Edited by David A. Weitz, Harvard University, Cambridge, MA, and approved June 26, 2018 (received for review April 4, 2018)
This approach offers a platform for controlled, light-induced motion with easily accessible equipment and facile manufacturing processes. Utility can be envisioned for flexible, simple, and cost-effective actuators from the micro- to the macroscale. Additional opportunity is offered by the ability of these composites to perform heliotactic motion, enabling formats that respond and track light sources such as the sun.
The interaction between light and matter has been long explored, leading to insights based on the modulation and control of electrons and/or photons within a material. An opportunity exists in optomechanics, where the conversion of radiation into material strain and actuation is currently induced at the molecular level in liquid crystal systems, or at the microelectromechanical systems (MEMS) device scale, producing limited potential strain energy (or force) in light-driven systems. We present here flexible material composites that, when illuminated, are capable of macroscale motion, through the interplay of optically absorptive elements and low Curie temperature magnetic materials. These composites can be formed into films, sponges, monoliths, and hydrogels, and can be actuated with light at desired locations. Light-actuated elastomeric composites for gripping and releasing, heliotactic motion, light-driven propulsion, and rotation are demonstrated as examples of the versatility of this approach.
↵1M.L. and Y.W. contributed equally to this work.
Author contributions: M.L. and F.G.O. designed research; M.L., Y.W., A.C., A.N., B.S.N., W.L., C.L.R., and S.A.C. performed research; M.L. contributed new reagents/analytic tools; M.L., Y.W., A.C., A.N., B.S.N., W.L., C.L.R., S.A.C., and F.G.O. analyzed data; and M.L., A.C., S.A.C., and F.G.O. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1805832115/-/DCSupplemental.
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