There's nothing worse than accidentally drinking sour milk. Well, apart from war and death and stuff. But that first problem might become a thing of the past with a 'smart cap' for bottles that can warn you before you ruin a nice cup of tea.
Engineers from the University of California Berkeley and Taiwan's National Chiao Tung University have been working on technology that allows electrical components to be embedded in 3D-printed plastics. Those components include resistors, inductors, capacitors and wireless electrical sensing systems.
They've now used that technology to create a smart milk carton cap which monitors signs of spoilage. Once fitted, you can tilt the container upside-down to quickly test for the changes in electrical signals that accompany high levels of bacteria.
"This 3D-printing technology could eventually make electronic circuits cheap enough to be added to packaging to provide food safety alerts for consumers", said Liwei Lin, a senior author on the paper describing the discovery. "You could imagine a scenario where you can use your cellphone to check the freshness of food while it's still on the store shelves."
As well as spoilt milk, the lab is also working on similar technology for health applications - including implantable devices that can monitor blood pressure, muscle strain and even concentrations of particular drugs.
The details of the smart cap were published in the journal Microsystems and Nanoengineering.