Optical Upconversion in Mononuclear Lanthanide Co-Crystal Assemblies.

In this work, we developed two kinds of co-crystal assemblies systems, consisting of discrete mononuclear Yb3+ and Er3+ and mononuclear Yb3+ and Pr3+, which can achieve Er3+ and Pr3+ upconversion luminescence, respectively, by Yb3+ sensitization under 980 nm excitation. The structure and composition of two co-crystal assemblies were determined by single crystal X-ray diffraction. By investigation of the series of two assemblies, respectively, it is found that the strongest upconversion luminescence is both obtained when the molar ratio of Yb3+ and Ln3+ (Ln=Er or Pr) is 1 : 1. The energy transfer mechanism of Er3+ assemblies is determined as energy transfer upconversion, while that of Pr3+ assemblies is determined as energy transfer upconversion and cooperative sensitization upconversion. This is the first example of Pr3+ upconversion luminescence at the molecular dimension at room temperature, which enriches the research in the field of upconversion luminescence with lanthanide complexes.

Novel miniature transendoscopic telerobotic system for endoscopic submucosal dissection (with videos).

BACKGROUND AND AIMS: The lack of tissue traction and instrument dexterity to allow for adequate visualization and effective dissection were the main issues in performing endoscopic submucosal dissection (ESD). Robot-assisted systems may provide advantages. In this study we developed a novel transendoscopic telerobotic system and evaluated its performance in ESD. METHODS: A miniature dual-arm robotic endoscopic assistant for minimally invasive surgery (DREAMS) was developed. The DREAMS system contained the current smallest robotic ESD instruments and was compatible with the commercially available dual-channel endoscope. After the system was established, a prospective randomized controlled study was conducted to validate the performance of the DREAMS-assisted ESD in terms of efficacy, safety, and workload by comparing it with the conventional technique. RESULTS: Two robotic instruments can achieve safe collaboration and provide sufficient visualization and efficient dissection during ESD. Forty ESDs in the stomach and esophagus of 8 pigs were completed by DREAMS-assisted ESD or conventional ESD. Submucosal dissection time was comparable between the 2 techniques, but DREAMS-assisted ESD demonstrated a significantly lower muscular injury rate (15% vs 50%, P = .018) and workload scores (22.30 vs 32.45, P < .001). In the subgroup analysis of esophageal ESD, DREAMS-assisted ESD showed significantly improved submucosal dissection time (6.45 vs 16.37 minutes, P = .002), muscular injury rate (25% vs 87.5%, P = .041), and workload (21.13 vs 40.63, P = .001). CONCLUSIONS: We developed a novel transendoscopic telerobotic system, named DREAMS. The safety profile and technical feasibility of ESD were significantly improved with the assistance of the DREAMS system, especially in the narrower esophageal lumen.

Capillary-based, multifunctional manipulation of particles and fluids via focused surface acoustic waves.

Surface acoustic wave (SAW)-enabled acoustofluidic technologies have recently atttracted increasing attention for applications in biology, chemistry, biophysics, and medicine. Most SAW acoustofluidic devices generate acoustic energy which is then transmitted into custom microfabricated polymer-based channels. There are limited studies on delivering this acoustic energy into convenient commercially-available glass tubes for manipulating particles and fluids. Herein, we have constructed a capillary-based SAW acoustofluidic device for multifunctional fluidic and particle manipulation. This device integrates a converging interdigitated transducer to generate focused SAWs on a piezoelectric chip, as well as a glass capillary that transports particles and fluids. To understand the actuation mechanisms underlying this device, we performed finite element simulations by considering piezoelectric, solid mechanic, and pressure acoustic physics. This experimental study shows that the capillary-based SAW acoustofluidic device can perform multiple functions including enriching particles, patterning particles, transporting particles and fluids, as well as generating droplets with controlled sizes. Given the usefulness of these functions, we expect that this acoustofluidic device can be useful in applications such as pharmaceutical manufacturing, biofabrication, and bioanalysis.

Sensitive detection of choline and nicotine in real samples by switching upconversion luminescence.

