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Abstract: Since Nobel Laureate Arthur Ashkin first introduced the trapping and manipulation of microparticles using light, numerous studies have explored this technique not only for dielectric/metallic particles but also for organic matter. This advancement has significantly expanded the landscape of non-contact and non-invasive micromanipulation at the nanometric scale. However, micromanipulation of particles with a refractive index smaller than the host medium, n p < n m, proves challenging with Gaussian beams. To overcome this obstacle, a force known as thermocapillary, or the Marangoni force, has emerged as a straightforward trapping mechanism for bubbles in liquids. The Marangoni force results from the surface tension of bubbles, induced either thermally or chemically—by creating a temperature gradient or adding surfactants, respectively. The surface tension gradient on the liquid host induces tangential stress on the bubble wall, causing the bubble to move toward the region of lower surface tension, where it faces less opposing force. When the Marangoni force is generated by a laser beam’s temperature gradient, it becomes an exceptionally effective mechanism for the steady-state trapping and three-dimensional manipulation of bubbles, even with low optical power lasers. This force produces both longitudinal and transversal forces, resembling optical forces, creating a three-dimensional potential well capable of handling bubbles with radii of tens to hundreds of microns. This work provides guidance and demonstrates, both experimentally and theoretically, the step-by-step process of quasi-steady-state trapping and three-dimensional manipulation of bubbles through optothermal effects. The bubbles in question are tens of microns in size, significantly larger than those that optical tweezers can trap/manipulate. Furthermore, the study emphasizes the crucial role of the Marangoni force in this process, outlining its various advantages.

This article explores the challenges and solutions in the physical characterization of materials at the microscale using robotized systems, with a specific focus on manipulating and characterizing micrometer-sized particles with different and complex 3D shapes and internal sub-micrometer structures. In this paper, the studied particles are Molybdenum diSulfide (MoS2) based materials generated within the contact interface during friction.These particles are being studied because they offer a particularly promising solution for reducing mechanical friction and the associated high energy losses. However, they are distributed randomly within the contact area and possess intricate sub-micrometer structures. Characterization demands precise manipulation techniques in an in-situ Scanning Electron Microscope(SEM) environment. To address these challenges, existing commercial micro and nanomanipulation tools are integrated within a vacuum SEM chamber, and robotics strategies are investigated to enable the whole process from particle preparation, and manipulation setup definition, to effective MoS 2 particle characterization all in-situ SEM. A set of several complementary experimental investigations are done and involve force measurement and deformation estimation studies, leading to the first qualitative results on MoS 2 based particles directly from the friction track. The work contributes to advancements in both microscale manipulation and characterization. It also has implications for lubrication research. [ABSTRACT FROM AUTHOR]

A deep understanding of the processes in soft matter systems with liquid-liquid phase boundaries is of particular importance for materials science, chemistry and life sciences. A vast variety of physicochemical techniques have been proposed for the study of interfacial properties of liquid systems. Among them, electron microscopy methods occupy an important place due to the possibility of direct observation of the sample areas of interest with high spatial resolution; however, the harsh conditions of the electron microscope chamber impose significant restrictions on the possibilities of observing and manipulating unprotected liquids and related soft systems. To overcome these difficulties, in this work, we developed a methodology for direct probing of liquid-liquid interfaces with simultaneous control of the process using electron microscopy. Practically relevant liquid mixtures based on vacuum-compatible ionic liquid (IL) with water additives were probed with micrometer accuracy in real time inside an electron microscope chamber, which made it possible to reveal the role of specific ions aggregation and electrostatic phenomena in the stabilization of liquid microdomains. To test the versatility of the proposed approach, the morphology of a typical IL/water mixture was examined using a series of electron microscopes of various configurations, and it was shown that the best level of contrast between two chemically related liquid phases can be obtained in the case of a cold field emission electron source in combination with an in-lens secondary electron detector, regardless of the specific instrument manufacturer.

In the past few decades, researchers have conducted extensive studies on cell micromanipulation methods. However, there has consistently been a lack of a micromanipulation system that excels in both precision and speed. Additionally, many of these methods rely on manual control, thus significantly reducing efficiency. In this paper, a robotized micromanipulation system employing a two-finger microhand is proposed. The microhand has a 3-DoF parallel mechanism driven by three piezoelectric actuators, enabling high-precision micromanipulation. Replacing the needle-tip end-effector with a hemispherical end-effector makes cell grasping easier and more stable. In addition, a vibration-based release method combined with gel coating is proposed to reduce the release difficulty caused by adhesion forces. Through multiple sets of experiments, we have determined the optimal grasping and releasing conditions while balancing precision, stability, and damage degree to cells. An automated cell assembly strategy based on microscopic visual feedback and pick-and-place path planning is proposed to achieve the robotized high-speed cell array. Hela cells were chosen as the operation objects, achieving a 95% success rate in grasping and a 97% success rate in releasing. A "T" letter array formed by cells was successfully assembled with an average grasp and release time of less than 0.8 s and an assembly accuracy of 4.5 μm for a single cell. This study holds significant implications for the fields of biology and medicine, presenting potential applications in tissue engineering. [ABSTRACT FROM AUTHOR]

