Fabrication and characterization of a helical propulsion millirobot with streamlined head and conical tail

Magnetic robots show wide applications in the fields of biomedical science, facilitating gastric treatment and transluminal procedures. However, the challenges of low velocity and poor control accuracy are faced by the helical millirobot. In the present study, the helical propulsion millirobot with streamlined head and inner helical groove was designed to enhance swimming velocity. The model of the helical propulsion millirobot was developed to analyze the swimming performance based on the resistance theory. The magnetic drive system was established to propel the millirobot through swimming. The rotating magnetic field was designed to regulate the direction of the motion. The permanent magnet was embedded in the head of the millirobot to receive the external magnetic field driving. The experiments investigated that the swimming velocity of the helical propulsion millirobots was increased by 69% compared with the millirobots of cylindrical head and cylindrical tail structures. The effects of magnetic field strength, magnetization strength, fluid viscosity, line radius, pitch, and cone angle tangent on swimming velocity were investigated based on the established experiment platform. Path experimental research was conducted to investigate the accuracy of the rotating magnetic field control.