NerdFun: Basic internals for a Tricorder?

I read this article on an "electronic nose" in the Mountain View voice today with glee!  This is basically the essential building block to an actual tricorder.  C'mon, admit it, you're a Star Trek fan, too.  How awesome will it be, when we can all carry around a device to see if the air is fit for human respiration? Check ourselves for toxins?  Very neat!