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Recent advancements in catalytic micromotors have shown significant potential for environmental applications, yet challenges such as particle agglomeration persist. In this study, we compare the degradation of methylene blue using hematite particles fully coated with platinum and those partially decorated with platinum. The selective decoration, confirmed through techniques like EDX, FESEM, TEM, and XPS, plays a crucial role in the micromotors' behavior. The decomposition of hydrogen peroxide (H2O2) by Pt nanoparticles on one side of the hematite particles generates thrust, propelling the micromotors and enhancing their interaction with pollutant molecules. This active mobility helps counteract agglomeration, preventing the formation of irregular 3D clusters and improving catalytic efficiency. Our findings show that partially decorated particles achieve up to 85% dye removal within 90 min, outperforming fully decorated particles, which reach only 33% efficiency due to aggregation and sedimentation. These results underscore the importance of optimized surface decoration for improving the performance and stability of catalytic systems in pollutant degradation. [ABSTRACT FROM AUTHOR]

In this study, self-propelled Pt/PPy-COOH micromotors were produced by using the sequential electrodeposition of Pt and PPy segments. Fabricated micromotors were modified with tyrosinase enzyme and was used to investigate the phenolic compound removal capacity. The micromotors was characterized by SEM and EDX analyses, and it was found that the shape of the motors was tubular and 10 µm long. The optimum pH values of free and immobilized enzymes were found to be 7.5, while the optimum temperature values were 45 °C. In the thermal stability study, it was determined that the immobilized enzyme showed 75 % activity after 5 h, while the activity of the free enzyme was around 21 %. Also, immobilized tyrosinase showed 55 % activity after 10 repeated uses. Finally, the phenol, p-cresol and o-phenylenediamine removal efficiencies of tyrosinase-based micromotors were found to be 54.54 %, 46.96 % and 53.87 % in 5 min, respectively. As a result, it can be concluded that it is possible to use tyrosinase-based micromotors as an alternative to traditional methods for phenol removal. [Display omitted] • The Pt/PPy-COOH micromotors were synthesized for tyrosinase immobilization. • The "Pt" segment breaks down H 2 O 2 and causes O 2 bubble formation. • O 2 bubbles enabled the micromotors to move autonomously. • Immobilized tyrosinase was more stable than the free enzyme. • Immobilized enzyme showed unique phenol degradation efficiency over free enzyme. [ABSTRACT FROM AUTHOR]

Synthetic Janus micro/nanomotors can efficiently convert ambient energy into asymmetrical self‐propulsive force, overcoming random thermal fluctuations and enabling autonomous migration. Further modifications to the motors can equip them with different functional modules to meet different needs. However, developing a versatile and high‐yield fabrication method for multifunctional Janus micromotors remains challenging. In this study, a modular fabrication approach for micromotors with a particle‐tip structure based on the self‐focusing lithography induced by an array of TiO2 microspheres is presented. By adjusting the tip composition or loading, precise programming of motor functionality is achieved, allowing for various capabilities such as photoredox reaction‐induced propulsion, fluorescent imaging, electric and magnetic navigation. Furthermore, the flexibility of this fabrication method by selectively loading materials onto two tips is demonstrated to achieve multifunctionality within a micromotor unit. This study proposes a straightforward and versatile approach for modular functional micromotors. [ABSTRACT FROM AUTHOR]

Asymmetric chemical reactions on the surfaces of colloidal particles are known to propel them into directional motion. The dynamics of such chemical micromotors are sensitive to their local chemical environments, which also continually evolve with the reactions on motor surfaces. This two‐way coupling between the motor dynamics and the local environment may result in complex nonlinear behaviors. As an example, we report that Janus Ag microspheres, which self‐propel in hydrogen peroxide (H2O2), spontaneously reverse their direction of motion two or more times. We hypothesize that two distinct chemical reactions between Ag and H2O2 drive the micromotor in opposite directions, and which reaction dominates depends on the local pH. Interestingly, the local pH near a Ag micromotor oscillates spontaneously in H2O2, likely due to a complex interplay between the kinetics of the reaction between Ag and H2O2 and the diffusion of chemical species. Consequently, the pH‐sensitive Ag micromotor reverses its direction of motion in response to these pH oscillations. This study introduces a new mechanism for regulating the speed and directionality of micromotors, highlights the potential of Ag micromotors in chemical sensing, and sheds new light on the interplay between chemical kinetics and micromotor dynamics. [ABSTRACT FROM AUTHOR]

Asymmetric chemical reactions on the surfaces of colloidal particles are known to propel them into directional motion. The dynamics of such chemical micromotors are sensitive to their local chemical environments, which also continually evolve with the reactions on motor surfaces. This two‐way coupling between the motor dynamics and the local environment may result in complex nonlinear behaviors. As an example, we report that Janus Ag microspheres, which self‐propel in hydrogen peroxide (H2O2), spontaneously reverse their direction of motion two or more times. We hypothesize that two distinct chemical reactions between Ag and H2O2 drive the micromotor in opposite directions, and which reaction dominates depends on the local pH. Interestingly, the local pH near a Ag micromotor oscillates spontaneously in H2O2, likely due to a complex interplay between the kinetics of the reaction between Ag and H2O2 and the diffusion of chemical species. Consequently, the pH‐sensitive Ag micromotor reverses its direction of motion in response to these pH oscillations. This study introduces a new mechanism for regulating the speed and directionality of micromotors, highlights the potential of Ag micromotors in chemical sensing, and sheds new light on the interplay between chemical kinetics and micromotor dynamics. [ABSTRACT FROM AUTHOR]

