Sequential Self-Folding Structures by 3D Printed Digital Shape Memory Polymers

By Yiqi Mao, Kai Yu, Michael Isakov, Jiangtao Wu, Martin L. Dunn, H. Jerry Qi. Scientific Reports, 2015

457 citations recorded by the source corpus.

Folding is ubiquitous in nature with examples ranging from the formation of cellular components to winged insects. It finds technological applications including packaging of solar cells and space structures, deployable biomedical devices and self-assembling robots and airbags. Here we demonstrate sequential self-folding structures realized by thermal activation of spatially-variable patterns that are 3D printed with digital shape memory polymers, which are digital materials with different shape memory behaviors. The time-dependent behavior of each polymer allows the temporal sequencing of activation when the structure is subjected to a uniform temperature. This is demonstrated via a series of 3D printed structures that respond rapidly to a thermal stimulus and self-fold to specified shapes in controlled shape changing sequences. Measurements of the spatial and temporal nature of self-folding structures are in good agreement with the companion finite element simulations. A simplified reduced-order model is also developed to rapidly and accurately describe the self-folding physics. An important aspect of self-folding is the management of self-collisions, where different portions of the folding structure contact and then block further folding. A metric is developed to predict collisions and is used together with the reduced-order model to design self-folding structures that lock themselves into stable desired configurations.

Subfields: Biomedical Engineering, Mechanical Engineering, Polymers and Plastics

View Paper: https://www.semanticscholar.org/paper/2051c7baeaae8eb86f74ab8f4cbdf6bc2fee059b

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Citations in the corpus

Harnessing bistability for directional propulsion of soft, untethered robots (2018, background): “It has been shown that, by varying the constituting inkjet materials, one can achieve different glass transition temperatures (36).”
Direct 4D printing via active composite materials (2017, methodology): “Photocured SMPs have been used in 4D printing with both commercial and research printing technologies based on photopolymer inkjetting (2, 10, 27) and projection microstereolithography (14, 16).”
Smart materials in additive manufacturing: state of the art and trends (2018, background): “Studies are able to design the time-dependent sequential shape recovery (Mao et al. 2015; Yu et al. 2015) of a structure fabricated with SMPs.”
Shape-memory polymers for multiple applications in the materials world (2016, background): “In most cases they are defined as multi-stimuli-responsive materials with conferred functionality [10,11], a feature which enlarges their implementation as smart textiles and apparels [12], intelligent medical devices [13], flexible electronic devices [14], sensor and actuators [15], high performanc”
Developments in 4D-printing: a review on current smart materials, technologies, and applications (2019, background): “sequentially during heating which leads to the creation of self-interlocking shape memory structures [36].”