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1. Generalized direct fabrication of embedded–magnet microrobots with enhanced material compatibility

   https://doi.org/10.1007/s12213-026-00208-8  

   Yang, Yang; Gan, Jeremy B; Huang, Jialong; Mucke, Sven; Davis, Aaron C; Wang, Haiyan; Cappelleri, David J (December 2026, Journal of Micro and Bio Robotics)

   Abstract Magnetically actuated microrobots offer transformative potential for biomedical applications such as targeted drug delivery and minimally invasive diagnostics. However, existing fabrication methods are constrained by challenges in magnetic material integration, structural robustness, and reproducibility. In this work, we present an improved direct-printing strategy that integrates permanent micro-magnets into microrobots during the two-photon polymerization (TPP) process, thereby eliminating the need for post-assembly alignment or insertion. To enhance magnetic-material compatibility and interfacial reliability, a sputtering-based surface modification technique is introduced, enabling robust integration of both pre-coated and surface-treated magnets. Using this approach, four functional microrobotic platforms are demonstrated: (1) a helical microswimmer for efficient propulsion, (2) a micro-scale tumbling microrobot for terrain locomotion, (3) a compliant micro-gripper for precise grasping and manipulation, and (4) a mini-MicroTumbler (MMT) incorporating a sputter-modified magnet for stable microscale actuation. Performance characterization was conducted under varying actuation frequencies and environments. The microswimmer exhibited frequency-dependent propulsion consistent with magnetic step-out behavior, the MicroTumbler achieved stable locomotion across inclined surfaces, the micro-gripper demonstrated controllable deformation and object manipulation, and the MMT showed reliable frequency-dependent motion. This study establishes a scalable, material-flexible, and high-fidelity fabrication method for embedded-magnet microrobots, broadening the design space and enabling the next generation of multifunctional, magnetically actuated microsystems. 

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2. Imaging-guided bioresorbable acoustic hydrogel microrobots

   https://doi.org/10.1126/scirobotics.adp3593  

   Han, Hong; Ma, Xiaotian; Deng, Weiting; Zhang, Junhang; Tang, Songsong; Pak, On Shun; Zhu, Lailai; Criado-Hidalgo, Ernesto; Gong, Chen; Karshalev, Emil; et al (December 2024, Science Robotics)

   Micro- and nanorobots excel in navigating the intricate and often inaccessible areas of the human body, offering immense potential for applications such as disease diagnosis, precision drug delivery, detoxification, and minimally invasive surgery. Despite their promise, practical deployment faces hurdles, including achieving stable propulsion in complex in vivo biological environments, real-time imaging and localization through deep tissue, and precise remote control for targeted therapy and ensuring high therapeutic efficacy. To overcome these obstacles, we introduce a hydrogel-based, imaging-guided, bioresorbable acoustic microrobot (BAM) designed to navigate the human body with high stability. Constructed using two-photon polymerization, a BAM comprises magnetic nanoparticles and therapeutic agents integrated into its hydrogel matrix for precision control and drug delivery. The microrobot features an optimized surface chemistry with a hydrophobic inner layer to substantially enhance microbubble retention in biofluids with multiday functionality and a hydrophilic outer layer to minimize aggregation and promote timely degradation. The dual-opening bubble-trapping cavity design enables a BAM to maintain consistent and efficient acoustic propulsion across a range of biological fluids. Under focused ultrasound stimulation, the entrapped microbubbles oscillate and enhance the contrast for real-time ultrasound imaging, facilitating precise tracking and control of BAM movement through wireless magnetic navigation. Moreover, the hydrolysis-driven biodegradability of BAMs ensures its safe dissolution after treatment, posing no risk of long-term residual harm. Thorough in vitro and in vivo experimental evidence demonstrates the promising capabilities of BAMs in biomedical applications. This approach shows promise for advancing minimally invasive medical interventions and targeted therapeutic delivery. 

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3. Size-dependent magnetic and magnetothermal properties of gadolinium silicide nanoparticles

   https://doi.org/10.1039/D0RA05394E  

   Nauman, Muhammad; Alnasir, Muhammad Hisham; Hamayun, Muhammad Asif; Wang, YiXu; Shatruk, Michael; Manzoor, Sadia (July 2020, RSC Advances)

   null (Ed.)

