The defense of the doctoral thesis titled “Magnetic soft robots toward localized therapy: magnetization programming and multimaterial integration” by Zhuoyue Wang was held on Wednesday, 26th of August 2026, at 12:45 hour in the Aula of the Academy Building at the University of Groningen. The doctoral thesis is available here. Dr. Zhuoyue Wang conducted his research at the Surgical Robotics Laboratory at the Department of Biomaterials and Biomedical Technology.

Thesis summary:

Magnetic soft robots have emerged as promising candidates for minimally invasive surgery and localized intervention. Their ability to convert externally applied magnetic fields into controlled deformation and locomotion enables wireless, untethered operation without on-board power, which is particularly advantageous in confined and deformable physiological environments. By embedding magnetic particles within soft matrices, these systems combine remote actuation with mechanical adaptability, allowing navigation through complex biological spaces while maintaining structural compliance. Diverse deformation and locomotion modes have been demonstrated in recent studies, and design principles for magnetic response under applied fields have been established. However, practical translation of magnetic soft robots toward clinical applications (e.g., localized sensing, minimally invasive surgery, and drug delivery) is still limited by two factors: scalable three-dimensional magnetization programming for controllable deformation and locomotion, and reliable multi-material integration for incorporating functional components.

Programmable three-dimensional magnetization is essential because it defines the deformation and locomotion modes by determining where magnetic torques and forces arise when the material is subjected to magnetic fields. The encoding of magnetization remains challenging because most magnetizing methods act globally on the entire magnetic material, and assembling separately magnetized components to localize magnetization compromises structural complexity, alignment, and manufacturing precision. In parallel, reliable multi-material integration is critical because therapeutic operation depends on the incorporation of functional materials or components (e.g., drug-loaded hydrogels, chemical sensing elements, and actuation mechanisms). It is challenging to keep interfacial integrity and functional stability under repeated loading.

This thesis addresses these challenges by introducing two fabrication strategies that enable controllable three-dimensional magnetization programming and robust integration of magnetic soft materials with diverse substrates and functional layers. These advances are validated through in vivo experiments that demonstrate magnetically guided navigation, positioning, and localized therapeutic delivery. The contributions of this thesis are presented across the chapters, moving from foundational programming and fabrication methods to integrated systems and application-level validation.

Chapter 2 establishes a methodology for scalable fabrication of magnetic soft metamaterials while preserving three-dimensional magnetization programming that is decoupled from structural fabrication. This chapter uses a voxel-based lattice that partitions the structure into responsive modules, where each unit can be assigned a prescribed magnetization direction. In order to achieve this, the chapter establishes a fluidic programming method that encodes these directions after the lattice is formed. The selected voxel groups are filled with magnetic ink, particles are aligned during processing, and sequential curing fixes multiple magnetization directions within a single continuous structure. This framework is subsequently used to guide elastic buckling through magnetic actuation. The controlled instability amplifies deformation and enables reconfigurable responses and switchable Poisson’s ratio under modest actuation conditions. Importantly, this three-dimensional magnetization programming capability provides a foundation for Chapter 3 and Chapter 4, where the same magnetization principles are incorporated into scalable fabrication workflows and extended to integrated multi-material devices.

Chapter 3 establishes a scalable fabrication and magnetic programming strategy based on multi-layer screen printing. A layer-by-layer deposition technique is developed to fabricate soft robots with patterned magnetic elastomers on various substrate materials. In this chapter, magnetic orientation is integrated directly into the printing sequences. By stacking different functional materials with carefully designed patterns, several devices are demonstrated. Biomedical soft robots are printed to travel within a vascular model under magnetic actuation. Soft devices integrated with on-board electronics are fabricated to switch among multiple operating modes. Bio-inspired robots are created with fluorescent afterglow for visual feedback. These demonstrations validate the versatility and scalability of the multi-layer screen-printing strategy and provide the fabrication and integration basis for the in vivo therapeutic validation presented in Chapter 4.

Chapter 4 builds on the fabrication methods established in the previous chapters and develops a bi-layer biohybrid magnetic carrier robot for microbiome-based therapy in ulcerative colitis. The robot integrates a magnetically responsive actuation layer with a bacteria-loaded hydrogel layer in a tightly coupled architecture. This bi-layer design enables precise, controllable locomotion together with site-specific release of probiotics. In vivo studies further show that the probiotic hydrogel–integrated magnetic carrier improves localization and retention in the colon, leading to a pronounced therapeutic recovery in a mouse model of colitis. This chapter provides a foundation for magnetic soft robots in localized, non-invasive diagnosis and therapy.

 

Promotor

• Prof. Dr. S. Misra (University of Twente/University Medical Center Groningen, The Netherlands)

Supervisor

• Dr. V. K. Venkiteswaran (University of Twente, The Netherlands)

Assessment Committee

• Prof. Dr. J.T.B. Overvelde (Eindhoven University of Technology)
• Prof. Dr. R. Schirhagl (University Medical Center Groningen)
• Prof. Dr. A. Sadeghi (University of Twente)

Opposition Committee

• Prof. Dr. A. Krushynska (University of Groningen)
• Prof. Dr. P. Onck (University of Groningen)
• Dr. M. Asseln (University of Twente)