The photoinduced crawling motion of crystals is a continuous motion that azobenzene molecular crystals exhibit under light irradiation. Such motion enables object manipulation at the microscale with a simple setup of fixed LED light sources. Transportation of nano-/micromaterials using photoinduced crawling motion has recently been reported. However, the details of the motion mechanism have not been revealed so far. Herein, we report visualization of the dynamics of fine particles in 4-(methylamino)azobenzene (4-MAAB) crystals under light irradiation via diffracted X-ray tracking (DXT). Continuously repeated melting and recrystallization of 4-MAAB crystals under light irradiation results in the flow of liquid 4-MAAB. Zinc oxide (ZnO) particles were introduced inside the 4-MAAB crystals to detect diffracted X-rays. The ZnO particles rotate with the flow of liquid 4-MAAB. By using white X-rays with a wide energy width, the rotation of each zinc oxide nanoparticle was detected as the movement of a bright spot in the X-ray diffraction pattern. It was clearly shown that the ZnO particles rotated increasingly as the irradiation light intensity increased. Furthermore, we also found anisotropy in the rotational direction of ZnO particles that occurred during the crawling motion of 4-MAAB crystals. It has become clear that the flow perpendicular to the supporting film of 4-MAAB crystals is enhanced inside the crystal during the crawling motion. DXT provides a unique means to elucidate the mechanism of photoinduced crawling motion of crystals. [ABSTRACT FROM AUTHOR]

We report automated nonprehensile magnetic micromanipulation of surrogate biological objects in the presence of a fluid flow. We utilise ferromagnetic microparticles (in the size range of 200 - 350 μm) as microbots and silica beads (having size range of 150 - 350 μm) as surrogate biological objects. The microbot is actuated using magnetic field generated by a set of electromagnetic coils placed in a quadrupole configuration and manipulated using a proportional controller developed for the purpose. We deploy a feedback-based manoeuvre planner that invokes one of the five motion manoeuvres, namely, Arrest, Approach, Align, Push, and Home, based on the instantaneous locations of the microbot, target object, and goal location, for automated nonprehensile manipulation of the target objects. Using this protocol we demonstrate the sorting of surrogate biological objects in a bifurcated fluidic channel. The developed system can be utilised to study the useful properties of large microscopic biological objects in an ambient fluid-flow environment. The demonstrated synergy between microrobotics and microfluidics has tremendous scope for applications in key areas including soft-matter science, cell biology and cancer research. [ABSTRACT FROM AUTHOR]

Abstract Background Since its discovery, somatic hybridization has been used to overcome the sexual barriers between cultivated and wild species. A combination of two somatic cells might provide a novel set of features, often of agronomical importance. Here, we report a successful approach for production and selection of interspecific somatic hybrid plants between cultivated and wild carrot using dual-labelling of protoplasts and an early selection of fused cells via micromanipulator. Both subspecies used in this study are characterised by a very high regenerative ability in protoplast cultures. Thus, a precise and effective method of hybrid selection is essential to assure the development and regeneration of much less numerous heterokaryons in the post-fusion cell mixture. Results Electrofusion parameters, such as alternating current and direct current, were optimised for an efficient alignment of protoplasts and reversible membrane breakdown followed by a cell fusion. Four hundred twenty-nine cells emitting green–red fluorescence, identified as hybrids, were obtained. Co-culture with donor-derived protoplasts in the alginate feeder layer system stimulated re-synthesis of the cell wall and promoted cell divisions of fusants. Somatic embryogenesis occurred in hybrid-derived microcalli cultures, followed by plant regeneration. Regenerated hybrids produced yellowish storage roots and leaves of an intermediate shape between cultivated and wild subspecies. The intron length polymorphism analysis revealed that 123 of 124 regenerated plants were hybrids. Conclusions The developed protocol for protoplast fusion and an early selection of hybrids may serve as an alternative to combining genomes and transferring nuclear or cytoplasmatic traits from wild Daucus species to cultivated carrot.

ATP synthases are proteins that catalyse the formation of ATP through the rotatory movement of their membrane‐spanning subunit. In mitochondria, ATP synthases are found to arrange as dimers at the high‐curved edges of cristae. Here, a direct link is explored between the rotatory movement of ATP synthases and their preference for curved membranes. An active curvature sorting of ATP synthases in lipid nanotubes pulled from giant vesicles is found. Coarse‐grained simulations confirm the curvature‐seeking behaviour of rotating ATP synthases, promoting reversible and frequent protein‐protein contacts. The formation of transient protein dimers relies on the membrane‐mediated attractive interaction of the order of 1.5 kBT produced by a hydrophobic mismatch upon protein rotation. Transient dimers are sustained by a conic‐like arrangement characterized by a wedge angle of θ ≈ 50°, producing a dynamic coupling between protein shape and membrane curvature. The results suggest a new role of the rotational movement of ATP synthases for their dynamic self‐assembly in biological membranes. [ABSTRACT FROM AUTHOR]

A distinct particle focusing spot occurs in the center of a rotating fluid, presenting an apparent paradox given the presence of particle inertia. It is recognized, however, that the presence of a secondary flow with a radial component drives this particle aggregation. In this study, we expand on the examination of this "Thomson–Einstein's tea leaf paradox" phenomenon, where we use a combined experimental and computational approach to investigate particle aggregation dynamics. We show that not only the rotational velocity, but also the vessel shape, have a significant influence on a particle's equilibrium position. We accordingly demonstrate the formation of a single focusing spot in a vessel center, as has been conclusively demonstrated elsewhere, but also the repeatable formation of stable ring-shaped particle arrangements. [ABSTRACT FROM AUTHOR]

