Design of Efficient Propulsion for Nanorobots

Due to the constraints imposed at low Reynolds number, the design of efficient propulsive systems for nanorobots has proven challenging. In this paper, an approach for the design of an efficient nanorobotic propulsive system was proposed. First, resistive force theory was used to develop a dynamic model for the propulsion of nanorobots, accounting for the fluid dynamics generated by the propeller (flagellum). Second, an optimal control problem was formulated and solved to balance the tradeoff between energy utilization and tracking efficiency. Finally, simulations were conducted to analyze the effect of different body to flagellum ratios (BFR) on propulsive efficiency. It was found that the optimal flexural rigidity of the nanorobot propeller was 5.8 × 10 ^-19N·m ², within the range of sperm flagellum, 0.7 × 10 ^-19 -74.0 × 10 ^-19N·m ². Simulations of multiple BFRs demonstrated that multipoint actuation of the nanopropeller was more efficient at BFRs of less than 1.0, while single actuation was only effective for nanorobots with a BFR >0.2. The results from this study could provide useful insights for the design of efficient nanorobotic propulsive systems, in terms of energy efficiency and trajectory tracking accuracy.