The convention facilities in Las Vegas are nothing to sneeze at, but this number is still impressive. At the International Consumer Electronics show this week, two million square feet of exhibit space is being used. And that means a lot of gizmos — big, small, airborne, and worn. Lindsey Turrentine, editor-in-chief of reviews at CNET, tells Marketplace Tech host Ben Johnson why she’s calling this year at CES “the year of the sensor.”