Three basic deformation modes of an object (bending, twisting, and contraction/extension) along with their various combinations and delicate controls lead to diverse locomotion. As a result, seeking mechanisms to achieve simple to complex deformation modes in a controllable manner is a focal point in related engineering fields. Here, a pneumatic-driven, origami-based deformation unit that offers all-purpose deformation modes, namely, three decoupled basic motion types and four combinations of these three basic types, with seven distinct motion modes in total through one origami module, was created and precisely controlled through various pressurization schemes. These all-purpose origami-based modules can be readily assembled as needed, even during operation, which enables plug-and-play characteristics. These origami modules with all-purpose deformation modes offer unprecedented opportunities for soft robots in performing complex tasks, which were successfully demonstrated in this work.
Flexible integration spurs diverse applications in metal-organic frameworks (MOFs). However, current configurations suffer from the trade-off between MOF loadings and mechanical compliance. We report a wrinkled configuration of MOF thin films. We established an interfacial synthesis confined and controlled by a polymer topcoat and achieved multiple Turing motifs in the wrinkled thin films. These films have complete MOF surface coverage and exhibit strain tolerance up to 53.2%. The enhanced mechanical properties allow film transfer onto various substrates. We obtained membranes with large H 2 /CO 2 selectivity (41.2) and high H 2 permeance (8.46 × 10 3 gas permeation units), showcasing negligible defects after transfer. We also achieved soft humidity sensors on delicate electrodes by avoiding exposure to harsh MOF synthesis conditions. These results highlight the potential of wrinkled MOF thin films for plug-and-play integration.
Inspired by the remarkable adaptability observed in biological organisms, multifunctional soft robotics have emerged as promising systems capable of navigating complex environments. In this study, we present a strategy for weaving fiber soft actuators to overcome the existing limitations in deformation capabilities and complex manufacturing processes. This strategy combines traditional rope artistry with the advanced responsive characteristics of electro-driven liquid crystal elastomer (LCE) fibers, facilitating the efficient creation of multifunctional soft actuators. Leveraging this strategy, we have developed four distinct types of soft actuators: the double twisting weaving actuator (DTWA), the circular four-strand weaving actuator (CFWA), the orthogonal weaving actuator (OWA), and the diagonal weaving actuator (DWA). These weaving fiber soft actuators can be readily assembled in various soft robots, granting multiple functionalities, including surface shape programmability, biomimetic blood pumping inspired by the cardiac muscle, and versatile locomotion modes such as crawling and swimming. Our proposed strategy offers unprecedented opportunities for multifunctional soft robots in performing complex tasks.
Artificial muscles that can reproduce the functions and biomimetic motions of natural muscles are widely used to construct soft robots with applications in various fields. However, it is still challenging to develop stimuli-responsive artificial muscles with multiple-mode actuation. Inspired by the forearm muscles, we propose a new type of stimuli-responsive artificial muscles with multiple-mode actuation using liquid crystal elastomers (LCEs), named FILAMs (forearm muscle-inspired LCE-based artificial muscles). The proposed FILAMs consist of active LCE driving units, a passive silicone rubber flexible skeleton and two quick connectors. By selectively actuating different types of LCE driving units, the FILAMs can achieve multiple-mode actuation, such as twisting, bending, combined twisting and bending. We introduce prototypical designs for the FILAMs and demonstrate that they can be used as ‘building blocks’ to reconfigure different soft robots. Three kinds of soft robots are constructed to show extensive applications through the cooperation of a combination FILAMs, i.e. a soft assembly robot, a soft crawling robot, and a soft flexible wrist.
The demand for larger and lighter mechanisms for next-generation space missions necessitates using deployable structures. High-strain fiber polymer composites show considerable promise for such applications due to their exceptional strength-to-weight ratio, manufacturing versatility, packaging efficiency, and capacity for self-deployment using stored strain energy. However, a significant challenge in using composite deployable structures for space applications arises from the unavoidable extended stowage periods before they are deployed into their operational configuration in orbit. During the stowage period, the polymers within the composites experience material degradation due to their inherent viscoelastic and/or plastic properties, causing stress relaxation and accumulation of plastic strains, thereby reducing the deployment capability and resulting in issues related to recovery accuracy. This paper aims to give a state-of-the-art review of recent advances in the design, modeling, and manufacturing of high-strain composites for deployable structures in space applications, emphasizing the long-term stowage effects. This review is intended to initiate discussion of future research to enable efficient, robust, and accurate design of composite deployable structures that account for the enduring challenges posed by long-term stowage effects.
9 December 2024 in International Journal of Mechanical Sciences