Microrobots
In article number 2310084, Salvador Pané, Minsoo Kim, Hao Ye, and co‐workers introduce microrobotic superstructures comprising a magnetic gelatin composite chassis threaded with iron ...helical micromachines. Magnetic inputs can be used to navigate the superstructure (gradients) and also dissolve the chassis through magnetic hyperthermia, thereby releasing the micromachines to navigate through narrow channels. The capability of these micromachines to disassemble on‐command to access narrower conduits enhances the microrobots' multifunctionality.
Abstract
The past decade has seen an upsurge in the development of small‐scale magnetic robots for various biomedical applications. However, many of the reported designs comprise components with ...biocompatibility concerns. Strategies for fabricating biocompatible and degradable microrobots are required. In this study, polyvinyl alcohol (PVA)‐based magnetic hydrogel microrobots with different morphologies and tunable stability are developed by combining a 3D printed template‐assisted casting with a salting‐out process. 3D sacrificial micromolds are prepared via direct laser writing to shape PVA‐magnetic nanoparticle composite hydrogel microrobots with high architectural complexity. By adjusting the PVA composition and salting‐out parameters, the hydrogel dissolubility can be customized. Due to their high mobility, tunable stability, and high biocompatibility, these PVA‐based magnetic microrobots are suitable platforms for targeted drug and cell delivery.
Magnetic microrobots have been developed for navigating microscale environments by means of remote magnetic fields. However, limited propulsion speeds at small scales remain an issue in the ...maneuverability of these devices as magnetic force and torque are proportional to their magnetic volume. Here, a microrobotic superstructure is proposed, which, as analogous to a supramolecular system, consists of two or more microrobotic units that are interconnected and organized through a physical (transient) component (a polymeric frame or a thread). The superstructures consist of microfabricated magnetic helical micromachines interlocked by a magnetic gelatin nanocomposite containing iron oxide nanoparticles (IONPs). While the microhelices enable the motion of the superstructure, the IONPs serve as heating transducers for dissolving the gelatin chassis via magnetic hyperthermia. In a practical demonstration, the superstructure's motion with a gradient magnetic field in a large channel, the disassembly of the superstructure and release of the helical micromachines by a high‐frequency alternating magnetic field, and the corkscrew locomotion of the released helices through a small channel via a rotating magnetic field, is showcased. This adaptable microrobotic superstructure reacts to different magnetic inputs, which can be used to perform complex delivery procedures within intricate regions of the human body.
A magnetically driven microrobotic superstructure is designed for navigation in microscale environments. The superstructure consists of microhelices interlocked with a gelatin composite chassis containing iron oxide nanoparticles. The helices serve as the motion component, while the nanoparticles enable the gelatin to dissolve via magnetic hyperthermia. Upon dissolution, the helices are released and navigate through smaller conduits using a rotating field.
Soft materials play a crucial role in small-scale robotic applications by closely mimicking the complex motion and morphing behavior of organisms. However, conventional fabrication methods face ...challenges in creating highly integrated small-scale soft devices. In this study, we leverage microfluidics to precisely control reaction-diffusion (RD) processes to generate multifunctional and compartmentalized calcium-cross-linkable alginate-based microfibers. Under RD conditions, we produce sophisticated alginate-based fibers for magnetic soft continuum robotics (mSCR) applications with customizable features, such as geometry (compact or hollow), degree of cross-linking, and the precise localization of magnetic nanoparticles (inside the core, surrounding the fiber, or on one side). This fine control allows for tuning the stiffness and magnetic responsiveness of the microfibers. Additionally, chemically cleavable regions within the fibers enable disassembly into smaller robotic units or roll-up structures under a rotating magnetic field. These findings demonstrate the versatility of microfluidics in processing highly integrated small-scale devices. This article is protected by copyright. All rights reserved.
Abstract Thermal decomposition of iron oleate is a simple and widespread method for synthesizing monodispersed iron oxide nanoparticles (IONPs) with well‐defined morphology. However, the complexity ...of the underlying mechanism makes this method rather sensitive to variations in experimental conditions, and the lack of simple techniques to monitor the reaction progress in situ usually results in poor reproducibility and time‐consuming optimizations. Here, a simple, robust, and versatile in situ marker to monitor particle formation based on a sudden change in the temperature during reflux is reported. A linear relationship between the onset of particle formation and the concentration of surfactants is unveiled, corroborating a ‘chemically activated’ burst nucleation mechanism. Using this linear relationship as a guide, highly uniform spherical, cubic, and star‐shaped particles between 12 and 30 nm can be obtained. This temperature marker and the derived linear relationship not only deepen the understanding of the reaction process, but also provide a powerful tool for the straightforward optimization of IONPs.
3D COF Nanoparticles
In article number 2306345, Carlos Franco, Salvador Pané, Josep Puigmartí‐Luis, and co‐workers present a water‐based nanoreactor technology that pioneers the creation of sub‐40 nm ...3D covalent organic framework (COF) nanoparticles under ambient conditions. This method not only improves the processability of 3D COFs but also unveils exciting possibilities in microrobotics. A notable achievement is the fabrication of the first COF‐based microrobots (COFBOTs).
Covalent organic frameworks (COFs) are crystalline materials with intrinsic porosity that offer a wide range of potential applications spanning diverse fields. Yet, the main goal in the COF research ...area is to achieve the most stable thermodynamic product while simultaneously targeting the desired size and structure crucial for enabling specific functions. While significant progress is made in the synthesis and processing of 2D COFs, the development of processable 3D COF nanocrystals remains challenging. Here, a water‐based nanoreactor technology for producing processable sub‐40 nm 3D COF nanoparticles at ambient conditions is presented. Significantly, this technology not only improves the processability of the synthesized 3D COF, but also unveils exciting possibilities for their utilization in previously unexplored domains, such as nano/microrobotics and biomedicine, which are limited by larger crystallites.
Herein, a water‐based nanoreactor technology that allows for the controlled generation of sub‐40 nm 3D covalent organic frameworks (COF) nanoparticles, boosting processability, and opening new frontiers in nano/microrobotics and biomedicine is presented. This breakthrough clearly overcomes the limitations posed by larger reported 3D COF crystal structures, unlocking exciting possibilities for previously unexplored domains.
Magnetic microrobots have been developed for navigating microscale
environments by means of remote magnetic fields. However, limited propulsion
speeds at small scales remain an issue in the ...maneuverability of these devices
as magnetic force and torque are proportional to their magnetic volume. Here,
we propose a microrobotic superstructure, which, as analogous to a
supramolecular system, consists of two or more microrobotic units that are
interconnected and organized through a physical (transient) component (a
polymeric frame or a thread). Our superstructures consist of microfabricated
magnetic helical micromachines interlocked by a magnetic gelatin nanocomposite
containing iron oxide nanoparticles (IONPs). While the microhelices enable the
motion of the superstructure, the IONPs serve as heating transducers for
dissolving the gelatin chassis via magnetic hyperthermia. In a practical
demonstration, we showcase the superstructure's motion with a gradient magnetic
field in a large channel, the disassembly of the superstructure and release of
the helical micromachines by a high-frequency alternating magnetic field, and
the corkscrew locomotion of the released helices through a small channel via a
rotating magnetic field. This adaptable microrobotic superstructure reacts to
different magnetic inputs, which could be used to perform complex delivery
procedures within intricate regions of the human body.
