Adv. Mater. (2012)

Credit: © 2012 WILEY

A tiny sensor may soon be able to tell you if the food you are about to eat is safe for consumption, as Fiorenzo Omenetto and collaborators show in a proof-of-principle demonstration. They monitored the ripening of fruit, the bacterial contamination of a piece of cheese and the spoilage of milk by placing their sensor — essentially a nano- or micro-receiver antenna — in intimate contact with the food. The resonance frequency of the antenna, which can be tuned in the megahertz to terahertz range, depends on the chemical and physical properties of the surrounding environment, allowing the design of experiments for monitoring the quality of the food over time. The electronic circuit of the device is made out of gold imprinted on top of an all-protein silk substrate. The silk confers both the robustness and flexibility necessary for the antenna to withstand handling and conform to the food surface. The device adheres onto the food by activation of the bottom surface by water vapours, which is then deposited in place by gentle pressure. Biodegradable, potentially edible sensors, such as this one, may offer a convenient way to directly monitor the quality of individual food items remotely.