Traditional light‐driven metal‐organic‐frameworks (MOFs)‐based micromotors (MOFtors) are typically constrained to two‐dimensional (2D) motion under ultraviolet or near‐infrared light and often demonstrate instability and susceptibility to ions in high‐saline environments. This limitation is particularly relevant to employing micromotors in water purification, as real wastewater is frequently coupled with high salinity. In response to these challenges, ultrastable MOFtors capable of three‐dimensional (3D) motion under a broad spectrum of light through thermophoresis and electrophoresis are successfully synthesized. The MOFtors integrated photocatalytic porphyrin MOFs (PCN‐224) with a photothermal component made of polypyrrole (PPy) by three distinct methodologies, resulting in micromotors with different motion behavior and catalytic performance. Impressively, the optimized MOFtors display exceptional maximum velocity of 1305 ± 327 µm s−1 under blue light and 2357 ± 453 µm s−1 under UV light. In harsh saline environments, these MOFtors are not only maintain high motility but also exhibit superior tetracycline hydrochloride (TCH) removal efficiency of 3578 ± 510 mg g−1, coupling with sulfate radical‐based advanced oxidation processes and peroxymonosulfate. This research underscores the significant potential of highly efficient MOFtors with robust photocatalytic activity in effectively removing TCH in challenging saline conditions, representing a substantial advancement in applying MOFtors within real‐world water treatment technologies. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Light-powered micromotors are a new type of micromotor that can be used for water purification treatment. This paper focuses on the synthesis processes and its application in water remediation. This mini review will highlight the great potential of these light powered micromotor as well as the significance of preparing them for environmental applications. Photocatalytic micromotors or light-powered micromotors have been intensively researched over the last several years for several applications, such as environmental remediation, biomedicine and micropumps. It has been found that conventional wastewater treatment is commercially inefficient in water remediation. The emphasis then was on a new solution of using micromotor as a potential replacement for water remediation. Many studies have been carried out over the years on the synthesis of these light-powered micromotors, which revolves around the materials used, and applications. This paper, therefore, reflects on the advancement of light-powered micromotors and will be concentrating on the synthesis processes and its application in water remediation. This mini-review will highlight the great potential of these light-driven micromotors as well as the significance of preparing them for environmental applications. [ABSTRACT FROM AUTHOR]

Biomimetic and biohybrid micro/nano‐structures involve the replication and creation of technologies, structures, and materials based on biological systems at the micrometer and nanometer scale. These strategies harness the natural biological principles to develop innovative treatment methods and advanced microstructure devices for noninvasive therapies. In this study, a detailed overview of fabrication processes, magnetically assisted locomotive techniques, and potential applications of biomimetic and biohybrid micro/nano‐machines are presented. The latest advancements in magnetically actuated biomimetic structures, such as annelid‐worm‐like microswimmers, jellyfish‐shaped microparticles, fish‐shaped microswimmers, and walnut‐shaped micromotors are explored. Additionally, the magnetic biohybrid systems, including sunflower seed‐based micro‐perforators, nanomotors extracted from the bamboo stem, sperm cell‐based micromotors, bacteria‐based robots, scaffold‐based microrobots, DNA‐based micromotors, microalgae‐based microswimmers, and red blood cell‐based microswimmers are also examined. A thorough investigation of the magnetically assisted locomotive behavior of these microstructure devices in biological Newtonian fluids, featuring cork‐screw motion, undulatory motion, surface wrinkling motion, traveling wave‐like motion, and ciliary stroke motion is discussed. Furthermore, unprecedented and innovative treatment methods developed using these minuscule devices such as cervical cancer treatment using tetrapod hybrid sperm micromotors, tissue regeneration using silk fibroin protein‐based magnetic microscale scaffolds, and doxorubicin drug delivery using mushroom‐based microrobots is extensively presented. [ABSTRACT FROM AUTHOR]

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Antibacterial micromotors with intriguing properties have represented frontiers of research in the biomedical and environmental fields. While single-powered micromotors still encounter some challenges for efficient propulsion in an intricate biological environment, herein, dual-propelled Fe3O4/BiOI/Ag (FBA) micromotors with hollow structure were synthesized via two facile steps without involving any sophisticated equipment. In this unique design, efficient propulsion of an FBA micromotor powered by magnetic stimuli/visible light was demonstrated. Impressively, the micromotor was capable of flexible propulsion with a remarkable velocity of 119.2 ± 5.9 μm s–1 without addition of toxic fuel. Taking advantage of the locomotion, bacterial capture ability, and photocatalytic capacity, 1 × 107 CFU mL–1 Escherichia coli (E. coli) can be totally inactivated by hollow FBA micromotors. The ideal universality of FBA for antibacterial application toward Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) was confirmed. Besides, the FBA micromotors manifested antibiofilm capacity toward E. coli , methicillin-resistant S. aureus (MRSA), and P. aeruginosa. It is worth mentioning that they also displayed ideal biocompatibility and lower toxicity. More importantly, the FBA micromotors can effectively accelerate S. aureus -infected wound healing without causing adverse effects. This work offers an innovative strategy for facile design of dual-propelled micromotors for various environmental and biomedical applications. [ABSTRACT FROM AUTHOR]

The excessive discharge of antibiotics into aquatic systems is a major issue in many countries worldwide and poses a threat to human health and the sustainable development of society. Hence, developing efficient treatment methods and purification technologies to degrade antibiotics is essential. Herein, we present the synthesis of low-cost, self-propelled tubular Fe3+-incorporated graphitic carbon nitride (g-C3N4-Fe@KF) micromotors using kapok fibers (KFs) as templates and their application as photo-catalysts for the photo-Fenton degradation of tetracycline (TC) under visible-light irradiation. The g-C3N4-Fe@KF micromotors moved rapidly when being propelled by oxygen bubbles generated in a hydrogen peroxide (H2O2) solution as a result of a photo-assisted Fenton reaction. The motion behavior of the g-C3N4-Fe@KF micromotors was dependent on the concentration of H2O2 and the length of the micromotors. The propulsion mechanism was discussed in detail. The micromotors efficiently degraded antibiotics via the photo-Fenton process. Photo-Fenton degradation efficiency was attributed to the synergistic effects of the doped Fe3+ and g-C3N4 under visible-light irradiation and self-propulsion of the micromotors. In addition, the micromotors possessed good reusability, thereby efficiently realizing multiple cycles of degradation. The current work offers an avenue for the design of micromotors, using inexpensive approaches, for various potential environmental applications. [ABSTRACT FROM AUTHOR]

