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Catalysis is a foundational pillar of modern synthetic chemistry, essential for countless industrial processes. Traditional catalysts are often static, either immobilized or dispersed in fluid media. The innovative concept of catalytic microrobots allows the introduction of self‐propelled and navigable catalyst particles that are engineered for dynamic and customizable catalysis. Catalytic microrobots are microscale devices with the inherent ability to move and swarm, designed to execute complex tasks in diverse environments, including biomedicine, and environmental remediation. Typically confined to aqueous media, their use in synthetic chemical reactions remains largely unexplored. Here, microrobots are presented as adaptable self‐propelled, self‐mixing micro‐catalysts for the Baeyer–Villiger oxidation, a key industrial process. Zeolite microstructures are tailored, outfitted with magnetic nanoparticles to create zeolite‐based microrobots (ZeoBOTs) that are maneuverable in magnetic fields. Uniquely, these ZeoBOTs are not limited to water but can operate in organic solvents, facilitating the Baeyer–Villiger oxidation in non‐aqueous conditions. Comparative analysis with static ZeoBOTs reveals that the dynamic, "on‐the‐fly" movement of the microrobots significantly enhances reaction yields. The findings herald a new era for synthetic chemistry, demonstrating the potential of microrobots as versatile catalysts beyond aqueous systems, and setting the stage for their broader application in synthetic processes. [ABSTRACT FROM AUTHOR]

This study investigates the dynamic fluctuations of pH caused by gastric acid secretion, a process of both biological and clinical significance, with microrobots. Abnormal patterns of acidity often indicate gastrointestinal diseases, underlying the importance of precise intragastric pH monitoring. Traditional methods using fluorescent probes face challenges due to their faint solid‐state fluorescence, limited target specificity, and accuracy. To overcome these obstacles, pH‐responsive fluorescent organic microparticles decorated with magnetite (Fe3O4) nanoparticles are engineered. These microrobots exhibit a unique fluorescence switching capability at a critical pH, enabling the monitoring of gastric acidity. The magnetic part of these microrobots ensures magnetic maneuverability to enable targeted navigation. The microrobots' fluorescence switching mechanism is elucidated through comprehensive spectroscopy, microscopy, and X‐ray diffraction analyses, revealing molecular‐level structural transformations upon interaction with gastric acid and antacids. These transformations, specifically protonation and deprotonation of the microrobots' fluorescent components, prompt a distinct fluorescence response correlating with pH shifts. In vitro and ex vivo experiments, simulating stomach conditions, confirm the microrobots' efficacy in pH‐responsive imaging. The results showcase the promising diagnostic potential of microrobots for gastrointestinal tract diseases, marking a significant advancement in imaging‐based medical diagnostics at targeted locations. [ABSTRACT FROM AUTHOR]

Magnetic fiber robots have revealed great potential for future minimally invasive robotic surgery. However, with the miniaturization of fiber robots, the integration of functional microtools at the distal end becomes extremely challenging, since it requires assembling multifunctional structures on the curved surfaces of fiber ends, which typically have very small curvature radii. In this study, a submillimeter fiber robot with integrated micro‐manipulation tool at the distal end is reported using a "Swiss roll" assembly strategy. This approach enables the one‐step assembly of multiscale structures (mm‐µm) from a 2D film to a 3D tool on the curved surface of the fiber robot. The multiscale structure consists of a millimeter‐scale (mm) magnetic thin film with integrated micrometer‐scale (µm) feature structures, which is inspired from the cat tongue covered by numerous little papillae. The fiber robot can perform multiple functions including endovascular clot grabbing, liquid delivery, and sampling under the manipulation of the magnetic field. The strategy provides a universal protocol for integrating and assembling functional components at the distal end of fiber robots, contributing significantly to the functionalization and miniaturization of interventional medical robots. [ABSTRACT FROM AUTHOR]

Magnetic microrobots have gained significant attention in the biomedical field due to their wireless actuation, strong controllability, fast response, and minimal impact on the environment. As the task complexity keeps increasing in the clinical applications of magnetic microrobots, more geometric structures and magnetization profiles have been included in the designs of magnetic microrobots, posing significant challenges to the fabrication of magnetic microrobots. Microassembly is a fabrication method that can create convoluted structures with small‐scale modules. It can accurately control the position and orientation of each magnetic module, resulting in a magnetic microrobot with arbitrary 3D geometries and magnetization profiles. This article reviews recent advanced assembly‐based fabrication methods of magnetic microrobots, including microassembly driven by contact mechanical forces and noncontact field forces. The principles, fabrication processes, and the advantages and disadvantages of each assembly‐based fabrication method are summarized. The existing challenges and future development of fabricating magnetic microrobots by assembly are discussed in detail. It is believed that this review will provide a methodological reference and inspire new ideas for manufacturing powerful magnetic microrobots in future biomedical applications. [ABSTRACT FROM AUTHOR]

