Wireless Precise Manipulation of Tumor Spheroids Using a Millirobot Controlled by Permanent Magnetic Traps

Spheroids are important 3D multicellular culture systems that recapitulate key structural and functional features of native tissues. However, label‐free long‐term and precise manipulation of spheroids in culture environments remains challenging. Here, we report a donut‐shaped magnetic millirobot (DonutBot) controlled by permanent magnetic traps for wireless pick‐and‐place of individual tumor spheroids. The DonutBot is fabricated from magnetic calcium–alginate hydrogel, exhibiting excellent cytocompatibility. A strong in‐plane magnetic trap is established by combining two opposing permanent magnet arrays. Under in vitro culture conditions, stable robot trapping is realized without external energy input or heat generation, ensuring secure positioning of the spheroid. The trapping force steadily holds the spheroid upon regular exchange of cell culture media. By integrating in‐plane control and dynamic vertical control, the DonutBot enables automated pick‐and‐place manipulation of PANC‐1 pancreatic tumor spheroids along designed trajectories. The miniature robotic manipulation system allows for continuous and precise spheroid manipulation under physiologically relevant conditions, offering new opportunities for long‐term studies of spheroid mechanobiology.