The complex anatomy of internal luminal organs, like bronchioles, poses challenges for endoscopic optical coherence tomography (OCT). These challenges include limited steerability for targeted imaging and nonuniform rotation distortion (NURD) with proximal scanning. Using rotary micromotors for distal scanning could address NURD but raises concerns about electrical safety and costs. We present pneumaOCT, the first pneumatic OCT endoscope, comprising a steerable catheter with a soft pneumatic actuator and an imaging probe with a miniature pneumatic turbine. With a diameter of 2.8 mm, pneumaOCT allows for a bending angle of up to 237°, facilitating navigation through narrow turns. The pneumatic turbine enables adjustable imaging speeds from 51 to 446 revolutions per second. We demonstrate the pneumaOCT in vivo imaging of mouse esophagus and colon, as well as targeted and distortion-free imaging of peripheral bronchioles in a bronchial phantom and a porcine lung. This advancement substantially improves endoscopic OCT for navigational imaging in curved and narrow lumens. [ABSTRACT FROM AUTHOR]

The NVH (Noise, Vibration, and Harshness) characteristics of micro-motors used in vehicles directly affect the comfort of drivers and passengers. However, various factors influence the motor's structural parameters, leading to uncertainties in its NVH performance. To improve the motor's NVH characteristics, we propose a method for optimizing the structural parameters of automotive micro-motors under uncertain conditions. This method uses the motor's maximum magnetic flux as a constraint and aims to reduce vibration at the commutation frequency. Firstly, we introduce the Pareto ellipsoid parameter method, which converts the uncertainty problem into a deterministic one, enabling the use of traditional optimization methods. To increase efficiency and reduce computational cost, we employed a data-driven method that uses the one-dimensional Inception module as the foundational model, replacing both numerical models and physical experiments. Simultaneously, the module's underlying architecture was improved, increasing the surrogate model's accuracy. Additionally, we propose an improved NSGA-III (Non-dominated Sorting Genetic Algorithm III) method that utilizes adaptive reference point updating, dividing the optimization process into exploration and refinement phases based on population matching error. Comparative experiments with traditional models demonstrate that this method enhances the overall quality of the solution set, effectively addresses parameter uncertainties in practical engineering scenarios, and significantly improves the vibration characteristics of the motor. [ABSTRACT FROM AUTHOR]

A brief description of the micromotors capture degradation of microplastics and other related fields are given, and the micromotors degradation of microplastics technology, which has been developing rapidly in recent years is introduced in detail, with a focus on the drive mode of micromotors and its application in the field of degradation of microplastics. Micromotors are widely used in environmental remediation due to their autonomous driving performance in the water environment. The research progress of micromotors driving mode and capturing degradation of microplastics in recent years is briefly summarized, with emphasis on the practical application of micromotors in capturing the degradation of microplastics in domestic and international research, and the differences in the removal effect of microplastics by different micromotors are discussed. Summarizing the research progress on microplastic degradation by micromotors provides scientific guidance for environmental protection and further promotes the application of micromotors in environmental pollution and other aspects. Finally, the challenges to be faced and future development direction for the capture of degraded microplastics by micromotors are analyzed. [ABSTRACT FROM AUTHOR]

The recent era of research has been focused on attaining precise and adjustable propulsion modes in micromotors, with remarkable implications in microrobotics and active‐matter applications. This study introduces a novel design of rod‐shaped micromotors featuring light‐driven motion and wavelength‐dependent multimodal swimming behavior. The micromotors are fabricated through the Glancing Angle Deposition (GLAD) technique, which offers a flexible approach to engineering surfaces by incorporating photocatalytic materials (TiO2 and Cu2O) at specific locations. Here, three distinct designs of micromotors (titania, hybrid‐1, and hybrid‐2) are presented that are programmed to showcase diverse behaviors of movements (linear, helical, and axial rotation) when exposed to a specific wavelength. The application of light facilitates convenient control over activity and mode switching by altering between UV and visible ranges. Numerical modeling using a finite element approach is performed to validate the experimental results, demonstrating excellent agreement with the experimental findings. The present study is anticipated to be helpful in tailoring such complex micro/nanoscale advanced functional materials with intricating swimming modes desired for various applications in micro/nanorobotics. [ABSTRACT FROM AUTHOR]

In response to the problems of large shaking, high noise, inconvenient walking, and lack of protective measures in traditional micro tillers, a small electric micro tiller was designed, with a designed width of 60 cm and a depth of more than 8 cm. Through calculation, a DC motor with a power of 2.2 kW and a voltage of 72 V was selected as the power output motor of the micro tiller. According to the operating conditions, the gearbox, transmission ratio, and gears of the micro tiller were designed, and key components were verified to meet the design requirements. According to actual work requirements, estimate and select the battery capacity, select 120 Ah lithium battery as the power supply battery, and ultimately establish a three-dimensional model of the entire machine. Electric micro tillers have more obvious advantages compared to traditional gasoline and diesel power in tea gardens and greenhouse planting. In addition to being pollution-free, they also have advantages such as low vibration and adjustable speed, which have broad market prospects. [ABSTRACT FROM AUTHOR]

Core–shell micro/nanomotors have garnered significant interest in biomedicine owing to their versatile task-performing capabilities. However, their effectiveness for photothermal therapy (PTT) still faces challenges because of their poor tumor accumulation, lower light-to-heat conversion, and due to the limited penetration of near-infrared (NIR) light. In this study, we present a novel core–shell micromotor that combines magnetic and photothermal properties. It is synthesized via the template-assisted electrodeposition of iron (Fe) and reduced graphene oxide (rGO) on a microtubular pore-shaped membrane. The resulting Fe-rGO micromotor consists of a core of oval-shaped zero-valent iron nanoparticles with large magnetization. At the same time, the outer layer has a uniform reduced graphene oxide (rGO) topography. Combined, these Fe-rGO core–shell micromotors respond to magnetic forces and near-infrared (NIR) light (1064 nm), achieving a remarkable photothermal conversion efficiency of 78% at a concentration of 434 µg mL−1. They can also carry doxorubicin (DOX) and rapidly release it upon NIR irradiation. Additionally, preliminary results regarding the biocompatibility of these micromotors through in vitro tests on a 3D breast cancer model demonstrate low cytotoxicity and strong accumulation. These promising results suggest that such Fe-rGO core–shell micromotors could hold great potential for combined photothermal therapy. [ABSTRACT FROM AUTHOR]

