Kirigami actuators

Thin elastic sheets bend easily and, if they are patterned with cuts, can deform in sophisticated ways. Here we show that carefully tuning the location and arrangement of cuts within thin sheets enables the design of mechanical actuators that scale down to atomically-thin 2D materials. We first show that by understanding the mechanics of a single non-propagating crack in a sheet, we can generate four fundamental forms of linear actuation: roll, pitch, yaw, and lift. Our analytical model shows that these deformations are only weakly dependent on thickness, which we confirm with experiments on centimeter-scale objects and molecular dynamics simulations of graphene and MoS₂ nanoscale sheets. We show how the interactions between non-propagating cracks can enable either lift or rotation, and we use a combination of experiments, theory, continuum computational analysis, and molecular dynamics simulations to provide mechanistic insights into the geometric and topological design of kirigami actuators.M. A. D. is grateful to M. Adda-Bedia, J. Bico, B. Roman, and K. Seffen for many insightful discussions. M. A. D. would also like to thank ENS-Lyon and ESPCI-Paris for hosting the author during part of the development of this manuscript and funding from the 4-VA program for collaborative research at JMU. D. P. H. is grateful to the National Science Foundation (CMMI CAREER-1454153) for financial support. M. A. D., D. R. K., and D. P. H. would like to thank I. Metta for useful discussions at the start of this project. D. K. C. acknowledges the Aspen Center for Physics, which is supported by the National Science Foundation grant PHY-1607611, where part of this work was completed. D. R. K. acknowledges funding from Academy of Finland. (4-VA program for collaborative research at JMU; CMMI CAREER-1454153 - National Science Foundation; PHY-1607611 - National Science Foundation; Academy of Finland)First author draf