Figure 3.

PR of an isolated collagen fiber at three cantilever orientations with respect to the sample: at an initial, arbitrary orientation (b and c); after a 90° clockwise rotation (e and f); and at 180° orientation (h and i). Images b, e, and h are constructed from the out-of-plane deflection signal, and c, f, and i represent the LPR. The topography of the area is shown in a (10 μm scan) and d (2 μm zoom of a). The plot in g shows the change in VPR along the same line of the sample (b and h) before and after the sample has been rotated by 180°. The cantilever orientation and the detection direction are overlaid on the PFM images.