The acoustic performance of automotive micro-motors directly impacts the comfort and driving experience of both drivers and passengers. However, various motor production and testing uncertainties can lead to noise fluctuations during operation. Thus, predicting the operational noise range of motors on the production line in advance becomes crucial for timely adjustments to production parameters and process optimization. This paper introduces a prediction model based on a Multi-Branch Channel–Spatial Adaptive Weighting Strategy (MCSAWS). The model includes a multi-branch feature extraction (MFE) network and a channel–spatial attention module (CSAM). It uses the vibration and noise data from micro-motors' idle operations on the production line as input to efficiently predict the operational noise uncertainty interval of automotive micro-motors. The model employs the VAE-GAN approach for data augmentation (DA) and uses Gammatone filters to emphasize the noise at the commutation frequency of the motor. The model was compared with Convolutional Neural Networks (CNNs) and Multilayer Perceptrons (MLPs). Experimental results demonstrate that the MCSAWS method is superior to conventional methods in prediction accuracy and reliability, confirming the feasibility of the proposed approach. This research can help control noise uncertainty in micro-motors' production and manufacturing processes in advance. [ABSTRACT FROM AUTHOR]

MEMS and micromotors may benefit from the increasing complexity of rotors by integrating a larger number of magnetic dipoles. In this article, a new microassembly and bonding process to integrate multiple Sm2Co17 micromagnets in a ferromagnetic core is presented. We experimentally demonstrate the feasibility of a multipolar micrometric magnetic rotor with 11 magnetic dipoles made of N35 Sm2Co17 micromagnets (length below 250 μm and thickness of 65 μm), integrated on a ferromagnetic core. We explain the micromanufacturing methods and the multistep microassembly process. The core is manufactured on ferromagnetic alloy Fe49Co49V2 and has an external diameter of 800 μm and a thickness of 200 μm. Magnetic and geometric measurements show good geometric fitting and planarity. The manufactured microrotor also shows good agreement among the magnetic measurements and the magnetic simulations which means that there is no magnetic degradation of the permanent magnet during the manufacturing and assembly process. This technique enables new design possibilities to significantly increase the performance of micromotors or MEMS. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) are recognized as the most promising functional nanotechnology, for which its discoverers are awarded the Nobel Prize in 2023. Their remarkable tunability of optoelectronic properties has attracted significant interest from both researchers and industries, placing QDs at the forefront of developing cutting‐edge technologies. This comprehensive review aims to explore the exciting results in terms of fundamental science, present and forthcoming applications. Beyond their contributions to biomedicine, energy, environmental science, quantum sensing, and quantum information processing, QDs have brought important results due to their integration into micro/nanorobotic systems, self‐propelled materials representing the state of the art research at the micro and nanoscale. These hybrid systems have demonstrated noteworthy outcomes, unlocking novel possibilities in biomedicine, quantum sensing, and environmental science, accurately reviewed in this article. In conclusion, this review addresses current challenges, offering insights to facilitate further research, stimulate new developments, and enhance the comprehension of the full potential of QDs. [ABSTRACT FROM AUTHOR]

Pathogenic bacteria pose a significant threat to human health, and their removal from food and water supplies is crucial in preventing the spread of waterborne and foodborne diseases. Recently, silver‐based photocatalytic micromotors have emerged as promising candidates for inactivating pathogenic microbes due to their high antibacterial activity. In this study, the synthesis of photoactive Ag3PO4 micromotors with a well‐defined tetrapod‐like structure (TAMs) is presented using a simple precipitation method. These TAMs autonomously move and release Ag ions/nanoparticles (NPs) through a photodegradation process when exposed to light, which enhances their antimicrobial activity against Gram‐negative (Escherichia coli) and Gram‐positive (Staphylococcus aureus) bacterial strains. Interestingly, different motion modes are observed under different manipulated light wavelengths and fuels. Furthermore, the self‐degradation of TAMs is accelerated in the presence of negatively charged bacteria, which results in higher removal rates of both bacteria, E. Coli and S. aureus. The findings introduce a new concept of self‐degradable micromotors based on photocatalytic components, which hold great potential for their use in antimicrobial applications. This work offers significant implications for materials chemistry, especially in designing and developing the next generation of light‐driven antimicrobial agents. [ABSTRACT FROM AUTHOR]

Active matter is an emerging area of interest but the broken symmetry necessary for motion increases the complexity of mathematical modeling. However, these models can be critical for the interpretation of experimental data and efficient optimization of these systems, particularly towards the practical realization of commercial applications. Here, we present a linearized solution (small Péclet and thin-interaction layer) to a generalized mixed boundary-value problem that can be used to describe a variety of active colloidal systems consisting of partially coated (Janus-type) chemically active spherical microparticles, where the size of the active patch is left arbitrary (although axisymmetric). The solution is derived using the Fourier–Legendre-Collocation approach and the accuracy of this methodology is validated against known exact solutions to some limiting cases. We demonstrate the application of the general formulation by solving the mobility of a catalytic "patchy" particle which has two surfaces of differing chemical reactivity which can be characterized by either a fixed-flux or fixed-rate reaction (characterized by an arbitrary Damköhler number (Da)). The analytic solution is shown to agree with limiting cases in the literature presented for both small and infinite Da. Comparison of the different models to experiments published in the literature, indicate that the characterization of the surface reaction by a Dirichlet boundary condition, as in the case of infinite Da is uniquely able to capture the dependence of the mobility on the size of the active patch. This finding highlights the role of mathematical modeling in experimental characterization and optimization of active colloid systems. [ABSTRACT FROM AUTHOR]

Traditional magnetic levitation planar micromotors suffer from poor controllability, short travel range, low interference resistance, and low precision. To address these issues, a distributed coil magnetically levitated planar micromotor with a gated recurrent unit (GRU)-extended state observer (ESO) control strategy is proposed in this paper. First, the structural design of the distributed coil magnetically levitated planar micromotor employs a separation of levitation and displacement, reducing system coupling and increasing controllability and displacement range. Then, theoretical analysis and model establishment of the system are conducted based on the designed distributed coil magnetically levitated planar micromotor and its working principles, followed by simulation verification. Finally, based on the established system model, a GRU-ESO controller is designed. An ESO feedback control term is introduced to enhance the system's anti-interference capability, and the GRU feedforward compensation control term is used to improve the system's tracking control accuracy. The experimental results demonstrate the reliability of the designed distributed coil magnetic levitation planar micromotor and the effectiveness of the controller. [ABSTRACT FROM AUTHOR]

