If you're not a fan on the ol' smell test to see if milk has spoiled, you might soon be in luck. Researchers from the University of California at Berkley and National Chiao Tung University in Taiwan created a "smart cap" for food storage containers that can detect spoilage. Using 3D-printed electronics, the lids house circuits and passive wireless sensors that are capable of determining if milk or juice has spoiled when it comes in contact with the lid. The components can detect changes in the liquid due to the presence of bacteria and transmit details wirelessly in real time. This means that you could potentially use a mobile app to check the freshness of food before you decide to buy it, for example. The group of engineers sees other uses for the technology too, including so-called smart implants that can relay pressure and drug concentrations to an external device.

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