3D-Printed Microrobots for Magnetic Actuation, Imaging, and Hyperthermia

Executive Summary

Microrobots offer transformative potential in biomedical applications, including targeted drug delivery, detoxification, and minimally invasive surgeries. However, two key challenges hinder their clinical translation: achieving scalable and precision fabrication, and enabling non-invasive imaging and tracking within deep biological tissues. MSU researchers have developed TriMag microrobots—biocompatible hydrogel microrobots that uniquely combine three magnetic functions in one platform: precise magnetic actuation, magnetic particle imaging (MPI) visibility, and magnetothermal heating for localized hyperthermia. They provide high-contrast MPI tracking and strong actuation response, while enabling rapid, localized heating under alternating magnetic fields. The TriMag platform demonstrated controlled locomotion, orientation-resolved MPI tracking in dense tissues (e.g., porcine brain phantom, porcine eye), in vivo gastric navigation in mice (CT–MPI co-registered), and proof-of-concept tumor hyperthermia with rapid temperature rise to therapeutic ranges and tumor signal reduction—all highlighting potential for minimally invasive interventions and theranostics.

Description of Technology

TriMag microrobots are printed from a PEGDA/PETA photosensitive hydrogel using two-photon polymerization. Instead of embedding opaque nanoparticles in the resin (which limits TPL), dissolved Fe and Co ions are co-printed in a transparent precursor and then converted post-printing to Fe3O4 and CoFe2O4 nanoparticles by exposure to hydroxide (e.g.,NaOH/NH4Cl). This in situ approach yields uniform nanoparticle distribution on/within the hydrogel lattice, preserving nanoscale print fidelity and enabling higher effective magnetic loading than direct nanoparticle doping or post-deposition coatings. Helical geometries (≈100 μm length) are actuated using rotating magnetic fields (Helmholtz coils) with optimized ~45° helix angle for propulsion efficiency; motion mode, speed, and trajectory are controlled via frequency and field orientation. The Fe3O4/CoFe2O4 combination balances MPI sensitivity and magnetothermal efficiency, enabling triple functionality in one microrobot. Rated at TRL 3.

Benefits

• Triple functionality in a single agent: magnetic actuation, MPI imaging/tracking, and magnetothermal hyperthermia.
• Transparent-ion printing + in situ NP formation preserves 2-photon printability and yields uniform magnetic loading.
• Demonstrated deep-tissue tracking and guidance (porcine brain phantom), ocular navigation (porcine eye), and in vivo gastric navigation (mouse) with CT–MPI co-registration.
• Localized heating reaches therapeutic temperatures faster with Fe3O4+CoFe2O4 vs. single-component systems; enables targeted tumor ablation in mice.
• Biocompatible hydrogel base; hemolysis <5% in safety assay; degradability profile characterized for relevant biofluids.
• Platform extensible to drug delivery, bioelectronic delivery, and minimally invasive procedures.

Applications

• Targeted oncologic hyperthermia and adjunct therapies (precise, localized heating with MPI guidance).
• Image-guided drug delivery and minimally invasive procedures in GI tract, ophthalmology, and soft tissues.
• Research tool for microrobot swarm control, navigation, and closed-loop MPI feedback studies.
• Theranostic microrobotics integrating imaging, actuation, and intervention in one platform.

Patent Status

Patent pending

Publications

“TriMag Microrobots: 3D-Printed Microrobots for Magnetic Actuation, Imaging, and Hyperthermia,” Advanced Materials, 2025,

Licensing Rights

Full licensing rights available

Inventors

Dr. Jinxing Li, Dr. Liuxi Xing

TECH ID

TEC2025-0093