Kirigami Actuators

TL;DR

This paper demonstrates how patterning cuts in thin elastic sheets, including atomically-thin 2D materials, enables the design of mechanical actuators with controllable motions such as roll, pitch, yaw, and lift, supported by experiments and simulations.

Contribution

It introduces a comprehensive understanding of kirigami-based actuators, linking crack mechanics to programmable deformation modes across scales from centimeters to atomic layers.

Findings

Four fundamental actuation modes identified: roll, pitch, yaw, lift.

Deformations are weakly dependent on sheet thickness.

Crack interactions enable complex motions like lift and rotation.

Abstract

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 at centimeter scale objects and molecular dynamics simulations of graphene and MoS$_{2}$ 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.