A unified model of drag force for bubble-propelled catalytic micro/nano-motors with different geometries in low Reynolds number flows

Motion of catalytic micro/nano-motors with various geometries is mainly determined by the drag force and the propulsion force acting on the motors as they move in low Reynolds number flows. A unified solution of drag force along with drag coefficient for all circular cross-sectional types of micro/nano-motors is derived. The effect of the geometric parameters of a micro/nano-motor, such as the semi-cone angle θ, the ratio ξ of length to larger radius, on the drag coefficient is identified. Results provided in this work are useful for optimizing the design and fabrication of catalytic micro/nano-motors, which can be potentially used in biomedical and environmental engineering.