Smart Materials for Microrobots

Size-dependent internalization of polystyrene microplastics as a key factor in macrophages and systemic toxicity

Microplastics are emerging pollutants with a wide range of ecological and biological effects, including the ability to accumulate in organisms and induce toxicity. Although numerous studies have investigated the distribution and toxicity of microplastics in murine models and cell lines, the conclusions are inconsistent owing to variations in experimental designs, particle sizes, exposure methods, and dose quantifications. To address these gaps, we systematically evaluated the size-dependent internalization and toxicity of polystyrene microplastics (PS-MPs) using in vitro and in vivo models. Fluorescently labeled PS-MPs were used to confirm the negligible toxicity of fluorophores on macrophages, demonstrating their suitability for tracking particle accumulation. In vitro experiments using RAW 264.7 cell lines and primary peritoneal macrophages revealed size-dependent phagocytosis and cytotoxicity, with smaller particles (0.5 µm) demonstrating higher internalization and causing greater mitochondrial depolarization, reactive oxygen species generation, and apoptosis compared to that with larger particles (5 µm). Acute in vivo experiments comparing oral administration and tail-vein injection revealed that the absorbed dose and toxicity were significantly influenced by particle size, with smaller PS-MPs showing higher organ retention and alterations in hematological and metabolic parameters. Additionally, a 28-day subacute oral exposure study highlighted systemic toxicity, including weight loss, disrupted food intake, elevated oxidative stress markers, and reduced antioxidant enzyme activity. By integrating multiple exposure routes, macrophage models, and fluorescence toxicity evaluations, this study provided a comprehensive and realistic assessment of microplastic toxicity, offering valuable insights for advancing toxicological evaluations and regulatory frameworks. However, this study did not address the influence of other plastic types, shapes, or environmental factors on toxicity. Future studies are thus needed to explore these variables and the long-term implications of real-world microplastic exposure.

Delivery vehicles for light-mediated drug delivery: microspheres, microbots, and nanoparticles: a review

This review delves into the evolving landscape of mediated drug delivery, focusing on the versatility of a variety of drug delivery vehicles such as microspheres, microbots, and nanoparticles (NPs). The review also expounds on the critical components and mechanisms for light-mediated drug delivery, including photosensitizers and light sources such as visible light detectable by the human eye, ultraviolet (UV) light, shorter wavelengths than visible light, and near-infra-red (NIR) light, which has longer wavelength than visible light. This longer wavelength has been implemented in drug delivery for its ability to penetrate deeper tissues and highlighted for its role in precise and controlled drug release. Furthermore, this review discusses the significance of these drug delivery vehicles towards a spectrum of diverse applications spanning gene therapy, cancer treatment, diagnostics, and microsurgery, and the materials used in the fabrication of these vehicles encompassing polymers, ceramics, and lipids. Moreover, the review analyses the challenges and limitations of such drug delivery vehicles as areas of improvement to provide researchers with valuable insights for addressing current obstacles in the progression of drug delivery. Overall, this review underscores the potential of light-mediated drug delivery to revolutionise healthcare and personalised medicine, providing precise, targeted, and effective therapeutic interventions.

Material selection, preparation, driving and applications of light-driven micro/nano motors: a review

As an external energy stimulus, light possesses the advantageous qualities of being reversible, wireless and remotely maneuverable while driving the motion of micro and nano motors. Despite the extensive publication of articles on light-driven micro- and nano-motors (LDMNMs) over the past two decades, reviews that address LDMNMs in general, from material selection, design, preparation, driving to applications, remain scarce. Therefore, it is necessary to highlight the superiority of light as a stimulating energy source for driving MNMs, as well as to promote the continuous development of LDMNMs and give newcomers a more basic and comprehensive knowledge in this field. This present review focuses on advanced preparation methods for LDNMNs, and provides a comprehensive comparison of the advantages and limitations of various techniques. In addition, general design strategies for building asymmetric fields around LDMNMs are introduced, as well as a variety of photoactive materials, including photocatalytic, photothermal, and photoinduced isomerization materials. The existing propulsive mechanisms and kinematic behaviours of LDMNMs are described in detail, including photocatalytic oxidation, photothermal effects and photoinduced isomerization. The principles of the various drive mechanisms are also analysed in detail and their merits and shortcomings summarized. Finally, following a comprehensive review of the potential applications in biomedicine, environmental remediation and other fields, further perspectives on future developments are presented with a view to overcoming key challenges.

3D Printing of Metal and Alloy Nanoarchitectures through a Complexation-Driven Strategy

3D metal/alloy nanoarchitectures demonstrate transformative potential for next-generation technologies including metamaterials, nanophotonics, and microrobotics. Current metal/alloy nanomanufacturing methods are often restricted to limited metals and simple geometries. Herein, we propose a versatile and scalable method for fabricating 3D metal-alloy nanoarchitectures through a complexation-driven strategy. By leveraging the complexation of metal ions with carboxyl groups, various metal ions are incorporated into acrylic acid-based polymer scaffolds. Subsequent thermal decomposition and reduction transform these scaffolds into metallic nanoarchitectures. As most metal ions can engage in complexation, we successfully fabricated seven distinct elemental metal nanoarchitectures and their corresponding alloy variants, substantiating the versatility of our method. This work establishes a scalable platform for nanoscale metal and alloy manufacturing, opening new possibilities for advanced nanoengineering applications.

Biomimetic swarm of active particles with coupled passive-active interactions

We study the universal behavior of a class of active colloids whose design is inspired by the collective dynamics of natural systems such as schools of fish and flocks of birds. These colloids, with off-center repulsive interaction sites, self-organize into polar swarms exhibiting long-range order and directional motion without significant hydrodynamic interactions. Our simulations show that the system transitions from motile perfect crystals to solid-like, liquid-like, and gas-like states depending on noise levels, repulsive interaction strength, and particle density. By analyzing swarm polarity and hexatic bond order parameters, we demonstrate that effective volume fractions based on force-range and torque-range interactions explain the system's universal behavior. This work lays a groundwork for biomimetic applications utilizing the cooperative polar dynamics of active colloids.

Chemically active colloidal superstructures

Mimicking biological systems, artificial active colloidal motors that continuously dissipate energy can dynamically self-assemble to form active colloidal superstructures with specific spatial configurations and complex functionalities, which offers a promising pathway for developing new active soft matter materials with adaptability, self-repair, and reconfigurability. Beyond merely propelling their own motion, chemically driven colloidal motors can also induce phoretic effects and osmotic flows to affect the motion of neighboring colloidal motors through local fluid fields generated by chemical reactions, thereby achieving spontaneous chemical communication and promoting dynamic self-assembly between motors. This review summarizes the latest progress in the dynamic self-assembly of chemically driven colloidal motors, ranging from single chemically driven colloidal motors to chemically driven colloidal motors with passive colloidal particles and then to different chemically driven colloidal motors, ultimately forming active colloidal superstructures with complex dynamic behaviors. Not only are the interactions between chemically driven colloidal motors with different self-propulsion mechanisms and passive colloidal particles focused on, but also the communication behaviors between chemically driven colloidal motors are explored. We explain the fundamental physicochemical mechanisms that regulate the assembly behavior of chemically driven colloidal motors, propose general strategies for the controlled construction of active colloidal superstructures, and discuss the potential applications that may emerge from the directed dynamic self-assembly of these superstructures.

