Li Zhang

Reconfigurable Magnetic Nanoparticle-Swarm for Targeted Delivery

Prof. Li Zhang
Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong (CUHK), Hong Kong, China


Recently, untethered microrobots have drawn extensive attention due to their great potential for biomedical applications, e.g. targeted drug delivery [1-4], and sensing [4-6]. In order to enhance the loading capacity, the contrast of imaging feedback, and the access rate in complex environments, swarm behaviours at the small scales need to be studied [7-9]. Inspired by nature, large-scale robotics systems can generate complex patterns, however, the investigations on microrbotic swarms that are capable of performing adaptive reconfiguration and effective locomotion require further development. Moreover, as the prerequisite for their in-vivo applications, whether the microrobotic swarms can take effect in bio-fluids with complex components and different physical conditions has neither been fully investigated. Herein, we report a strategy to reconfigure paramagnetic nanoparticles into ribbon-like swarms using oscillating magnetic fields. By tuning the parameters of the input fields, the microswarm can perform a reversible elongation with an extremely high aspect ratio, as well as merging and splitting behaviours. In order to understand the swarm behaviours in bio-fluids, we individually investigate the influence of fluidic viscosities, ionic strength and fibrous meshes on the swarms. Based on their performances, the optimised type of swarms in different bio-fluids is chosen based on their specific physical properties. Moreover, we also validate the analytic results by employing serum, gastric acid, blood plasma, hyaluronic acid, whole blood and vitreous humor as fluidic environments. Finally, we successfully realize the generation and navigated locomotion of microrobotic swarms in bovine eyeballs, which sheds light on the potential targeted delivery applications [10].


Li Zhang is an Associate Professor in the Department of Mechanical and Automation Engineering (MAE) at The Chinese University of Hong Kong (CUHK). His main research interests include micro-/nanorobotics and their biomedical applications, and functional materials for sensors, actuators and practical applications. Dr. Zhang is a senior member of IEEE, who has won several awards or in the Finalist from IEEE international conferences including ICRA IROS, ROBIO and NANOMED. Since 2004 he has authored and co-authored over 200 papers, including Science Robotics, Science Advances, Nature Communications, TRO and IJRR. He won the Hong Kong Research Grants Committee (RGC) Early Career Award in 2013, and the CUHK Young Researcher Award 2017. He currently serves as an Associate Editor of IEEE/ASME Transactions on Mechatronics (TMECH), IEEE Transactions on Automation Science and Engineering (TASE), IEEE Robotics and Automation Letters (RA-L), and IEEE Open Journal of Nanotechnology (OJNANO).



[1] Brad Nelson et al., “Microrobots for minimally invasive medicine.” Annual review of biomedical engineering 12 (2010): 55-85.

[2] Metin Sitti et al., “Biomedical Applications of Untethered Mobile Milli/Microrobots”, Proceedings of IEEE, 13 (2015): 205-224.

[3] Stefano Palagi and Peer Fischer. “Bioinspired microrobots”, Nature Reviews Materials, 3 (2018): 113-124.

[4] Joseph Wang, et al., “Micro/nanorobots for biomedicine: Delivery, surgery, sensing, and detoxification”, Science Robotics, 2.4 (2017): aam6431.

[5] Li Zhang, et al., “Multifunctional biohybrid magnetite microrobots for imaging-guided therapy.” Science Robotics, 2.12 (2017): eaaq1155.

[6] Li Zhang, et al., “Real-time tracking of fluorescent magnetic spore–based microrobots for remote detection of C. diff toxins.” Science advances 5.1 (2019): eaau9650.

[7] Oliver Schmidt et al., “Medical microbots need better imaging and control”, Nature 545 (2017): 406

[8] Li Zhang, et al., “Ultra-extensible ribbon-like magnetic microswarm.” Nature communications 9.1 (2018): 3260.

[9] Li Zhang, et al., “Pattern generation and motion control of a vortex-like paramagnetic nanoparticle swarm.” The International Journal of Robotics Research, 37.8 (2018): 912-930.

[10] Li Zhang et al., “Active generation and magnetic actuation of microrobotic swarms in bio-fluids” Nature Communications , 10 (2019):5631