Fabrication and characterization of magnetically actuated flexible microrobot based on guidewire for intravascular treatment

Abstract

In this research, medical microrobot based on guidewire was fabricated for intravascular treatment such as chronic total occlusion (CTO). Chronic total occlusion (CTO) is totally clogged vessel disease for two or more months. Percutaneous coronary intervention (PCI) procedure is conventional treatment method using medical tools such as guidewire, balloon catheter, and stent. Guidewire takes a role to be guidance toward the lesion in human body with path of blood vessel. However, this guidewire has low controllability due to manipula-tion by operator’s hand. To increase controllability of guidewire for enhanced percutaneous coronary intervention (PCI) procedure, a flexible microrobot for medical tool was used at the guidewire. Structure of this flexible microrobot consist of the permanent magnet, beam, and connector. The proposed cylindrical microrobots were successfully fabricated by a replica molding method with polydimethylsiloxane (PDMS) material for formability, flexibility, and biocompatibility. This fabricated microrobot was attached to tip of guidewire using epoxy. Steering experiments of flexible microrobot were conducted by controlling external magnetic field. This magnetic field was generated by half-sphere type eight electromagnetic coil sys-tem (Minimag) using current control. Flexible microrobot was deformed toward all of direc-tion under magnetic field. Deformation angle of flexible microrobot is maximum almost 80 degrees at the magnetic field with 15 mT of intensity and 170 degrees of direction. Also, this results were compared with analytic solution driven by Euler-Bernoulli beam theory and fi-nite element method (FEM) analysis of multiphysics modeling. Designed microrobot for im-provement of performance of guidewire was conducted in vitro experiments in blood vessel phantom to confirm track-ability. Flexible microrobots was confirmed to success until 60 de-grees of branch angle in blood vessel phantom. Also, Flexible microrobot based on guide-wire was demonstrated in blood vessel networks phantom with multiple branch. This re-search confirmed the remotely steerable microrobot with magnetic actuation and track-ability of microrobot based on guidewire. Flexible microrobot based on guidewire was shown pos-sibility of robotic assisted percutaneous coronary intervention (PCI) for intravascular treat-ment. ⓒ 2017 DGIST