By leveraging the benefits of a high energy density, miniaturization and integration, acoustic-wave-driven micromotors have recently emerged as powerful tools for microfluidic actuation. In this study, a Lamb-wave-driven micromotor is proposed for the first time. This motor consists of a ring-shaped Lamb wave actuator array with a rotor and a fluid coupling layer in between. On a driving mechanism level, high-frequency Lamb waves of 380 MHz generate strong acoustic streaming effects over an extremely short distance; on a mechanical design level, each Lamb wave actuator incorporates a reflector on one side of the actuator, while an acoustic opening is incorporated on the other side to limit wave energy leakage; and on electrical design level, the electrodes placed on the two sides of the film enhance the capacitance in the vertical direction, which facilitates impedance matching within a smaller area. As a result, the Lamb-wave-driven solution features a much lower driving voltage and a smaller size compared with conventional surface acoustic-wave-driven solutions. For an improved motor performance, actuator array configurations, rotor sizes, and liquid coupling layer thicknesses are examined via simulations and experiments. The results show the micromotor with a rotor with a diameter of 5 mm can achieve a maximum angular velocity of 250 rpm with an input voltage of 6 V. The proposed micromotor is a new prototype for acoustic-wave-driven actuators and demonstrates potential for lab-on-a-chip applications. [ABSTRACT FROM AUTHOR]

Gastric perforation refers to the complete rupture of the gastric wall, leading to the extravasation of gastric contents into the thoracic cavity or peritoneum. Without timely intervention, the expulsion of gastric contents may culminate in profound discomfort, exacerbating the inflammatory process and potentially triggering perilous sepsis. In clinical practice, surgical suturing or endoscopic closure procedures are commonly employed. Magnetic-driven microswarms have also been employed for sealing gastrointestinal perforation. However, surgical intervention entails significant risk of bleeding, while endoscopic closure poses risks of inadequate closure and the need for subsequent removal of closure clips. Moreover, the efficacy of microswarms is limited as they merely adhere to the perforated area, and their sealing effect diminishes upon removal of the magnetic field. Herein, we present a Fe&Mg@Lard-Paraffin micromotor (LPM) constructed from a mixture of lard and paraffin coated with magnesium (Mg) microspheres and iron (Fe) nanospheres for sutureless sealing gastric perforations. Under the control of a rotating magnetic field, this micromotor demonstrates precise control over its movement on gastric mucosal folds and accurately targets the gastric perforation area. The phase transition induced by the high-frequency magnetothermal effect causes the micromotor composed of a mixed oil phase of lard and paraffin to change from a solid to a liquid phase. The coated Mg microspheres are subsequently exposed to the acidic gastric acid environment to produce a magnesium protonation reaction, which in turn generates hydrogen (H2) bubble recoil. Through a Mg-based micropower traction, part of the oil phase could be pushed into the gastric perforation, and it would then solidify to seal the gastric perforation area. Experimental results show that this can achieve long-term (>2 h) gastric perforation sealing. This innovative approach holds potential for improving outcomes in gastric perforation management. [ABSTRACT FROM AUTHOR]

[Display omitted] Colloid science has classically concerned itself with the investigation of the properties of dispersed phases in a bulk medium. This has led to the development of a rich amount of chemistry, physics, and engineering that have facilitated the evolution and maturation of this field. One of the many developments made over the last 30 years is the introduction of particles that are heterogeneous in chemistry and shape. These heterogeneities can introduce behaviors that are not achievable in homogeneous systems and that are specific to the type and class of nonuniformity. This has led to the development of numerous technologies, two of which are Janus micromotors and solid surfactants. This review aims to familiarize the reader with the field of heterogeneous particles. We begin with an overview of various synthetic methods to produce colloidal particles that are heterogeneous in chemistry and shape. We then discuss their use as solid surfactants and autonomous micromotors. We then close by summarizing and providing a future perspective on the field. [ABSTRACT FROM AUTHOR]

In the article, a mathematical model has been constructed and investigated by analyzing the problem of disintegration during torsion of the cylindrical shaped piezo element in the linear piezoelectric engine. Nonlinear differential equations expressing the expansion of the disintegration surface formed during the torsion of the piezo element under the influence of variable torsional moment have been formulated. Guidelines determining the initial degradation period for the development of the disintegration process have been obtained, and based on the developed mathematical model, displacement curves of the disintegration surface motion have been established. [ABSTRACT FROM AUTHOR]

Abstract Traditional light‐driven metal‐organic‐frameworks (MOFs)‐based micromotors (MOFtors) are typically constrained to two‐dimensional (2D) motion under ultraviolet or near‐infrared light and often demonstrate instability and susceptibility to ions in high‐saline environments. This limitation is particularly relevant to employing micromotors in water purification, as real wastewater is frequently coupled with high salinity. In response to these challenges, ultrastable MOFtors capable of three‐dimensional (3D) motion under a broad spectrum of light through thermophoresis and electrophoresis are successfully synthesized. The MOFtors integrated photocatalytic porphyrin MOFs (PCN‐224) with a photothermal component made of polypyrrole (PPy) by three distinct methodologies, resulting in micromotors with different motion behavior and catalytic performance. Impressively, the optimized MOFtors display exceptional maximum velocity of 1305 ± 327 µm s−1 under blue light and 2357 ± 453 µm s−1 under UV light. In harsh saline environments, these MOFtors are not only maintain high motility but also exhibit superior tetracycline hydrochloride (TCH) removal efficiency of 3578 ± 510 mg g−1, coupling with sulfate radical‐based advanced oxidation processes and peroxymonosulfate. This research underscores the significant potential of highly efficient MOFtors with robust photocatalytic activity in effectively removing TCH in challenging saline conditions, representing a substantial advancement in applying MOFtors within real‐world water treatment technologies.

