Tunne領(lǐng) AFM (TUNA) and conductive AFM (C-AFM) are powerful current sensing techniques for the electrical characterization of conductivity variations in highly-to-medium resistive samples. C-AFM allows the user to measure currents in the range of 1pA to 1A, while TUNA can map ultra-low currents in the range of 60fA to 120pA at a lateral resolution better than 10nm. TUNA can be applied on a wide range of materials, including thin dielectric films, ferro-electric films, nanotubes, conductive polymers. organic samples, or other low conductivity samples. C-AFM can be applied on similar materials with medium conductivity. By simultaneously mapping the topography and current distribution, the direct correlation of a sample location with its electrical properties is easily possible. Applications include identification of leakage paths, mapping of contaminants and different components in composite materials, and differentiating regions of higher and lower conductivity.