Nicotine (3-(1-methyl-2-pyrrolidinyl)pyridine) is one of the most common addictive substances, causing the trace detection of nicotine to be very necessary. Herein, we designed and prepared a functionalized nanocomposite CS-PAA (NaYF4:19.5%Yb,0.5%Tm@NaYF4-PAA) using a simple method. The nicotine concentration was quantitatively detected through the inhibition of choline oxidase activity by nicotine and the luminescence intensity of CS-PAA being quenched by Fe3+. The mechanism of Fe3+ quenching CS-PAA emission was inferred by luminescence lifetime and UV-vis absorption spectra characterization. During the nicotine detection, both excitation (980 nm) and emission (802 nm) wavelengths of CS-PAA enable the avoidance of the interference of background fluorescence in complicated food objects, thus providing high selectivity and sensitivity with a linear range of 5-750 ng/mL and a limit of detection of 9.3 nM. The method exhibits an excellent recovery and relative standard deviation, indicating high accuracy and repeatability of the detection of nicotine.

Fish-like magnetic microrobots for microparts transporting at liquid surfaces.

Magnetic microrobots have tremendous potential applications due to their wireless actuation and fast response in confined spaces. Herein, inspired by fish, a magnetic microrobot working at liquid surfaces was proposed in order to transport microparts effectively. Different from other fish-like robots propelled by flexible caudal fins, the microrobot is designed as a simple sheet structure with a streamlined shape. It is fabricated monolithically utilizing polydimethylsiloxane doped with magnetic particles. The unequal thicknesses of different parts of the fish shape enable the microrobot to move faster via a liquid level difference around the body under an oscillating magnetic field. The propulsion mechanism is investigated through theoretical analysis and simulations. The motion performance characteristics are further characterized through experiments. It is interesting to find that the microrobot moves in a head-forward mode when the vertical magnetic field component is upward, whereas it moves in a tail-forward mode when the component is downward. Relying on the modulation of capillary forces, the microrobot is able to capture and deliver microballs along a given path. The maximum transporting speed can reach 1.2 mm s-1, which is about three times the microball diameter per second. It is also found that the transporting speed with the microball is much higher than that of the microrobot alone. The reason for this is that when the micropart and microrobot combine, the increased asymmetry of the liquid surfaces caused by the forward movement of the gravity center can increase the forward driving force. The proposed microrobot and the transporting method are expected to have more applications in micromanipulation fields.

3D actuation of foam-core liquid metal droplets.

Precise manipulation of liquid metal (LM) droplets possesses the potential to enable a wide range of applications in reconfigurable electronics, robotics, and microelectromechanical systems. Although a variety of methods have been explored to actuate LM droplets on a 2D plane, versatile 3D manipulation remains a challenge due to the difficulty in overcoming their heavy weight. Here, foam-core liquid metal (FCLM) droplets that can maintain the surface properties of LM while significantly reducing the density are developed, enabling 3D manipulation in an electrolyte. The FCLM droplet is fabricated by coating LM on the surface of a copper-grafted foam sphere. The actuation of the FCLM droplet is realized by electrically inducing Marangoni flow on the LM surface. Two motion modes of the FCLM droplet are observed and studied and the actuation performance is characterized. Multiple FCLM droplets can be readily controlled to form 3D structures, demonstrating their potential to be further developed to form collaborative robots for enabling wider applications.

Upconversion Luminescence in Mononuclear Yb/Sm Co-crystal Assemblies at Room Temperature.

Metal-based upconversion luminescence transforming high-energy photons into low-energy photons is an attractive anti-Stokes shift process for fundamental research and promising applications. In this work, we developed the upconversion luminescence in co-crystal assemblies consisting of discrete mononuclear Yb and Sm complexes. The characteristic visible emissions of Sm3+ were observed under the excitation of absorption band of Yb3+ at 980 nm. A series of co-crystal assemblies were investigated based on mononuclear Yb and Sm complexes, and the strongest luminescence was obtained when the molar concentration between Yb3+ and Sm3+ is equivalent. The crystal structure was fully characterized by the single crystal X-ray diffraction and upconverting energy transfer mechanisms were verified as cooperative sensitization upconversion and energy transfer upconversion. This is the first example of Sm3+ -based upconverting luminescence in discrete lanthanide complexes which present as co-crystal assemblies at room temperature.

Upconversion Luminescence through Cooperative and Energy-Transfer Mechanisms in Yb3+ -Metal-Organic Frameworks.

