Tumbleweed-Like Aggregation-Induced-Emission Microrobots: Swarming for Ultra-Tracing of Hydrazine

Hydrazine (N2H4) poses severe health risks even in trace amounts due to the highly carcinogenic and teratogenic degeneration while it is frequently used in industrial products. However, current techniques are difficult to perform in-situ detection of N2H4 within confined sophisticated reactors or slim apparatus. Bioinspired by natural plant tumbleweed, we have demonstrated that swarming aggregation-induced emission microrobots (AIE-bots), which have a tumbleweed-like macroporous structure, are capable of performing motile-targeting detection of N2H4 leakage or accumulation. In this protocol, the AIE-bots are assembled from emulsion droplets containing AIEgens and hydrophobic Fe3O4 nanoparticles evenly distributed in CHCl3 and n-hexane through phase separation during the evaporation of volatile solvents. Upon the application of a precessing B(t), the AIE-bots can wobble in swarms and adaptively navigate through narrow channels without adjusting B(t). Additionally, they can efficiently ascend steep slopes with angles up to 45° due to the lightweight and coarse surface. While moving, the swarming AIE-bots can in-situ perceive the N2H4 concentration surrounding with an LOD of 3.81 ppb via fluorescence enhancement based on the Schiff base reaction. This work provides a microrobot detecting unknown toxin leakage or accumulation in hard-to-reach microenvironments, and will inspire the development of fluorescent micro-/nanorobots for intelligent motile sensing.