Walking and rolling of crystals induced thermally by phase transition

Takuya Taniguchi, Haruki Sugiyama, Hidehiro Uekusa, Motoo Shiro, Toru Asahi, Hideko Koshima*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

81 Citations (Scopus)


The mechanical motion of materials has been increasingly explored in terms of bending and expansion/contraction. However, the locomotion of materials has been limited. Here, we report walking and rolling locomotion of chiral azobenzene crystals, induced thermally by a reversible single-crystal-to-single-crystal phase transition. Long plate-like crystals with thickness gradient in the longitudinal direction walk slowly, like an inchworm, by repeated bending and straightening under heating and cooling cycles near the transition temperature. Furthermore, thinner, longer plate-like crystals with width gradient roll much faster by tilted bending and then flipping under only one process of heating or cooling. The length of the crystal is shortened above the transition temperature, which induces bending due to the temperature gradient to the thickness direction. The bending motion is necessarily converted to the walking and rolling locomotion due to the unsymmetrical shape of the crystal. This finding of the crystal locomotion can lead to a field of crystal robotics.

Original languageEnglish
Article number538
JournalNature communications
Issue number1
Publication statusPublished - 2018 Dec 1

ASJC Scopus subject areas

  • General Chemistry
  • General Biochemistry,Genetics and Molecular Biology
  • General Physics and Astronomy


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