Field-Driven Out-of-Equilibrium Collective Patterns for Swarm Micro-Robotics

Soft robotics has been rapidly advancing, offering significant improvements over traditional rigid robotic systems through the use of compliant materials that enhance adaptability and interaction with the environment. However, current approaches face critical challenges, including the reliance on complex "top-down" fabrication techniques and the difficulty of wireless powering and control at the microscale. Swarm robotics introduces a paradigm shift, leveraging collective dynamics to achieve cooperative and adaptable behaviors among multiple robotic units. Inspired by nature, this "bottom-up" approach enables swarm robots to execute task-specific reconfigurations, enhancing flexibility and robustness. Field-driven active colloids emerge as a promising platform for swarm microrobotics, capable of self-propulsion and self-organization into dynamic collective patterns under external field excitation and manipulation. These systems mimic biologically inspired swarm behaviors, such as flocking and vortex formation, providing a versatile foundation for designing innovative swarm microrobots. This review discusses the principles of electric and magnetic field-driven collective self-organization, focusing on the particle dynamics, the emergence of collective swarm patterns, and illustrative examples of functional swarm microrobots. It concludes with future perspectives on harnessing these systems for adaptive, scalable, and multifunctional microrobotic applications.

Biotemplated Diatom Microrobots for Dual-Drug Delivery in Targeted Neuroblastoma Therapy

Neuroblastoma, a highly malignant pediatric tumor, demands innovative targeted drug delivery strategies to overcome the limitations of conventional therapies. In this study, we developed magnetic diatom microrobots (DMs) using diatom frustules as biotemplates, leveraging their natural hierarchical porosity and biocompatibility. Functionalized with amino groups and folic acid, these microrobots demonstrated enhanced drug conjugation and tumor-targeting capabilities. Designed to carry either cisplatin (CDDP) or paclitaxel (PTX), the DMs facilitated complementary therapeutic effects through pH-responsive release, enabling synergistic neuroblastoma therapy. Magnetic actuation tests confirmed multimodal propulsion and precise motion control. In vitro experiments demonstrated enhanced therapeutic efficacy and reduced off-target effects compared to those of conventional approaches. These diatom-templated magnetic microrobots, with their facile fabrication and superior performance, represent a promising platform for targeted drug delivery and advanced cancer therapy.

Asymmetric Laser Enabled High-Throughput Manufacturing of Multiform Magnetically Actuated Graphene-Based Robots for Various Water Depths

Achieving large-scale and facile manufacturing for diverse small-scale robots is critical in the field of small-scale robots. At present, conventional manufacturing methods have limitations in terms of efficiency, environmental friendliness, and operability. In particular, it is difficult to facilely process multiform small-scale robots through a single processing technology only. In this work, with the introduction of an asymmetric laser, multiforms of graphene, including powders, helical, and sheet, were successfully fabricated by simply adjusting laser processing parameters only. This allowed the development of multiform graphene-based robots capable of being actuated in various water depths, including underwater swarm, suspended helical, and floated sheet robots. Importantly, such robots can move smoothly in various trajectories under magnetic fields, including simple geometrical shapes and complicated words, demonstrating good maneuverability. Moreover, this manufacturing method enables the efficient production of multiform robots in different sizes, from 5 to 48 units, within 1 min. The proposed asymmetric laser technology is possible to provide a new means for manufacturing high-performance small-scale robots at high throughput.

Untethered Miniature Tensegrity Robot with Tunable Stiffness for High-Speed and Adaptive Locomotion

Miniature robots are increasingly used in unstructured environments and require higher mobility, robustness, and multifunctionality. However, existing purely soft and rigid designs suffer from inherent defects, such as low load capacity and compliance, respectively, restricting their functionality and performance. Here, we report new soft-rigid hybrid miniature robots applying the tensegrity principle, inspired by biological organisms' remarkable multifunctionality through tensegrity micro-structures. The miniature robot's speed of 25.07 body lengths per second is advanced among published miniature robots and tensegrity robots. The design versatility is demonstrated by constructing three bio-inspired robots using miniature tensegrity joints. Due to its internal load-transfer mechanisms, the robot has self-adaptability, deformability, and high impact resistance (withstand dynamic load 143,868 times the robot weight), enabling the robot to navigate diverse barriers, pipelines, and channels. The robot can vary its stiffness to greatly improve load capacity and motion performance. We further demonstrate the potential biomedical applications, such as drug delivery, impurity removal, and remote heating achieved by integrating metal into the robot.

From Autonomous Chemical Micro-/Nanomotors to Rationally Engineered Bio-Interfaces

Developing micro-/nanomotors that convert a chemical energy input into a local gradient field and motion is an appealing but challenging task that holds particular promise for the intersection of materials and nanoengineering. Over the past two decades, remarkable advancements have refined these out-of-equilibrium chemically powered micro-/nanomotors, enabling them to orchestrate in situ chemical transformations that dynamically change local environments. The ionic products, radicals, gases, and electric fields from these active materials reshape the microenvironment, paving the way for ecofriendly disease interventions. This review discusses the state-of-the-art reactions that propel these energy-consuming micro-/nanomotors and elucidates the emerging implications of their products on biological systems. Particular emphasis has been placed on their potential for neural modulation, reactive oxygen species (ROS) regulation, synergistic tumor therapy, antibacterial strategies, and tissue regeneration. Collectively, these sketches provide a landscape of therapeutic modalities, heralding a new era of biomedicine. By harnessing the in situ product field of this active matter, we envision a paradigm shift toward active therapies that transcend conventional approaches, promising breakthroughs in disease diagnosis, treatment, and prevention.

Soft Materials and Devices Enabling Sensorimotor Functions in Soft Robots

Sensorimotor functions, the seamless integration of sensing, decision-making, and actuation, are fundamental for robots to interact with their environments. Inspired by biological systems, the incorporation of soft materials and devices into robotics holds significant promise for enhancing these functions. However, current robotics systems often lack the autonomy and intelligence observed in nature due to limited sensorimotor integration, particularly in flexible sensing and actuation. As the field progresses toward soft, flexible, and stretchable materials, developing such materials and devices becomes increasingly critical for advanced robotics. Despite rapid advancements individually in soft materials and flexible devices, their combined applications to enable sensorimotor capabilities in robots are emerging. This review addresses this emerging field by providing a comprehensive overview of soft materials and devices that enable sensorimotor functions in robots. We delve into the latest development in soft sensing technologies, actuation mechanism, structural designs, and fabrication techniques. Additionally, we explore strategies for sensorimotor control, the integration of artificial intelligence (AI), and practical application across various domains such as healthcare, augmented and virtual reality, and exploration. By drawing parallels with biological systems, this review aims to guide future research and development in soft robots, ultimately enhancing the autonomy and adaptability of robots in unstructured environments.