Herein, T4‐bacteriophage‐funcionalizated magnetic Janus micromotors are used for the first time for highly selective Escherichia coli (E. coli) recognition and detection. The micromotors propel at speeds of up to 40 µm s−1 in complex biological samples for on‐the‐fly capture of E. coli "strain B"‐thiolated T4 bacteriophage complex. Detection is achieved by a simplified colorimetric readout in connection with gold nanoparticles. The detection limit meets the cut‐off for the fast diagnosis of urinary tract infections. The bacteriophage‐engineered micromotors are tested on bacteria isolated from urine samples and in serum isolated from negative blood cultures from hospital patients with excellent selectivity and reliability. The new strategy described here holds considerable promise for the multiplexed detection of a myriad of bacteria strains using tailored bacteriophages. Technically, this is the first microplate‐reader integrated micromotor approach, crossing another bridge from the research lab to the practical use of micromotors. Specifically, these results represent a qualitative step forward in the use of micromotor technology with sophisticated functionalization for fast bacteria screening in clinical settings. [ABSTRACT FROM AUTHOR]

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Magnetically actuated microrobots have become a research hotspot in recent years due to their tiny size, untethered control, and rapid response capability. Moreover, an increasing number of researchers are applying them for micro-/nano-manipulation in the biomedical field. This survey provides a comprehensive overview of the recent developments in magnetic microrobots, focusing on materials, propulsion mechanisms, design strategies, fabrication techniques, and diverse micro-/nano-manipulation applications. The exploration of magnetic materials, biosafety considerations, and propulsion methods serves as a foundation for the diverse designs discussed in this review. The paper delves into the design categories, encompassing helical, surface, ciliary, scaffold, and biohybrid microrobots, with each demonstrating unique capabilities. Furthermore, various fabrication techniques, including direct laser writing, glancing angle deposition, biotemplating synthesis, template-assisted electrochemical deposition, and magnetic self-assembly, are examined owing to their contributions to the realization of magnetic microrobots. The potential impact of magnetic microrobots across multidisciplinary domains is presented through various application areas, such as drug delivery, minimally invasive surgery, cell manipulation, and environmental remediation. This review highlights a comprehensive summary of the current challenges, hurdles to overcome, and future directions in magnetic microrobot research across different fields. [ABSTRACT FROM AUTHOR]

Nano-doped hollow fiber is currently receiving extensive attention due to its multifunctionality and booming development. However, the microfluidic fabrication of nano-doped hollow fiber in a simple, smooth, stable, continuous, well-controlled manner without system blockage remains challenging. In this study, we employ a microfluidic method to fabricate nano-doped hollow fiber, which not only makes the preparation process continuous, controllable, and efficient, but also improves the dispersion uniformity of nanoparticles. Hydrogel hollow fiber doped with carbon nanotubes is fabricated and exhibits superior electrical conductivity (15.8 S m−1), strong flexibility (342.9%), and versatility as wearable sensors for monitoring human motions and collecting physiological electrical signals. Furthermore, we incorporate iron tetroxide nanoparticles into fibers to create magnetic-driven micromotors, which provide trajectory-controlled motion and the ability to move through narrow channels due to their small size. In addition, manganese dioxide nanoparticles are embedded into the fiber walls to create self-propelled micromotors. When placed in a hydrogen peroxide environment, the micromotors can reach a top speed of 615 μm s−1 and navigate hard-to-reach areas. Our nano-doped hollow fiber offers a broad range of applications in wearable electronics and self-propelled machines and creates promising opportunities for sensors and actuators. [ABSTRACT FROM AUTHOR]

To achieve a lightweight design and wide field of view for the automatic alignment system in wireless optical communication, in the receiving antenna—a fisheye lens is incorporated as the receiving optical system. This feature enables the detection and tracking of lasers. The system utilizes a micro motor as the control servo system and a four-quadrant detector as the detection unit. Sequential and non-sequential ray tracing techniques were used to simulate the analysis of the fish-eye lens. Point array diagrams, ray trace diagrams, and encircled energy analysis were utilized to evaluate the spot's quality. The simulation results demonstrate that the fish-eye lens has a field of view of 120°, and the spot with 80% energy has a diameter smaller than 30 μm. The experimental results indicate that the fish-eye lens effectively captures the light beam within the range of ±30°. The simulated and experimental results for the sum and difference frequency amplitudes show good agreement. The outdoor experiments have demonstrated a tracking error of 22.757 μrad in this system. After alignment, the average output optical power of the detector is 3.23 μW, and the detected waveform amplitude is 12.48 mV. These findings demonstrate the system's potential for automatic alignment in wireless optical communication. Additionally, the system is relatively simple and practical. [ABSTRACT FROM AUTHOR]

Inspired by the collective behaviors of active systems in nature, the collective behavior of micromotors has attracted more and more attention in recent years. However, little attention has been paid to the collective behavior of the immobilized micromotor, i.e., the micropump. In this paper, a unique pentacene-based micropump is reported, which demonstrates dynamic collective behavior activated by white light irradiation. The light irradiation may generate the photochemical reactions between pentacene and water, leading to the electroosmotic flow. As a result, this micropump is capable of pumping the surrounding solution inward along the substrate surface based on the electroosmosis mechanism. Intriguingly, the inward pumping causes the agglomeration of the tracer particles on the surface of the micropump. In addition, the aggregation can migrate following the change in the light irradiation position between two adjacent micropumps. Based on the aggregating and migrating behaviors of this pentacene-based micropump, we have achieved the conductivity restoration of the cracked circuit. [ABSTRACT FROM AUTHOR]

Recent progress in the development of MnO2-based micromotors has shown the immense potential of these motile devices to remediate environmental contamination. However, the production of such micromotors on an industrial scale through a facile, efficient and reproducible process remains challenging. The present work aimed to address this issue using naturally occurring and abundant pine pollen (PP) grains. The immersion of PP in potassium permanganate (KMnO4) solutions was found to generate MnO2 nanoparticles (NPs) on the PP surfaces, the amount and distribution of which was readily adjusted by varying the coating time. Because of the asymmetrical shape of the PP grains, the MnO2/PP composites exhibited rapid self-propulsion at a maximum speed of 360.686 μm/s (approximately eight body lengths/s) in low-concentration hydrogen peroxide (H2O2) solutions. The ability of these materials to remediate heavy metal pollutants was also examined and was evidently increased by a factor of 1.5 compared with static counterparts. These composites could also be recovered and reused over three consecutive cycles. The competitive cost, continuous motion and superior decontamination capacity of these materials suggests potential applications in the rapid removal or degradation of heavy metal ions, toxic organic dyes, pathogenic bacteria and other pollutants in wastewater. These micromotors represent a new approach to the utilization of natural materials in environmental remediation. [ABSTRACT FROM AUTHOR]

