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1. Encoding reprogrammable properties into magneto-mechanical materials via topology optimization

   https://doi.org/10.1038/s41524-023-00980-2  

   Zhao, Zhi; Zhang, Xiaojia Shelly (December 2023, npj Computational Materials)

   Abstract The properties of materials and structures typically remain fixed after being designed and manufactured. There is a growing interest in systems with the capability of altering their behaviors without changing geometries or material constitutions, because such reprogrammable behaviors could unlock multiple functionalities within a single design. We introduce an optimization-driven approach, based on multi-objective magneto-mechanical topology optimization, to design magneto-active metamaterials and structures whose properties can be seamlessly reprogrammed by switching on and off the external stimuli fields. This optimized material system exhibits one response under pure mechanical loading, and switches to a distinct response under joint mechanical and magnetic stimuli. We discover and experimentally demonstrate magneto-mechanical metamaterials and metastructures that realize a wide range of reprogrammable responses, including multi-functional actuation responses, adaptable snap-buckling behaviors, switchable deformation modes, and tunable bistability. The proposed approach paves the way for promising applications such as magnetic actuators, soft robots, and energy harvesters. 

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2. Fictitious Magnetic Charge Model for Magneto-Mechanical Metamaterials

   https://doi.org/10.1115/1.4070273  

   Zhang, Yuying; Alkuino, Gabriel; Zhang, Teng (January 2026, Journal of Applied Mechanics)

   Abstract Magnetically actuated intelligent structures have shown great promise in various applications ranging from soft robotics to biomedical devices. One important type of structure involves embedding rigid magnets in polymer matrices, thanks to their simplicity in manufacturing and flexibility in structure design. However, accurately modeling their behavior remains challenging due to the strong nonlinear coupling between large deformation and spatially varying magnetic fields. To address this, we employ a fictitious magnetic charge method to transfer the magnetic forces and torques into surface traction under both uniform and nonuniform external magnetic actuation. We implement the proposed method in the commercial finite element software abaqus and validate it through a series of benchmark examples, which cover tuning the area of magneto-mechanical metamaterials, the shape changing of magnetic lattice structures, and the magnetic-field-driven buckling of cellular structures. Our approach enables accurate prediction of shape transformations in magnetically responsive structures, offering a practical tool for the design and optimization of future magneto-mechanical metamaterials and devices. 

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3. Designing Programmable Ferromagnetic Soft Metastructures for Minimally Invasive Endovascular Therapy

   https://doi.org/10.1115/DETC2023-116342  

   Zhuang, Ran; Tian, Jiawei; Tassiopoulos, Apostolos; Sadasivan, Chandramouli; Gu, Xianfeng; Chen, Shikui (August 2023, American Society of Mechanical Engineers)

   Abstract Minimally invasive endovascular therapy (MIET) is an innovative technique that utilizes percutaneous access and transcatheter implantation of medical devices to treat vascular diseases. However, conventional devices often face limitations such as incomplete or suboptimal treatment, leading to issues like recanalization in brain aneurysms, endoleaks in aortic aneurysms, and paravalvular leaks in cardiac valves. In this study, we introduce a new metastructure design for MIET employing re-entrant honeycomb structures with negative Poisson’s ratio (NPR), which are initially designed through topology optimization and subsequently mapped onto a cylindrical surface. Using ferromagnetic soft materials, we developed structures with adjustable mechanical properties called magnetically activated structures (MAS). These magnetically activated structures can change shape under noninvasive magnetic fields, letting them fit against blood vessel walls to fix leaks or movement issues. The soft ferromagnetic materials allow the stent design to be remotely controlled, changed, and rearranged using external magnetic fields. This offers accurate control over stent placement and positioning inside blood vessels. We performed magneto-mechanical simulations to evaluate the proposed design’s performance. Experimental tests were conducted on prototype beams to assess their bending and torsional responses to external magnetic fields. The simulation results were compared with experimental data to determine the accuracy of the magneto-mechanical simulation model for ferromagnetic soft materials. After validating the model, it was used to analyze the deformation behavior of the plane matrix and cylindrical structure designs of the Negative Poisson’s Ratio (NPR) metamaterial. The results indicate that the plane matrix NPR metamaterial design exhibits concurrent vertical and horizontal expansion when subjected to an external magnetic field. In contrast, the cylindrical structure demonstrates simultaneous axial and radial expansion under the same conditions. The preliminary findings demonstrate the considerable potential and practicality of the proposed methodology in the development of magnetically activated MIET devices, which offer biocompatibility, a diminished risk of adverse reactions, and enhanced therapeutic outcomes. Integrating ferromagnetic soft materials into mechanical metastructures unlocks promising opportunities for designing stents with adjustable mechanical properties, propelling the field towards more sophisticated minimally invasive vascular interventions. 