Photochromic Metal-Organic Frameworks Based on Host-Guest Strategy and Different Viologen Derivatives for Organic Amines Sensing and Information Anticounterfeiting

The encapsulation of viologen derivatives in metal-organic frameworks (MOFs) to construct host-guest materials has been widely discussed owing to their distinctive spatial arrangement and physical/chemical properties. Herein, three new photochromic MOFs (NWM-1-3) have been successfully synthesized by 1,1,2,2-Tetra(4-carboxylphenyl)ethylene (H4TCPE) ligand as well as three different viologen derivatives based on host-guest strategy. Remarkably, NWM-1-3 exhibit a notable reversible photochromism change from yellow to green under 365 nm UV irradiation. The distance between the electron-deficient N atom in the viologens and the electron-rich carboxylate oxygens satisfies the electron transfer (ET) pathway, and thus ET occurs upon irradiation, producing intermolecular viologen radicals. NWM-1 is able to produce colored responses to different volatile amines by ET and can be recognizable to the naked eye. Differential pulse voltammetry (DPV) analysis and comparative experiments have demonstrated that the host-guest strategy significantly enhances the electron-accepting ability of viologens, thereby achieving superior amine sensing performance. NWM-2 and 3 have been realized in various applications, such as security code, fingerprint, and QR codes for anticounterfeiting. This work provides new host-guest strategy for designing highly sensitive photochromic materials and color-tunable luminescent materials, advancing the development of assembled photochromic materials closer to commercialization.

Research advances of acoustic particle manipulation techniques in field-assisted manufacturing

Field-assisted manufacturing (FAM) technology, which employs external fields to transport and manipulate micro/nanoparticles for tailored arrangements and structures, can produce novel materials with specific properties and functions. Acoustic particle manipulation has attracted increasing attention in FAM due to its various advantages, such as a wide range of materials, ease of fabrication, rapid actuation, non-invasive operation and high biocompatibility. The present review summarizes the recent progress of acoustic particle manipulation in the FAM area, with respect to operation principles, fabrication and control of particles, and particle cluster patterning. The emphasis is placed on the recent innovative applications of microparticle manipulation realized by acoustic fields in different advanced manufacturing technologies. Finally, we provide our perspective on the current challenges and potential prospects of acoustic particle manipulation technology in FAM.

Metareview: a survey of active matter reviews

In the past years, the amount of research on active matter has grown extremely rapidly, a fact that is reflected in particular by the existence of more than 1000 reviews on this topic. Moreover, the field has become very diverse, ranging from theoretical studies of the statistical mechanics of active particles to applied work on medical applications of microrobots and from biological systems to artificial swimmers. This makes it very difficult to get an overview over the field as a whole. Here, we provide such an overview in the form of a metareview article that surveys the existing review articles and books on active matter. Thereby, this article provides a useful starting point for finding literature about a specific topic.

Magnetic Micro/nanorobots in Cancer Theranostics: From Designed Fabrication to Diverse Applications

Cancer poses a substantial threat and a serious challenge to public human health, driving the promotion of sophisticated technologies for cancer therapy. While conventional chemotherapy has bottlenecks such as low delivery efficiency, strong toxic side effects, and tumor enrichment barriers, magnetic micro/nanorobots (MNRs) emerge as promising therapeutic candidates that provide alternative strategies for cancer therapy. MNR is a kind of human-made machine that is micro- or nanosized, is reasonably designed, and performs command tasks through self-actuated or externally controlled propulsion mechanisms, which can be potentially applied in cancer theranostics. Here, this review first introduces the components that constitute a typical magnetic MNR, including the body part, the driving part, the control part, the function part, and the sensing part. Subsequently, this review elucidates representative fabrication methods to construct magnetic MNRs from top-down approaches to bottom-up approaches, covering injection molding, self-rolling, melt electrospinning writing, deposition, biotemplate method, lithography, assembling, 3D printing, and chemical synthesis. Furthermore, this review focuses on multiple applications of magnetic MNRs facing cancer diagnosis and treatment, encompassing imaging, quantification, drug release, synergy with typical therapies, cell manipulation, and surgical assistance. Then, this review systematically elaborates on the biocompatibility and biosafety of magnetic MNRs. Finally, the challenges faced by magnetic MNRs are discussed alongside future research directions. This review is intended to provide scientific guidance that may improve the comprehension and cognition of cancer theranostics through the platform of magnetic MNRs, promoting and prospering the practical application development of magnetic MNRs.

Multifunctional Microflowers for Precise Optoacoustic Localization and Intravascular Magnetic Actuation In Vivo

Efficient drug delivery remains a significant challenge in modern medicine and pharmaceutical research. Micrometer-scale robots have recently emerged as a promising solution to enhance the precision of drug administration through remotely controlled navigation within microvascular networks. Real-time tracking is crucial for accurate guidance and confirmation of target arrival. However, deep-tissue monitoring of microscopic structures in vivo is limited by the sensitivity and spatiotemporal resolution of current bioimaging techniques. In this study, biocompatible microrobots are synthesized by incorporating indocyanine green and iron oxide nanoparticles onto copper phosphate microflowers using a layer-by-layer approach, enhancing optoacoustic contrast and enabling magnetic navigation. Magnetic control of these particles under optoacoustic guidance is demonstrated in vivo. Furthermore, super-resolution optoacoustic imaging, achieved through individual particle tracking, is shown to enable the characterization of microvascular structures and quantification of blood flow. The combination of the microflowers' high carrying capacity, in vivo actuation, and high-resolution tracking capabilities opens new opportunities for precise microvascular targeting and localized administration of theranostic agents via intravascular routes.

Nano-/Microrobots for Environmental Remediation in the Eyes of Nanoarchitectonics: Toward Engineering on a Single-Atomic Scale

Nano-/microrobots have been demonstrated as an efficient solution for environmental remediation. Their strength lies in their propulsion abilities that allow active "on-the-fly" operation, such as pollutant detection, capture, transport, degradation, and disruption. Another advantage is their versatility, which allows the engineering of highly functional solutions for a specific application. However, the latter advantage can bring complexity to applications; versatility in dimensionality, morphology, materials, surface decorations, and other modifications has a crucial effect on the resulting propulsion abilities, compatibility with the environment, and overall functionality. Synergy between morphology, materials, and surface decorations and its projection to the overall functionality is the object of nanoarchitectonics. Here, we scrutinize the engineering of nano-/microrobots with the eyes of nanoarchitectonics: we list general concepts that help to assess the synergy and limitations of individual procedures in the fabrication processes and their projection to the operation at the macroscale. The nanoarchitectonics of nano-/microrobots is approached from microscopic level, focusing on the dimensionality and morphology, through the nanoscopic level, evaluating the influence of the decoration with nanoparticles and quantum dots, and moving to the decorations on molecular and single-atomic level to allow very fine tuning of the resulting functionality. The presented review aims to lay general concepts and provide an overview of the engineering of functional advanced nano-/microrobot for environmental remediation procedures and beyond.