Background: Since its discovery, somatic hybridization has been used to overcome the sexual barriers between cultivated and wild species. A combination of two somatic cells might provide a novel set of features, often of agronomical importance. Here, we report a successful approach for production and selection of interspecific somatic hybrid plants between cultivated and wild carrot using dual-labelling of protoplasts and an early selection of fused cells via micromanipulator. Both subspecies used in this study are characterised by a very high regenerative ability in protoplast cultures. Thus, a precise and effective method of hybrid selection is essential to assure the development and regeneration of much less numerous heterokaryons in the post-fusion cell mixture. Results: Electrofusion parameters, such as alternating current and direct current, were optimised for an efficient alignment of protoplasts and reversible membrane breakdown followed by a cell fusion. Four hundred twenty-nine cells emitting green–red fluorescence, identified as hybrids, were obtained. Co-culture with donor-derived protoplasts in the alginate feeder layer system stimulated re-synthesis of the cell wall and promoted cell divisions of fusants. Somatic embryogenesis occurred in hybrid-derived microcalli cultures, followed by plant regeneration. Regenerated hybrids produced yellowish storage roots and leaves of an intermediate shape between cultivated and wild subspecies. The intron length polymorphism analysis revealed that 123 of 124 regenerated plants were hybrids. Conclusions: The developed protocol for protoplast fusion and an early selection of hybrids may serve as an alternative to combining genomes and transferring nuclear or cytoplasmatic traits from wild Daucus species to cultivated carrot. [ABSTRACT FROM AUTHOR]

This article discusses the potential applications of robotic micropositioning systems in applications ranging from industry to research. The demand for micropositioning systems is increasing due to the rapid development of the technology and its wide range of applications. This paper describes a general-purpose microobject manipulation platform consisting of a microtool control system and a microobject detection/recognition system. The development of the manipulation tool is discussed, and experimental studies on micropositioning are carried out. The workflow, accuracy, repeatability, and resonant frequencies of the system are the most important precision characteristics required for the design of the manipulation system under development. The paper concludes with the results of the investigations and the technical characteristics of the microobject manipulation platform. [ABSTRACT FROM AUTHOR]

Abstract ATP synthases are proteins that catalyse the formation of ATP through the rotatory movement of their membrane‐spanning subunit. In mitochondria, ATP synthases are found to arrange as dimers at the high‐curved edges of cristae. Here, a direct link is explored between the rotatory movement of ATP synthases and their preference for curved membranes. An active curvature sorting of ATP synthases in lipid nanotubes pulled from giant vesicles is found. Coarse‐grained simulations confirm the curvature‐seeking behaviour of rotating ATP synthases, promoting reversible and frequent protein‐protein contacts. The formation of transient protein dimers relies on the membrane‐mediated attractive interaction of the order of 1.5 kBT produced by a hydrophobic mismatch upon protein rotation. Transient dimers are sustained by a conic‐like arrangement characterized by a wedge angle of θ ≈ 50°, producing a dynamic coupling between protein shape and membrane curvature. The results suggest a new role of the rotational movement of ATP synthases for their dynamic self‐assembly in biological membranes.

Acoustic holography offers the ability to generate designed acoustic fields to manipulate microscale objects. However, the static nature or large aperture sizes of 3D printed acoustic holographic phase plates limits the ability to rapidly alter generated fields. In this work， a programmable acoustic holography approach is demonstrated by which multiple discrete or continuously variable acoustic targets can be created. Here, the holographic phase plate encodes multiple images, where the desired field is produced by modifying the sound speed of an intervening fluid media. Its flexibility is demonstrated in generating various acoustic patterns, including continuous line segments, discrete letters and numbers, using this method as a sound speed indicator and fluid identification tool. This programmable acoustic holography approach has the advantages of generating reconfigurable and designed acoustic fields, with broad potential in microfluidics, cell/tissue engineering, real‐time sensing, and medical ultrasound. [ABSTRACT FROM AUTHOR]

The mechanical properties of yeast play an important role in many biological processes, such as cell division and growth, maintenance of internal pressure, and biofilm formation. In addition, the mechanical properties of cells can indicate the degree of damage caused by antifungal drugs, as the mechanical parameters of healthy and damaged cells are different. Over the past decades, atomic force microscopy (AFM) and micromanipulation have become the most widely used methods for evaluating the mechanical characteristics of microorganisms. In this case, the reliability of such an estimate depends on the choice of mathematical model. This review presents various analytical models developed in recent years for studying the mechanical properties of both cells and their individual structures. The main provisions of the applied approaches are described along with their limitations and advantages. Attention is paid to the innovative method of low-invasive nanomechanical mapping with scanning ion-conductance microscopy (SICM), which is currently starting to be successfully used in the discovery of novel drugs acting on the yeast cell wall and plasma membrane. [ABSTRACT FROM AUTHOR]

The revolutionary economic potential of micro and nanotechnology is already recognized. Micro and nano-scale technologies that use electrical, magnetic, optical, mechanical, and thermal phenomena separately or in combination are either already in the industrial phase or approaching it. The products of micro and nanotechnology are made of small quantities of material but have high functionality and added value. This paper presents such a product: a system with micro-tweezers for biomedical applications—a micromanipulator with optimized constructive characteristics, including optimal centering, consumption, and minimum size, for handling micro-particles and constructive micro components. The advantage of the proposed structure consists mainly in obtaining a large working area combined with a good working resolution due to the double actuation principle: electromagnetic and piezoelectric. [ABSTRACT FROM AUTHOR]

In the realm of automatic wire-traction micromanipulation systems, the alignment of the central axis of the coil with the rotation axis of the rotary stage can be a challenge, which leads to the occurrence of eccentricity during rotation. The wire-traction is conducted at a micron-level of manipulation precision on micron electrode wires; eccentricity has a significant impact on the control accuracy of the system. To resolve the problem, a method for measuring and correcting the coil eccentricity is proposed in this paper. First, models of radial and tilt eccentricity are established respectively based on the eccentricity sources. Then, measuring eccentricity is proposed by an eccentricity model and microscopic vision; the model is used to predict eccentricity, and visual image processing algorithms are used to calibrate model parameters. In addition, a correction based on the compensation model and hardware is designed to compensate for the eccentricity. The experimental results demonstrate the accuracy of the models in predicting eccentricity and the effectiveness of correction. The results show that the models have an accurate prediction for eccentricity that relies on the evaluation of the root mean square error (RMSE); the maximal residual error after correction was within 6 μm, and the compensation was approximately 99.6%. The proposed method, which combines the eccentricity model and microvision for measuring and correcting eccentricity, offers improved wire-traction micromanipulation accuracy, enhanced efficiency, and an integrated system. It has more suitable and wider applications in the field of micromanipulation and microassembly. [ABSTRACT FROM AUTHOR]