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4. Dual‐Programmable Architected Magnetic Soft Materials: Tuning Mechano–Electric Responses by Inverse Design

   https://doi.org/10.1002/adfm.202600068  

   Zhao, Zhi; Zhang, Xiaojia Shelly (June 2026, Advanced Functional Materials)

   ABSTRACT Materials that can deform, sense, and autonomously generate power in response to wireless magnetic fields, through both magnetic‐actuated shape transformation and charge generation, are an emerging focus in advanced functional materials research. Magneto–mechano–electric intelligent materials, created by embedding ferromagnetic particles into soft elastomers with immobile charges, are bringing this vision closer to reality. Under wireless magnetic actuation, they undergo rapid deformation that drives charge flow, enabling controlled responses. Yet realizing such materials to unleash their full potential remains a major challenge because of the complex multiphysics coupling under large deformation and independent mechanical and electrical responses. In this work, we create a new class of dual‐programmable magnetic soft materials with unprecedented dual properties by establishing a multiphysics inverse‐design framework that simultaneously optimizes geometry and remanent magnetization distributions to tune both magneto–elastic and magneto–electric behaviors. The framework is complemented by a tailored fabrication approach and experimental validation, forming a comprehensive and automated pipeline for creating multifunctional advanced materials for biomedical devices with dually programmable behaviors. Its effectiveness is demonstrated through an electrical stimulation guidewire for endovascular therapy, mechano–electric treatment robots for injury‐specific tissue recovery, and multifunctional self‐powering and self‐sensing bio‐robots with on‐demand mechanical motions. Together, these results establish an effective inverse‐design‐to‐fabrication paradigm for dual‐programmable magnetic soft materials in next‐generation biomedical applications. 

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5. Local resonance bandgap control in a particle-aligned magnetorheological metamaterial

   https://doi.org/10.1038/s43246-023-00419-7  

   Moghaddaszadeh, Mohammadreza; Ragonese, Andrew; Hu, Yong; Guo, Zipeng; Aref, Amjad; Zhou, Chi; Ren, Shenqiang; Nouh, Mostafa (December 2023, Communications Materials)

   Stimuli-responsive elastic metamaterials augment unique subwavelength features and wave manipulation capabilities with a degree of tunability, which enables them to cut across different time scales and frequency regimes. Here, we present an experimental framework for robust local resonance bandgap control enabled by enhanced magneto-mechanical coupling properties of a magnetorheological elastomer, serving as the resonating stiffness of a metamaterial cell. During the curing process, ferromagnetic particles in the elastomeric matrix are aligned under the effect of an external magnetic field. As a result, particle chains with preferred orientation form along the field direction. The resulting anisotropic behavior significantly boosts the sensitivity of the metamaterial’s elastic modulus to the imposed field during operation, which is then exploited to control the dispersive dynamics and experimentally shift the location and width of the resonance-based bandgap along the frequency axis. Finally, numerical simulations are used to project the performance of the magnetically-tunable metamaterial at stronger magnetic fields and increased levels of material anisotropy, as a blueprint for broader implementations of in situ tunable active metamaterials. 

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