Lanthanide-doped metal-organic frameworks (Ln-MOFs) have versatile luminescence properties, however it is challenging to achieve lanthanide-based upconversion luminescence in these materials. Here, 1,3,5-benzenetricarboxylic acid (BTC) and trivalent Yb3+ ions were used to generate crystalline Yb-BTC MOF 1D-microrods with upconversion luminescence under near infrared excitation via cooperative luminescence. Subsequently, the Yb-BTC MOFs were doped with a variety of different lanthanides to evaluate the potential for Yb3+ -based upconversion and energy transfer. Yb-BTC MOFs doped with Er3+ , Ho3+ , Tb3+ , and Eu3+ ions exhibit both the cooperative luminescence from Yb3+ and the characteristic emission bands of these ions under 980 nm irradiation. In contrast, only the 497 nm upconversion emission band from Yb3+ is observed in the MOFs doped with Tm3+ , Pr3+ , Sm3+ , and Dy3+ . The effects of different dopants on the efficiency of cooperative luminescence were established and will provide guidance for the exploitation of Ln-MOFs exhibiting upconversion.

Cooperative Sensitization Upconversion in Solution Dispersions of Co-Crystal Assemblies of Mononuclear Yb3+ and Eu3+ Complexes.

Lanthanide upconversion luminescence in nanoparticles has prompted continuous breakthroughs in information storage, temperature sensing, and biomedical applications, among others. Achieving upconversion luminescence at the molecular scale is still a critical challenge in modern chemistry. In this work, we explored the upconversion luminescence of solution dispersions of co-crystals composed of discrete mononuclear Yb(DBM)3 Bpy and Eu(DBM)3 Bpy complexes (DBM: dibenzoylmethane, Bpy: 2,2'-bipyridine). The 613 nm emission of Eu3+ was observed under excitation of Yb3+ at 980 nm. From the series of molecular assemblies studied, the most intense luminescence was obtained for a 1 : 1 molar ratio of Yb3+ : Eu3+ , resulting in a high quantum yield of 0.67 % at 2.1 W cm-2 . The structure and energy transfer mechanism of the assemblies were fully characterized. This is the first example of an Eu3+ -based upconverting system composed of two discrete mononuclear lanthanide complexes present as co-crystals in non-deuterated solution.

Energy Migration Control of Multimodal Emissions in an Er3+ -Doped Nanostructure for Information Encryption and Deep-Learning Decoding.

Modulating the emission wavelengths of materials has always been a primary focus of fluorescence technology. Nanocrystals (NCs) doped with lanthanide ions with rich energy levels can produce a variety of emissions at different excitation wavelengths. However, the control of multimodal emissions of these ions has remained a challenge. Herein, we present a new composition of Er3+ -based lanthanide NCs with color-switchable output under irradiation with 980, 808, or 1535 nm light for information security. The variation of excitation wavelengths changes the intensity ratio of visible (Vis)/near-infrared (NIR-II) emissions. Taking advantage of the Vis/NIR-II multimodal emissions of NCs and deep learning, we successfully demonstrated the storage and decoding of visible light information in pork tissue.

Autonomous Biohybrid Urchin-Like Microperforator for Intracellular Payload Delivery.

A magnetic urchin-like microswimmer based on sunflower pollen grain (SPG) that can pierce the cancer cell membrane and actively deliver therapeutic drugs is reported. These drug loaded microperforators are fabricated on a large scale by sequentially treating the natural SPGs with acidolysis, sputtering, and vacuum loading. The microswimmers exhibit precise autonomous navigation and obstacle avoidance in complex environments via association with artificial intelligence. Assemblies of microswimmers can further enhance individual motion performance and adaptability to complicated environments. Additionally, the experimental results demonstrate that microswimmers with nanospikes can accomplish single-cell perforation for direct delivery under an external rotating magnetic field. Drugs encapsulated in the inner cavity of the microperforators can be accurately delivered to a specific site via remote control. These dual-action microswimmers demonstrate good biocompatibility, high intelligence, precision in single-cell targeting, and sufficient drug loading, presenting a promising avenue for many varieties of biomedical applications.

Baicalin reverses radioresistance in nasopharyngeal carcinoma by downregulating autophagy.

BACKGROUND: Radiation resistance is the main cause of recurrence after radiotherapy, and increased autophagy after radiotherapy is related to radiotherapy resistance. This study aims to investigate the reversal effect of baicalin on radioresistance and its related mechanism. METHODS: CCK-8 and flow cytometry were used to detect the effect of proliferation and apoptosis by baicalin. Clone formation test was used to verify the effect of baicalin radiosensitization. Western blot analysis and electron microscopy were employed to observe the effect of baicalin on autophagy. RESULTS: Compared with the radiation therapy (RT) group, the RT combined baicalin (RT + BA) group showed a significantly low 2 Gy survival fraction of radiation therapy (P < 0.05). LC3-II protein expression in the RT group was significantly higher than which in the RT + BA group (P < 0.05). Electron microscopy showed that more autophagic vacuoles were observed in the RT group than those in the RT + BA group. CONCLUSIONS: Overall, baicalin can reverse the radioresistance of human nasopharyngeal carcinoma CNE-2R cells by downregulating RT-enhanced autophagy.

