The EnEMA System-Ennead Electromagnetic Actuation System-Towards locomotion control for targeted drug delivery

This paper presents an optimized design and development of the electromagnetic actuation (EMA) system, which can generate a strong electromagnetic field to control micro/nanomagnetic objects. The EMA system consists of nine electromagnetic sources, so called Ennead Electromagnetic Actuation (EnEMA) system. The system configuration is designed based on our proposed optimization algorithm considering the design constraints given by the user, and the optimal configuration has the most isotropic and the strongest generated field among all available candidates considering the same design constraints. The EnEMA system can control the magnetic object in 5-DoFs without singularity, which is capable of multi-task control of the micro/nanomagnetic objects. The maximum achievable magnetic field and gradient field of the system are 174 mT and 5 T/m. A prototype of the system was constructed, and calibrated, which was then used to perform precise control of magnetic particle in three-dimensional space. The system is ready for in-vivo in small animal such as rats for targeted drug delivery.

1. Introduction

Targeted drug delivery (TDD) using the magnetic micro/nanorobots demonstrates a significant impact on the cancer treatment with potential of dramatically reducing patient side effects caused by the spread of chemotherapeutic drugs [1]–[4]. Magnetic manipulation of micro/nanorobot has demonstrated its promising capabilities in terms of power, controllability, and accuracy compared the other external sources. Moreover, the low-frequency electromagnetic field can safely and effectively penetrate the human body and show its high compatibility with medical applications in the last century. In order to generate the electromagnetic field to control micro-/nanorobots, a magnetic manipulation system containing different types of electromagnetic coils has been developed. The air-filled coils such as Helmholtz coils, Maxwell coils, saddle coils are widely used in the general purpose with capable creating uniform field and gradient field [5]–[7]. The clinical MRI system was used to perform the tracking and control of the microrobot [8], [9]. However, the field generated by these coils is not relatively strong enough for controlling of micro-/nanorobot in TDD application. The core-filled coils, on the other hand, can create a much stronger magnetic field and field gradient which may a good candidate for TDD. Several stationary system such as OctoMag [10], MiniMag [11], BatMag [12] demonstrated an interesting performance with capable of 5DOF control of the microrobot.