Translational nanorobotics breaking through biological membranes

In the dynamic realm of translational nanorobotics, the endeavor to develop nanorobots carrying therapeutics in rational in vivo applications necessitates a profound understanding of the biological landscape of the human body and its complexity. Within this landscape, biological membranes stand as critical barriers to the successful delivery of therapeutic cargo to the target site. Their crossing is not only a challenge for nanorobotics but also a pivotal criterion for the clinical success of therapeutic-carrying nanorobots. Nevertheless, despite their urgency, strategies for membrane crossing in translational nanorobotics remain relatively underrepresented in the scientific literature, signaling an opportunity for further research and innovation. This review focuses on nanorobots with various propulsion mechanisms from chemical and physical to hybrid mechanisms, and it identifies and describes four essential biological membranes that represent the barriers needed to be crossed in the therapeutic journey of nanorobots in in vivo applications. First is the entry point into the blood stream, which is the skin or mucosa or intravenous injection; next is the exit from the bloodstream across the endothelium to the target site; further is the entry to the cell through the plasma membrane and, finally, the escape from the lysosome, which otherwise destroys the cargo. The review also discusses design challenges inherent in translating nanorobot technologies to real-world applications and provides a critical overview of documented membrane crossings. The aim is to underscore the need for further interdisciplinary collaborations between chemists, materials scientists and chemical biologists in this vital domain of translational nanorobotics that has the potential to revolutionize the field of precision medicine.

Magnetically driven bionic nanorobots enhance chemotherapeutic efficacy and the tumor immune response via precise targeting

We developed magnetically driven bionic drug-loaded nanorobots (MDNs) to accurately target tumors and deliver chemotherapy agents using a customized three-dimensional (3D) magnetic manipulation platform (MMP) system to precisely control their movement mode. MDNs were based on polyethylene glycol-modified homogeneous ultrasmall iron oxide nanoparticles (7.02 ± 0.18 nm). Doxorubicin (12% ± 2% [w/w]) was encapsulated in MDNs by an imide bond. MDNs could imitate the movement mode of a school of wild herrings (e.g., re-dispersion/arrangement/vortex/directional movement) to adapt to the changing and complex physiological environment through the 3D MMP system. MDNs overcame blood flow resistance and biological barriers using optimized magnetic driving properties according to in vivo imaging (magnetic resonance imaging and fluorescence) and histopathology. The performance of fabricated MDNs was verified through cells and tumor-bearing mouse models. The MDNs showed high efficiency of drug delivery and targeting at the tumor site (>10-fold), lower toxicity than free doxorubicin (5 mg/kg body weight), activated immune response in the tumor site, and significantly lengthened survival for mice. The synergistic interaction between MDNs and the 3D MMP system underscores the immense potential of this drug delivery system, indicating a potential revolution in the field of tumor chemotherapy.

Influence of the neck length of urease-powered flask-like colloidal motors on their kinematic behavior

Enzyme-powered synthetic colloidal motors hold promising potential for in vivo medical applications because of their unique features such as self-propulsion, sub-micrometer size, fuel bioavailability, and structural and functional versatility. However, the key parameters influencing the propulsion efficiency of enzyme-powered colloidal motors still remain unclear. Here, we report the effect of the neck length of urease-powered pentosan flask-like colloidal motors on their kinematic behavior resembling the role of bacterial flagella. The sub-micrometer-sized and streamlined pentosan flask-like colloidal motors with variable neck lengths are synthesized through a facile interfacial dynamic assembly and polymerization strategy. The urease molecules are loaded through vacuum infusion technology and thus the urease-triggered catalytic reaction can propel the pentosan flask-like colloidal motors to move autonomously in the urea solution. The self-propelled speed of these pentosan flask-like colloidal motors significantly increases with the elongating neck lengths. The mechanism of the relationship between the neck length and self-propelled motion is that a longer neck can provide a larger self-propelled force due to the larger force area and stabilize the rotation because of the increased rotational friction. This research can provide guidance for the design of biomedical colloidal motors.

Inhalable biohybrid microrobots: a non-invasive approach for lung treatment

Amidst the rising prevalence of respiratory diseases, the importance of effective lung treatment modalities is more critical than ever. However, current drug delivery systems face significant limitations that impede their efficacy and therapeutic outcome. Biohybrid microrobots have shown considerable promise for active in vivo drug delivery, especially for pulmonary applications via intratracheal routes. However, the invasive nature of intratracheal administration poses barriers to its clinical translation. Herein, we report on an efficient non-invasive inhalation-based method of delivering microrobots to the lungs. A nebulizer is employed to encapsulate picoeukaryote algae microrobots within small aerosol particles, enabling them to reach the lower respiratory tract. Post nebulization, the microrobots retain their motility (~55 μm s-1) to help achieve a homogeneous lung distribution and long-term retention exceeding five days in the lungs. Therapeutic efficacy is demonstrated in a mouse model of acute methicillin-resistant Staphylococcus aureus pneumonia using this pulmonary inhalation approach to deliver microrobots functionalized with platelet membrane-coated polymeric nanoparticles loaded with vancomycin. These promising findings underscore the benefits of inhalable biohybrid microrobots in a setting that does not require anesthesia, highlighting the substantial translational potential of this delivery system for routine clinical applications.

Oscillatory Motion of a Camphor Disk on a Water Phase with an Ionic Liquid Sensitive to Transition Metal Ions

We investigated oscillatory motion of a camphor disk floating on water containing 5 mM hexylethylenediaminium trifluoroacetate (HHexen-TFA) as an ionic liquid (IL). The frequency of the oscillatory motion increased with increasing concentrations of the transition metal ions Cu2+ and Ni2+ but was insensitive to Na+, Ca2+, and Mg2+, the typical metal ions in the water phase. The surface tension of the water phase containing 5 mM HHexen-TFA also increased with increasing concentrations of Cu2+ and Ni2+ but was insensitive to Na+, Ca2+, and Mg2+. Based on density functional theory, metal-ion species-dependent frequency response is discussed with regard to surface tension as the force of self-propulsion and complex formation between HHexen-TFA and metal ions. These results suggest that complex formation between the transition metal ions (Cu2+, Ni2+) and the ethylenediamine group in the IL increases the surface tension around the camphor disk, resulting in an increase in the frequency of oscillatory motion with increasing concentrations of Cu2+ or Ni2+. The present study suggests that the nature of self-propulsion can be created by complexation, which changes the force of self-propulsion.

Chlorella-Based Biohybrid Microrobot for Removing Both Nutrient and Microalgae toward Efficient Water Eutrophication Treatment

Excessive nutrients and explosive growth of harmful microalgae in water environments are key challenges in the treatment of eutrophication. The development of a low-cost, time-saving, and small-space-suitable research method that can simultaneously remove nutrients and microalgae is highly anticipated. This work first proposed applying microrobots to eutrophication treatment. Phosphate and Microcystisaeruginosa (M. aeruginosa) were selected as representative nutrients and harmful microalgae, respectively, to investigate the efficient removal effect of the microrobots on the two. The Chlorella@Fe3O4@ZIF-8 biohybrid microrobot can not only perform the dual removal of phosphates and M. aeruginosa but also take advantage of its small size and controllable motion to achieve targeted treatment of eutrophication of water in microenvironments such as microchannels, thereby achieving the effect of fundamentally treating the eutrophication. The Chlorella@Fe3O4@ZIF-8 microrobot reveals a new strategy for the treatment of eutrophication and also exploits a new perspective for application research of microrobots.

