Modeling and experimental characterization of propulsion of a spiral-type microrobot for medical use in gastrointestinal tract

In this paper, a spiral-type medical robot based on an

endoscopic capsule was propelled in a fluidic and tubular environment

using electromagnetic actuation. Both modeling and experimental

methods have been employed to characterize the propulsion

of the robotic capsule. The experiments were performed not only

in a simulated environment (vinyl tube filled with silicone oil) but

also in a real small intestine. The effects of the spiral parameters

including lead, spiral height, the number of spirals, and cross section

of the spirals on the propulsion efficiency of the robot are

investigated. Based on the transmission efficiency from rotation to

translation as well as the balancing of the microrobot in operation,

it is demonstrated that the robot with two spirals could provide

the best propulsion performance when its lead is slightly smaller

than the perimeter of the capsule. As for the spiral height, it is

better to use a larger one as long as the intestine’s size allows.

Based on the simulation and experimental results presented, this

study quantifies the influence of the spiral structure on the capsule’s

propulsion. It provides a helpful reference for the design and

optimization of the traction topology of the microrobot navigating

inside the mucus-filled small intestine.