Poster W9 - Bioresorbable Shape-morphing Microrobots for Safer Precision Medicine

Introduction: Shape-morphing microrobots, which adapt to environmental changes and transform their geometry or functionality, represent a significant advance in intelligent systems technology. These microrobots can autonomously perform functions such as locomotion and biomedical tasks, including drug delivery and microsurgery, with minimal invasiveness in unstructured in vivo environments. Despite their capabilities, current medical microrobots are either made of soft polymeric materials, which lack the mechanical rigidity needed for surgical operations, or non-degradable metallic materials that necessitate surgical removal after task completion—a major safety concern limiting their translational use in biomedical applications

Materials and

Methods: We introduce a novel class of microfabricated, bioresorbable, shape-morphing microrobots composed of metallic materials such as iron, molybdenum, zinc, and magnesium oxide. We developed a liquid-free shadow mask fabrication method to overcome the limitations of photolithography with water-soluble materials. This method uses stencil lithography to create 2D layouts on a dissolvable polymeric sacrificial layer, preserving the microstructures' integrity until deployment. The self-folding mechanism of these microrobots is driven by intrinsic stresses within metal bilayers, fabricated to precise thicknesses to control self-folding dynamics and degradation timelines.

Results, Conclusions, and Discussions: We fabricated bioresorbable microrobots in various designs, capable of transforming from 2D layouts to complex 3D shapes, including self-rolling microtubes and multi-fingered microgrippers. The folding configurations of these microrobots can be precisely controlled by fabrication parameters and predicted by our finite element analysis model. These microrobots show controlled degradation rates, completely dissolving in physiological conditions within predetermined timescales ranging from a day to a month. Our cell culture study confirmed the biocompatibility of these microrobots before and after degradation. The results indicate that these microrobots can effectively perform medical tasks such as biopsies and drug delivery inside the body. The inherent biodegradability of these devices eliminates the need for surgical retrieval, thereby enhancing patient safety and broadening the potential applications of microrobotic technologies in medicine. We anticipate this development could lead to significant advancements in minimally invasive diagnosis and therapy, offering a safer, more efficient alternative for medical interventions.

Acknowledgements (Optional): Research reported in this publication was supported by the National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health under Award Number R01EB017742. The content is solely the authors' responsibility and does not necessarily represent the official views of the National Institutes of Health. Johns Hopkins University has filed patents related to the technology. Under an option to license agreement between Kley Dom Biomimetics, LLC and the Johns Hopkins University, Prof. D. H. Gracias and the Johns Hopkins University are entitled to royalty distributions related to the technology described in the study discussed in this publication. Part of the fabrication was performed at the UD Nanofabrication Facility (UDNF) at the University of Delaware.