3D-printed 'smart cap' for milk cartons detects signs of spoilage: Study


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3D-printed 'smart cap' for milk cartons detects signs of spoilage: Study
Engineers at the University of California Berkeley (UC Berkeley) have created a 3D-printed 'smart cap' for milk cartons that detects signs of spoilage.

As detailed in the study, 3D-printed microelectronics for integrated circuitry and passive wireless sensors,​ UC Berkeley engineers, working in collaboration with colleagues from Taiwan's National Chiao Tung University, printed a variety of electronic components, including inductors and capacitors, using a mix of polymers and wax.

The wax was removed, and silver was injected into the hollow spaces to create circuits.

"wirelessly readable"​ 3D-printed inductor-capacitor tank (LC tank) was then embedded in a milk carton cap.


With a "quick flip"​ of the carton, a small amount of milk becomes trapped in the capacitor gap.

Any change in the electrical signals that accompany an increase in bacteria levels can then be measured with a reader.

To test their 3D-printed 'smart cap', a carton of milk was left unopened at room temperature for 36 hours.

“The results showed a 4.3% frequency shift for a milk package stored under the room temperature environment for 36 hours,"​ the study, published in Microsystems and Nanoengineering​, concluded.

Speaking with Berkeley News, Liwei Lin, a professor of mechanical engineering at the Berkeley Sensor and Actuator Center, said future development of 3D-printed food safety technology like the 'smart cap' is realistic.

"This 3D-printing technology could eventually make electronic circuits cheap enough to be added to packaging to provide food safety alerts for consumers,"​ he said.

"You could imagine scenario where you can use your cellphone to check the freshness of food while it's still on the store shelves."

Source: Microsystems and Nanoengineering
Title: 3D-printed microelectronics for integrated circuitry and passive wireless sensors
Authors: S-Y Wu, C Yang, W Hsu, L Lin

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