The stimuli-responsive self-folding structure is ubiquitous in nature, for instance, the mimosa folds its leaves in response to external touch or heat, and the Venus flytrap snaps shut to trap the insect inside. Thus, modeling self-folding structures has been of great interest to predict the final configuration and understand the folding mechanism. Here, we apply a simple yet effective method to predict the folding angle of the temperature-responsive nanocomposite hydrogel/elastomer bilayer structure manufactured by 3D printing, which facilitates the study of the effect of the inevitable variations in manufacturing and material properties on folding angles by comparing the simulation results with the experimentally measured folding angles. The defining feature of our method is to use thermal expansion to model the temperature-responsive nanocomposite hydrogel rather than the nonlinear field theory of diffusion model that was previously applied. The resulted difference between the simulation and experimentally measured folding angle ( i.e. , error) is around 5%. We anticipate that our method could provide insight into the design, control, and prediction of 3D printing of stimuli-responsive shape morphing ( i.e. , 4D printing) that have potential applications in soft actuators, robots, and biomedical devices.
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Shape Morphable Hydrogel/Elastomer Bilayer for Implanted Retinal Electronics
Direct fabrication of a three-dimensional (3D) structure using soft materials has been challenging. The hybrid bilayer is a promising approach to address this challenge because of its programable shape-transformation ability when responding to various stimuli. The goals of this study are to experimentally and theoretically establish a rational design principle of a hydrogel/elastomer bilayer system and further optimize the programed 3D structures that can serve as substrates for multi-electrode arrays. The hydrogel/elastomer bilayer consists of a hygroscopic polyacrylamide (PAAm) layer cofacially laminated with a water-insensitive polydimethylsiloxane (PDMS) layer. The asymmetric volume change in the PAAm hydrogel can bend the bilayer into a curvature. We manipulate the initial monomer concentrations of the pre-gel solutions of PAAm to experimentally and theoretically investigate the effect of intrinsic mechanical properties of the hydrogel on the resulting curvature. By using the obtained results as a design guideline, we demonstrated stimuli-responsive transformation of a PAAm/PDMS flower-shaped bilayer from a flat bilayer film to a curved 3D structure that can serve as a substrate for a wide-field retinal electrode array.
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- Award ID(s):
- 1707316
- NSF-PAR ID:
- 10250969
- Date Published:
- Journal Name:
- Micromachines
- Volume:
- 11
- Issue:
- 4
- ISSN:
- 2072-666X
- Page Range / eLocation ID:
- 392
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/mi11040392
