Fabrication and performance evaluation of magnetically driven double curved conical ribbon micro-helical robot

In this research, a magnetically driven double curved conical ribbon micro-helical robot was proposed to improve the swimming stability and swimming performance. Its swimming performance as well as magnetization characteristics were analyzed by fluid dynamics simulation. Meanwhile, a transverse bidirectional fold-line scanning method was proposed to fabricate the designed microrobots via voxel-modulation two-photon polymerization microfabrication technology. After optimizing the machining parameters, the length dimension error of the double curved conical ribbon micro-helical robot could be further reduced to less than 1%. Furthermore, a conical rotating three-dimensional uniform magnetic field was established to drive the microrobots. Microrobot driven experiment of the conical rotating three-dimensional uniform magnetic field was conducted and compared with the planar uniform magnetic field. It is proved that the micro-helical robot driven by the conical rotating three-dimensional uniform magnetic field can achieve high stability and no swing swimming in the low-frequency spiral propulsion state. This work may provide a reference for the future application of micro-helical robots in the fields of drug delivery, cell sorting, sensing and environmental repair in vivo.