Locomotion adaptability is one of the most significant evolutionary steps in the story of life. Organism self-adjusted displacement in a controlled manner is essential for survival, reproduction, morphogenesis, and to respond to pathological processes. For example, Escherichia coli (E. coli) swim by rotating or tumbling their helical flagella to seek prey or nutrients.1 In their quest to fertilize the ovum, sperm cells propel with rotating and undulatory locomotion in a bulk and a confined fluid environment, respectively.2 This implies that the ability to modulate the locomotion mechanism provides the critical advantages when designing artificial swimmers.
Recent advances in template-assisted electrochemical manufacturing have enabled to create a plethora of advanced functional inorganic nanoarchitectures, which have been exploited as locomotion building blocks in mobile nanoswimmers.3 In this presentation, we capitalize on our wide expertise in template-assisted electrochemical processing to fabricate the simplest artificial swimmers, hard-magnetic CoPt nanowires. The CoPt nanowires are magnetized with a 60offset direction with respect to the nanowire’ long axis by a pre-magnetization process. Specifically, the pre-magnetized nanowires can show selective locomotion in a fluid, namely tumbling, precession, and rolling, by adjusting only the rotation speed of an external rotating magnetic field. This choice of displacement mode using a single input is achieved due to the intrinsic memory effects and dynamics of our developed hard-magnetic materials that constitute our swimmers.
Our results not only trigger a substantial body of research in the magnetism of nanomaterials, but also open new avenues in sensing and delivering cargos at nanoscale, performing intelligent behaviour in a confined fluid environment.
1. Darnton, N. C.; Turner, L.; Rojevsky, S.; Berg, H. C. J. Bacteriol. 2007, 189, 1756-1764.
2. Nosrati, R.; Driouchi, A.; Yip, C. M.; Sinton, D. Nat. Commun. 2015, 6, 8703.
3. Jang, B., et al. Nano Lett. 2015, 15, 4829-4833.