PiFM imaging reveals buried silver nanowires in transparent and conductive thin film:

Silver nanowires underneath the protective layer are not visible in AFM topography and phase images. However, they are easily visible in the PiFM images. The PiFM image at 1730 cm^-1 of the protective layer shows less signal for the tall structures in the topography. This suggests that it is foreign material on top of the protective layer. However, the buried silver nanowires show up in PiFM images at all wavenumbers since the near-field from the tip is coupled effectively to the conductive nanowire, creating a strong attractive force even through a rather thick protective layer (>100 nm).