Despite many studies in humans and mice using genome transfer (GT), there are few reports using this technique in oocytes of wild or domestic animals. Therefore, we aimed to establish a GT technique in bovine oocytes using the metaphase plate (MP) and polar body (PB) as the sources of genetic material. In the first experiment, GT was established using MP (GT-MP), and a sperm concentration of 1 × 106 or 0.5 × 106 spermatozoa/ml gave similar fertilization rates. The cleavage rate (50%) and blastocyst rate (13.6%) in the GT-MP group was lower than that of the in vitro production control group (80.2% and 32.6%, respectively). The second experiment evaluated the same parameters using PB instead of MP; the GT-PB group had lower fertilization (82.3% vs. 96.2%) and blastocyst (7.7% vs. 36.8%) rates than the control group. No differences in the amount of mitochondrial DNA (mtDNA) were observed between groups. Finally, GT-MP was performed using vitrified oocytes (GT-MPV) as a source of genetic material. The cleavage rate of the GT-MPV group (68.4%) was similar to that of the vitrified oocytes (VIT) control group (70.0%) and to that of the control IVP group (81.25%, P < 0.05). The blastocyst rate of GT-MPV (15.7) did not differ neither from the VIT control group (5.0%) nor from the IVP control group (35.7%). The results suggested that the structures reconstructed by the GT-MPV and GT-PB technique develop in embryos even if vitrified oocytes are used. [ABSTRACT FROM AUTHOR]

The manufacturing and testing methods of an acoustic manipulated microfluidic chip are introduced in this study. The basic structure of the rigid microfluidic chip is designed based on the working principle and functional requirements of the acoustic microfluidic chip. The open boundary microchannel made of polymethyl methacrylate (PMMA) is fabricated by laser cutting. The machining of microchannel with closed boundary is realized by computerized numerical control (CNC) fine carving method. The rigid microchannel and substrate are bonded at room temperature by photocuring ultra violet (UV) adhesive. Pumpless injection of fluid is enabled by using surface modification technology and capillary action. The influence of different manufacturing technology and parameters on the micro-channel morphology is investigated. According to the requirements of the acoustically controlled microparticles, the working frequency of the acoustic platform is selected by comprehensive simulation analysis, impedance test, and doppler laser vibration measurement. This kind of microfluidic chip has the advantages of low cost, high processing efficiency, and ease-to-use to meet the needs in diverse applications of micro/ nano assembly, micro/nano-manufacturing, and biochemical detection, etc. [ABSTRACT FROM AUTHOR]

In several cases, it is desirable to have prototypes of low-cost fabrication and adequate performance. In academic laboratories and industries, miniature and microgrippers can be very useful for observations and the analysis of small objects. Piezoelectrically actuated microgrippers, commonly fabricated with aluminum, and with micrometer stroke or displacement, have been considered as Microelectromechanical Systems (MEMS). Recently, additive manufacture using several polymers has also been used for the fabrication of miniature grippers. This work focuses on the design of a piezoelectric-driven miniature gripper, additive manufactured with polylactic acid (PLA), which was modeled using a pseudo rigid body model (PRBM). It was also numerically and experimentally characterized with an acceptable level of approximation. The piezoelectric stack is composed of widely available buzzers. The aperture between the jaws allows it to hold objects with diameters lower than 500 μm, and weights lower than 1.4 g, such as the strands of some plants, salt grains, metal wires, etc. The novelty of this work is given by the miniature gripper's simple design, as well as the low-cost of the materials and the fabrication process used. In addition, the initial aperture of the jaws can be adjusted, by adhering the metal tips in the required position. [ABSTRACT FROM AUTHOR]

Microneedles, including dissolvable ones made from biocompatible and biodegradable materials, have been widely studied and can potentially be used for transdermal drug delivery, disease diagnosis (sampling), skin care, etc. Characterizing their mechanical properties is essential, as being mechanically strong enough to pierce the skin barrier is one of the most fundamental and crucial requirements for them. The micromanipulation technique was based on compressing single microparticles between two flat surfaces to obtain force and displacement data simultaneously. Two mathematical models had already been developed to calculate the rupture stress and apparent Young's modulus, which can identify variations of these parameters in single microneedles within a microneedle patch. In this study, a new model has been developed to determine the viscoelasticity of single microneedles made of hyaluronic acid (HA) with a molecular weight of 300 kDa loaded with lidocaine by using the micromanipulation technique to gather experimental data. The modelling results from the micromanipulation measurements suggest that the microneedles were viscoelastic and their mechanical behaviour was strain-rate dependent, which implies that the penetration efficiency of viscoelastic microneedles can be improved by increasing their piercing speed into the skin. [ABSTRACT FROM AUTHOR]

Abstract Acoustic holography offers the ability to generate designed acoustic fields to manipulate microscale objects. However, the static nature or large aperture sizes of 3D printed acoustic holographic phase plates limits the ability to rapidly alter generated fields. In this work， a programmable acoustic holography approach is demonstrated by which multiple discrete or continuously variable acoustic targets can be created. Here, the holographic phase plate encodes multiple images, where the desired field is produced by modifying the sound speed of an intervening fluid media. Its flexibility is demonstrated in generating various acoustic patterns, including continuous line segments, discrete letters and numbers, using this method as a sound speed indicator and fluid identification tool. This programmable acoustic holography approach has the advantages of generating reconfigurable and designed acoustic fields, with broad potential in microfluidics, cell/tissue engineering, real‐time sensing, and medical ultrasound.

