Honeycomb Actuators Inspired by the Unfolding of Ice Plant Seed Capsules

PLoS One. 2016 Nov 2;11(11):e0163506. doi: 10.1371/journal.pone.0163506. eCollection 2016.

Abstract

Plant hydro-actuated systems provide a rich source of inspiration for designing autonomously morphing devices. One such example, the pentagonal ice plant seed capsule, achieves complex mechanical actuation which is critically dependent on its hierarchical organization. The functional core of this actuation system involves the controlled expansion of a highly swellable cellulosic layer, which is surrounded by a non-swellable honeycomb framework. In this work, we extract the design principles behind the unfolding of the ice plant seed capsules, and use two different approaches to develop autonomously deforming honeycomb devices as a proof of concept. By combining swelling experiments with analytical and finite element modelling, we elucidate the role of each design parameter on the actuation of the prototypes. Through these approaches, we demonstrate potential pathways to design/develop/construct autonomously morphing systems by tailoring and amplifying the initial material's response to external stimuli through simple geometric design of the system at two different length scales.

MeSH terms

  • Algorithms
  • Mechanical Phenomena
  • Mesembryanthemum* / physiology
  • Models, Theoretical
  • Polymers
  • Seeds* / anatomy & histology
  • Seeds* / chemistry
  • Seeds* / physiology

Substances

  • Polymers

Grants and funding

This work was financially supported by Max Planck Institute of Colloids and Interfaces of Potsdam, the DFG Deutsche Forschungsgemeinschaft through SPP1420 Priority Program: "Biomimetic Materials Research: Functionality by Hierarchical Structuring of Materials," “Image Knowledge Gestaltung: An Interdisciplinary Laboratory” Cluster of Excellence at the Humboldt University of Berlin through DFG contract EXC1027/1, ETHZ, Institute for Building Materials (IfB) of Zurich, Switzerland, and Empa, Applied Wood Materials Laboratory of Dübendorf, Switzerland. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.