These 3D Printed Milk Carton Caps Can Tell When The Milk Goes Bad

Research team from UC Berkeley and Taiwan’s National Chio Tung University has created an amazing sensor that can ascertain the freshness of milk. It is a low-cost electronic sensor that can wirelessly monitor the milk’s freshness. The team employed a 3D printing method for manufacturing this sensor and believes that it could impact the industry on quite a big scale.

In order to create electronic components sensitive enough via 3D printing, the team made use of polymer structures that featured micro-channels and cavities. The team injected holes thus allowing the molds to be filled using a liquid metal paste that solidifies and thus forms the components.

A number of different electronic components were created using this approach by the researchers. The components included inductors, resistors and capacitors. The milk cap idea was coined when the team was looking for ways to test the components. The team teamed up an inductor and a capacitor to create a resonant circuit that was then affixed inside the cap. The cap was designed so that a quick flip of the carton caused a small amount of liquid to gather in the capacitor gap thus enabling the team to take note of the changes in electrical signals in response to bacteria level.

The test carton was kept under observation by the team at room temperature for a total of 36 hours and readings were taken every 12 hours. It was observed that the peak vibration frequency of the milk decreased by 4.3 percent due to a significant increase in the bacteria levels. However, a carton placed inside the refrigerator experienced a frequency drop of 0.12 percent.

Liwei Lin, team member said, “This 3D-printing technology could eventually make electronic circuits cheap enough to be added to packaging to provide food safety alerts for consumers. 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.”

The findings have been published in the journal Microsystems and Nanoengineering.