World's first MPI-trackable alginate-based microrobot: breakthrough platform enables targeted stimulation, position tracking, and cell delivery without cameras or radiation

A research team led by Professor Sung Hoon Kim from Korea University has developed the world's first alginate-based microrobots that can be tracked using Magnetic Particle Imaging (MPI).

The newly developed system, reported in the International Journal of Extreme Manufacturing, marks a major milestone in microrobotics by enabling real-time localization, selective thermal therapy, and cell delivery—all powered and controlled through a single magnetic actuation system, completely independent of conventional medical imaging devices such as cameras, CT, or X-ray machines.

The research team engineered an advanced calcium alginate hydrogel microrobot by embedding two types of magnetic materials—superparamagnetic iron oxide nanoflowers (SPNF) and NdFeB (neodymium-iron-boron) microparticles—into the hydrogel matrix. Unlike previous microrobots that relied on a single magnetic component, this synergistic combination enabled the world's first triple-functional magnetic hydrogel robot, capable of:

• Magnetic heating: Raising localized plasma fluid temperature by over 10°C at 13 kA/m and 200 kHz
• Low-field locomotion: Achieving speeds up to 25 mm/s in magnetic fields below 2 mT
• Real-time tracking: Achieving 2.8 mm spatial accuracy with MPI under a selection field of 0.4 mT/mm

Traditional microrobot tracking has relied heavily on CT, X-ray, or camera-based systems, which come with several limitations including radiation exposure, high cost, and poor compatibility with in vivo environments. In contrast, this new robot utilizes MPI, a novel and emerging magnetic imaging modality, to track both the position and magnetic concentration of the robot in real-time, without the need for radiation or optical devices.

The microrobots were successfully used to deliver and release therapeutic cells, guided precisely to target areas, and to induce localized heating upon arrival for potential oncological or regenerative applications. The researchers also demonstrated cell viability and growth after delivery, validating the robot’s therapeutic potential.

Even within a flowing fluid phantom mimicking physiological blood flow (up to 50 mm/s), the robot maintained stable locomotion and positional accuracy, underscoring its robustness for eventual in vivo clinical applications.

Professor Kim emphasized the significance of the study, stating:

“This research goes beyond the conventional concept of magnetic robots performing imaging, actuation, and therapy as separate systems. We’ve successfully demonstrated an all-in-one platform that integrates all functions into a single, compact electromagnetic coil system, laying the groundwork for the next generation of magnetically actuated theranostic systems.”

The work paves the way for a variety of high-impact biomedical applications, including precision cancer therapy, neural stimulation, and localized cell-based treatment.

Looking ahead, the team plans to validate the robot further through long-term biological testing and animal models, with the vision of creating a fully autonomous, image-free intelligent microrobot capable of navigating, treating, and tracking inside the human body—without the aid of cameras or CT scanners.

International Journal of Extreme Manufacturing (IJEM, IF: 21.3) is dedicated to publishing the best advanced manufacturing research with extreme dimensions to address both the fundamental scientific challenges and significant engineering needs.

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