Doctors estimate that each year more than 200,000 people in the U.S. visit hospital emergency rooms because of food allergies. This number includes an estimated 90,000 cases of life-threatening anaphylaxis. The main approach doctors recommend when it comes to food allergies is simply to avoid those foods. But that can be difficult when eating at restaurants or when traveling to countries that have less-stringent food allergen labeling laws. Researchers led by Massachusetts General Hospital’s Hakho Lee and Ralph Weissleder have now developed a prototype point-of-use allergen detection system that picks up traces of peanuts, hazelnuts, wheat, milk, and egg whites in less than 10 minutes (ACS Nano 2017, DOI: 10.1021/acsnano.7b04318). The system, dubbed iEAT, requires two steps: antigen extraction followed by detection. Antigens in the food are captured with antibody-containing magnetic beads, which are subsequently labeled with other antibodies conjugated to the oxidizing agent horseradish peroxidase. A sheathed magnet collects the magnetic beads, which are then placed on the detector, where they undergo an electrochemical reaction. The major innovation, Lee notes, is the detector that fits on a key chain, which can differentiate up to eight allergens, connect to smartphones via Bluetooth, and charge wirelessly. Each disposable antigen extraction system costs about $4.00, and the detector costs $40.