A Comment on AFM vs. Replicas for High Resolution Imaging

Extract

High-resolution Pt/C shadowing and replication provided important insights into the size and shape of polymers beginning over 40 years ago. The first images of DNA molecules were made this way. However, in my opinion, this methodology has largely been supplanted by the use of Atomic Force Microscopy (AFM), both for direct height measurements (available in Pt/C replicas by measuring shadow lengths when the coating is deposited from one direction only) and for imaging molecular contours.

As an everyday example, consider that making a magnetic read and write head for a hard disk drive requires controlling the relative heights of several different regions to a tolerance of about 1 nm. AFM supports production by providing a rapid means of offline analysis, far faster and more precise than any replica method could be.