Proc. Natl Acad. Sci. USA 115, 7509–7514 (2018)

The discrete nature of memory storage typically lends itself to lattice-like structures. But doing away with the lattice may confer flexibility without sacrificing memory density. Jun Young Chung and colleagues have taken this approach to build a programmable device from a thin elastic shell — a read–write memory that is akin to a kind of lattice-free Braille.

Inspiration for the device came from the idea that a rubber hemisphere can find stability when it’s turned inside out. By forcing a long thin elastic sheet to arch between parallel rails and then applying an axial compressive strain, Chung et al. found that they could use a stylus to form localized dimples that persisted when the force was removed. The team succeeded in programming multiple non-interacting dimples that could be simply erased by relaxing the axial compression. And for higher strains, they found that they could even programme dimple doublets.