Magnetically actuated pick-and-place operations of cellular micro-rings for high-speed assembly of micro-scale biological tube

Tissue engineering is trying to use modular tissue micro-rings to construct artificial biological microtubes as substitute of autologous tissue tubes to alleviate the shortage of donor sources. However, because of the lack of effective assembly strategies, it is still challenging to achieve high-speed fabrication of biological microtubes with high cell density. In this paper, we proposed a robotic-based magnetic assembly strategy to handle this challenge. We first encapsulated magnetic alginate microfibers into micro-rings formed by cell self-assembly to enhance the controllability. Afterwards, a 3D long-stroke manipulator with visual servoing system was designed to achieve magnetic pick-and-place operations of micro-rings for 3D assembly. Moreover, we developed a mathematical model of the motion of micro-ring in solution environments. Based on visual feedback, we analyzed the feasibility of automatic assembly and following response of micro-rings with the moving magnets, which shows our proposed method has great potential to achieve high-speed bio-assembly. Finally, we successfully assembled multi-micro-rings into a biological microtube with high cell density.