In the past few decades, researchers have conducted extensive studies on cell micromanipulation methods. However, there has consistently been a lack of a micromanipulation system that excels in both precision and speed. Additionally, many of these methods rely on manual control, thus significantly reducing efficiency. In this paper, a robotized micromanipulation system employing a two-finger microhand is proposed. The microhand has a 3-DoF parallel mechanism driven by three piezoelectric actuators, enabling high-precision micromanipulation. Replacing the needle-tip end-effector with a hemispherical end-effector makes cell grasping easier and more stable. In addition, a vibration-based release method combined with gel coating is proposed to reduce the release difficulty caused by adhesion forces. Through multiple sets of experiments, we have determined the optimal grasping and releasing conditions while balancing precision, stability, and damage degree to cells. An automated cell assembly strategy based on microscopic visual feedback and pick-and-place path planning is proposed to achieve the robotized high-speed cell array. Hela cells were chosen as the operation objects, achieving a 95% success rate in grasping and a 97% success rate in releasing. A “T” letter array formed by cells was successfully assembled with an average grasp and release time of less than 0.8 s and an assembly accuracy of 4.5 μm for a single cell. This study holds significant implications for the fields of biology and medicine, presenting potential applications in tissue engineering.

The photoinduced crawling motion of crystals is a continuous motion that azobenzene molecular crystals exhibit under light irradiation. Such motion enables object manipulation at the microscale with a simple setup of fixed LED light sources. Transportation of nano-/micromaterials using photoinduced crawling motion has recently been reported. However, the details of the motion mechanism have not been revealed so far. Herein, we report visualization of the dynamics of fine particles in 4-(methylamino)azobenzene (4-MAAB) crystals under light irradiation via diffracted X-ray tracking (DXT). Continuously repeated melting and recrystallization of 4-MAAB crystals under light irradiation results in the flow of liquid 4-MAAB. Zinc oxide (ZnO) particles were introduced inside the 4-MAAB crystals to detect diffracted X-rays. The ZnO particles rotate with the flow of liquid 4-MAAB. By using white X-rays with a wide energy width, the rotation of each zinc oxide nanoparticle was detected as the movement of a bright spot in the X-ray diffraction pattern. It was clearly shown that the ZnO particles rotated increasingly as the irradiation light intensity increased. Furthermore, we also found anisotropy in the rotational direction of ZnO particles that occurred during the crawling motion of 4-MAAB crystals. It has become clear that the flow perpendicular to the supporting film of 4-MAAB crystals is enhanced inside the crystal during the crawling motion. DXT provides a unique means to elucidate the mechanism of photoinduced crawling motion of crystals.

Multifunctional magnetic nanoparticles have shown great promise as next-generation imaging and perturbation probes for deciphering molecular and cellular processes. As a consequence of multicomponent integration into a single nanosystem, pre-existing nanoprobes are typically large and show limited access to biological targets present in a crowded microenvironment. Here, we apply organic-phase surface PEGylation, click chemistry, and charge-based valency discrimination principles to develop compact, modular, and monovalent magnetofluorescent nanoparticles (MFNs). We show that MFNs exhibit highly efficient labeling to target receptors present in cells with a dense and thick glycocalyx layer. We use these MFNs to interrogate the E-cadherin-mediated adherens junction formation and F-actin polymerization in a three-dimensional space, demonstrating the utility as modular and versatile mechanogenetic probes in the most demanding single-cell perturbation applications.

Abstract The use of intracytoplasmic sperm injection (ICSI), an assisted reproductive technique (ART), is increasing widely. ICSI is currently performed by specially skilled embryologists. However, with the increasing demand for ART, the shortage of skilled embryologists has become a problem. Therefore, we propose an immersive micromanipulation system that requires no special skills for efficient and accurate micromanipulation. Our proposed system is composed of a real-time three-dimensional (3D) imaging microscope and 3D operation interfaces. The 3D operation interfaces are stationary pen-type or wearable glove-type interfaces. In this system, an operator wearing a head-mounted display (HMD) and using 3D operation interfaces is immersed in a virtual micromanipulation space. The operator can move the pipettes by 3D operation interface and freely change the viewpoint. We verified that the proposed system improves the speed and accuracy of operating a pipette through two types of experiments with subjects.

Purpose: To determine if deep learning artificial intelligence algorithms can be used to accurately identify key morphologic landmarks on oocytes and cleavage stage embryo images for micromanipulation procedures such as intracytoplasmic sperm injection (ICSI) or assisted hatching (AH). Methods: Two convolutional neural network (CNN) models were trained, validated, and tested over three replicates to identify key morphologic landmarks used to guide embryologists when performing micromanipulation procedures. The first model (CNN-ICSI) was trained (n = 13,992), validated (n = 1920), and tested (n = 3900) to identify the optimal location for ICSI through polar body identification. The second model (CNN-AH) was trained (n = 13,908), validated (n = 1908), and tested (n = 3888) to identify the optimal location for AH on the zona pellucida that maximizes distance from healthy blastomeres. Results: The CNN-ICSI model accurately identified the polar body and corresponding optimal ICSI location with 98.9% accuracy (95% CI 98.5–99.2%) with a receiver operator characteristic (ROC) with micro and macro area under the curves (AUC) of 1. The CNN-AH model accurately identified the optimal AH location with 99.41% accuracy (95% CI 99.11–99.62%) with a ROC with micro and macro AUCs of 1. Conclusion: Deep CNN models demonstrate powerful potential in accurately identifying key landmarks on oocytes and cleavage stage embryos for micromanipulation. These findings are novel, essential stepping stones in the automation of micromanipulation procedures. [ABSTRACT FROM AUTHOR]