Bipedal microwalkers actuated by oscillating magnetic fields.

Microrobots have attracted considerable attention due to their immense potential for biomedical and engineering applications in recent years. Inspired by human walks, a bipedal microwalker capable of standing and walking like humans regulated by external weak magnetic fields was reported in this paper. The walker has a submillimeter size and a simple arrowhead shape. Its standing and walking locomotion is controlled by external oscillating magnetic fields generated by orthogonal electromagnetic coil pairs. The walking speeds of the microwalker are controlled using magnetic fields with varying parameters. The walking speeds on a glass substrate immersed in water could reach up to 2.2 mm s-1. Designed walking paths of the microwalker on a horizontal substrate are also demonstrated. Besides walking on horizontal flat surfaces, the microwalker can climb up slopes and walk freely in circular microtubes. The microwalker is of interest in fundamental robotic gait research and for micromanipulation applications.

Optimization of virtual and real registration technology based on augmented reality in a surgical navigation system.

BACKGROUND: The traditional navigation interface was intended only for two-dimensional observation by doctors; thus, this interface does not display the total spatial information for the lesion area. Surgical navigation systems have become essential tools that enable for doctors to accurately and safely perform complex operations. The image navigation interface is separated from the operating area, and the doctor needs to switch the field of vision between the screen and the patient's lesion area. In this paper, augmented reality (AR) technology was applied to spinal surgery to provide more intuitive information to surgeons. The accuracy of virtual and real registration was improved via research on AR technology. During the operation, the doctor could observe the AR image and the true shape of the internal spine through the skin. METHODS: To improve the accuracy of virtual and real registration, a virtual and real registration technique based on an improved identification method and robot-assisted method was proposed. The experimental method was optimized by using the improved identification method. X-ray images were used to verify the effectiveness of the puncture performed by the robot. RESULTS: The final experimental results show that the average accuracy of the virtual and real registration based on the general identification method was 9.73 ± 0.46 mm (range 8.90-10.23 mm). The average accuracy of the virtual and real registration based on the improved identification method was 3.54 ± 0.13 mm (range 3.36-3.73 mm). Compared with the virtual and real registration based on the general identification method, the accuracy was improved by approximately 65%. The highest accuracy of the virtual and real registration based on the robot-assisted method was 2.39 mm. The accuracy was improved by approximately 28.5% based on the improved identification method. CONCLUSION: The experimental results show that the two optimized methods are highly very effective. The proposed AR navigation system has high accuracy and stability. This system may have value in future spinal surgeries.

Design and analysis of full-scale scanning system for curved glass based on motion and 3D features.

In recent years, mobile phones with glass curved screens have become more and more widely used. The irregular shape of the curved screen and the light transmittance characteristic of the glass have brought great challenges to its automatic defect detection. Aiming at the defect detection of the glass cover of the curved screen, this paper designs a full-scale scanning system by combining motion and three-dimensional (3D) features. First, a scanning system is constructed, and a geometric error modeling method is proposed to improve the accuracy of the scanning system; second, based on the point cloud of the 3D glass cover obtained by the scanning system, a point cloud registration method is presented by integrating the motion and 3D features; finally, the laser tracker is further used to calibrate the scanning system to analyze the mechanical error. Experimental results show that the introduction of straightness error and perpendicularity error can effectively solve the mismatch and fault problems of point cloud registration, and improve the accuracy of the scanning system. In addition, the registration method proposed in this paper can effectively reconstruct the complete point cloud of 3D glass cover for detection. The reconstruction accuracy of the plane part can reach 0.031 mm, and that of the curved part can reach 0.091 mm.

Three-dimensional reconstruction method based on bionic active sensing in precision assembly.

With the prevailing application of new materials and the higher requirements for the quality and efficiency of production in the equipment manufacturing industry, traditional assembly methods can hardly meet the needs of large-scale production, especially in the field of high-precision assembly. Robot assembly guided by visual perception has become the key of the research in the field of engineering technology. It requires higher accuracy of robot visual perception and the control over force, position and so on. However, in 3C assembly, most products are made of transparent materials such as glass. Because of the transparency and specular reflection of the surface, 3D reconstruction of transparent objects is a very difficult problem in computer vision, in that the traditional visual perception methods could not be accurate enough. The present research proposes a bionic active sensing algorithm for 3D perception and reconstruction and realizes high-precision 3D by applying the registration algorithm. The purpose is to solve the problems existing in the traditional visual perception method, such as difficulties in achieving active sensing, low accuracy of point clouds registration, and complex computation. The results of the experiments show that the present method is efficient and accurate in 3D reconstruction. It reduces the planar reconstruction error to 0.064 mm and the surface reconstruction error to 0.177 mm.

