Putting Food-Safety Detection in the Hands of Consumers

Estimated reading time: 5 minutes

The system’s concept derives from a technique called radio frequency spectroscopy, which excites a material with electromagnetic waves over a wide frequency and measures the various interactions to determine the material’s makeup.

But there was one major challenge in adapting this technique for the system: RFID tags only power up at a very tight bandwidth wavering around 950 megahertz. Extracting signals in that limited bandwidth wouldn’t net any useful information.

The researchers built on a sensing technique they developed earlier, called two-frequency excitation, which sends two frequencies — one for activation, and one for sensing — to measure hundreds more frequencies. The reader sends a signal at around 950 megahertz to power the RFID tag. When it activates, the reader sends another frequency that sweeps a range of frequencies from around 400 to 800 megahertz. It detects the feature changes across all these frequencies and feeds them to the reader.

“Given this response, it’s almost as if we have transformed cheap RFIDs into tiny radio frequency spectroscopes,” Adib says.

Because the shape of the container and other environmental aspects can affect the signal, the researchers are currently working on ensuring the system can account for those variables. They are also seeking to expand the system’s capabilities to detect many different contaminants in many different materials.

“We want to generalize to any environment,” Adib says. “That requires us to be very robust, because you want to learn to extract the right signals and to eliminate the impact of the environment from what’s inside the material.”

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