Swarm Autonomy: From Agent Functionalization to Machine Intelligence

Swarm behaviors are common in nature, where individual organisms collaborate via perception, communication, and adaptation. Emulating these dynamics, large groups of active agents can self-organize through localized interactions, giving rise to complex swarm behaviors, which exhibit potential for applications across various domains. This review presents a comprehensive summary and perspective of synthetic swarms, to bridge the gap between the microscale individual agents and potential applications of synthetic swarms. It is begun by examining active agents, the fundamental units of synthetic swarms, to understand the origins of their motility and functionality in the presence of external stimuli. Then inter-agent communications and agent-environment communications that contribute to the swarm generation are summarized. Furthermore, the swarm behaviors reported to date and the emergence of machine intelligence within these behaviors are reviewed. Eventually, the applications enabled by distinct synthetic swarms are summarized. By discussing the emergent machine intelligence in swarm behaviors, insights are offered into the design and deployment of autonomous synthetic swarms for real-world applications.

Magnetic-Powered Spora Lygodii Microrobots Loaded with Doxorubicin for Active and Targeted Therapy of Bladder Cancer

Background and Purpose

Bladder cancer has high recurrence rates despite standard treatments, necessitating innovative therapeutic approaches. This study introduces magnetically powered microrobots utilizing Traditional Chinese Medicine (TCM) Spora Lygodii (SL) encapsulated with Doxorubicin (DOX) and Fe3O4 nanoparticles (Fe/DOX@SL) for targeted therapy.

Methods

Fe3O4 nanoparticles were synthesized via co-precipitation and combined with SL spores and DOX through dip-coating to form Fe/DOX@SL microrobots. Their propulsion was controlled by a rotating magnetic field (RMF) for precise delivery. The microrobots' mobility and adherence were assessed in various biological media. Therapeutic efficacy was evaluated using an orthotopic bladder cancer model in mice treated intravesically with Fe/DOX@SL under RMF guidance, compared to controls.

Results

Fe/DOX@SL microrobots demonstrated efficient movement and stable navigation in biological environments. In vivo experiments showed superior retention in the bladder, prolonged adherence to the mucosa, and significantly enhanced tumor suppression in the RMF-guided group. Bioluminescence imaging confirmed reduced tumor growth, and histological analysis revealed substantial tumor regression compared to other treatments.

Discussion and Conclusion

This study highlights the potential of integrating TCM with advanced microrobotics. The biocompatible Fe/DOX@SL microrobots leverage SL's therapeutic properties and fuel-free magnetic control to overcome challenges in bladder cancer treatment, such as poor drug retention and off-target toxicity. This novel platform represents a promising advancement in targeted cancer therapy. The innovative fusion of TCM and microrobotics introduces a potent, targeted therapeutic strategy for bladder cancer, paving the way for broader biomedical applications.

Bioinspired microrobots and their biomedical applications

Natural organisms and biological systems provide a rich source of inspiration for the development of bioinspired microrobots. These diminutive automatons, designed to emulate the intricate structures and functions of living entities, extend human capabilities across a spectrum of applications. This review endeavors to amalgamate and elucidate the underpinnings of such bioinspired microrobots design, traversing the interdisciplinary expanse of research. It delineates a spectrum of biomedical applications for bioinspired microrobots, encompassing targeted drug delivery, cellular manipulation, and minimally invasive surgical procedures, among others. Moreover, the current technical challenges and future directions of bioinspired microrobots in the biomedical field are discussed. The objective is to impart a holistic view to the readership, illuminating the significance of bioinspired microrobots in contemporary biomedicine and charting potential trajectories of innovation.

Towards multifunctional robotic pills

Robotic pills leverage the advantages of oral pharmaceutical formulations-in particular, convenient encapsulation, high loading capacity, ease of manufacturing and high patient compliance-as well as the multifunctionality, increasing miniaturization and sophistication of microrobotic systems. In this Perspective, we provide an overview of major innovations in the development of robotic pills-specifically, oral pills embedded with robotic capabilities based on microneedles, microinjectors, microstirrers or microrockets-summarize current progress and applicational gaps of the technology, and discuss its prospects. We argue that the integration of multiple microrobotic functions within oral delivery systems alongside accurate control of the release characteristics of their payload provides a basis for realizing sophisticated multifunctional robotic pills that operate as closed-loop systems.

Generalized and Scalable Synthesis of Manganese Dioxide-Based Tubular Micromotors for Heavy Metal Ion Removal

Synthetic nano- and micromachines hold immense promise in biomedicine and environmental science. Currently, bubble-driven tubular micro/nanomotors have garnered increasing attention owing to their exceptional high-speed self-propulsions. However, complex and low-yield preparation methods have hindered their widespread applications. Herein, we present a generalized, scalable, and low-cost electrospinning-based strategy to fabricate MnO2-based composite tubular micromotors (MnO2-TMs) for efficient heavy metal ion removal. The inherent flexibility of precursor nanofibers derived from diverse matrix materials enables the creation of MnO2-TMs with a wide range of morphologies. In response to morphology changes, the MnO2-TMs, based on a bubble-propelled mechanism, exhibit multimodal motion patterns, including linear, circular, and spiral to stochastic swinging. To elucidate the underlying morphology-to-motion relationship, we conducted systematic simulations of fluid dynamics around the MnO2-TMs. Furthermore, by incorporation of Fe3O4 nanoparticles, the capabilities of MnO2-TMs can be expanded to include magnetic manipulation for directional navigation and efficient retrieval. Benefiting from these attributes, MnO2-TMs excel in removing heavy metal ions from water. The developed MnO2-MnWO4@Fe3O4 TMs exhibit prominent adsorption capacities of 586.5 mg g-1 for Cu2+ and 156.4 mg g-1 for Pb2+. Notably, the magnetic property facilitates rapid separation and retrieval of the micromotors, and the absorbed ions can be simply recovered by pH adjustment. This work establishes a general framework for developing MnO2-based tubular micro/nanomotors to address environmental challenges.

Robo-Matter towards reconfigurable multifunctional smart materials

Maximizing materials utilization efficiency via enhancing their reconfigurability and multifunctionality offers a promising avenue in addressing the global challenges in sustainability. To this end, significant efforts have been made in developing reconfigurable multifunctional smart materials, which can exhibit remarkable behaviors such as morphing and self-healing. However, the difficulty in efficiently manipulating and controlling matter at the building block level with manageable cost and complexity, which is crucial to achieving superior responsiveness to environmental clues and stimuli, has significantly hindered the further development of such smart materials. Here we introduce a concept of Robo-Matter, which can be activated and controlled through external information exchange at the building block level, to enable a high-level of controllability, mutability and versatility for reconfigurable multifunctional smart materials. Using specially designed micro-robot building blocks with symmetry-breaking active motion modes, tunable anisotropic interactions, and interactive coupling with a programmable spatial-temporal dynamic light field, we demonstrate an emergent Robot-Matter duality, which enables a spectrum of desirable behaviors spanning from matter-like properties such as ultra-fast self-assembly and adaptivity, to robot-like properties including active force output, smart healing, smart morphing and infiltration. Our work demonstrates a promising direction for designing next-generation smart materials and large-scale robotic swarms.