3D locomotion of magnetic microrobots requires at least one pair of coils per axis and 3D feedback of the position of the microrobot. This results in voluminous systems with high‐power usage and a small working space, which require complex and expensive controllers. This study presents a single‐coil magneto‐electromagnetic system, comprising a parallel robot and coil, capable of precise 3D locomotion control of magnetic millirobots while requiring only feedback of the vertical position of the millirobot. The coil current creates a 2D magnetic trapping point in the horizontal plane, which depends on the position and orientation of the coil and toward which the millirobot moves, eliminating the need for position feedback at such plane. The vertical position of the millirobot is controlled by varying the coil current while receiving feedback from the vertical position of the millirobot. Feedbackless 2D control and 1‐axis feedback 3D automatic control of magnetic millirobots are experimentally demonstrated, achieving higher speeds and similar position errors when compared to control systems with 3D position feedback. Furthermore, selective control of two millirobots is demonstrated by matching the region of maximum vertical magnetic force and the targeted millirobot, achieving selective levitation and control of such millirobots. [ABSTRACT FROM AUTHOR]

Magnetic microrobots can be miniaturized to a nanometric scale owing to their wireless actuation, thereby rendering them ideal for numerous biomedical applications. As a result, nowadays, there exist several mechano‐electromagnetic systems for their actuation. However, magnetic actuation is not sufficient for implementation in biomedical applications, and further functionalities such as imaging and heating are required. This study proposes a multimodal electromagnetic system comprised of three pairs of Helmholtz coils, a pair of Maxwell coils, and a high‐frequency solenoid to realize multimodal locomotion and heating control of magnetic microrobots. The system produces different configurations of magnetic fields that can generate magnetic forces and torques for the multimodal locomotion of magnetic microrobots, as well as generate magnetic traps that can control the locomotion of magnetic swarms. Furthermore, these magnetic fields are employed to control the magnetization of magnetic nanoparticles, affecting their magnetic relaxation mechanisms and diminishing their thermal properties. Thus, the system enables the control of the temperature increase of soft‐magnetic materials and selective heating of magnetic microrobots at different positions, while suppressing the heating properties of magnetic nanoparticles located at undesired areas. [ABSTRACT FROM AUTHOR]

Controlled microrobotic navigation in the vascular system can revolutionize minimally invasive medical applications, such as targeted drug and gene delivery. Magnetically controlled surface microrollers have emerged as a promising microrobotic platform for controlled navigation in the circulatory system. Locomotion of micrororollers in strong flow velocities is a highly challenging task, which requires magnetic materials having strong magnetic actuation properties while being biocompatible. The L10‐FePt magnetic coating can achieve such requirements. Therefore, such coating has been integrated into 8 µm‐diameter surface microrollers and investigated the medical potential of the system from magnetic locomotion performance, biocompatibility, and medical imaging perspectives. The FePt coating significantly advanced the magnetic performance and biocompatibility of the microrollers compared to a previously used magnetic material, nickel. The FePt coating also allowed multimodal imaging of microrollers in magnetic resonance and photoacoustic imaging in ex vivo settings without additional contrast agents. Finally, FePt‐coated microrollers showed upstream locomotion ability against 4.5 cm s−1 average flow velocity with real‐time photoacoustic imaging, demonstrating the navigation control potential of microrollers in the circulatory system for future in vivo applications. Overall, L10‐FePt is conceived as the key material for image‐guided propulsion in the vascular system to perform future targeted medical interventions. [ABSTRACT FROM AUTHOR]

Mobile microrobots with shape morphing capability show great advantages for conducting tasks in complex environments. Combination of magnetically driven locomotion and stimuli‐responsive shape morphing is an effective strategy to realize these microrobots. However, most existing microrobots fabricated by the combination strategy are of low locomotion efficiency due to the limited amount of magnetic material loaded. Herein, a novel scheme for coating the magnetic nanoparticles (NPs) on the surface of microrobot is proposed to increase the magnetic material loading amount. Theoretical analyses demonstrate that, below a critical size at microscale, surface coating NPs can load more magnetic material than embedding NPs into the volume due to the high surface area‐to‐volume ratio. Microrobots with both shape morphing and enhanced magnetically driven locomotion are fabricated by coating magnetic NPs on the surface of stimuli‐responsive hydrogel microstructures. It is experimentally demonstrated that surface coating ensures that the microstructure has not only an efficient locomotion but also an excellent deformability. A four‐claw microgripper is fabricated, which is smaller and has higher magnetically driven locomotion speed than the most existing shape morphing microrobots. This microgripper demonstrating carrying and delivery capabilities is of immediate interest to microobject manipulation and minimally invasive surgery. [ABSTRACT FROM AUTHOR]

