MIT Media Lab researchers have developed a wireless system that leverages the cheap RFID tags already on hundreds of billions of products to sense potential food contamination — with no hardware modifications needed. With the simple, scalable system, the researchers hope to bring food-safety detection to the general public.
The researchers’ system, called RFIQ, includes a reader that senses minute changes in wireless signals emitted from RFID tags when the signals interact with food. For this study they focused on baby formula and alcohol, but in the future, consumers might have their own reader and software to conduct food-safety sensing before buying virtually any product.
Systems could also be implemented in supermarket back rooms or in smart fridges to continuously ping an RFID tag to automatically detect food spoilage.
In the researchers’ system, a reader emits a wireless signal that powers the RFID tag on a food container. Electromagnetic waves penetrate the material inside the container and return to the reader with distorted amplitude (strength of signal) and phase (angle).
When the reader extracts the signal features, it sends those data to a machine-learning model on a separate computer. For this study, they used pure alcohol and alcohol tainted with 25, 50, 75, and 100 percent methanol; baby formula was adulterated with a varied percentage of melamine, from 0 to 30 percent.
Then, the model will automatically learn which frequencies are most impacted by this type of impurity at this level of percentage. 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.
They are also seeking to expand the system’s capabilities to detect many different contaminants in many different materials.
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