Engineered Microrobots for Targeted Delivery of Bacterial Outer Membrane Vesicles (OMV) in Thrombus Therapy

In the realm of thrombosis treatment, bioengineered outer membrane vesicles (OMVs) offer a novel and promising approach, as they have rich content of bacterial-derived components. This study centers on OMVs derived from Escherichia coli BL21 cells, innovatively engineered to encapsulate the staphylokinase-hirudin fusion protein (SFH). SFH synergizes the properties of staphylokinase (SAK) and hirudin (HV) to enhance thrombolytic efficiency while reducing the risks associated with re-embolization and bleeding. Building on this foundation, this study introduces two cutting-edge microrobotic platforms: SFH-OMV@H for venous thromboembolism (VTE) treatment, and SFH-OMV@MΦ, designed specifically for cerebral venous sinus thrombosis (CVST) therapy. These platforms have demonstrated significant efficacy in dissolving thrombi, with SFH-OMV@H showcasing precise vascular navigation and SFH-OMV@MΦ effectively targeting cerebral thrombi. The study shows that the integration of these bioengineered OMVs and microrobotic systems marks a significant advancement in thrombosis treatment, underlining their potential to revolutionize personalized medical approaches to complex health conditions.

Field-Directed Motion, Cargo Capture, and Closed-Loop Controlled Navigation of Microellipsoids

Microrobots have the potential for diverse applications, including targeted drug delivery and minimally invasive surgery. Despite advancements in microrobot design and actuation strategies, achieving precise control over their motion remains challenging due to the dominance of viscous drag, system disturbances, physicochemical heterogeneities, and stochastic Brownian forces. Here, a precise control over the interfacial motion of model microellipsoids is demonstrated using time-varying rotating magnetic fields. The impacts of microellipsoid aspect ratio, field characteristics, and magnetic properties of the medium and the particle on the motion are investigated. The role of mobile micro-vortices generated is highlighted by rotating microellipsoids in capturing, transporting, and releasing cargo objects. Furthermore, an approach is presented for controlled navigation through mazes based on real-time particle and obstacle sensing, path planning, and magnetic field actuation without human intervention. The study introduces a mechanism of directing motion of microparticles using rotating magnetic fields, and a control scheme for precise navigation and delivery of micron-sized cargo using simple microellipsoids as microbots.

Design and batch fabrication of anisotropic microparticles toward small-scale robots using microfluidics: recent advances

Small-scale robots with shape anisotropy have garnered significant scientific interest due to their enhanced mobility and precise control in recent years. Traditionally, these miniature robots are manufactured using established techniques such as molding, 3D printing, and microfabrication. However, the advent of microfluidics in recent years has emerged as a promising manufacturing technology, capitalizing on the precise and dynamic manipulation of fluids at the microscale to fabricate various complex-shaped anisotropic particles. This offers a versatile and controlled platform, enabling the efficient fabrication of small-scale robots with tailored morphologies and advanced functionalities from the microfluidic-derived anisotropic microparticles at high throughput. This review highlights the recent advances in the microfluidic fabrication of anisotropic microparticles and their potential applications in small-scale robots. In this review, the term 'small-scale robots' broadly encompasses micromotors endowed with capabilities for locomotion and manipulation. Firstly, the fundamental strategies for liquid template formation and the methodologies for generating anisotropic microparticles within the microfluidic system are briefly introduced. Subsequently, the functionality of shape-anisotropic particles in forming components for small-scale robots and actuation mechanisms are emphasized. Attention is then directed towards the diverse applications of these microparticle-derived microrobots in a variety of fields, including pollution remediation, cell microcarriers, drug delivery, and biofilm eradication. Finally, we discuss future directions for the fabrication and development of miniature robots from microfluidics, shedding light on the evolving landscape of this field.

Advanced materials for micro/nanorobotics

Autonomous micro/nanorobots capable of performing programmed missions are at the forefront of next-generation micromachinery. These small robotic systems are predominantly constructed using functional components sourced from micro- and nanoscale materials; therefore, combining them with various advanced materials represents a pivotal direction toward achieving a higher level of intelligence and multifunctionality. This review provides a comprehensive overview of advanced materials for innovative micro/nanorobotics, focusing on the five families of materials that have witnessed the most rapid advancements over the last decade: two-dimensional materials, metal-organic frameworks, semiconductors, polymers, and biological cells. Their unique physicochemical, mechanical, optical, and biological properties have been integrated into micro/nanorobots to achieve greater maneuverability, programmability, intelligence, and multifunctionality in collective behaviors. The design and fabrication methods for hybrid robotic systems are discussed based on the material categories. In addition, their promising potential for powering motion and/or (multi-)functionality is described and the fundamental principles underlying them are explained. Finally, their extensive use in a variety of applications, including environmental remediation, (bio)sensing, therapeutics, etc., and remaining challenges and perspectives for future research are discussed.

Phoresis kernel theory for passive and active spheres with nonuniform phoretic mobility

By introducing geometry-based phoresis kernels, we establish a direct connection between the translational and rotational velocities of a phoretic sphere and the distributions of the driving fields or fluxes. The kernels quantify the local contribution of the field or flux to the particle dynamics. The field kernels for both passive and active particles share the same functional form, depending on the position-dependent surface phoretic mobility. For uniform phoretic mobility, the translational field kernel is proportional to the surface normal vector, while the rotational field kernel is zero; thus, a phoretic sphere with uniform phoretic mobility does not rotate. As case studies, we discuss examples of a self-phoretic axisymmetric particle influenced by a globally-driven field gradient, a general scenario for axisymmetric self-phoretic particle and two of its special cases, and a non-axisymmetric active particle.

Alignment and actuation of liquid crystals via 3D confinement and two-photon laser printing

Liquid crystalline (LC) materials are especially suited for the preparation of active three-dimensional (3D) and 4D microstructures using two-photon laser printing. To achieve the desired actuation, the alignment of the LCs has to be controlled during the printing process. In most cases studied before, the alignment relied on surface modifications and complex alignment patterns and concomitant actuation were not possible. Here, we introduce a strategy for spatially aligning LC domains in three-dimensional space by using 3D-printed polydimethylsiloxane-based microscaffolds as confinement barriers, which induce the desired director field. The director field resulting from the boundary conditions is calculated with Landau de Gennes theory and validated by comparing experimentally measured and theoretically predicted birefringence patterns. We demonstrate our procedures for structures of varying complexity and then employed them to fabricate 4D microstructures that show the desired actuation. Overall, we obtain excellent agreement between theory and experiment. This opens the door for rational design of functional materials for 4D (micro)printing in the future.

Transcervical uterine flushing and embryo transfer in sheep: Morphophysiological basis for approaches currently used, major challenges, potential improvements, and new directions (alas, including some old ideas)

At present, the success of non-surgical embryo recovery (NSER) and transfer (NSET) hinges upon the cervical passage of catheters, but penetration of the uterine cervix in ewes is problematic due to its anatomical structure (i.e., long and narrow cervical lumen with misaligned folds and rings). It is a major obstacle limiting the widespread application of NSER and NSET in sheep. While initial attempts to traverse the uterine cervix focused on adapting or re-designing insemination catheters, more recent studies demonstrated that cervical relaxation protocols were instrumental for transcervical penetration in the ewe. An application of such protocols more than tripled cervical penetration rates (currently at 90-95 %) in sheep of different breeds (e.g., Dorper, Lacaune, Santa Inês, crossbred, and indigenous Brazilian breeds) and ages/parity. There is now sufficient evidence to suggest that even repeatedly performed cervical passages do not adversely affect overall health and reproductive function of ewes. Despite these improvements, appropriate selection of donors and recipients remains one of the most important requirements for maintaining high success rates of NSER and NSET, respectively. Non-surgical ovine embryo recovery has gradually become a commercially viable method as even though the procedure still cannot be performed by untrained individuals, it is inexpensive, yields satisfactory results, and complies with current public expectations of animal welfare standards. This article reviews critical morphophysiological aspects of transcervical embryo flushing and transfer, and the prospect of both techniques to replace surgical methods for multiple ovulation and embryo transfer (MOET) programs in sheep. We have also discussed some potential pharmacological and technical developments in the field of non-invasive embryo recovery and deposition.