   Gadolinium silicide (Gd 5 Si 4 ) nanoparticles are an interesting class of materials due to their high magnetization, low Curie temperature, low toxicity in biological environments and their multifunctional properties. We report the magnetic and magnetothermal properties of gadolinium silicide (Gd 5 Si 4 ) nanoparticles prepared by surfactant-assisted ball milling of arc melted bulk ingots of the compound. Using different milling times and speeds, a wide range of crystallite sizes (13–43 nm) could be produced and a reduction in Curie temperature ( T C ) from 340 K to 317 K was achieved, making these nanoparticles suitable for self-controlled magnetic hyperthermia applications. The magnetothermal effect was measured in applied AC magnetic fields of amplitude 164–239 Oe and frequencies 163–519 kHz. All particles showed magnetic heating with a strong dependence of the specific absorption rate (SAR) on the average crystallite size. The highest SAR of 3.7 W g −1 was measured for 43 nm sized nanoparticles of Gd 5 Si 4 . The high SAR and low T C , (within the therapeutic range for magnetothermal therapy) makes the Gd 5 Si 4 behave like self-regulating heat switches that would be suitable for self-controlled magnetic hyperthermia applications after biocompatibility and cytotoxicity tests. 

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4. Polydopamine‐Assisted Electroless Deposition of Magnetic Functional Coatings for 3D‐Printed Microrobots

   https://doi.org/10.1002/aisy.202400702  

   Zhang, Shuo; Harms, Caroline F; Zhang, Zenghao; Lim, Jiwon; Heron, John T; Kim, Jinsang; Pena‐Francesch, Abdon (January 2025, Advanced Intelligent Systems)

   Magnetic microrobots are attractive tools for operation in confined spaces due to their small size and untethered wireless operation, particularly in biomedical and environmental applications. Over years of development, many microrobot fabrication methods have been developed; however, they typically require costly specialized physical vapor deposition (PVD) vacuum instrumentation and present homogeneity and conformality coating problems (especially in complex 3D structures). Herein, a solution‐based polydopamine (PDA)‐assisted electroless deposition method is developed to deposit a superparamagnetic nickel thin film on microrobots. The multilayered functional film design comprises PDA as an adhesive primer and reducing agent, silver nanoclusters as catalysts, and a nickel magnetic top film, all deposited in a batch solution‐based process on glass and 3D‐printed polymer substrates. This multilayer magnetic coating is implemented and demonstrated in three magnetic microrobot archetypes, including arbitrarily‐shaped active particles, microrollers, and helical swimming microrobots, each using distinct actuation working mechanisms. Due to the material‐independent interfacial adhesive properties of PDA, this multilayer functionalization strategy can open up new magnetic microrobot fabrication schemes with a broad compatibility with materials and structures (including complex 3D‐printed polymer microstructures) and without the need for and limitations of PVD coating approaches. 

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5. Nanozyme Microrobots: Programmable Spatiotemporal Catalysis for Targeted Therapy and Diagnostics

   https://doi.org/10.1002/advs.202523365  

   Tran, Hong Huy; Pandey, Nil Kanatha; Cormode, David P; Lee, Daeyeon; Steager, Edward; Koo, Hyun (March 2026, Advanced Science)

   Nanozyme microrobots combine catalytic nanomaterials with small‐scale robotic control to deliver programmable, spatiotemporal catalysis for biomedical applications with precision. Actuated by external stimuli, such as magnetic, acoustic, optical, or chemical gradients, these systems localize and modulate catalytic activity on demand, overcoming long‐standing limitations of bulk catalysis, including poor spatial precision, restricted substrate access, and limited adaptability in complex biological environments. By uniting targeted navigation with stimulus‐responsive activation, nanozyme microrobots facilitate precise intervention in anatomically challenging and inaccessible niches, from biofilms to solid tumors, and support theranostic workflows with real‐time readouts. This review focuses on design principles for integrating nanozymes with microrobotics, surveys actuation, automation, and control strategies, and highlights biomedical applications across biofilm infection control, oncology, and catalytic diagnostics. Together, the convergence of nanozyme catalysis and microrobotic mobility is yielding versatile, adaptive platforms with the potential to transform targeted diagnostics and therapy. 

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