Many plants autonomously change morphology and function in response to environmental stimuli or sequences of stimuli. In contrast with the electronically-integrated sensors, actuators, and microprocessors in traditional mechatronic systems, natural systems embody these sensing, actuation, and control functions within their compositional and structural features. Inspired by nature, we embody logic in autonomous systems to enable them to respond to multiple stimuli. Using 3D printable fibrous composites, we fabricate structures with geometries near bifurcation points associated with a transition between bistability and monostability. When suitable stimuli are present, the materials swell anisotropically. This forces a key geometric parameter to pass through a bifurcation, triggering rapid and large-amplitude self-actuation. The actuation time can be programmed by varying structural parameters (from 0.6 to 108 s for millimeter-scale structures). We demonstrate this bioinspired control strategy with examples that respond to their environment according to their embodied logic, without electronics, external control, or tethering.
The
ability for materials to adapt their shape and mechanical properties
to the local environment is useful in a variety of applications, from
soft robots to deployable structures. In this work, we integrate liquid
crystal elastomers (LCEs) with multistable structures to allow autonomous
reconfiguration in response to local changes in temperature. LCEs
are incorporated in a kirigami-inspired system in which squares are
connected at their vertices by small hinges composed of LCE–silicone
bilayers. These bend and soften as the temperature increases above
room temperature. By choosing geometric parameters for the hinges
such that bifurcation points in the stability exist, a transition
from mono- or tristability to bistability can be triggered by a sufficient
increase in temperature, forcing rearrangements of the structure as
minima in the energy landscape are removed. We demonstrate temperature-induced
propagation of transition waves, enabling local structural changes
to autonomously propagate and affect other parts of the structure.
These effects could be harnessed in applications in interface control,
reconfigurable structures, and soft robotics.
We explore unique wave dynamics in a chain of tristable structures, inspired by multistable origami. We specifically focus on the frequency band structure of the chain, and conduct numerical and theoretical analysis. The band gap of the chain can be controlled by switching the stable state of each tristable structure. We also show that if two regions of the chain have different topological properties then wave localization can occur at the interface of the two regions. Interestingly, this interface mode is observed within the band gap. We demonstrate that the interface mode can be altered by leveraging the reconfigurable nature of the tristable structure. Our findings suggest a new strategy for controlling wave propagation in reconfigurable structures, which could be relevant for engineering applications such as energy harvesting.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.