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RFID Sensor Platform from GE Breaks New Ground

GE Global Research has developed a new battery-less RFID sensing platform that can detect multiple chemical or biological substances using a single sensor.
Oct 15, 2008This article was originally published by RFID Update.

October 15, 2008—GE Global Research has developed a low-cost, RFID-based sensor platform that is capable of detecting multiple chemical or biological agents -- all without a battery. The passive RFID tags could potentially be used in healthcare, food safety, water treatment and security applications.

The GE system (which will not be commercially available for at least two years) combines passive 13.56 MHz RFID tags with special chemically or biologically sensitive films that are placed on the tag's antenna structure. When an RFID reader excites the tag, the chemical film produces complex differences in the impedance signal that indicate the presence and concentration of specific substances.

"Our approach is to take advantage of the fact that there are ubiquitous RFID tags operating in the 13.56 MHz range, but instead of putting the smarts into the sensors, we put the smarts in the reader itself," said Radislav Potyrailo, principal scientist at GE Global Research who led the development team, in an interview with RFID Update.

By measuring multiple complex impedance parameters and applying multivariate statistical analysis methods to the data, the system is able to detect and quantify multiple substances (such as chemical vapors). The sensor can identify and measure individual chemicals in different mixtures and variable conditions, and detect trace concentrations of toxic gases, volatile organic compounds (VOCs) and chemicals in liquids.

"We can scan across the frequency range using extremely low power, and instead of detecting the single spike where a normal reader operates, we read the whole resonance response," Potyrailo says. "When we look at complex impedance, we can correlate changes in the signal with concentration changes of a biological or chemical compound."

As Potyrailo describes it, the sensor acts in a similar fashion to "electronic nose" technology, but instead of using multiple sensors to detect for a variety of substances, a single sensor does the work.

"That gives us the powerful capability of measuring closely related vapors such as ethanol and methanol using just one sensor," he says, adding that the system can even correct for variable humidity present in the atmosphere. During GE's tests, the sensors were able to achieve parts-per-billion vapor detection limits.

RFID-Sensor Convergence

The convergence of RFID and sensor technology has been developing for a number of years. That a company the size of GE is moving forward with a low-cost sensing platform lends further weight to an already burgeoning market.

The most common RFID-sensor applications utilize temperature monitoring for food safety and logistics applications to prevent spoilage. Other RFID applications have utilized presence/absence sensors, shock and vibration sensors, and even a flow monitoring sensor to track alcohol consumption at the Peabody Memphis hotel.

The development of ubiquitous sensor networks (USN) is one of the factors contributing to the significant growth in active RFID solutions over the next ten years, according to a recent report from Cambridge, Massachusetts-based IDTechEx.

The GE platform, however, uses passive RFID technology and a single sensor to provide a highly selective response to multiple chemicals, overcoming a key limitation of many sensor solutions. The ability to measure multiple variables also sets the GE tags apart from other types of RFID sensors that only indicate simple, single parameters, such as whether or not the tagged item has exceeded a temperature threshold.

By eliminating the onboard power source, the sensors can also be manufactured at a lower cost and in smaller form factors -- as small as a penny, in some cases.

"Because these sensors can be made at such low cost, they also can be made for one-time use," Potyrailo said. "Similar to how your groceries get scanned for a price, imagine pointing a hand-held sensor reader at a milk carton or packaged food to see whether it has been spoiled. This is just one of the new applications you can begin to consider with disposable, low-cost, multi-detection RFID sensors."

GE employed a multidisciplinary team comprised of analytical chemists, RF engineers, polymer scientists, and microfabrication engineers to develop the new sensors. The company has been working on the sensors for about two years.

Initially, the company will target safety and security applications, such as detecting chemical or biological weapons; water purification monitoring; food and beverage safety monitoring; vaccine purity monitoring; and monitoring the emissions at power plants or other industrial facilities.

The company is currently studying the shelf life of the new tags and their long-term stability. Potyrailo said that commercial solutions would most likely not be available "for a few years."
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