Copper Film Enables Accurate Optical Humidity Sensing

Today’s food packaging gives you a lot of information about your food, including ingredients and number of calories, but it cannot tell you whether the fruit salad you want to buy is drying out or if your breakfast cereal is crunchy or soggy.

The freshness of many consumer goods often depends on the humidity inside the packaging. However, incorporating humidity sensors into consumer packaging is currently not feasible because conventional sensors require electronics, a power source and a display.

A humidity sensor being developed at Swiss Federal Institute of Technology (ETH) in Zurich, however, does not require any of these. The device is simply a copper-based strip that changes color when a certain humidity level is reached.


The work is detailed in a Langmuir paper published March 13.

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