Hydrogel microparticles, generally accepted as significant green materials, have been widely used in chemical, biological, and biomedical fields owing to their excellent biocompatibility, biodegradability, and noncytotoxicity. Among these, non-spherical hydrogel microparticles with diverse shape anisotropy have great potential in applications such as drug delivery, cellular interaction, micromotors, etc. Benefiting from their shapes, their functionalities in such fields cannot be satisfied by the typical spherical types. Recently, microfluidics with precise control and domination of fluids at microflow sizes has emerged as a powerful method for synthesizing shape-controllable hydrogel microparticles with good monodispersity and unique morphology. In this review, we tried to provide an overview of the production of non-spherical microparticles composed of green hydrogel materials, emphasizing the microfluidic approaches. Furthermore, a brief introduction to their current applications is also presented. [ABSTRACT FROM AUTHOR]

Leveraging advancements in micro-scale technology, we propose a fleet of autonomous, low-cost, small solar sails for interplanetary exploration. The Berkeley Low-cost Interplanetary Solar Sail (BLISS) project aims to utilize small-scale technologies to create a fleet of tiny interplanetary spacecraft for rapid, low-cost exploration of the inner solar system. This paper describes the hardware required to build a ∼10 g spacecraft using a 1 m2 solar sail steered by micro-electromechanical systems (MEMS) inchworm actuators. The trajectory control to a NEO, here 101955 Bennu, is detailed along with the low-level actuation control of the solar sail and the specifications of proposed onboard communication and computation. Two other applications are also shortly considered: sample return from dozens of Jupiter-family comets and cometary nuclei imaging. The paper concludes by discussing the fundamental scaling limits and future directions for steerable autonomous miniature solar sails with onboard custom computers and sensors. • An autonomous 10−2 kg spacecraft to navigate the solar system is proposed. • Low-cost spacecraft composed of mostly off-the-shelf parts to return images of NEOs. • Propelled by a 1 m2 solar sail controlled by micro-electromechanical systems motors. • Autonomous trajectory control to a NEO, communication, and computation is detailed. [ABSTRACT FROM AUTHOR]

Abstract Quantum dots (QDs) are recognized as the most promising functional nanotechnology, for which its discoverers are awarded the Nobel Prize in 2023. Their remarkable tunability of optoelectronic properties has attracted significant interest from both researchers and industries, placing QDs at the forefront of developing cutting‐edge technologies. This comprehensive review aims to explore the exciting results in terms of fundamental science, present and forthcoming applications. Beyond their contributions to biomedicine, energy, environmental science, quantum sensing, and quantum information processing, QDs have brought important results due to their integration into micro/nanorobotic systems, self‐propelled materials representing the state of the art research at the micro and nanoscale. These hybrid systems have demonstrated noteworthy outcomes, unlocking novel possibilities in biomedicine, quantum sensing, and environmental science, accurately reviewed in this article. In conclusion, this review addresses current challenges, offering insights to facilitate further research, stimulate new developments, and enhance the comprehension of the full potential of QDs.

The proliferation of micro/nanoplastics derived from the fragmentation of plastic waste released in the environment represents an increasingly alarming issue with adverse implications for aquatic ecosystems worldwide. Conventional approaches for mitigating such contamination are inadequate in removing plastic fragments with exceptionally tiny sizes. Therefore, it is highly urgent to develop efficient strategies to address the threats posed by micro/nanoplastics. Here, biohybrid microrobots, integrating the magnetic properties of Fe3O4 nanoparticles, are investigated for the dynamic removal of micro/nanoplastics from various aquatic environments via high‐precision magnetic actuation and reliable electrostatic interactions. After the surface decoration with Fe3O4 nanoparticles, algae cells can achieve precise locomotion and wireless manipulation by regulating an external magnetic field. Taking advantage of this active movement, magnetic algae robots (MARs) display considerable capture and removal efficiencies for micro/nanoplastics in water with extensive application scenarios. The reusability of MARs is also investigated, proving great recyclable performance. The growth and cell viability experiments elucidate that the presence of Fe3O4 nanoparticles may result in hormesis stimulation of algae growth. Such recyclable microrobots with eco‐friendly and low‐cost characteristics offer an attractive strategy for sustainably tackling micro/nanoplastics pollution. [ABSTRACT FROM AUTHOR]

Nano/micromotors are artificial robots at the nano/microscale that are capable of transforming energy into mechanical movement. In cancer diagnosis or therapy, such "tiny robots" show great promise for targeted drug delivery, cell removal/killing, and even related biomarker sensing. Yet biocompatibility is still the most critical challenge that restricts such techniques from transitioning from the laboratory to clinical applications. In this review, we emphasize the biocompatibility aspect of nano/micromotors to show the great efforts made by researchers to promote their clinical application, mainly including non-toxic fuel propulsion (inorganic catalysts, enzyme, etc.), bio-hybrid designs, ultrasound propulsion, light-triggered propulsion, magnetic propulsion, dual propulsion, and, in particular, the cooperative swarm-based strategy for increasing therapeutic effects. Future challenges in translating nano/micromotors into real applications and the potential directions for increasing biocompatibility are also described. [ABSTRACT FROM AUTHOR]

Plastics, primarily microplastics, are among the greatest pollutants in aquatic environments. Their removal and/or degradation in these environments are crucial to ensure an optimal future of these ecosystems. In this work, MnO2 particles were synthesized and characterized for the removal of polystyrene microplastics as a model. MnO2 catalyzes the peroxide reaction, resulting in the formation of oxygen bubbles that propel the pollutants to the surface, achieving removal efficiencies of up to 80%. To achieve this, hydrothermal synthesis was employed using various methods. Parameters such as MnO2, pH, microplastics, and H2O2 concentrations were varied to determine the optimal conditions for microplastics recovering. The ideal conditions for a low microplastic concentrations (10 mg L−1) are 0.2 g L−1 MnO2, 1.6% of H2O2 and 0.01 triton as a surfactant. In these conditions, the micromotors can recover approximately 80% of 300 nm sized polystyrene microplastic within 40 min. [ABSTRACT FROM AUTHOR]

