Figure 3. Surface-strain analysis of mechanically and photochemically bent azobenzene-containing liquid-crystalline elastomer films at the same radius of curvature.

(a), Upon mechanical bending, the inner surface of the film contracts and the outer surface expands along the bending direction. (b), Upon photoinduced bending, both the inner and outer surfaces contract, which highlights that the bending of soft matter can be distinct from that of hard matter.