Magnetic Resonance Guided Navigation of Untethered Microgrippers

Abstract

Microsurgical tools offer a path to less invasive clinical procedures with improved access, reduced trauma, and better recovery outcomes. There are a variety of rigid and flexible endoscopic devices that have significantly advanced diagnostics and microsurgery. However, they rely on wires or tethers for guidance and operation of small end‐effector tools. While untethered physiologically responsive microgrippers have been previously shown to excise tissue from deep gastrointestinal locations in animal models, there are challenges associated with guiding them along paths and moving them to specific locations. In this communication, the magnetic dipole moment of untethered thermally responsive grippers is optimized for efficient coupling to external magnetic resonance (MR) fields. Gripper encapsulation in a millimeter sized wax pellet reduces the friction with the surrounding tissue and MR Navigation (MRN) of a 700 µm sized microgripper is realized within narrow channels in tissue phantoms and in an ex vivo porcine esophagus. The results show convincing proof‐of‐concept evidence that it is possible to sequentially image, move, and guide a submillimeter functional microsurgical tool in tissue conduits using a commercial preclinical MR system, and when combined with prior demonstrations of physiologically responsive in vivo biopsy are an important step towards the clinical translation of untethered microtools.

Medical Micro/Nanorobots in Precision Medicine

“…[258] Biocompatible designs made of responsive hydrogels embedded with magnetic alginate microbeads were magnetically guided and presented infrared light-induced gripping (Figure 8b). [259][260][261][262] Micro/nanorobotics were also explored to collect bacteria inside the body. The use of motile robotic collectors could help expand the understanding of the biome.…”

“…[ 258 ] Biocompatible designs made of responsive hydrogels embedded with magnetic alginate microbeads were magnetically guided and presented infrared light‐induced gripping (Figure 8b). [ 259–262 ]…”

A Magnetically Guided Self‐Rolled Microrobot for Targeted Drug Delivery, Real‐Time X‐Ray Imaging, and Microrobot Retrieval

“…For the targeted drug delivery (DD) task, the robot structure is also considered as an important factor, in which the self‐rolling/‐folding microrobots are the preferable structures for DD with capable of pick and place and carrying a larger amount of drug/cell. [ 24–28 ] However, the challenge for applying these type of robots to the in vivo experiment is remain opened since it requires to change the environmental temperature to unfold these type of structure and release the drug. On the other hand, the unrolling/unfolding microrobots with the porous cylindrical/helical/spherical structure shows a higher possibility in a practical viewpoint.…”

Image‐Guided Magnetic Thermoseed Navigation and Tumor Ablation Using a Magnetic Resonance Imaging System

“…Preclinical in vivo studies have previously demonstrated the efficacy of MRN to target magnetically labeled cells, [13] resulting in increased tumor macrophage infiltration and reduction in tumor burden. [14] Alternatively, MRN can be used to steer larger ferromagnetic devices, [16] with one proof of concept study navigating an untethered ferromagnetic sphere through the vasculature of a swine. [15] Michaud et al have further developed this concept, with the aim of using microbeads to perform liver embolization.…”