By Devin Coldewey

If a food item isn’t safe to eat, it’s best to find that out before someone eats it. But manual testing of every jar and bottle isn’t possible, even when a threat, like the recent baby food scare, is known. MIT researchers have found a way to check many items instantly, non-invasively, and from a distance—using the RFID tags many products already have.

RFID, or radio frequency identification, uses a tiny antenna embedded in a sticker or label that’s activated and powered by radio waves at a very specific frequency. When a transceiver sends out a 950Mhz signal, the RFID tag wakes up and re-transmits a slightly different signal identifying itself. Products that announce themselves? Convenient for doing inventory!