Chemical detection via organic dyes and a smartphone

Via the New York Times, a new use of smartphones for farmers: 

If the farmer suspects a late blight infection is underway, she can remove a leaf from a living plant and place it in a small, covered glass jar. After the leaf’s volatile compounds have accumulated for 15 minutes or so, the cap is removed and the air is pumped from the jar into a reader device attached to the back of a smartphone. 

Inside the smartphone reader is a strip of paper specially treated with organic dyes and nanoparticle sensors developed by the researchers. Upon interacting with the plant’s volatile compounds, the strip changes color to indicate the presence or absence of the pathogen. It’s like a home-pregnancy kit for tomatoes, or a strep test for tubers.

Here's the Nature Plants* article. It will be really interesting to see when a GC is sufficiently miniaturized to fit in a pocket...

*who knew?!?!