Magnetic Resonance Imaging‐Compatible Optically Powered Miniature Wireless Modular Lorentz Force Actuators

Abstract

Minimally invasive medical procedures under magnetic resonance imaging (MRI) guidance have significant clinical promise. However, this potential has not been fully realized yet due to challenges regarding MRI compatibility and miniaturization of active and precise positioning systems inside MRI scanners, i.e., restrictions on ferromagnetic materials and long conductive cables and limited space around the patient for additional instrumentation. Lorentz force‐based electromagnetic actuators can overcome these challenges with the help of very high, axial, and uniform magnetic fields (3–7 Tesla) of the scanners. Here, a miniature, MRI‐compatible, and optically powered wireless Lorentz force actuator module consisting of a solar cell and a coil with a small volume of 2.5 × 2.5 × 3.0 mm3 is proposed. Many of such actuator modules can be used to create various wireless active structures for future interventional MRI applications, such as positioning needles, markers, or other medical tools on the skin of a patient. As proof‐of‐concept prototypes toward such applications, a single actuator module that bends a flexible beam, four modules that rotate around an axis, and six modules that roll as a sphere are demonstrated inside a 7 Tesla preclinical MRI scanner.

Ultrafast small-scale soft electromagnetic robots

“…In summary, we have presented small-scale SEMRs with ultrahigh speed (up to 70 BL/s), featuring high robustness, multimodal locomotion and untethered operation that render them highly suitable for versatile applications in electrically-controlled intelligent systems. Furthermore, stronger magnetic fields, such as the interior of an MRI machine 28 , will greatly enhance the speed, power output and efficiency of SEMRs 9 . Straightforward and scalable fabrication using 3D direct ink writing renders them highly suitable for versatile applications in electrically-controlled intelligent systems and empowers the development of future high-performance microrobots for flexible microfabrication, targeted drug delivery and non-invasive surgery, where agility is of paramount importance 5 , 29 , 30 .…”

Magnetically Driven Micro and Nanorobots

“…To translate medical micro/nanorobots from the bench to the bedside, imaging technologies are of vital importance to achieve real-time tracking of the MagRobots in vivo . ,− Clinically established imaging modalities, including but not limited to optical imaging, magnetic resonance imaging (MRI), ,,,− magnetic particle imaging (MPI), fluorescence imaging, − ultrasound (US) imaging, ,,− photoacoustic (PA) imaging, , X-ray computed tomography (CT), photoacoustic computed tomography (PACT), optical coherence tomography (OCT), , single-photoemission computed tomography (SPECT), positron emission tomography (PET), and their combined imaging techniques (e.g., MR/CT, PET/CT, PET/MRI) can be integrated into miniaturized robotics systems. Although many challenges remain, many researchers have attempted to use these imaging techniques as powerful tools to assist the tracking of MagRobots for site-specific drug delivery, targeted therapy, and precision surgery.…”

Evolving from Laboratory Toys towards Life-Savers: Small-Scale Magnetic Robotic Systems with Medical Imaging Modalities

“…Also towards this end, Erin et al proposed a robot design that can rotate in 3D in MRI-like magnetic environments using commercially available MRI gradient coil in 2019 [78]. In 2020, Mutlu et al from the same research group presented a Lorentz force-based electromagnetic actuator with MRI compatibility which is optically powered via a solar cell [74]. The actuator has a dimension of 2.5-by-2.5-by-3.0 mm 2 .…”

“…Micro/nanorobot with a ferromagnetic core In vitro and in vivo with tortuous phantom and animal models 2008 [71] Flagellated magnetotactic bacterium Carotid artery of a living swine 2009 [72,73] Ferromagnetic catheter Renal arteries of rabbits 2015 [77] Biohybrid helical microswimmers Rodent stomachs 2017 [75] Millirobot Silicone oil pool in a square clear container 2019 [78] Millimetre-scale Lorentz force actuator module A square clear plastic container 2020 [74] Centermetre-scale capsule reversible orientation-locking robot (REVOLBOT) A synthetic maze embedded in a phosphate-buffered saline (PBS) solution 2021 [79,80] Neutrophil-based microrobot ("neutrobot")…”