A nonlinear beam model of photomotile structures

Kevin Korner, Alexa S. Kuenstler, Ryan C. Hayward, Basile Audoly, Kaushik Bhattacharya

Research output: Contribution to journalArticlepeer-review


Actuation remains a significant challenge in soft robotics. Actuation by light has important advantages: Objects can be actuated from a distance, distinct frequencies can be used to actuate and control distinct modes with minimal interference, and significant power can be transmitted over long distances through corrosion-free, lightweight fiber optic cables. Photochemical processes that directly convert photons to configurational changes are particularly attractive for actuation. Various works have reported light-induced actuation with liquid crystal elastomers combined with azobenzene photochromes. We present a simple modeling framework and a series of examples that study actuation by light. Of particular interest is the generation of cyclic or periodic motion under steady illumination. We show that this emerges as a result of a coupling between light absorption and deformation. As the structure absorbs light and deforms, the conditions of illumination change, and this, in turn, changes the nature of further deformation. This coupling can be exploited in either closed structures or with structural instabilities to generate cyclic motion.

Original languageEnglish (US)
Pages (from-to)9762-9770
Number of pages9
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number18
StatePublished - May 5 2020
Externally publishedYes


  • Actuation
  • Azobenzene
  • Liquid crystal elastomers
  • Photomechanical materials
  • Propulsion

ASJC Scopus subject areas

  • General


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