Fig. 2. Representative SEM top views and the corresponding structure diagrams (upper inset) of the (a) PAA stamps (Vstamp = 40 V), (b) imprinted Al sheets (imprinting pressure = 1.5 GPa), and (c) new-type PAAs (VPAA = 28 V). The lower insets in (a), (b) and (c) show the corresponding optical photograph of the PAA stamp, SEM side views of the nanocap and new-type PAA, respectively. The scale bar represents 100 nm.
