Fig. 1. Principle of aniso-electrodeposition method and illustration of the aniso-electrodeposited MMRs.

(A) In aniso-electrodeposition, a 3D electric field is used to embed complex heterogeneous cross-link density into hydrogel networks to generate different types of shape morphing. (B) Schematic illustration of MMRs in the rat gastrointestinal tract. Through aniso-electrodeposition, drugs, contrast agents, cells, and magnetic nanoparticles (MNPs) can be loaded onto the different hydrogel microstructure modules of the MMR. Under magnetic control, there are two locomotion modes, fish-like and caterpillar-like locomotion, which allow the microrobots to move toward and self-grasp the target, release the payload, and remove the magnetic modules after payload delivery.