Limited transport efficiency of remediation reagents in the subsurface environment is regarded as a key challenge facing in situ soil remediation. Herein, taking advantage of natural hollow fibers, tubular micromotors capable of autonomous movement to facilitate the migration of remediation reagents and achieve efficient degradation of organic pollutants in soil are developed. Widely‐used nanocatalysts in soil treatment, Fe3O4 and MnO2, are integrated on the fiber surface to enable self‐propulsion via recoil of micro/nanobubbles and activation of hydrogen peroxide (H2O2) and peroxymonosulfate. Featured with tiny sizes and wireless motion, the micromotors navigate in microchannels and microenvironments with complex terrain. The dependence of transport efficiency in heterogeneous and porous environments on H2O2 concentration is revealed based on column studies. With fluorescent g‐C3N4 decorated on the surface to enable visualization, the horizontal/vertical migration of prepared micromotors in soil is proved to be greatly enhanced due to self‐propulsion and bubble generation. The micromotors exhibit excellent catalytic performances toward the degradation of a wide spectrum of water‐soluble antibiotics and water‐insoluble polycyclic aromatic hydrocarbons. Overall, the bioinspired micromotors unveil a new strategy to improve the transport of remediation reagents in the subsurface environment, which holds great potential for efficient in situ soil treatment. [ABSTRACT FROM AUTHOR]

Autonomous micromotors demonstrate remarkable advancements in biomedical applications. A noteworthy example is streamlined motors, which display enhanced movement efficiency with low fluid‐resistance. However, existing streamlined motors, primarily constructed from inorganic materials, present challenges due to their complex fabrication procedures and lack of a soft interface for interaction with biological systems. Herein, a novel design of biodegradable streamlined alginate hydrogel micromotors with a teardrop shape by microfluidics is introduced. The platform enables the high‐throughput fabrication of monodisperse micromotors with varied dimensions. By incorporating Pt‐coated Fe3O4 nanoparticles, micromotors are equipped with dual capabilities of catalytic propulsion and accurate magnetic guidance. Through precisely tuning the localization regions of catalysts within the micromotors, the streamlined hydrogel micromotors not only exhibit enhanced propelling efficiency, but also accomplish distinct motion patterns of run and tumble. The design provides insights for developing advanced micromotors capable of executing intricate tasks across diverse application scenarios. [ABSTRACT FROM AUTHOR]

Spermbots are robotic sperms formed out of sperm cells conjugated to artificial microstructures, having potential applications ranging from biomedical processes, drug delivery systems, in situ real time imagery and assisted reproduction. The robotic sperm can act as an exploratory microdevice in biological networks. Incorporation of a biological entity like sperm into microstructures under the environment of magnetic or electric fields helps in shape templating and carrying chemotherapeutic agents to target sites. Besides its role in drug delivery systems, spermbots can potentially contribute in combating infertility, especially in oligo-zoospermia and necro-zoospermia in males. Numerous checkpoints may impede sperm cells to reach the oocyte in vivo. Spermbots bypass these sites and carry sperm to oocyte. Targeted delivery always requires interventions of natural functional aspects of living systems. Sperm flagellum, being a biological motor in nature, can be harnessed as a driving force in spermbots to ensure delivery of fertile sperm cells with impaired motile machinery to the target. Moreover, the technology has a potential to unravel sperm migration patterns and understanding the processes in vivo. After a review of documented literature on possible use of spermbot technology in assisted reproduction, we hereby discuss the application of this new and innovative technology in humans and animals. The paper also highlights certain shortfalls in the widespread application of this cargo delivery technology in assisted reproduction. [ABSTRACT FROM AUTHOR]

Wastewater pollution with organic compounds poses a serious threat to human health. One of the possible methods for solving these problems can be the use of micro/nanomotors. Among them, manganese‐based micro/nanomotors have a number of important advantages related to high catalytic activity, powerful motion, and low cost. Due to their mobility, micro/nanomotors promote an increase in the intensity of mass transfer in the reacting system. When introducing ferromagnetic elements into manganese‐based micro/nanomotors, it is possible not only to increase their motion speed, but also to make their motion more controllable. Herein, for the first time it demonstrates a synthesis method for MnFe2O4@Fe3O4/graphite and Mn2O3@Fe2O3@Fe3O4/graphite magnetic catalytic micromotors, which have remarkable photocatalytic properties. Micromotors are clusters of nanoparticles whose motion in a hydrogen peroxide solution in a non‐uniform magnetic field is caused by the action of magnetic force and self‐diffusiophoresis. Nanoparticles are synthesized by the plasma‐arc method with subsequent annealing in the air. When changing the annealing temperature, the catalytic and magnetic properties of nanoparticles can vary within a wide range of values. Micromotors MnFe2O4@Fe3O4/graphite have the most optimal catalytic and magnetic properties. The results of the research show that these micromotors are effective catalysts in the decomposition of methylene blue. [ABSTRACT FROM AUTHOR]

Micro-and nanorobots have the potential to perform non-invasive drug delivery, sensing, and surgery in living organisms, with the aid of diverse medical imaging techniques. To perform such actions, microrobots require high spatiotemporal resolution tracking with real-time closed-loop feedback. To that end, photoacoustic imaging has appeared as a promising technique for imaging microrobots in deep tissue with higher molecular specificity and contrast. Here, we present different strategies to track magnetically-driven micromotors with improved contrast and specificity using dedicated contrast agents (Au nanorods and nanostars). Furthermore, we discuss the possibility of improving the light absorption properties of the employed nanomaterials considering possible light scattering and coupling to the underlying metal-oxide layers on the micromotor's surface. For that, 2D COMSOL simulation and experimental results were correlated, confirming that an increased spacing between the Au-nanostructures and the increase of thickness of the underlying oxide layer lead to enhanced light absorption and preservation of the characteristic absorption peak. These characteristics are important when visualizing the micromotors in a complex in vivo environment, to distinguish them from the light absorption properties of the surrounding natural chromophores. [ABSTRACT FROM AUTHOR]