Fig. 1: Design of the robotic system for distal-endovascular applications.
From: Adaptive wireless millirobotic locomotion into distal vasculature
a Overall concept of the application scenarios in the distal vasculature. The M4 segment of the middle cerebral artery (MCA) case is shown here, where catheterization is challenging. Major locomotion capability of the proposed wireless soft robot: forward and backward shape adaptation in lumens with varying diameters; flow withstanding when no magnetic field is applied; traversing among curved routes and branches. The robot can function as a mobile carrier for other functional tools to treat acute ischemic stroke, aneurysm, and arteriovenous malformation. b Robot CAD design drawing and the photo of the robot prototype. A stent-shaped structure was chosen for its high radial deformability and low fluidic drag property. There are three critical design parameters: the strut spacing h, the radius of curvature at the crown junction ρ, and the axial amplitude of each segment f. The NdFeB ferromagnetic microparticles inside the robot body were uniformly magnetized using 1.8 T homogeneous magnetic field. Right-handed helical structures with a helix angle φ were coated to assist the locomotion utilizing anisotropic frictional forces when the robot was rotated around its body-attached yr-axis. c Magnetic actuation system composed of a 7-DoF robotic arm, a step motor, and a 50 mm cubic NdFeB permanent magnet. The communication framework was realized by Robot Operating System (ROS). d Robot actuation using both magnetic torques and forces. The magnet with moment ma is rotated around the ya-axis of the magnet-attached local coordinate xr-yr-zr, such that the robot at the \({{{{{{\bf{p}}}}}}}_{{{{{{\rm{a}}}}}}}^{{{{{{\rm{r}}}}}}}\) away from the magnet with moment mr is rotated around the yr-axis of the robot-attached local coordinate xr-yr-zr by magnetic torques (direction is reversed). The magnet is also translated with the speed of vmag and reorientated with the angle of αmag with respect to the global coordinate x-y-z. Given the requirement on cortex-to-scalp distance ls = 15 mm, the magnet should be placed at least 50 mm away from the robot along the zr-axis, i.e., lmag ≥ 50 mm. All scale bars: 1 mm.
