Stop sniffing. New 3-D printed cap checks milk

The sniff test for milk may be on its way out.

Engineers at the University of California-Berkeley have created a cap with electronics embedded in it to wirelessly monitor the freshness of milk.

And they did it through 3D printing.

It's one of the first examples of printing a plastic circuit with electronic components in it.

It could eventually be used in many other foods to make sure they are safe.