Researchers declare 3D printed "smart cap" detects spoiled milk

Researchers with the University of California at Berkeley have put 3D printing technology to the test by building electronic components into a milk carton cap that can detect signs of spoilage.

As polymers, the main building material in 3D printing, are bad electric conductors, the researchers used polymers to form much of the cap and wax to form tubes with desired shapes, then remove the wax and fill the hollowed tubes with silver.

Liwei Lin, professor of mechanical engineering and senior author of a paper about the work in the recent issue of Microsystems & Nanoengineering, told Xinhua that "we created capacitators and resistors within the cap and put it to the test trying out if it could detect spoiled milk."

The circuitry includes a passive sensor that does not need battery power, and its readings can be retrieved wirelessly via a smartphone. It detects changes in electrical signals indicative of the presence of bacteria, informing researchers every few hours through a quick check with their cell phones.

"We believe this could be a game changer in the food industry, because expiration dates are not always accurate and so much food gets thrown away," Li said, adding that the technology can be used with any kind of beverages. "It would only require minor adjustments depending on the kind of fluid."

However, the main goal of the research was not geared towards the food industry. It was designed to prove that it is possible to print sensitive electronic components.

Li and his team envision a not-so-distant future where just by downloading a file, users will be able to print electronic devices at home. The possibilities of such technology, according to Li, are almost endless.

Consumers may be able to see "smart caps" soon on shelves at supermarkets, because some U.S. food companies have shown interest in the technology. Endite