Metal-Organic Framework-Based Micro-/Nanomotors for Wastewater Remediation

Micro-/nanomotors (MNMs) in water remediation have garnered significant attention over the past two decades. More recently, metal-organic framework-based micro-/nanomotors (MOF-MNMs) have been applied for environmental remediation; however, a comprehensive summary of research in this research area is yet to be reported. Herein, a review is presented to cover the recent advances in MOF-MNMs and their various applications in wastewater remediation. The review presents a comprehensive introduction to MNMs, including different propulsion approaches, fabrication, and functionalization strategies, in addition to the unique features of MOF-MNMs. The conception and various synthetic routes of MOF-MNMs are extensively covered and the implementation of MOF-MNMs in water-related applications, including adsorption, degradation, sensing, and disinfection of different pollutants, is in depth discussed. Meanwhile, the propulsion and mechanism of action behind each MOF-MNM are systematically studied. Finally, the review provides insights into the challenges and perspectives to build more effective MOF-MNMs to cover versatile applications for wastewater treatment.

Nanoarchitectonic Engineering of Thermal-Responsive Magnetic Nanorobot Collectives for Intracranial Aneurysm Therapy

Stent-assisted coiling is a main treatment modality for intracranial aneurysms (IAs) in clinics, but critical challenges remain to be overcome, such as exogenous implant-induced stenosis and reliance on antiplatelet agents. Herein, an endovascular approach is reported for IA therapy without stent grafting or microcatheter shaping, enabled by active delivery of thrombin (Th) to target aneurysms using innovative phase-change material (PCM)-coated magnetite-thrombin (Fe3O4-Th@PCM) FTP nanorobots. The nanorobots are controlled by an integrated actuation system of dynamic torque-force hybrid magnetic fields. With robust intravascular navigation guided by real-time ultrasound imaging, nanorobotic collectives can effectively accumulate and retain in model aneurysms constructed in vivo, followed by controlled release of the encapsulated Th for rapid occlusion of the aneurysm upon melting the protective PCM (thermally responsive in a tunable manner) through focused magnetic hyperthermia. Complete and stable aneurysm embolization is confirmed by postoperative examination and 2-week postembolization follow-up using digital subtraction angiography (DSA), contrast-enhanced ultrasound (CEUS), and histological analysis. The safety of the embolization therapy is assessed through biocompatibility evaluation and histopathology assays. This strategy, seamlessly integrating secure drug packaging, agile magnetic actuation, and clinical interventional imaging, avoids possible exogenous implant rejection, circumvents cumbersome microcatheter shaping, and offers a promising option for IA therapy.

Orbits, Spirals, and Trapped States: Dynamics of a Phoretic Janus Particle in a Radial Concentration Gradient

A long-standing goal in colloidal active matter is to understand how gradients in fuel concentration influence the motion of phoretic Janus particles. Here, we present a theoretical description of the motion of a spherical phoretic Janus particle in the presence of a radial gradient of the chemical solute driving self-propulsion. Radial gradients are a geometry relevant to many scenarios in active matter systems and naturally arise due to the presence of a point source or sink of fuel. We derive an analytical solution for the Janus particle's velocity and quantify the influence of the radial concentration gradient on the particle's trajectory. Compared to a phoretic Janus particle in a linear gradient in fuel concentration, we uncover a much richer set of dynamic behaviors including circular orbits and trapped stationary states. We identify the ratio of the phoretic mobilities between the two domains of the Janus particle as a central quantity in tuning their dynamics. Our results provide a path for developing optimum protocols for tuning the dynamics of phoretic Janus particles and mixing fluid at the microscale. In addition, this work suggests a method for quantifying the surface properties of phoretic Janus particles, which have proven to be challenging to probe experimentally.

3D-printed microrobots for biomedical applications

Microrobots, which can perform tasks in difficult-to-reach parts of the human body under their own or external power supply, are potential tools for biomedical applications, such as drug delivery, microsurgery, imaging and monitoring, tissue engineering, and sensors and actuators. Compared with traditional fabrication methods for microrobots, recent improvements in 3D printers enable them to print high-precision microrobots, breaking through the limitations of traditional micromanufacturing technologies that require high skills for operators and greatly shortening the design-to-production cycle. Here, this review first introduces typical 3D printing technologies used in microrobot manufacturing. Then, the structures of microrobots with different functions and application scenarios are discussed. Next, we summarize the materials (body materials, propulsion materials and intelligent materials) used in 3D microrobot manufacturing to complete body construction and realize biomedical applications (e.g., drug delivery, imaging and monitoring). Finally, the challenges and future prospects of 3D printed microrobots in biomedical applications are discussed in terms of materials, manufacturing and advancement.

Programming hierarchical anisotropy in microactuators for multimodal actuation

Microactuators, capable of executing tasks typically repetitive, hazardous, or impossible for humans, hold great promise across fields such as precision medicine, environmental remediation, and swarm intelligence. However, intricate motions of microactuators normally require high complexity in design, making it increasingly challenging to realize at small scales using existing fabrication techniques. Taking inspiration from the hierarchical-anisotropy principle found in nature, we program liquid crystalline elastomer (LCE) microactuators with multimodal actuation tailored to their molecular, shape, and architectural anisotropies at (sub)nanometer, micrometer, and (sub)millimeter scales, respectively. Our strategy enables diverse deformations with individual LCE microstructures, including expanding, contracting, twisting, bending, and unwinding, as well as re-programmable shape transformations of assembled LCE architectures with negative Poisson's ratios, locally adjustable actuation, and changing from two-dimensional (2D) to three-dimensional (3D) structures. Furthermore, we design tetrahedral microactuators with well-controlled mobility and precise manipulation of both solids and liquids in various environments. This study provides a paradigm shift in the development of microactuators, unlocking a vast array of complexities achievable through manipulation at each hierarchical level of anisotropy.

Bacterial outer membrane vesicles in the fight against cancer

ABSTRACT

Bacterial outer membrane vesicles (OMVs) are diminutive vesicles naturally released by Gram-negative bacteria. These vesicles possess distinctive characteristics that attract attention for their potential use in drug administration and immunotherapy in cancer treatment. Therapeutic medicines may be delivered via OMVs directly to the tumor sites, thereby minimizing exposure to healthy cells and lowering the risk of systemic toxicity. Furthermore, the activation of the immune system by OMVs has been demonstrated to facilitate the recognition and elimination of cancer cells, which makes them a desirable tool for immunotherapy. They can also be genetically modified to carry specific antigens, immunomodulatory compounds, and small interfering RNAs, enhancing the immune response to cancerous cells and silencing genes associated with disease progression. Combining OMVs with other cancer treatments like chemotherapy and radiation has shown promising synergistic effects. This review highlights the crucial role of bacterial OMVs in cancer, emphasizing their potential as vectors for novel cancer targeted therapies. As researchers delve deeper into the complexities of these vesicles and their interactions with tumors, there is a growing sense of optimism that this avenue of study will bring positive outcomes and renewed hope to cancer patients in the foreseeable future.

