Deciphering, Designing, and Realizing Self-Folding Biomimetic Microstructures Using a Mass-Spring Model and Inkjet-Printed, Self-Folding Hydrogels

Abstract

Flat, organic microstructures that can self-fold into 3D microstructures are promising for tissue regeneration, for being capable of distributing living cells in 3D while forming highly complex, biomimetic architectures to assist cells in performing regeneration. However, the design of self-folding microstructures is difficult due to a lack of understanding of the underlying formation mechanisms. This study helps bridge this gap by deciphering the dynamics of the self-folding using a mass-spring model. This numerical study reveals that self-folding procedure is multi-modal, which can become random and unpredictable by involving the interplays between internal stresses, external stimulation, imperfection, and self-hindrance of the folding body. To verify the numerical results, bilayered, hydrogel-based micropatterns capable of self-folding are fabricated using inkjet-printing and tested. The experimental and numerical results are consistent with each other. The above knowledge is applied to designing and fabricating self-folding microstructures for tissue-engineering, which successfully creates 3D, cell-scaled, and biomimetic microstructures, such as microtubes, branched microtubes, and hollow spheres. Embedded in self-folded microtubes, human mesenchymal stem cells proliferate and form linear cell-organization mimicking the cell morphology in muscles and tendons. The above knowledge and study platforms can greatly contribute to the research on self-folding microstructures and applications to tissue regeneration.