S. M. Jeon

Magnetic Navigation System With Gradient and Uniform Saddle Coils for the Wireless Manipulation of Micro-Robots in Human Blood Vessels

A magnetic navigation system (MNS) for the wireless manipulation of micro-robots in human blood vessels is a possible surgical tool for coronary artery disease. This paper proposes a novel MNS composed of one conventional pair of Maxwell and Helmholtz coils and one newly developed pair of gradient and uniform saddle coils. The proposed system was theoretically developed using the Biot-Savart law, and it was verified experimentally after constructing the proposed MNS. The proposed MNS is geometrically compact to allow a patient to lie down, and magnetically efficient compared with the conventional MNS which has two pairs of Maxwell and Helmholtz coils.

Magnetic navigation system for the precise helical and translational motions of a microrobot in human blood vessels

Different magnetic navigation systems (MNSs) have been investigated for the wireless manipulation of microrobots in human blood vessels. Here we propose a MNS and methodology for generation of both the precise helical and translational motions of a microrobot to improve its maneuverability in complex human blood vessel. We then present experiments demonstrating the helical and translational motions of a spiral-type microrobot to verify the proposed MNS.

A self-positioning and rolling magnetic microrobot on arbitrary thin surfaces

We propose a novel self-positioning and rolling magnetic microrobot (SPRMM) actuated by a magnetic navigation system. The proposed microrobot can effectively anchor or move on an arbitrary three-dimensional thin surface by overcoming external forces. Furthermore, we derive a no-slip rolling constraint equation for the SPRMM. We also examine the equilibrium characteristics of the SPRMM by utilizing the point-dipole model. Experiments demonstrating the locomotion abilities of the SPRMM in complex working environments are then conducted to verify the proposed SPRMM.

Precise manipulation of a microrobot in the pulsatile flow of human blood vessels using magnetic navigation system

This paper proposes a method to precisely manipulate a microrobot in the pulsatile flow that simulates the flow characteristics of human blood vessels by utilizing the electromagnetic transfer function of a magnetic navigation system (MNS). The frequency response characteristics of the MNS were utilized so that the input voltages in each coil can precisely generate the required time-varying magnetic force of a microrobot. An experiment which successfully anchoring a microrobot in a pulsatile flow was conducted to verify the proposed method.

Capsule-Type Magnetic Microrobot Actuated by an External Magnetic Field for Selective Drug Delivery in Human Blood Vessels

In this paper, we propose a novel capsule-type magnetic microrobot (CMM) that can navigate along a tubular environment and selectively release drugs in different target points actuated by a magnetic navigation system. The proposed CMM is a capsule-type structure with two cylindrical drug chambers that contain different drugs. It can navigate through a tubular environment by a magnetic gradient and release drugs at different positions by using uniform rotating magnetic fields. The proposed CMM was prototyped using 3-D printing technology. The operating conditions of a drug-releasing motion were determined by investigating the magnetic and friction torques within the body. Finally, we performed various experiments in a tubular environment to verify the validity of the proposed CMM.

Utilization of Magnetic Gradients in a Magnetic Navigation System for the Translational Motion of a Micro-Robot in Human Blood Vessels

This paper proposes a method to generate the translational motions of a micro-robot in human blood vessels by utilizing the magnetic gradients of a magnetic navigation system (MNS). The proposed method was applied to the MNS composed of a Maxwell coil, Helmholtz coil, and uniform and gradient saddle coils, and it was verified through the experiment demonstrating the rectilinear and translational motions of a micro-robot in a plane. This paper also discusses the effective aligning angle for the translational motion of a micro-robot to reduce the required magnetic gradients of the MNS. This research contributes to the effective and therapeutic manipulation of a micro-robot in human blood vessels.

Precise Steering and Unclogging Motions of a Catheter With a Rotary Magnetic Drill Tip Actuated by a Magnetic Navigation System

We developed a novel structure of a catheter actuated by an external magnetic field. The catheter is capable of steering and unclogging motions that improve its therapeutic maneuverability and functionality in human blood vessels. The tilting angle and vertical deflection of the catheter is described using the Euler-Bernoulli beam equation and defining two dimensionless variables. We also propose a methodology to precisely generate and control the steering and unclogging motions via a magnetic navigation system. We then conduct several experiments to show that the proposed system can control the vertical deflection, tilting angle, and drilling motion independently and effectively.

Dual-body magnetic helical robot for drilling and cargo delivery in human blood vessels

We propose a novel dual-body magnetic helical robot (DMHR) manipulated by a magnetic navigation system. The proposed DMHR can generate helical motions to navigate in human blood vessels and to drill blood clots by an external rotating magnetic field. It can also generate release motions which are relative rotational motions between dual-bodies to release the carrying cargos to a target region by controlling the magnitude of an external magnetic field. Constraint equations were derived to selectively manipulate helical and release motions by controlling external magnetic fields. The DMHR was prototyped and various experiments were conducted to demonstrate its motions and verify its manipulation methods.

Control of a three-dimensional magnetic force generated from a magnetic navigation system to precisely manipulate the locomotion of a magnetic microrobot

We propose a method to generate a three-dimensional (3D) magnetic force to manipulate a magnetic microrobot in various environments by using a magnetic navigation system. The proposed method is based on the control of the magnetic force with respect to the change in the magnetization direction of the microrobot and an external magnetic flux gradient. We derived the nonlinear constraint equations which can determine the required direction of the uniform magnetic fields and magnetic gradients to generate the 3D magnetic force of a microrobot. The solutions of the equations were calculated using a geometrical analysis of the equations without any singular point. The proposed methodology was verified on 3D planar environments considering gravitational force, and we also conducted an experiment in a 3D water-filled tubular environment to verify the possibility of the clinical application in human blood vessels.

A crawling and drilling microrobot driven by an external oscillating or precessional magnetic field in tubular environments

We propose a crawling and drilling microrobot actuated by an external precessional magnetic field (EPMF) to effectively unclog obstructed blood vessels. Conventional crawling microrobots can only generate crawling motions using an external oscillating magnetic field. The proposed microrobot can generate navigating (crawling) and drilling motions selectively or simultaneously by controlling the EPMFs. We prototyped the proposed microrobot, and conducted several experiments to verify the efficacy of the crawling and drilling ability of the microrobot in a tubular environment.