This paper presents a typical grasp–hold–release micromanipulation simulator based on MATLAB and Simulink. Closed-loop force and position control were implemented only based on a camera. The work was mainly focused on control performance improvements and GUI design. Different types of control strategies were investigated in both the position and force control processes. Finally, incremental PID and positional PID were adopted in the gripper position control and force control processes, respectively. The best performance of the gripper position control was the fast response of 0.3 s without overshoot and steady-state errors in the range of 10–40 Hz. The new camera control algorithm kept a big motion range (4.48 × 4.48 mm) and a high position resolution of 0.56 µm, with a high force resolution of 1.56 µN in the force control stage. The maximum error between the measured force and the real force was maintained below 4 µN. The steady-state error and the setting time were less than 1.2% and less than 1.5 s, respectively. A separate app, the Image Generation Simulator app, was developed to assist users in getting suitable initial coordinates, camera parameters, desired position resolutions, and force resolutions, which are packed as a standalone executable file. The main app can run the simulation model, debug, playback, and report simulation results, and calculate the calibration equation. Different initial coordinates, camera parameters, sample frequencies, controller parameters, and even controller types can be adjusted from this app. [ABSTRACT FROM AUTHOR]

The motion of liquid droplets is studied across many physics subfields and manipulation of nanoscale droplets on demand holds great promise in, e.g., nanotechnology. In this study, AuGe droplets on a germanium substrate are manipulated by an electron beam in a scanning electron microscope. The electron beam exposure creates a local temperature gradient in a substrate and induces a directional thermomigration of droplets nearby. To quantitatively analyse this phenomenon and to reveal the mechanism behind it, experimental observations under different conditions (beam current, sample temperature, scanning strategy) and simulations are combined. The obtained insights suggest that the droplet motion is limited by the dissolution of the substrate below the droplet. In addition, it is shown that the electron tractor beam is not only able to control the droplet motion but can also be used to split the droplets, thus opening new possibilities for droplet manipulation inside an SEM. [ABSTRACT FROM AUTHOR]

Micromanipulation is a powerful technique to measure the mechanical properties of microparticles including microcapsules. For microparticles with a homogenous structure, their apparent Young's modulus can be determined from the force versus displacement data fitted by the classical Hertz model. Microcapsules can consist of a liquid core surrounded by a solid shell. Two Young's modulus values can be defined, i.e., the one is that determined using the Hertz model and another is the intrinsic Young's modulus of the shell material, which can be calculated from finite element analysis (FEA). In this study, the two Young's modulus values of microplastic-free plant-based microcapsules with a core of perfume oil (hexyl salicylate) were calculated using the aforementioned approaches. The apparent Young's modulus value of the whole microcapsules determined by the classical Hertz model was found to be EA = 0.095 ± 0.014 GPa by treating each individual microcapsule as a homogeneous solid spherical particle. The previously obtained simulation results from FEA were utilised to fit the micromanipulation data of individual core–shell microcapsules, enabling to determine their unique shell thickness to radius ratio (h/r)FEA = 0.132 ± 0.009 and the intrinsic Young's modulus of their shell (EFEA = 1.02 ± 0.13 GPa). Moreover, a novel theoretical relationship between the two Young's modulus values has been derived. It is found that the ratio of the two Young's module values (EA/EFEA) is only a function on the ratio of the shell thickness to radius (h/r) of the individual microcapsule, which can be fitted by a third-degree polynomial function of h/r. Such relationship has proven applicable to a broad spectrum of microcapsules (i.e., non-synthetic, synthetic, and double coated shells) regardless of their shell chemistry. [ABSTRACT FROM AUTHOR]

Summary: Primordial germ cells transplantation is a unique approach for conservation and reconstitution of endangered fish species. This study aimed to establish techniques to culture dechorionated embryos in different incubation systems and also to determine anaesthetic concentration for fish recipients in the larval stage for subsequent primordial germ cell transplantation. Intact and dechorionated embryos were divided into three incubation systems: (1) a control group with manual replacement of the solution; (2) a closed environment with high oxygen with manual replacement of the solution; and (3) constant solution recirculation. This combination resulted in six treatments. For the evaluation of anaesthetics for larvae, the concentrations evaluated were 19.5 mM, 24.4 mM, 29.3 mM, and 34.2 mM of 2-phenoxyethanol. Anaesthesia concentration and recovery at different stages were evaluated. For transplantation, primordial germ cells of Astyanax altiparanae were transplanted into anaesthetised larvae (1 dph) of Prochilodus lineatus. Better results were obtained in the recirculation system for dechorionated embryos of P. lineatus for hatching (54.18%) and normal morphology (50.06%). The 2-phenoxyethanol anaesthetic with a dose of 29.3 mM resulted in shorter induction times, in addition to the recovery time between 5 and 10 min. By using this anaesthetic concentration at transplantation, GFP-positive cells were seen in two recipients, but the cells did not proliferate. This study established an effective incubation system for the development of the dechorionated embryo and determined an effective anaesthetic concentration for P. lineatus larvae. In addition, micromanipulation and transplantation of primordial germ cells in neotropical species were conducted for the first time. [ABSTRACT FROM AUTHOR]

