MRI-powered Magnetic Microrobotics
OPEN ACCESS
Author / Producer
Date
2023
Publication Type
Doctoral Thesis
ETH Bibliography
yes
Citations
Altmetric
OPEN ACCESS
Data
Rights / License
Abstract
Minimally invasive surgeries have replaced many open surgical operations in clinics today, and their success created a high demand for less and less invasive methods. Recently, magnetic microrobotic approaches have been proposed to address the miniaturization challenges of minimally invasive methods. Since magnetically actuated microrobots do not require tethered force transmissions systems, such as
tendons and hydraulics, they could be miniaturized down to submillimeter-size scales and even operate wirelessly to access hard-to-reach regions in the patient body. However, the localization of these microrobots in the patient’s body during operations is still a major challenge for medical microrobotic applications. Since the small scale of microrobots prohibits on-board localization systems, an external localization system is needed. Therefore, medical imaging platforms bringing magnetic actuation and image-based localization have been proposed for microrobots.
Among many medical imaging modalities, magnetic resonance imaging (MRI) attracts the most attention with superior image contrast, unlimited imaging depth, and ionizing radiation-free nature. MRI is considered the gold standard in many diagnostic applications, such as brain tumor and stroke diagnosis, and has already proven itself in guiding medical tools, such as biopsy needles and focus ultra-
sound. Besides its high-quality medical imaging, MRI scanners are human-sized electromagnetic systems that could be used for magnetic actuation purposes, which makes them a perfect candidate for a combined imaging and actuation platform for magnetic microrobots. However, transforming MRI scanners to a microrobotic platform is a major scientific and engineering challenge and requires an in-depth investigation of magnetic actuation concepts in high magnetic fields, MR imaging, and tracking principles for magnetic microrobots.
This dissertation elucidates MRI-powered magnetic actuation and MR imaging principles for magnetic microrobots to transform MRI scanners into microrobotic platforms for future minimally invasive medical applications. First, we introduced an MRI-powered magnetic micro-capsule robot design actuated by MRI gradient coils and developed one-dimensional and two-dimensional MRI-based tracking methods using template matching and deep learning algorithms. Then, combining MRI-based position feedback and magnetic actuation, we demonstrated closed-loop control and precise navigation methods for wireless magnetic microrobots. Later, we showed on-demand microrobotic drug delivery as a potential biomedical
operation using acoustic triggering.
In the second part, we proposed magnetic actuation methods using the ultrahigh magnetic field of MRI scanners. First, elucidating the uniaxial magnetization characteristics of permanent magnets in ultrahigh magnetic fields, we developed ultrahigh field (UHF) magnetic actuation principles. Later, we proposed magnetic guidewire steering methods using MRI scanners’ UHF. Finally, we developed a magnetic guidewire prototype that could be steered in the vasculature system. Overall, we provided the fundamental scientific background for magnetic microrobot actuation and tracking methods in MRI scanners and developed microrobotic tools for future minimally invasive medical operations.
Permanent link
Publication status
published
External links
Editor
Contributors
Book title
Journal / series
Volume
Pages / Article No.
Publisher
ETH Zurich
Event
Edition / version
Methods
Software
Geographic location
Date collected
Date created
Subject
Microrobotics; Medical Robotics; MRI (magnetic resonance imaging)
Organisational unit
03628 - Prüssmann, Klaas P. / Prüssmann, Klaas P.
09726 - Sitti, Metin (ehemalig) / Sitti, Metin (former)