Enhanced EFM subsurface imaging of 0.5% SWCNT (LA) polyimide nanocomposite film using an HAR probe. EFM bias voltage and lift height is 12 V and 50 nm, respectively. (a) SEM image of a conventional probe, (b) SEM image of an HAR probe. Inset: enlarged image of circled area near tip apex. (c) and (d) EFM phase image of subsurface CNTs using a conventional and HAR probe, respectively. (e) and (f) Cross-section analysis of segmented line at (c) and (d), respectively. EFM phase scale 20◦. The EFM phase signal at circled peak in (f) is both stronger and sharper than that in (e).