Microcomponent manipulation (MCM) technology plays a decisive role in assembling complex systems at the micro- and nanoscale. However, the existing micromanipulation methods are difficult to widely apply in the manufacturing of microelectromechanical systems (MEMSs) due to the limited manipulation space and complex application objects, and the manipulation efficiency is relatively low, which makes it difficult to industrialize these micromanipulating systems. To solve the above problems, this paper proposes an efficient metal MCM strategy based on the electrochemical method. To verify the feasibility and repeatability of the strategy, the finite element model (FEM) incorporating the hydrodynamic and electrochemical theories is used to calculate the local stress distribution of the contact position during the dynamic pick-up process. Based on the simulation results, we defined the relationship between the parameters, such as the optimal manipulating position and angle for picking, transferring and releasing. The failure behaviors of pick-up are built to realize the efficient three-dimensional manipulation of microcopper wire of 300 μm. By establishing a theoretical model and experimental verification, it was concluded that the middle point was the best manipulating position when picking up the microcopper wire, the most efficient picking angle was between 45 and 60 degrees for the pipette, and the average time was 480 s in three sets of picking–release manipulation experiments. This paper provides an achievable idea for different types of micro-object manipulations and promotes the rapid application of micromanipulation techniques in MEMSs. [ABSTRACT FROM AUTHOR]

Cell rotation is one of the most important techniques for cell manipulation in modern bioscience, as it not only permits cell observation from any arbitrary angle, but also simplifies the procedures for analyzing the mechanical properties of cells, characterizing cell physiology, and performing microsurgery. Numerous approaches have been reported for rotating cells in a wide range of academic and industrial applications. Among them, the most popular are micro-robot-based direct contact manipulation and field-based non-contact methods (e.g., optical, magnetic, electric, acoustic, and hydrodynamic methods). This review first summarizes the fundamental mechanisms, merits, and demerits of these six main groups of approaches, and then discusses their differences and limitations in detail. We aim to bridge the gap between each method and illustrate the development progress, current advances, and prospects in the field of cell rotation.

A distinct particle focusing spot occurs in the center of a rotating fluid, presenting an apparent paradox given the presence of particle inertia. It is recognized, however, that the presence of a secondary flow with a radial component drives this particle aggregation. In this study, we expand on the examination of this “Thomson–Einstein’s tea leaf paradox” phenomenon, where we use a combined experimental and computational approach to investigate particle aggregation dynamics. We show that not only the rotational velocity, but also the vessel shape, have a significant influence on a particle’s equilibrium position. We accordingly demonstrate the formation of a single focusing spot in a vessel center, as has been conclusively demonstrated elsewhere, but also the repeatable formation of stable ring-shaped particle arrangements.

Abstract A light-driven gel actuator is a potential candidate for a single-cell manipulation tool because it allows cells to be manipulated while ensuring less damage. Moreover, a large number of actuators can be integrated into a microfluidic chip because no wiring is required. Previously, we proposed a method for cell manipulation using light-driven gel actuators. However, the system used in the previous work did not allow the targeted cells to be manipulated in real time because the system used in the previous work could only irradiate preprogrammed patterned light. Moreover, when a large number of gel actuators are integrated into a chip, the Gaussian distribution of the laser light source results in the response characteristics of the gel actuators varying with the location of the actuator. In this work, we constructed a system that homogenized the intensity of the patterned light used for irradiation, allowing multiple gel actuators to be driven in parallel in real time. The intensity-homogenized patterned light improved the variations in the response characteristics of the gel actuators, and as a result, we succeeded in actuating gel actuators with various light patterns in real time.

Abstract The motion of liquid droplets is studied across many physics subfields and manipulation of nanoscale droplets on demand holds great promise in, e.g., nanotechnology. In this study, AuGe droplets on a germanium substrate are manipulated by an electron beam in a scanning electron microscope. The electron beam exposure creates a local temperature gradient in a substrate and induces a directional thermomigration of droplets nearby. To quantitatively analyse this phenomenon and to reveal the mechanism behind it, experimental observations under different conditions (beam current, sample temperature, scanning strategy) and simulations are combined. The obtained insights suggest that the droplet motion is limited by the dissolution of the substrate below the droplet. In addition, it is shown that the electron tractor beam is not only able to control the droplet motion but can also be used to split the droplets, thus opening new possibilities for droplet manipulation inside an SEM.

Volumetric imaging tools that are simple to adopt, flexible, and robust are in high demand in the field of neuroscience, where the ability to image neurons and their networks with high spatiotemporal resolution is essential. Using an axially elongated focus approximating a Bessel beam, in combination with two-photon fluorescence microscopy, has proven successful at such an endeavor. Here, we demonstrate three-photon fluorescence imaging with an axially extended Bessel focus. We use an axicon-based module that allowed for the generation of Bessel foci of varying numerical apertures and axial lengths, and apply this volumetric imaging tool to image mouse brain slices and for in vivo imaging of the mouse brain.

The use of model organisms is important for basic and applied sciences. Several laboratory species of fishes are used to develop advanced technologies, such as the zebrafish (Danio rerio), the medaka (Oryzias latipes), and loach species (Misgurnus spp.). However, the application of these exotic species in the Neotropical region is limited due to differences in environmental conditions and phylogenetic distances. This situation emphasizes the establishment of a model organism specifically for the Neotropical region with the development of techniques that may be applicable to other Neotropical fish species. In this work, the previous research efforts are described in order to establish the yellowtail tetra Astyanax altiparanae as a model laboratory species for both laboratory and aquaculture purposes. Over the last decade, starting with artificial fertilization, the yellowtail tetra has become a laboratory organism for advanced biotechnology, such as germ cell transplantation, chromosome set manipulation, and other technologies, with applications in aquaculture and conservation of genetic resources. Nowadays, the yellowtail tetra is considered the most advanced fish with respect to fish biotechnology within the Neotropical region. The techniques developed for this species are being used in other related species, especially within the characins class. [ABSTRACT FROM AUTHOR]

