Self-Adaptive Magnetic Liquid Metal Microrobots Capable of Crossing Biological Barriers and Wireless Neuromodulation

Magnetic liquid-bodied microrobots (MRs) possess nearly infinite shape adaptivity. However, they currently confront the risk of structure instability/crushes during shape-morphing in tiny biological environments. This article reports that magnetic liquid metal (LM) MRs (LMMRs) show high structure stability and robust magnetic maneuverability. In this protocol, Fe nanoparticles are encapsulated inside less-than-10-μm LM microdroplets by establishing interfacial chemical potential barriers, yielding LMMRs. Their robust magnetic maneuverability originates from the magnetically controlled assembly of Fe nanoparticles inside LM and distinct liquid-solid interaction. With the self-adaptive shape-recovering capabilities even after 50% deformation, LMMRs can implement vertical climbing over walls up to 400% of its body length and traverse channels with the size of its two-thirds. The in vitro and in vivo experiments have both verified the effective magneto-mechanical stimulation of LMMRs upon neurons after their shape-adaptive crossing the blood-brain barrier under a driven magnetic field. Our work provides a promising strategy for wireless therapies with MRs by safely and effectively overcoming biological barriers.