Magnetic soft composites are a type of stimuli-responsive materials that can generate large deformation and locomotion under external magnetic fields. They have recently attracted great interest due to the increasing demand for programmable materials that can be easily controlled to achieve complex functionalities for untethered morphing and reconfigurable structures. In particular, these composites are considered to be competitive candidates for developing soft robots as biomedical devices for drug delivery and minimally invasive surgeries for two major reasons: &nbsp;the magnetic untethered control (1) offers a safe and effective operation method for biomedical applications, which typically require remote actuation in enclosed and confined spaces; and (2) separates the power source and controller from the device, making miniaturized robots possible. However, it is still a great challenge to design and fabricate high-performance multifunctional magnetic soft composites for advanced engineering applications, due to the lack of design guidance on materials, fabrication, and stimulation control. In this talk, a mechanics-guided methodology is first introduced to achieve structures with precise actuation control for multifunctionality of magnetic soft composites. &nbsp;This methodology is then used to guide the design of functional devices potentially for medical applications.&nbsp;&nbsp;The first example is the magnetic shape magnetic shape memory polymer we recently developed. The composite consists of two types of magnetic particles in an amorphous shape memory polymer matrix. The matrix softens via magnetic inductive heating of low-coercivity particles, and high-remanence particles with reprogrammable magnetization profiles drive the rapid and reversible shape change under actuation magnetic fields. Once cooled, the actuated shape can be locked. Additionally, varying the particle loadings for heating enables sequential actuation. The integrated multifunctional shape manipulations are further exploited for applications including soft magnetic grippers with large grabbing force and reconfigurable antennas that can be potentially applied as techniques for biomedical devices for various operations. The magnetic shape memory polymer can be further expanded to design metamaterials for retrievable medical stents.&nbsp;The second example is the magnetically actuated origami device for targeted drug delivery. A magnetically actuated crawling and swimming origami robots for effective locomotion and targeted drug delivery in severely confined spaces and aqueous environments will be introduced. We design our robots based on the Kresling origami, whose thin shell structure 1) provides an internal cavity for drug storage, 2) permits torsion-induced contraction as the mechanism for crawling and controllable drug release, 3) serves as propellers that spin for propulsion to swim, 4) offers anisotropic stiffness to overcome the large resistance from the severely confined spaces in biomedical environments. These magnetic origami robots can potentially serve as minimally invasive devices for biomedical diagnoses and treatments.

Magnetic Soft Composites With Integrated Multiphysics Responses for Medical Devices

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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