In recent years, magnetism has gained an enormous amount of interest among researchers for actuating different sizes and types of bio/soft robots, which can be via an electromagnetic‐coil system, or a system of moving permanent magnets. Different actuation strategies are used in robots with magnetic actuation having a number of advantages in possible realization of microscale robots such as bioinspired microrobots, tetherless microrobots, cellular microrobots, or even normal size soft robots such as electromagnetic soft robots and medical robots. This review provides a summary of recent research in magnetically actuated bio/soft robots, discussing fabrication processes and actuation methods together with relevant applications in biomedical area and discusses future prospects of this way of actuation for possible improvements in performance of different types of bio/soft robots. [ABSTRACT FROM AUTHOR]

Wireless magnetic microrobots are envisioned to revolutionize minimally invasive medicine. While many promising medical magnetic microrobots are proposed, the ones using hard magnetic materials are not mostly biocompatible, and the ones using biocompatible soft magnetic nanoparticles are magnetically very weak and, therefore, difficult to actuate. Thus, biocompatible hard magnetic micro/nanomaterials are essential toward easy‐to‐actuate and clinically viable 3D medical microrobots. To fill such crucial gap, this study proposes ferromagnetic and biocompatible iron platinum (FePt) nanoparticle‐based 3D microprinting of microrobots using the two‐photon polymerization technique. A modified one‐pot synthesis method is presented for producing FePt nanoparticles in large volumes and 3D printing of helical microswimmers made from biocompatible trimethylolpropane ethoxylate triacrylate (PETA) polymer with embedded FePt nanoparticles. The 30 μm long helical magnetic microswimmers are able to swim at speeds of over five body lengths per second at 200 Hz, making them the fastest helical swimmer in the tens of micrometer length scale at the corresponding low‐magnitude actuation fields of 5–10 mT. It is also experimentally in vitro verified that the synthesized FePt nanoparticles are biocompatible. Thus, such 3D‐printed microrobots are biocompatible and easy to actuate toward creating clinically viable future medical microrobots. [ABSTRACT FROM AUTHOR]

Developing microrobots with multiple deformabilities has become extremely challenging due to the lack of materials that are soft enough at the microscale level and the inability to be reconfigured after fabrication. In this study, it is aimed to prove that liquid microrobots composed of ferrofluid droplets are inherently deformable and they can be controlled, individually or in aggregate, with multiple programmable deformabilities. For example, the liquid‐microrobot monomer (LRM) can pass through narrow channels via elongation and achieve scaling via splitting and coalescence. LRMs can also reassemble into various kinds of functional liquid‐robot aggregates, such as microsticks, micropies, microtrains, microkayaks, and microrollingpins. Thus, they can respond to multi‐terrain surfaces or perform various complex tasks. Moreover, the authors' physics‐based theoretical model demonstrates dynamic self‐assembly and group behavior of a multiple LRM system, which is conducive to investigating the mechanisms behind it. These ferrofluid droplet robots provide novel solutions for some potential applications, such as untethered micromanipulation and targeted cargo delivery. [ABSTRACT FROM AUTHOR]

Wireless capsule endoscopy ( WCE) is a powerful tool for medical screening and diagnosis, where a small capsule is swallowed and moved by means of natural peristalsis and gravity through the human gastrointestinal ( GI) tract. The camera-integrated capsule allows for visualization of the small intestine, a region which was previously inaccessible to classical flexible endoscopy. As a diagnostic tool, it allows to localize the sources of bleedings in the middle part of the gastrointestinal tract and to identify diseases, such as inflammatory bowel disease (Crohn's disease), polyposis syndrome, and tumors. The screening and diagnostic efficacy of the WCE, especially in the stomach region, is hampered by a variety of technical challenges like the lack of active capsular position and orientation control. Therapeutic functionality is absent in most commercial capsules, due to constraints in capsular volume and energy storage. The possibility of using body-exogenous magnetic fields to guide, orient, power, and operate the capsule and its mechanisms has led to increasing research in Magnetically Guided Capsule Endoscopy ( MGCE). This work shortly reviews the history and state-of-art in WCE technology. It highlights the magnetic technologies for advancing diagnostic and therapeutic functionalities of WCE. Not restricting itself to the GI tract, the review further investigates the technological developments in magnetically guided microrobots that can navigate through the various air- and fluid-filled lumina and cavities in the body for minimally invasive medicine. [ABSTRACT FROM AUTHOR]