Can Packaging Materials Foil RFID Success?

May 5, 2006
Little research has been done on the impact that metals, glass and other drug packaging materials have on the effectiveness and read ranges of RFID. Even cardboard can affect RF signals if it has a certain moisture content, says Michigan State’s Robb Clarke.

If there’s anything that’s well understood about how drug packaging materials impact the success of RFID applications, it is that nothing is well understood. Some materials, such as metal foils, can compromise signal strength and significantly reduce the read-rate percentages that manufacturers will experience in their RFID applications. There is much guesswork but little research and data to support any hypotheses.

Robb Clarke, assistant professor in the school of packaging at Michigan State University has probably done more work in this area than anybody, and has come to some tentative conclusions, with the understanding that future research possibilities are wide open.

We spoke with Clarke to get some general impressions of the effect that packaging materials can have on RF signals. A more detailed article based upon talks with various experts — including Pfizer’s Tim Marsh, Purdue Pharma’s Harry Ramsey, IBM’s Paul Chang, and Odin Technologies’ Patrick Sweeney — will appear in the June issue of Pharmaceutical Manufacturing and on (Editor's Note: Gain rapid access to such articles and keep your finger on the pulse of drug security and supply chain management issues by clicking here to register for our monthly Pharma Track & Trace e-newsletter.)

“Anything with metal is a killer,” Clarke says. This is particularly true of UHF (ultra high frequency) applications, which simply will not work in the vicinity of water or metallic substances. “A lot of applications have water-based compounds, which renders UHF unreliable,” he says. “HF has better opportunities around water and some degrading metals.”

For this reason, most agree that HF is the only viable option for item-level RFID tagging in the pharmaceutical industry. HF tags can work around metals such as foils on blister packs, Clarke says, if there is significant separation (at least a few millimeters) between the tag and metal.

The effect that water can have is less understood. Some of the earliest tests on UHF, such as those that Ortho Biotech did with Procrit, may have been misleading, Clarke notes. The UHF tags read easily, but there is less than 1% water in Procrit tablets, he says, and the packaging materials were fairly straightforward. For liquid products such as biologicals, RF signals can be significantly compromised and manufacturers will likely undergo significant trial and error before finding suitable solutions.

Like many, Clarke is intrigued by the work that RFID hardware supplier Impinj is doing on “near-field” applications of UHF, which are based on the concept of inductive coupling and may circumvent the issues with water and metals. If the technology can be perfected, Clarke says that it could reignite the debate over whether HF or UHF is best for item-level applications, and allow manufacturers to reliably use UHF at the item, case and pallet level.

Clarke has also studied the impact that even slight amounts of moisture in packaging materials can have on RF signal readability. If, for example, cardboard packaging pulls moisture out of the air, it can seriously degrade the radio signal. Even after it has dried, the cardboard will still retain a “memory” of the moisture and continue to inhibit the performance of the RFID equipment — an effect known as hysteresis.

Finally, Clarke notes that certain glasses and plastics are not RF-friendly, particularly if they contain chemical additives. In some tests, Clarke and colleagues placed tags inside and outside of glass bottles, and found that reading distances were reduced by as much as 50%.

There is much yet to be learned about the mysteries of RFID, Clarke notes. “We’re still working on it — everyone is!” he says. “Nobody is getting near 100% read rates consistently.”

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Paul Thomas | Managing Editor