Harnessing Disparities in Magnetic Microswarms: From Construction to Collaborative Tasks

Individual differences in size, experience, and task specialization in natural swarms often result in heterogeneity and hierarchy, facilitating efficient and coordinated task accomplishment. Drawing inspiration from this phenomenon, a general strategy is proposed for organizing magnetic micro/nanorobots (MNRs) with apparent differences in size, shape, and properties into cohesive microswarms with tunable heterogeneity, controlled spatial hierarchy, and collaborative tasking capability. In this strategy, disparate magnetic MNRs can be manipulated to show reversible transitions between synchronization and desynchronization by elaborately regulating parameter sets of the rotating magnetic field. Utilizing these transitions, alongside local robust hydrodynamic interactions, diverse heterospecific pairings of disparate magnetic MNRs can be organized into heterogeneous microswarms, and their spatial organization can be dynamically adjusted from egalitarian to leader-follower-like hierarchies on the fly, both in open space and complex microchannels. Furthermore, when specializing the disparate MNRs with distinct functions ("division of labor") such as sensing and drug carrying, they can execute precise drug delivery targeting unknown sites in a collaborative sensing-navigating-cargo dropping sequence, demonstrating significant potential for precise tumor treatment. These findings highlight the critical roles of attribute differences and hierarchical organization in designing efficient swarming micro/nanorobots for biomedical applications.

Single Atom Engineering for Nanorobotics

The fields of single atom engineering represent cutting-edge areas in nanotechnology and materials science, pushing the boundaries of how small we can go in engineering functional devices and materials. Nanorobots, or nanobots, are robotic systems scaled down to the nanometer level and designed to perform tasks at similarly small scales. Single atom engineering, on the other hand, involves manipulating individual atoms to create precise materials and devices with controlled properties and functionalities. By integrating single atom engineering into nanorobotics, we unlock the potential to enable the precise incorporation of multiple functionalities onto these minuscule machines with nanometer-level precision. In this perspective, we describe the nascent field of single atom engineering in nanorobotics.

Robotic Nanomanipulation Based on Spatiotemporal Modulation of Optical Gradients

Robotic nanomanipulation emerges as a cutting-edge technique pivotal for in situ nanofabrication, advanced sensing, and comprehensive material characterization. In this study, we develop an optical robotic platform (ORP) for the dynamic manipulation of colloidal nanoparticles (NPs). The ORP incorporates a human-in-the-loop control mechanism enhanced by real-time visual feedback. This feature enables the generation of custom optical landscapes with adjustable intensity and phase configurations. Based on the ORP, we achieve the parallel and reconfigurable manipulation of multiple NPs. Through the application of spatiotemporal phase gradient-reversals, our platform demonstrates capabilities in trapping, binding, rotating, and transporting NPs across custom trajectories. This presents a previously unidentified paradigm in the realm of in situ nanomanipulation. Additionally, the ORP facilities a "capture-and-print" assembly process, utilizing a strategic interplay of phase and intensity gradients. This process operates under a constant laser power setting, streamlining the assembly of NPs into any targeted configuration. With its precise positioning and manipulation capabilities, underpinned by the spatiotemporal modulation of optical gradients, the ORP will facilitate the development of colloid-based sensors and on-demand fabrication of nanodevices.

Delivering Microrobots in the Musculoskeletal System

Disorders of the musculoskeletal system are the major contributors to the global burden of disease and current treatments show limited efficacy. Patients often suffer chronic pain and might eventually have to undergo end-stage surgery. Therefore, future treatments should focus on early detection and intervention of regional lesions. Microrobots have been gradually used in organisms due to their advantages of intelligent, precise and minimally invasive targeted delivery. Through the combination of control and imaging systems, microrobots with good biosafety can be delivered to the desired area for treatment. In the musculoskeletal system, microrobots are mainly utilized to transport stem cells/drugs or to remove hazardous substances from the body. Compared to traditional biomaterial and tissue engineering strategies, active motion improves the efficiency and penetration of local targeting of cells/drugs. This review discusses the frontier applications of microrobotic systems in different tissues of the musculoskeletal system. We summarize the challenges and barriers that hinder clinical translation by evaluating the characteristics of different microrobots and finally point out the future direction of microrobots in the musculoskeletal system.

Template-Guided Silicon Micromotor Assembly for Enhanced Cell Manipulation

Light-driven micro/nanorobots (LMNRs) are tiny, untethered machines with great potential in fields like precision medicine, nano manufacturing, and various other domains. However, their practicality hinges on developing light-manipulation strategies that combine versatile functionalities, flexible design options, and precise controllability. Our study introduces an innovative approach to construct micro/nanorobots (MNRs) by utilizing micro/nanomotors as fundamental building blocks. Inspired by silicon Metal-Insulator-Semiconductor (MIS) solar cell principles, we design a new type of optomagnetic hybrid micromotors (OHMs). These OHMs have been skillfully optimized with integrated magnetic constituent, resulting in efficient light propulsion, precise magnetic navigation, and the potential for controlled assembly. One of the key features of the OHMs is their ability to exhibit diverse motion modes influenced by fracture surfaces and interactions with the environment, streamlining cargo conveyance along "micro expressway"-the predesigned microchannels. Further enhancing their versatility, a template-guided assembly strategy facilitates the assembly of these micromotors into functional microrobots, encompassing various configurations such as "V-shaped", "N-shaped", and 3D structured microrobots. The heightened capabilities of these microrobots, underscore the innovative potential inherent in hybrid micromotor design and assembly, which provides a foundational platform for the realization of multi-component microrobots. Our work moves a step toward forthcoming microrobotic entities boasting advanced functionalities.

Unveiling Trends: Nanoscale Materials Shaping Emerging Biomedical Applications

The realm of biomedical materials continues to evolve rapidly, driven by innovative research across interdisciplinary domains. Leveraging big data from the CAS Content Collection, this study employs quantitative analysis through natural language processing (NLP) to identify six emerging areas within nanoscale materials for biomedical applications. These areas encompass self-healing, bioelectronic, programmable, lipid-based, protein-based, and antibacterial materials. Our Nano Focus delves into the multifaceted utilization of nanoscale materials in these domains, spanning from augmenting physical and electronic properties for interfacing with human tissue to facilitating intricate functionalities like programmable drug delivery.

Colloidal bubble propulsion mediated through viscous flows

Bubble-propelled catalytic colloids stand out as a uniquely efficient design for artificial controllable micromachines, but so far lack a general theoretical framework that explains the physics of their propulsion. Here we develop a combined diffusive and hydrodynamic theory of bubble growth near a spherical catalytic colloid, that allows us to explain the underlying mechanism and the influence of environmental and material parameters. We identify two dimensionless groups, related to colloidal activity and the background fluid, that govern a saddle-node bifurcation of the bubble growth dynamics, and calculate the generated flows analytically for both slip and no slip boundary conditions on the bubble. We finish with a discussion of the assumptions and predictions of our model in the context of existing experimental results, and conclude that some of the observed behaviour, notably the ratchet-like gait, may stem from peculiarities of the experimental setup rather than fundamental physics of the propulsive mechanism.