Fig. 4a and 4b show the fixed SEM images of differentiated PC12 cells being penetrated by the nanopillars without any loss of cellular function.  It is interesting to observe that the PC12 neurite outgrowth grasping onto the nanopillars. Additionally, it is evident from Fig. 6b that the nanopillars are clearly assessing the interior of the cells’ cytosol.  This image was taken after focused ion milling (FIB) milling of one half of the electrode-cell interface. The cross-section image shows clearly that the cell has surrounded the nanopillars.  The  FIB-SEM results shown here are consistent with the confocal images, which showed cell membrane deformation around the nanopillars.