Resistance model of an active capsule endoscope in a peristaltic intestine.

In the past studies, the resistance of magnetically controlled capsules running through the small intestine has been modeled assuming that the small intestine was a circular tube with a constant diameter. Peristalsis is an important character of the human gastrointestinal system, and it would result in some changes in the diameter of the intestine, meaning that the existing resistance models would no longer be applicable. In this paper, based on the assumption that intestinal peristalsis is actually a sinusoidal wave, a resistance model of the capsule running in the peristaltic intestine is established, and then it is validated experimentally. The model provides a realistic foundation for the optimization and control of the magnetically controlled endoscopy.

Hemodynamic study of blood flow in the aorta during the interventional robot treatment using fluid-structure interaction.

An interventional robot is a means for vascular diagnosis and treatment, and it can perform dredging, releasing drug and operating. Normal hemodynamic indicators are a prerequisite for the application of interventional robots. The current hemodynamic research is limited to the absence of interventional devices or interventional devices in fixed positions. Considering the coupling effect of blood, vessels and robots, based on the bi-directional fluid-structure interaction, using the computational fluid dynamics and particle image velocimetry methods, combined with the sliding and moving mesh technologies, we theoretically and experimentally study the hemodynamic indicators such as blood flow lines, blood pressure, equivalent stress, deformation and wall shear stress of blood vessels when the robot precesses, rotates or does not intervene in the pulsating blood flow. The results show that the intervention of the robot increase the blood flow rate, blood pressure, equivalent stress and deformation of the vessels by 76.4%, 55.4%, 76.5%, and 346%, respectively. The operating mode of the robot during low-speed operation has little impact on the hemodynamic indicators. Using the methyl silicone oil as the experimental fluid, the elastic silicone pipe as the experimental pipe, and the intervention robot having a bioplastic outer shell, the velocity of the fluid around the robot is measured on the developed experimental device for fluid flow field in a pulsating flow when the robot runs. The experimental results are similar to the numerical results. Our work provides an important reference for the hemodynamic study and optimization of the mobile interventional devices.

Orthogonal Optimal Design of Multiple Parameters of a Magnetically Controlled Capsule Robot.

Magnetically controlled capsule robots are predominantly used in the diagnosis and treatment of the human gastrointestinal tract. In this study, based on the permanent magnet method, magnetic driving and fluid measurement systems for in-pipe capsule robots were established. Using computational fluid dynamics (CFD) and particle image velocimetry (PIV), the fluid velocity and vorticity in the pipe of the capsule robot were calculated and measured. The running characteristics of the capsule robot were numerically analyzed in the curved pipe and the peristaltic flow. Furthermore, the range and variance method of orthogonal design was used to analyze the influence of four typical parameters (namely, pipe diameter, robotic translational speed, robotic rotational speed, and fluid viscosity) on the three operating performance indicators of the capsule robot (namely, the forward resistance of the robot, fluid turbulent intensity near the robot, and maximum fluid pressure to the pipe wall). In this paper, the relative magnitude and significance of the influence of each typical parameter on different performance indicators of the robot are presented. According to the different performance requirements of the robot, the different four parameter combinations are optimized. It is hoped that this work provides a reference for the selection of the appropriate mucus, translational speed, and rotational speed of the robot when it is working in pipes with different diameters.