While it'hard to remember when do we buy the food, and how long could it keep fresh, we come up an idea why not turning common fresh wrap into a auto-waring label.
Two kinds of labels which is actually transforming from one, white logo, to the other, black cross, by a specific chemical stuff that will expire due to the time span, and presented by color change.
This makes it easy to distinguish whether
it's still fresh or not!
Lin, Hsin-Ju Teng, Chih-Chin Tang, Ching-Wen Yang, Han-Chuan