Fig. 3: Lateral resolution of BSPM.

a Schematic illustration depicting the deformation of the metal-coated elastomer tip. b Simulated result of the overall stress in the metal-coated elastomeric composite during the compressive-relaxation cycle. Simulated stress distribution in the metal-coated elastomeric composite in the compression (c) and relaxation (d) steps. The inset in c shows the geometry of a metal-coated elastomeric composite at the initial state. e Magnitude of the irreversible deformation of the tip depending on the base/curing agent ratio of the PDMS and the thickness of the gold film. SEM images of the metal-coated elastomer tip after the compression-relaxation test under 5:1 PDMS/Au 50 nm (Tip-1, f) and 30:1 PDMS/Au 100 nm (Tip-2, g). h, Line profiles of the 16 × 16-μm² square patterns with a thickness of 600 nm measured by the two tips under different deformation conditions. Topography images of the 4-μm-diameter circle patterns with a thickness of 400 nm measured by tip-1 (i) and tip-2 (j). k SEM image of the wrinkled structure on the tip. Topography (l) and line profile (m) of the features with a width of 83 nm and a thickness of 40 nm. SEM (n) and BSPM (o) images of the Siemens star test chart with a thickness of 32 nm. The insets show enlarged views of the images.