A Strong Tracking Mixed-Degree Cubature Kalman Filter Method and Its Application in a Quadruped Robot.

The motion state of a quadruped robot in operation changes constantly. Due to the drift caused by the accumulative error, the function of the inertial measurement unit (IMU) will be limited. Even though multi-sensor fusion technology is adopted, the quadruped robot will lose its ability to respond to state changes after a while because the gain tends to be constant. To solve this problem, this paper proposes a strong tracking mixed-degree cubature Kalman filter (STMCKF) method. According to system characteristics of the quadruped robot, this method makes fusion estimation of forward kinematics and IMU track. The combination mode of traditional strong tracking cubature Kalman filter (TSTCKF) and strong tracking is improved through demonstration. A new method for calculating fading factor matrix is proposed, which reduces sampling times from three to one, saving significantly calculation time. At the same time, the state estimation accuracy is improved from the third-degree accuracy of Taylor series expansion to fifth-degree accuracy. The proposed algorithm can automatically switch the working mode according to real-time supervision of the motion state and greatly improve the state estimation performance of quadruped robot system, exhibiting strong robustness and excellent real-time performance. Finally, a comparative study of STMCKF and the extended Kalman filter (EKF) that is commonly used in quadruped robot system is carried out. Results show that the method of STMCKF has high estimation accuracy and reliable ability to cope with sudden changes, without significantly increasing the calculation time, indicating the correctness of the algorithm and its great application value in quadruped robot system.

Attitude Trajectory Optimization to Ensure Balance Hexapod Locomotion.

This paper proposes a simple attitude trajectory optimization method to enhance the walking balance of a large-size hexapod robot. To achieve balance motion control of a large-size hexapod robot on different outdoor terrains, we planned the balance attitude trajectories of the robot during walking and introduced how leg trajectories are generated based on the planned attitude trajectories. While planning the attitude trajectories, high order polynomial interpolation was employed with attitude fluctuation counteraction considered. Constraints that the planned attitude trajectories must satisfy during walking were well-considered. The trajectory of the swing leg was well designed with the terrain attitude considered to improve the environmental adaptability of the robot during the attitude adjustment process, and the trajectory of the support leg was automatically generated to satisfy the demand of the balance attitude trajectories planned. Comparative experiments of the real large-size hexapod robot walking on different terrains were carried out to validate the effectiveness and applicability of the attitude trajectory optimization method proposed, which demonstrated that, compared with the currently developed balance motion controllers, the attitude trajectory optimization method proposed can simplify the control system design and improve the walking balance of a hexapod robot.

Spatial Topological Relation Analysis for Cluttered Scenes.

The spatial topological relations are the foundation of robot operation planning under unstructured and cluttered scenes. Defining complex relations and dealing with incomplete point clouds from the surface of objects are the most difficult challenge in the spatial topological relation analysis. In this paper, we presented the classification of spatial topological relations by dividing the intersection space into six parts. In order to improve accuracy and reduce computing time, convex hulls are utilized to represent the boundary of objects and the spatial topological relations can be determined by the category of points in point clouds. We verified our method on the datasets. The result demonstrated that we have great improvement comparing with the previous method.

Recent Advances on the Model, Measurement Technique, and Application of Single Cell Mechanics.

Since the cell was discovered by humans, it has been an important research subject for researchers. The mechanical response of cells to external stimuli and the biomechanical response inside cells are of great significance for maintaining the life activities of cells. These biomechanical behaviors have wide applications in the fields of disease research and micromanipulation. In order to study the mechanical behavior of single cells, various cell mechanics models have been proposed. In addition, the measurement technologies of single cells have been greatly developed. These models, combined with experimental techniques, can effectively explain the biomechanical behavior and reaction mechanism of cells. In this review, we first introduce the basic concept and biomechanical background of cells, then summarize the research progress of internal force models and experimental techniques in the field of cell mechanics and discuss the latest mechanical models and experimental methods. We summarize the application directions of cell mechanics and put forward the future perspectives of a cell mechanics model.