Fast-moving consumer goods (FMCG) industry has long included many appealing essential oils in products to meet consumers' needs. Among all, the demand for limonene (LM) has recently surged due to its broad-spectrum health benefits, with applications in cosmetic, detergent, and food products. However, LM is extremely volatile, hence has often been encapsulated for a longer shelf-life. To date, mostly non-biodegradable synthetic polymers have been exploited to fabricate the microcapsule shells, and the resulting microcapsules contribute to the accumulation of microplastic in the environment. So far, information on LM-entrapping microcapsules with a natural microplastic-free shell and their mechanism of formation is limited, and there is lack of an in-depth characterisation of their mechanical and adhesive properties, which are crucial for understanding their potential performance at end-use applications. The present research aims towards developing safe microcapsules with a core of LM fabricated via complex coacervation (CC) using gum Arabic (GA) and fungally sourced chitosan (fCh) as shell precursors. The encapsulation efficiency (EE) for LM was quantified by gas chromatography (GC) separation method. The morphology of microcapsules was investigated via bright-field optical microscopy and scanning electron microscopy, and their mechanical properties were characterised using a micromanipulation technique. Moreover, the adhesive properties of the resulting microcapsules were studied via a bespoke microfluidic device fitted with a polyethylene-terephthalate (PET) substrate and operating at increasingly hydrodynamic shear stress (HSS). Spherical core-shell microcapsules (EE ~45%) with a mean size of 38 ± 2 μm and a relatively smooth surface were obtained. Their mean rupture force and nominal rupture stress were 0.9 ± 0.1 mN and 2.1 ± 0.2 MPa, respectively, which are comparable to those of other microcapsules with synthetic shells, e.g., urea- and melamine-formaldehyde. It was also found that the fCh-GA complexed shell provided promising adhesive properties onto PET films, leading to a microcapsule retention of ~85% and ~60% at low (≤50 mPa) and high shear stress (0.9 Pa), respectively. Interestingly, these values are similar to the adhesion data available in literature for microplastic-based microcapsules, such as melamine-formaldehyde (50–90%). Overall, these findings suggest that microplastics-free microcapsules with a core of oil have been successfully fabricated, and can offer a potential for more sustainable, consumer- and environmentally friendly applications in FMCGs. [ABSTRACT FROM AUTHOR]

There is a growing trend for beers with novel flavor profiles, as consumers demand a more diversified product range. Such beers can be produced by using non-Saccharomyces yeasts. The yeast species Saccharomycopsis fibuligera is known to produce exceptionally pleasant plum and berry flavors during brewer’s wort fermentation while its mycelia growth is most likely a technological challenge in industrial-scale brewing. To better understand and optimize the physiological properties of this yeast species during the brewing process, maltose and maltotriose uptake activity trials were performed. These revealed the existence of active transmembrane transporters for maltose in addition to the known extracellular amylase system. Furthermore, a single cell isolate of S. fibuligera was cultured, which showed significantly less mycelial growth during propagation and fermentation compared to the mother culture and would therefore be much more suitable for application on an industrial scale due to its better flocculation and clarification properties. Genetic differences between the two cultures could not be detected in a (GTG)5 rep-PCR fingerprint and there was hardly any difference in the fermentation process, sugar utilization and flavor profiles of the beers. Accordingly, the characteristic plum and berry flavor could also be perceived by using the culture from the single cell isolate, which was complemented by a dried fruit flavor. A fermentation temperature of 20°C at an original gravity of 10 °P proved to be optimal for producing a low-alcohol beer at around 0.8% (v/v) by applying the S. fibuligera yeast culture from the single cell isolate. [ABSTRACT FROM AUTHOR]

Electromagnetic actuation systems (EMA) have excelled themselves in microscale manipulation. Yet, the fastened structure of the current systems tethers the controlled workspace. In this paper, a new electromagnetic actuation principle is investigated. The actuator structure consists of a pair of coaxially movable electromagnets integrated to a robotic manipulator. The pair induces a coaxial homogeneous magnetic field or gradient to control the magnitude of the magnetic torque or force by changing the distance between the electromagnets asymmetrically. The robotic manipulator, on the other hand, transports the pair at five degrees of freedom to manipulate a microrobot in 3D space by closed-loop control with integrated vision feedback system. Numerical analyses are performed to investigate the induced electromagnetic field at the symmetrical/asymmetrical configuration of the coaxial pair. Accordingly, a correlation between the magnitude of the magnetic force and the asymmetric distance is obtained for flexible force control. A proof of concept prototype is constructed to validate the proposed actuation principle and evaluate its performance experimentally. The experimental results verify the numerical analysis and show the system applicability of inducing controlled forces on a micro-object in 2D and 3D workspaces at a velocity range of 65 to 157 $\mu$ m/s. Moreover, micromanipulation on a helical route is also demonstrated with an absolute error mean from the reference path of 191 $\mu$ m. [ABSTRACT FROM AUTHOR]

The remarkable properties of liquid crystal elastomers (LCE) for spatially controlled actuation are utilized to perform complex tasks such as to mimic versatile motion of living organisms and cilia in soft robotics. As opposed to the common out‐of‐plane bending in flat LCE films, many planar micro‐electro‐mechanical and microfluidic systems typically operate based on the lateral movement of the functional parts. The challenge of implementing the in‐plane bending of LCE actuators is often associated with the limited capability for miniaturization of the existing techniques, along with the requirement for post‐fabrication assembly. In this paper a method for fabrication of thermally actuated LCE beams for in‐plane bending applications, which is based on direct laser writing and micromolding is reported. Mesogenic alignment is modified near the sidewalls of the channel structures patterned with vertical microgrooves. The method allows monolithic fabrication of LCE‐based microgrippers for micromanipulation and microassembly applications in life sciences and in manufacture of microsystems. It is shown that the photothermally driven microgrippers can perform soft grasping of micro‐objects, providing large gripping strokes with relatively low actuation stimuli. The fabrication method offers more design opportunities for LCE‐based microactuators and a useful route toward realization of gripping and cargo transportation functionality in microrobotics. [ABSTRACT FROM AUTHOR]