An embodiment of the present invention is a technique to form stress sensors on a package in situ. A first array of carbon nanotubes (CNTs) aligned in a first orientation is deposited at a first location on a substrate or a die in a wafer. The first array is intercalated with polymer. The first polymer-intercalated array is covered with a protective layer. A second array of CNTs aligned in a second orientation is deposited at a second location on the substrate or the die. The second array is intercalated with polymer.