Flexible Magnetic Soft Stent for Mobile Flow Diversion

With the advantages in dimensions and exceptional locomotion capabilities, small-scale mobile robots have offered new opportunities for medical interventions in hard-to-reach regions, including the distal arteries in the circulatory systems. In this field, the wireless soft robots fabricated with compliant materials further provide unique adaptation capabilities and, thus, many exciting potential applications [1]. Although various locomotion abilities have been demonstrated and studied from the aspects of robot design, control strategies, and soft- bodied interactions [2], rare effective functions other than drug delivery have been properly incorporated into these robots for potential in-vivo utilities. Our group has recently developed a medical robotic system with a stent- shaped magnetic soft device (Stentbot) and the associated spatial magnetic actuation setup, which realized the on- demand local drug delivery and the flow diversion using a millimeter wireless robot design [3]. Its flexible locomotion capabilities have indicated its benefits of working as a mobile flow diverter if clinical migrations or misplacements happen when treating brain aneurysms using stent-like structures. However, this single-material development traded off the performance in locomotion abilities and the efficacy of flow diversion. For example, pure mesh-like structures ensure full body adaptation for the retrievable locomotion among the lumens with varying diameters, but the effectiveness of flow diversion is reduced since flow could go through the meshes freely. On the other hand, a full surface-sealed, hollow tube structure where all the gaps among meshes are filled could have a perfect flow diversion effect. However, the radial stiffness of the structure is notably increased, such that the shape adaptation capability is reduced. Therefore, there is a missing solution for the effective flow diverter with proper adaptation for the future treatments of brain aneurysms and other diseases, such as arteriovenous malformation.