction of the RFID challenge. Paper product companies such as Kimberly-Clark Corp. are having problems placing RFID tags on baby wipes because the RF signals are absorbed by the moisture in them.

Gutierrez acknowledged that "the technology is not there" to make item-level tagging a reality.

Indeed, even Wal-Mart, which has ordered its top-100 suppliers to apply passive RFID tags based on global Electronic Product Code standards for merchandise shipped to specific distribution centers, is currently focused only on case- and pallet-level tagging. A Wal-Mart spokeswoman told EE Times, "We don't foresee every item in our stores being tagged for at least 10 to 15 years."

The UW RFID Lab is engaged in initiatives that include the "initial assessment of opportunities for implementing RFID," said Gutierrez, and "testing product ideas such as conductive inks for antennae and defining substrates in an RFID tag." Many projects are still evolving, since the lab will not only work on basic and applied RFID research, but also with individual companies on sponsored, company-specific projects.

At a time when a number of universities around the country, including the Massachusetts Institute of Technology, the University of Kansas and the University of Arkansas, are setting up similar RFID labs to study RFID implementation, Gutierrez's group hopes to differentiate itself by leveraging its core competencies in antenna design and materials science.

'Pure environment'
The university lab is furnished with a portal/dock door station and a conveyor belt system capable of moving at 600 feet per minute. Both help to simulate real-world conditions that allow users in the RFID community to determine how well their system works.

One of the lab's most important features is its large anechoic chamber, which includes RF field measurement and analysis instrumentation and simulation software. It can be used to create the "pure environment" that's vital to tag antenna design; to measure RFID-tag chip impedance; and to establish antenna parameters such as radiation pattern, gain and polarization. It can also conduct electrostatic discharge analysis for RFID tags, which is essential for judging their durability. ESD can short-circuit a chip or trigger mechanical failure.

In the future, the lab hopes to integrate RFID tags with sensors. The promise of RFID is "making a network of sensors a reality at the right cost," said Gutierrez. While an RFID tag today may warn a supermarket manager about the expiring freshness of his beef supply, RFID technology will evolve eventually toward sophisticated sensors that measure the level of bacterial buildup inside the meat and communicate such information wirelessly.

The University of Wisconsin has provided more than $60,000 in seed money for the lab. The RFID industry will provide the lion's share — about $500,000 — including hardware, software and labor.