New UHF RFID Tag Can Be Read On and Around Metal

By Claire Swedberg

Securitag Assembly Group's Overmolded Uni Metal Tag is designed to bring on-metal reading to users that had been unable to make RFID technology work in the past.

Taiwan's Securitag Assembly Group (SAG) has built its company history around solving radio frequency identification technology challenges, such as difficult form factors and reading environments. This year, the firm has developed the Overmolded Uni Metal Tag to bring on-metal RFID reading to users that had previously not been able to make RFID technology work. The tag uses a metal object to which it is attached as an RF antenna. It is being used in the industrial and logistics sectors, as well as by manufacturers to track work-in-progress and enable assembly automation.

SAG, launched in 1999 as an RFID card manufacturer, provides the millions of TaipeiPass EasyCard transport cards used ty Taipei Metro passengers annually. The company more recently expanded its product offerings and its geographic market with access-controls technology. After two decades in the access-control industry, says Jasmine Shih, SAG's deputy sales director, the company has moved into the industrial market with HF and UHF RFID tags.

SAG's Overmolded Uni Metal Tag

These days, Shih says, "Our transponders can go for access control, track and trace, and health care," as well as manufacturing, payment solutions and logistics. "We collaborate with market players in each industry." For instance, she adds, the company's NFC-enabled sensor patch records ambient temperatures. The tag can be interrogated by an NFC-enabled smartphone with an app to capture and interpret temperature data.

The company is especially adept at solving challenges for unique deployment requirements, Shih says. Its engineers have developed tags that are miniaturized for products with a very small amount of space available for tagging, and also provides RF antenna fine-tuning, high-temperature-resistant cards and roll-to-roll on-metal tags.

One frequent request from customers has been for an on-metal tag that can be used in the industrial sector, in which interference tends to make RFID transmissions difficult or impossible. "Reflection and absorptions of metallic surfaces and objects challenge the reading performance of most common tags," Shih explains. Typically, metal-mount tags can operate when attached to metal, often due to a separator built into the tag to lift it away from the metal surface. However, they usually work best when applied to the front surface of a metallic object, facing the reader.

With the passive UHF Overmolded Uni Metal Tag, SAG aims to provide greater flexibility by receiving RF transmissions from readers, even on the other side of a metal object to which it is attached, and responding to that signal. It accomplishes this by using the metal object as part of the RF antenna. Other tags similarly leverage an object's metal content to serve as an antenna, but SAG's product is unique, Shih claims, in that it can be created and encoded in mass production, despite being enclosed in an industrial-grade plastic housing.

SAG has initially been selling the tags to existing customers, beginning in the second quarter of this year. One customer in Asia has begun using the tags to track metal cylinders in which liquefied petroleum gas (LPG) is stored, the company reports. The tags ensure that the gas bottle in use at any given time is under a well-maintained condition, so as to prevent safety issues.

As the cylinders are refilled with gas, SAG reports, the unnamed company needs its operators to check the inspection date marked on each gas bottle's neck ring, thereby ensuring that the cylinder is still safe for refilling. Traditionally, the maintenance record is tracked on the bottle housing by painting or hand-writing on that housing. This, however, slows down the process and could lead to errors, the company notes.

Jasmine Shih

"With the help of the RFID system implemented in the refill station," Shih says, "the Overmolded Uni Metal Tag attached to each cylinder can help keep track of its usage and maintenance history accurately."

The tags can also be used for asset management to ensure that the company knows each cylinder's location and status. Automating the process of identifying each gas bottle, SAG explains, enables operators to ensure that they never incorrectly fill a gas bottle that was not intended to be filled with a specific type of gas.

Other companies are using the Overmolded Uni Metal Tag to track such metal assets as cartridges or battery storage devices. The tags can be read even if they face away from the reader on metal shelving, the company reports.